Hydropower for isolated rural communities Analysis of the Knoydart community system in Scotland

Hydropower for isolated rural communities Analysis of the Knoydart community system in Scotland

MSc Sustainable Energy

Student: Nikolaos Karamitsos 2054312k

Advisor: Prof. Paul L. Younger

Glasgow, August 2013

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In the memory of my father, Dimitrios G. Karamitsos

For the completion and the final outcome of this dissertation, I would like to express my gratitude

first and foremost to my supervisor, Professor Paul L. Younger for his guidance and support

throughout my research and his valuable directions. His vast knowledge and skills contributed,

not only to the completion of the Knoydart proposal but also to a true and rewarding experience

in the Knoydart community. Also, I would like to thank Ph.D. student Sotirios Kyriakis for his

excellent collaboration and pointed comments throughout the dissertation. Additional thanks to

Gwenn Barrell, of Knoydart Renewables Board of Directors and Jim Brown, the Knoydart

Community Maintenance Manager for their valuable information about Knoydart and the hydro

scheme. Moreover, the help of Sean Allan, project engineer of PowerTech Labs Inc., was of

great importance because of his experience from similar projects.

On a more personal level, I would like to thank for their unconditional support, both financially

and emotionally, my mother Georgia Karamitsou, my sister Maria, my brother Georgios and my

uncle Athanassios Karelas. Last but not least, I would like to acknowledge my friends and

especially Theodora Felekou. Their patience and support is greatly appreciated.

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Abstract One of the most important issues in the energy sector is the sustainable electrification of rural communities. Efficient and renewable storage systems can also play a leading role in order to address this problem. The aim of this project is to provide a sustainable solution to the energy problems that the rural community of Knoydart faces. Initially, this dissertation examines the existing hydropower scheme and the backup diesel generator, which provides power when the scheme is inefficient to satisfy the demand, in the isolated community of Knoydart. Also the benefits of hydrogen as a fuel are presented and the operational characteristics, advantages and disadvantages of the existing fuel cell technologies are analysed. The capability of using the surplus of energy from the hydropower plant to produce hydrogen through electrolysis is making the application of a hydrogen renewable energy storage system reliable in the specific area. The last part includes the analysis of the electrical demand and presents the breakdowns that occurred in the previous years in the Knoydart hydro-scheme. By using the facts and observations, a representative model for the breakdowns due to failure and the extended or scheduled maintenances is created. A simulating excel is calculating the potential hydrogen production from the energy surplus and the different performances for various storage tanks. One of the greatest benefits of this application is the decreasing usage of the diesel generator and consequently of diesel itself as a fuel. Last but not least, a financial assessment is attempted, based on the balance between the estimated expenditures for the whole project and the potential financial savings from the decreased use of diesel.

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Table of Contents Acknowledgements ............................................................................................................................................. 1

Abstract ................................................................................................................................................................... 3

Figures ..................................................................................................................................................................... 6

Tables ....................................................................................................................................................................... 7

Abbreviation .......................................................................................................................................................... 8

1. Introduction ................................................................................................................................................. 9 1.1 Energy and rural communities ............................................................................................................ 9 1.2 Site background ........................................................................................................................................ 9 1.3 Electrification .......................................................................................................................................... 10 1.4 Description and objectives ................................................................................................................. 10

2. Electrical Energy Supply and Demand .............................................................................................. 12 2.1 General ...................................................................................................................................................... 12 2.2 Hydro-‐scheme ......................................................................................................................................... 12 2.2.1 Dam .......................................................................................................................................................................... 13 2.2.2 Pipeline ................................................................................................................................................................... 13 2.2.3 Turbine ................................................................................................................................................................... 13

2.3 Diesel generator ..................................................................................................................................... 14 2.4 Distribution system ............................................................................................................................... 14 2.5 Monitoring system ................................................................................................................................. 14 2.6 Head Losses .............................................................................................................................................. 15 2.7 Energy demand ....................................................................................................................................... 17

3. Hydrogen technology .............................................................................................................................. 19 3.1 General overview of hydrogen (H) ................................................................................................... 19 3.2 Hydrogen as an energy fuel ................................................................................................................ 20 3.2.1 Minimization of the environmental pollution ....................................................................................... 20 3.2.2 Adequacy of stocks ............................................................................................................................................ 20 3.2.3 Security of supply ............................................................................................................................................... 21 3.2.4 Satisfaction of the demand ............................................................................................................................. 21

3.3 Electrolysis ............................................................................................................................................... 21 3.4 Fuel Cells ................................................................................................................................................... 23 3.4.1. History of fuel cells ........................................................................................................................................... 23 3.4.2 Principle of Fuel Cells ....................................................................................................................................... 23 3.4.3 Polymer Electrolyte Membrane Fuel Cell (PEMFC) ............................................................................ 24 3.4.4 Alkaline Fuel Cell (AFC) ................................................................................................................................... 25 3.4.5 Phosphoric Acid Fuel Cell (PAFC) ............................................................................................................... 26 3.4.6 Molten Carbonate Fuel Cell (MCFC) ........................................................................................................... 27 3.4.7 Solid Oxide Fuel Cell (SOFC) .......................................................................................................................... 27 3.4.8 Direct Methanol Fuel Cell (DMFC) .............................................................................................................. 28 3.4.9 Comparison between Fuel Cell technologies ......................................................................................... 29

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4. Application Study ..................................................................................................................................... 30 4.1 Aim of the case study ............................................................................................................................ 30 4.2 Appropriate Fuel Cell Technology .................................................................................................... 30 4.3 Electrical demand analysis ................................................................................................................. 31 4.4 Breakdowns, Extended and Scheduled Maintenance ................................................................ 32 4.4.1 Facts ......................................................................................................................................................................... 32 4.4.2 Observations ........................................................................................................................................................ 34 4.4.3 Creating a representative model ................................................................................................................. 34

4.5 Simulating the process ......................................................................................................................... 35 4.5.1 Description of the system ............................................................................................................................... 35 4.5.2 Parameters and Assumptions ....................................................................................................................... 36 4.5.3 Excel process ........................................................................................................................................................ 37

4.6 Simulation results .................................................................................................................................. 38 4.6.1 Demand .................................................................................................................................................................. 38 4.6.2 Over Marginal Demand Breakdowns ........................................................................................................ 39 4.6.3 Annual total hydrogen needs ........................................................................................................................ 40

4.7 Hydrogen Storage .................................................................................................................................. 41 4.7.1 Low pressure hydrogen storage (buffer tank) ...................................................................................... 41 4.7.2 High pressure hydrogen storage (K-‐Type cylinders) ......................................................................... 42 4.7.3 Dimensioning tank storage ............................................................................................................................ 42 4.7.4 Performance with various storage tanks ................................................................................................. 43 4.7.5 Diesel usage .......................................................................................................................................................... 44

4.8 Financial Assessment ........................................................................................................................... 44 4.8.1. Future diesel expenditures ........................................................................................................................... 45 4.8.2. Balance between project cost and savings from diesel .................................................................... 46

Conclusion ............................................................................................................................................................ 47

References ............................................................................................................................................................ 49

Appendices ........................................................................................................................................................... 52 Appendix I. Inverie Hydro Investigation comments (email) .......................................................... 52 Appendix II. Brief Description of the demand (email) ..................................................................... 54 Appendix III. Safety in application for hydrogen ............................................................................... 55 Appendix IV. Information about fuel cell technology (email) ........................................................ 56 Appendix V. Breakdown Failure/Extended Maintenance (BF/EM) ............................................. 57 Appendix VI. Electrolyser ........................................................................................................................... 58 Appendix VII. Hydrogen Data .................................................................................................................... 59 Appendix VIII. Hours of future diesel generator use per year in various storage tank capacities and average demand power ................................................................................................. 60 Appendix IX. High pressure tank (K-‐type cylinders) ........................................................................ 61 Appendix X. Diesel price from Jan 1990 to Jul 2013 ......................................................................... 62

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Figures Figure 1 -‐ Knoydart Peninsula ....................................................................................................................................................................... 10 Figure 2 -‐ Power generated 2009 from hydro-‐scheme ....................................................................................................................... 12 Figure 3 – Turbine selection chart ............................................................................................................................................................... 13 Figure 4 – Head losses versus flow rate for the Knoydart hydro-‐scheme ................................................................................... 16 Figure 5 -‐ Head losses at 96l/s in every part of the pipeline ............................................................................................................ 17 Figure 6 -‐ Water Electrolysis .......................................................................................................................................................................... 22 Figure 7 -‐ Fuel cell components ................................................................................................................................................................... 24 Figure 8 -‐ Polymer Electrolyte Membrane Fuel Cell (PEMFC) ........................................................................................................ 24 Figure 9 – Alkaline Fuel Cell (AFC) .............................................................................................................................................................. 26 Figure 10 -‐ Phosphoric Acid Fuel Cell (PAFC) ......................................................................................................................................... 26 Figure 11 -‐ Molten Carbonate Fuel Cell (MCFC) .................................................................................................................................... 27 Figure 12 -‐ Solid Oxide Fuel Cell (SOFC) .................................................................................................................................................... 28 Figure 13 -‐ Direct Methanol Fuel Cell (DMFC) ....................................................................................................................................... 28 Figure 14 -‐ Electrical demand in 2009 ....................................................................................................................................................... 32 Figure 15-‐ No of Breakdowns / Extended Maintenance from Jan 2007 to Sep 2010 ............................................................ 33 Figure 16 -‐ Breakdowns/ Extended Maintenance hours per month ............................................................................................. 33 Figure 17 – Representative model for the No of Breakdowns Failure/Extended maintenance ....................................... 35 Figure 18 – Representative model for the total hours of Breakdowns Failure/Extended Maintenance ...................... 35 Figure 19 -‐ Average power demand per year based on steady annual increase of 2.66% .................................................. 39 Figure 20 -‐ Estimated No of breakdown half-‐hour periods caused in Over Marginal Demand (OMDB) in the following years ..................................................................................................................................................................................................... 39 Figure 21-‐ Annual total needs of hydrogen (kg) per year ................................................................................................................. 40 Figure 22 -‐ Low Pressure Hydrogen Storage Tank .............................................................................................................................. 41 Figure 23 -‐ K-‐type cylinders ............................................................................................................................................................................ 42 Figure 24 -‐ Hours of diesel generator usage in various storage tanks ........................................................................................ 43 Figure 25 -‐ Expenditures (£) for Diesel per year in various H storage tanks ............................................................................ 45 Figure 26 -‐ Balance between project cost and diesel savings .......................................................................................................... 46

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Tables Table 1 -‐ Measurement summary at Knoydart hydro-‐scheme ........................................................................................................ 15 Table 2 – Annual electrical energy usage ................................................................................................................................................. 18 Table 3 -‐ Properties of hydrogen ................................................................................................................................................................. 19 Table 4 -‐ Energy density for various fuels ................................................................................................................................................. 20 Table 5 -‐ Comparison between low and high temperature PEMFC ............................................................................................. 25 Table 6 -‐ Comparison between fuel cell technologies ......................................................................................................................... 29 Table 7 -‐ Representative model for breakdowns, extended and scheduled maintenance. ................................................. 34 Table 8 -‐ Dimensioning the tank in high and low pressure for various capacities (300kg, 200kg and 150kg) ........ 42 Table 9 – Equivalent annual diesel consumption for various storage tanks ............................................................................. 44 Table 10 -‐ Safety in application for hydrogen ....................................................................................................................................... 55 Table 11 -‐ Breakdown Failure/Extended Maintenance dates from Jan 2007 to Sep 2010 ................................................. 57 Table 12 – Number of total hours and average hours per month of Breakdown Failure/Extended Maintenance . 57 Table 13 -‐ Hydrogen Data ................................................................................................................................................................................ 59 Table 14 -‐ Hours of future diesel generator use per year in various storage tank capacities and average power demand .................................................................................................................................................................................................................... 60 Table 15 -‐ K-‐type cylinder technical characteristics ............................................................................................................................ 61 Table 16 -‐ Diesel Price from Jan 1990 to Jul 2013 ................................................................................................................................. 62

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Abbreviation AFC: Alkaline Fuel Cell BF/EM: Breakdown Failure/Extended Maintenance CHP: Combined Heat and Power DMFC: Direct Methanol Fuel Cell ERDF: European Regional Development Funds HARP: Hydrogen Assisted Renewable Power HIE: Highland and Island Enterprise K: Potassium’s chemical symbol MCFC: Molten Carbonate Fuel Cell Na: Sodium’s chemical symbol NASA: National Aeronautics and Space Administration OMDB: Over Marginal Demand Breakdown PAFC: Phosphoric Acid Fuel Cell PEM: Polymer Electrolyte Membrane RPM: Revolutions per minute S: Sulphur’s chemical symbol SOFC: Solid Oxide Fuel Cell SM: Scheduled Maintenance YSZ: Yttria-Stabilized Zirconia (YSZ)

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1. Introduction

1.1 Energy and rural communities One of the major problems in the modern world is energy management. Different researchers are trying to come up with innovative technologies, seize new sources to fill the energy gap and decrease the dependency from fossil fuels. For many years, the scientific community and many government policies have focused on the development of a variety of renewable energy sources like solar, wind, hydropower tidal, wave, geothermal etc., trying to find solutions on how these sources can help the decarbonisation of electricity supply, from an economic and energetic point of view. Nevertheless, additional problems have risen in the energy sector such as the electrification of rural and isolated communities. The high cost, which is needed to connect these communities to the national grid and the fact that electricity production does not always coincide with the demand, make a redefinition of the energy agenda necessary. Nowadays, it is generally agreed that the development of energy storage technologies is crucial in order to minimize energy losses from renewable energy sources and to match the supply with demand. Additionally, developed technologies of renewable energy storage can assist rural communities in creation of totally independent systems. Thus, their connection with the national grid is not necessary, avoiding the connection costs. The aim of this final report is to make a sustainable proposal in order to face the energy demand in Knoydart Peninsula.

1.2 Site background The Knoydart Peninsula is located in the West Highlands opposite the Isle of Skye with approximately 120 permanent residents, with the main settlement in the area being Inverie. There is no access road through the mainland and the area is not connected to the national grid. The only main access to the peninsula is by boat seven miles away through Loch Nevis from the fishing port of Mallaig. The Knoydart Foundation was set up in 1997. Its main goal was to buy and subsequently manage the hydro power plant to cover the demand of the peninsula. It is a limited company by guarantee with charitable status. Currently, the Foundation owns and manages 17,200 acres of land from the total of 55,000 acres in the peninsula, between the sea lochs Nevis and Hourn (see figure 1) [1].

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Figure 1 - Knoydart Peninsula [1]

1.3 Electrification In the 1950’s a generator was installed in Inverie to cover the basic needs of electrification. After two decades, Major Macdonald started the installation of the hydroelectric scheme in the peninsula. During the 80’s and 90’s, due to the lack of maintenance and disagreements with the local community, the development scheme faced many problems. The community bought the scheme in 1999 and the refurbishment of the hydropower plant became a prior necessity. The refurbishment started in August 2001 and lasted for almost one year. [2]. Today the micro hydropower scheme and a diesel generator in Inverie supply 79 connected properties out of the total 102 with electricity and have been running by the Foundation’s subsidiary company Knoydart Renewables. In theory, the rated power of the hydropower is 280 KW but in practice it has only reached 180 KW. A diesel generator (160 KW) is used as a back-up unit when the hydro plant is shut down for scheduled maintenance, extended maintenance or during breakdowns. Also, the diesel generator assists the hydro scheme when its production is not sufficient during peak times.

1.4 Description and objectives The main objective of this project is to provide a proposal in order to minimize the use of the diesel generator at this specific rural community. In addition, it examines the possibility of installing a hydrogen storage system to assist the grid. This system will convert the surplus of electricity to hydrogen through electrolysis. Subsequently, the hydrogen will be stored and then the stored hydrogen will be used as a fuel into fuel cells in order to produce electricity. The only raw material to produce hydrogen is water, which is plentiful in the region, and after the whole procedure, the waste is also clean water. This method can provide renewable energy storage and help the community during the times that the hydropower scheme is shut down as well as during peak demand times.

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The project focuses on presenting a complete hydrogen solution and the following issues will be examined:

• Presentation of current energy supply and energy demand. • The hydrogen storage technology and the different fuel cell types. • The Hydrogen Assisted Renewable Power (HARP) system and how that can minimize

the use of the diesel generator. • The energy surplus times during which the hydropower scheme can produce more

energy than the demand and the amount of energy that can be stored. • The feasibility of hydrogen storage technology in this specific area. • Dimensioning of the HARP system that is needed in the specific grid. • Analysis of the HARP system. • Energy savings from the diesel generator. • Financial assessment with estimation of the total expenditures and savings from the

application of the HARP system.

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2. Electrical Energy Supply and Demand

2.1 General For Inverie and for the connected properties, the main electrical energy supply comes from the hydropower plant and from a diesel generator, which works as a backup power supply when the hydropower plant is out of order or the demand is not satisfied by the production.

2.2 Hydro-‐scheme The hydro scheme started to work during the 1970’s. The refurbishment cost in 2002 was £500,000 with funding from the i) Highlands and Islands Enterprise (HIE), ii) the European Regional Development Funds (ERDF) and iii) the Knoydart Foundation. The repairs covered all the parts of the scheme like the dam, the pipeline, the turbine and also parts in the distribution system [2]. As mentioned, even if the nominal installed capacity of the hydro scheme is 280 KW the system has never reached this power output. After examining the power generated data for 2009 and viewing the half hourly data (see figure 2) the system does not exceed 180 KW. According to the data for 2009, which is the only year without gaps in data, the production was 672,293 KWh [3].

Figure 2 - Power generated 2009 from hydro-scheme [3]

The zero production is documented whenever there is maintenance or system failure. There are two types of maintenance: i) the scheduled maintenance which takes part every two weeks for 30 minutes and ii) the extended maintenance, which could last for days. During the breakdowns and the extended maintenance, the diesel generator will be the stand-alone provider and could operate roughly from 7 am to 12 at midnight.

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2.2.1 Dam The dam is located at the Bhraomisaig Reservoir and was originally built in 1978. It is a gravity structure measuring 33 metres long and 2.8 metres high and was constructed from stone and original bedrock together with a cement mortar [4]. The spillway measured 15.9 metres, is on the left abutment and releases over the downstream face into the Allt River.

2.2.2 Pipeline Through the dam and above the sediment pipe is a steel penstock. The penstock is sealed at its bottom with a metal plate consisting of metal strips, working as a filter to prevent any undesirable material or fishes from coming into the pipeline. According to the maintenance manager Mr. Jim Brown during our visit in Knoydart hydro–electric scheme, the pipe section consists of plastic and steel pipes with a total horizontal distance of 1150 m and a height of 332 m. At the beginning (for approximately 40 metres) there are steel pipes having a diameter of 273 mm, a length of 6.1 m, a minimum pressure of 52 bars. The pipes are connected with Viking Johnson Couplings, standing on concrete anchor blocks. Then the pipeline changes to a series of plastic pipes with a 315 mm diameter, a 6 m length, with a minimum pressure of 10 bars, connected with ‘lock-rings’ sockets.

2.2.3 Turbine The turbine house follows the pipeline. In this hydro–scheme a Pelton turbine is used because the head is high and the flow rate is quite small (see figure 3).

Figure 3 – Turbine selection chart [5]

The generating plant consists of a Pelton turbine manufactured by Gilbert Gilkes & Gordon Ltd, which drives to an alternator AC exciter, 300 KVA, 3phase, 50 Hz synchronous generator manufactured by Mawdsley Ltd.

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The turbine is rated to produce 280 KW of electrical power when operating at 900 feet (274.3 m) and the passing flow is 4.6 cfs (129 litres/sec) [6]. Furthermore, the turbine has an 18” pitch circle diameter, phosphor bronze runner Wheel, is fitted with a Woodward Governor with direct control and a hydraulic operated spear valve to achieve 1500 rpm [6]. Also there is an economizer, which controls the water flow to the turbine in order to use only the amount of water that is actually needed to satisfy the demand at the time.

2.3 Diesel generator In addition, there is a diesel generator at Inverie as a backup power source, which can be used in the three following cases:

a) Scheduled maintenance for 30 minutes every 2 weeks. In that case, it will start manually 10-15 minutes before the maintenance and will run with zero load in order to warm up.

b) Extended maintenance and breakdowns. In that case the generator could be running roughly from 7 am to 12 at midnight.

c) During peak times when the demand is increased, like in winter season and cannot be covered completely by the hydro scheme.

Recent breakdowns have increased the diesel generator use. Also, the diesel generator is not synchronized with the hydro-generator and has to be started manually when is needed. The diesel generator is rated at 160 KW, manufactured by SDMO Industries and the model is J200K. It is a 3-phase generator, having a frequency at 50 Hz, voltage of 400/230V and cosφ equal to 0.8. Its total weight is 1730 kg and the capacity of the fuel tank is 340 litres. The dimensions are 2.37m x 1.11m x 1.48 m. It is a 6-cylinder engine with a speed at 1500 rpm. The consumption at full load is 45.20 litres per hour and at full pump flow, it can reach 108 litres per hour.

2.4 Distribution system The electrical distribution system consists of a 3-phase 11,000 V single spur network, with cables either underground or mounted on wooden poles. There is also a local low voltage sub-distribution system (415 V, 3-phase and 240 volts per phase) [6]. In addition, according to the maintenance manager, the transmission system today is approximately 4 miles long and contains 13 transformers, 11 KV to 240 KV pole that are ground mounted.

2.5 Monitoring system For every hydropower scheme the monitoring system is a crucial source of information. With a proper monitoring system the future production can be predicted or compared with the

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production of previous years and that can provide useful conclusions about the function of the hydropower plant. The monitoring system in the specific scheme contains hydrological and energy meters, a data logger, a communication system and a computer. Specifically, the data logger gathers all the measurements, stores them in an internal memory and sends them, through a remote communication system, to the computer for further analyzing. In the past, the communication system was a radio link and has now changed to a wireless local network system. Several, data are collected in the dam concerning the hydro scheme for the dam level, the spillway level and the rainfall. In the powerhouse can be found only the instruments for the flow measurements in penstock near the turbine and the data logger [3]. Table 1 shows the data of the monitoring system, the units of the measurements and the location of each instrument

Data Unit Location Penstock Flow m3/30 minutes Powerhouse

Dam Level metres (m) Dam Spillway level metres (m) Dam

Rainfall milimetres (mm) Dam Energy KWh/ 30 minutes Powerhouse

Table 1 - Measurement summary at Knoydart hydro-scheme [3]

2.6 Head Losses In the hydro plants the measurement of the head losses in the pipeline is very important. They are also called friction losses and are the power losses between the two moving surfaces when the water flows through the pipe. [7] The head losses (δh) in a pipeline can be expressed in the following form:

𝜹𝒉 = 𝒌 ∗ 𝑸𝟐 Where:

k: a constant value 𝐦(𝐥 𝐬)𝟐

Q: volume flow rate (l/s) [7]. It has to be noted that the dimensions of the constant k in the above equation depend solely on the dimensions of δh and Q. The absolute value is system specific, and below the appropriate value for the Knoydart system is calculated. The final head including the losses (HL) can be calculated from the difference of the elevation head (h) and the head losses (δh),

𝑯𝑳 = 𝒉 − 𝜹𝒉

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Then using (HL) and (Q) the generated power (P) in the hydro-scheme can be calculated.

𝑷 = 𝝆 ∗ 𝒈 ∗𝑯𝑳 ∗ 𝑸 ∗ 𝒏 Where

• ρ is the density of the water (tonne/m3), • g is the acceleration due to gravity (9.81 m/s2) • HL is the final head including the losses (m) • Q is the volume flow rate (l/s) • n is the efficiency of the hydro-turbine (dimensionless) • P is the generated power (KW) [7].

The latest pipeline head loss inspection was undertaken in November 2011 by John Duncanson. In January 2012, further calculations by Ed Carrick showed that the total head losses in the system at a volume flow rate 96 l/s have been measured at 60 metres, which was the only flow rate value with available full data (see appendix I). Hence, the value of the constant k can be found as follows:

𝜹𝒉 = 𝒌 ∗ 𝑸𝟐 ⟹ 𝒌 =𝜹𝒉𝑸𝟐

=𝟔𝟎𝟗𝟔𝟐

⟹ 𝒌 = 𝟎.𝟎𝟎𝟔𝟓𝟏 𝒎

(𝒍 𝒔)𝟐

The following graph (see figure 4) shows how the flow rate (Q) affects the head losses (δh) and therefore the final head.

Figure 4 – Head losses versus flow rate for the Knoydart hydro-scheme

The different value of the head losses in the part which is close to the dam compared to those in the part close to the powerhouse are justified because of the two different types of pipes (plastic and steel) in the pipeline (see figure 5).

0 10 20 30 40 50 60 70 80 90

0 20 40 60 80 100 120

δh: m

etres

Q : _low rate (l/s)

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Figure 5 - Head losses at 96l/s in every part of the pipeline (Appendix I)

From figure 5, it is obvious that the main problem in the pipeline is detected in the steel part and especially close to the turbine in which, at the last 230 metres, the head losses increased dramatically by 25 metres. In addition, at the beginning of the steel pipe part (from 465m to 945m) the losses are 15 metres more than what was theoretically expected, which means 3 or 4 times greater. Last but not least, at the plastic pipe the theoretical friction losses were estimated to be 4 metres but in practice there is a 6-metre extra head loss.

2.7 Energy demand In Knoydart community, the electricity demand is increasing in order to satisfy the needs of new residents or tourists. The fact that Knoydart is a rural community means that the existing connected properties are mostly private households with a percentage close to 42 [8]. Unsurprisingly, more energy is required during winter months, for additional heating in the colder winter days. According to Jim Brown, maintenance manager of Knoydart Renewable Ltd: “Over the last years the regular peak demand has risen from about 100KW to 130 KW, and the average off peak load from around 50 KW to 70KW” (see appendix II). The electrification is almost always satisfied by the hydro scheme because the consumption rarely exceeds the limit of 180 KW instantaneous power. Table 2, shows the total energy usage in KWh from 2005 to 2007 and 2009. Unfortunately, the energy usage for 2008 contains missing data, due to an extended breakdown, for almost a month during March and April and therefore was not included in the table.

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Year Total energy usage (KWh) 2005 653,235 2006 684,338 2007 613,558 2009 707,787

*2008 Missing data Table 2 – Annual electrical energy usage [9]

The increased demand in 2005 and 2006 was caused by the construction of the new pier in Knoydart, a project that was carried out and completed [9]. The significant rise in 2009 can be explained for three reasons: i) the regular increase in population, ii) the increase in the number of tourists, and iii) the increased usage of thermal stores for heating (an increase was observed during the night hours). Consequently, any major development projects planned for infrastructure or heating may require significant amounts of energy for extended periods of time [9].

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3. Hydrogen technology

3.1 General overview of hydrogen (H) Hydrogen is the most abundant element, constituting 90% of the total mass of the universe. However it constitutes less than 1% of the total mass of the earth, because it is the lightest element encountered in nature. It is rarely found in a pure gas form, although many minerals and microorganisms contain hydrogen bonds. Consequently, hydrogen is found in keratin, in enzymes, in molecules of DNA and in nutrition in the form of fats, proteins and carbohydrates. Hydrogen was discovered by the British chemist Henry Cavendish and named by Antoine Lavoisier. The name came from the ancient Greek words “hydro” which means water and “genes” which means generator. It is the first chemical element in the periodical table and is symbolized with the letter “H”. Every atom of it is composed from one proton and one electron, while the union of two atoms produces a molecule of hydrogen with a molecular formula: H2 (H – H). Also, hydrogen can react with almost any other chemical element and for that reason gives plenty of different compounds, more than any other element in the periodical table. The most important compounds are water (H2O), organic compounds (with carbon) and various natural hydrocarbons (petroleum or natural gas) [10]. In room temperature hydrogen is found in a gaseous state, in which it is odourless, colourless and flammable. When hydrogen reacts with atmospheric oxygen or clean oxygen the result is pure water and an amount of heat is released as shown in the reaction below:

𝟐𝑯𝟐 + 𝑶𝟐 → 𝟐𝑯𝟐𝑶 + 𝒉𝒆𝒂𝒕 Hydrogen’s density in normal conditions of 1 atm (101.325 kPa) pressure and 0 oC (273.15) temperature is 0.08987 kg/m3, which is ten times smaller than the air’s density. It has the second lowest boiling point at 20.268 K and melting point at 14.01 K after Helium (He). When the temperature of hydrogen gas is reduced below -253 oC in normal conditions with a pressure of 1 atm, hydrogen starts to liquify and when the temperature is reduced below -259 oC, hydrogen starts to solidify (see table 3). The solid and liquid hydrogen are also colourless and odourless [11].

Table 3 - Properties of hydrogen [11]

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3.2 Hydrogen as an energy fuel Hydrogen as an energy source is not something new, having been used as an industrial energy fuel for decades. In 2003, 50% of the total hydrogen production was consumed by the ammonia industry and almost 37% was consumed by the petroleum industry. The rest 13% was consumed by other industrial sectors [12]. Besides its use as an industrial fuel, hydrogen can be used for energy storage by storing it and using it whenever is needed. As mentioned H is rarely found in a pure form so additional energy is needed to separate H from the various compounds. There are two types of hydrogen:

• “Green” hydrogen when the energy used to produce it comes from renewable energy sources with no associated greenhouse gas emissions or pollution.

• “Brown” hydrogen, which is produced from fossil fuels, resulting in carbon and other emissions [13].

The increasing energy need, the carbon emissions and the lack of some resources (e.g. petroleum) forced the scientific community to examine alternative technologies and fuels, which have the following characteristics:

1. Annihilation or minimization of the environmental pollution 2. Adequacy of stocks 3. Security of supply 4. Satisfaction of the demand and energy independency [14].

3.2.1 Minimization of the environmental pollution Hydrogen fuel cell technology can produce electricity based on reverse electrolysis and by consuming hydrogen as a fuel. Hydrogen is oxidized electrochemically by oxygen with a simultaneous production of electricity and heat, the only waste being pure water.

3.2.2 Adequacy of stocks Hydrogen is plentiful in nature and the stocks are inexhaustible on earth. Moreover, it is very important that hydrogen has the biggest energy generation capacity than any other fuel with 33.33 KWh/kg. On the other hand, hydrogen shows the lowest energy density per volume unit with approximately 0.53 kWh/lt compared with the conventional fuels (see table 4). The small gas density of hydrogen in normal conditions can explain the small density per volume, which is the main barrier for the implementation of hydrogen technology.

Energy Density Fuel Hydrogen Natural gas Propane Crude oil Methanol Petrol

Energy density per weight (kWh/kg)

33.33 13.90 12.90 12.10 5.60 12.70

Energy density per volume (kwh/lt)

0.53 2.60 7.50 10.80 4.40 8.70

Table 4 - Energy density for various fuels [14]

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3.2.3 Security of supply Safety is one of the most important issues for every fuel and any potential hazard should be minimized. Today, gasoline is probably the safest and easiest fuel to store, but hydrogen and methane can also be safely stored with the current technologies [11]. The efficient use and storage of hydrogen (compressed gas or liquefied) from industries, has contributed in having safe and reliable commercial systems. Also the toxicity of hydrogen is minimal and can be ignored (see appendix III). The main problem in hydrogen lies in the transportation because it is so volatile that leakages are a common phenomenon [11].

3.2.4 Satisfaction of the demand Hydrogen technology can provide energy to countries “poor” in fossil fuels and can also be used as a “clever” way to store energy. Hydrogen technology could be beneficial when it is used to store the surplus of energy, assisting the systems when needed. There are many pilot storage systems in wind farms. Similarly, hydrogen technology can assist renewable sources, which feed rural communities not connected to the national grid. There is a hydrogen storage technology application in Bella Coola, Canada in which the surplus of energy from a hydro plant is used to produce hydrogen through electrolysis and then the hydrogen is stored as a gas in high-pressure tanks. When the energy is needed, the electrochemical regenerative fuel cells use the stored hydrogen to produce electricity and assist the system, known as HARP system [15]

3.3 Electrolysis The cleanest and most environmental friendly way to produce hydrogen is by water electrolysis. In this technology, electricity is used from any contractual source like coal gas and fossil fuel or a renewable source such as solar, wind or hydroelectric etc. The electrolysis phenomenon was discovered by Jan Rudolph Deiman and Adriaan Paets van Troostwijk in 1789 [16]. The basic principle of electrolysis is that two electrodes are placed in the liquid and connected to an electrical power supply. The electrodes are made from an inert metal like platinum, stainless steel or iridium. Between the two electrodes there might be a membrane. The electrodes in a device could be from different materials and the type of liquid varies. The one electrode is positively charged (cathode) and the other negatively (anode). When the power source is feeding the electrodes and the electrolyte is water, hydrogen will appear at the cathode and oxygen at the anode (see figure 6) [17].

22

Figure 6 - Water Electrolysis [18]

During electrolysis the following reactions take place:

• In the electrolyte solution:

𝟒𝑯𝟐𝑶 → (𝑶𝑯)! + 𝟒𝑯 • At the anode:

𝟒𝑯𝑶 → 𝟒𝒆! + 𝟐𝑯𝟐𝑶 + 𝑶𝟐 • At the cathode:

𝟒𝑯! + 𝟒𝒆! → 𝟐𝑯𝟐 The reaction at the anode is an oxidation and the reaction at the cathode is a reduction. Coexistence of an oxidation and a reduction is called redox and can be considered as a sum of these two semi-reactions. The redox (the final reaction) in water electrolysis is:

𝟐𝑯𝟐𝑶 → 𝟐𝑯𝟐 + 𝑶𝟐 The result from the reaction at the anode is electrons, pure water and oxygen (see figure 6). The ions of hydrogen react with the electrons and the result is hydrogen gas, which is collected in the external part of the device [14]. The production efficiency of hydrogen by electrolysis of water is defined by the ratio of the voltage that is theoretically needed, divided by the voltage that is used in practice. In theory a voltage of approximately 1.23 V is needed but because of thermal losses and magnetic field losses this value varies between 1.55 V and 1.65 V. Consequently the hydrogen production efficiency from water is between 75% and 80%, which is however much better than the hydrogen production efficiency from fossil fuels, which is around 60% [14].

23

3.4 Fuel Cells Fuel cells are a promising technology for the future and are based in the conversion of chemical energy to electrical. They have multiple applications and can supply electricity to tiny chips, to cars, to entire buildings, to power plants and recently to assist the electrical grids and energy storage units. The principle of a fuel cell device is like a reverse electrolysis and can use the stored chemical energy to convert it to electricity.

3.4.1. History of fuel cells In 1839 Welsh physicist William Grove invented the “gas battery” which is the ancestor of the fuel cell and 50 years later Charles Langer and Ludwig Mond create a device, called fuel cell. It took many years until Francis Bacon created a 5 KW alkaline fuel cell and only one year later NASA started to use fuel cells in space missions. The fuel cell technology developed slowly because of the high costs and the high maintenance that is needed for these systems. Fortunately, recent developments in this area have created more efficient and feasible fuel cells, which are capable to overcome the previews barriers [19,20].

3.4.2 Principle of Fuel Cells The main difference of a fuel cell from other renewable technologies like solar and wind is that the fuel cells produce current while the other technologies usually produce voltage difference, which can be absorbed by the grids. Moreover, a fuel cell can use the chemical energy of any available fuel like hydrogen, methane and gasoline and then, through two electrochemical reactions, converts fuel directly to electricity. The optimum performance of fuel cells is achieved when hydrogen is used as a fuel. The main components of a fuel cell are (see figure 7):

i. Electrolyte: which is also a separator and keeps the reactors from mixing together

ii. Electrodes: which are the catalysts where the electrochemical reaction occurs.

iii. Bipolar Plate: Some times called separator. This is the most common way to collect the current [21].

In the hydrogen fuel cell, hydrogen and oxygen are separately placed with a wall between them. This wall, which is called electrolyte or separator, allows only ions of hydrogen (H+) to pass through it. Since the electrons cannot flow through the separator, they flow through an external circuit to the cathode (see figure 7). As mentioned, this is a direct way to get electricity and subsequently that electrical current can rotate a motor in order to produce voltage. The hydrogen ions react with the oxygen creating water as a waste material of the whole procedure [22].

24

Figure 7 - Fuel cell components [23]

There are different types of fuel cells depending on the electrolyte and the fuel. Some of them need pure hydrogen as fuel like the Polymer Electrolyte Membrane Fuel Cell (PEMFC), the Alkaline Fuel Cell (AFC) the Phosphoric Acid Fuel Cell (PAFC), while others need hydrogen with organic compounds such as the Molten Carbonate Fuel Cell (MCFC), the Solid Oxide Fuel Cell (SOFC) and the Direct Methanol Fuel Cell (DMFC). Each technology of fuel cells operates in a different temperature and with a different efficiency rate. Fuel cells can help to decentralize the production, in some cases assist the grid with a relatively quick response and could also be a great solution especially for isolated areas where any installation of transmission lines is expensive and difficult, like in the Knoydart peninsula [24].

3.4.3 Polymer Electrolyte Membrane Fuel Cell (PEMFC) The Polymer Electrolyte Membrane Fuel Cell (PEMFC) is a promising technology, which is widely used as an alternative source for vehicles. PEMFCs are water-based fuel cells, with platinum electrodes, using an exchange membrane as an electrolyte (see figure 8). For that reason, the technology is also known as Proton Exchange Membrane Fuel Cell.

Figure 8 - Polymer Electrolyte Membrane Fuel Cell (PEMFC) [25]

The main advantages of this fuel cell are that it can operate in relatively low temperatures below 100 0C and can deliver various electrical outputs (from 10 to 250 kW) to meet the specific power

25

requirements. The electrical efficiency rate ranges between 40% and 60% [26]. This flexibility of PEMFCs made them the leading technology for vehicles and for small stationary applications. The principle function of PEMFC is the same as explained before (chapter 3.4.2) [25] The chemical reactions occurring at each electrode are shown below:

Anode: 𝑯𝟐(𝒈) → 𝟐𝑯! + 𝟐𝒆! Cathode:

𝟏𝟐𝑶𝟐(𝒈) + 𝟐𝑯! + 𝟐𝒆! → 𝑯𝟐𝑶(𝒍𝒕)

Overall reaction: 𝑯𝟐(𝒈) +

𝟏𝟐𝑶𝟐(𝒈) → 𝑯𝟐𝑶 [27]

Maybe, the only disadvantage of a PEMFC is the bad operation without “pure” hydrogen and consequently with fuels which do not have large hydrogen concentration. To overcome the problem of hydrogen purity in the fuel, high temperature PEMFC is used that can operate in up to 100 0C (between 120-210 0C) and the electrolyte is a mineral acid based membrane. Below is a comparison between the two PEMFC technologies (see table 5) [25].

Operating T (oC)

Electrolyte Pt loading

CO tolerance

Other impurity

Tolerance

Power Density

Cold Start

H2O manage

ment LT

PEMFC 80-100 Water-

based 0.2-0.8 mg/cm2

< 50 parts per million

Low Higher Yes Complex

HT PEMFC

120-210

Mineral acid-based

1.0-2.0 mg/cm2

1-5% by volume

Higher Lower No None

Table 5 - Comparison between low and high temperature PEMFC [25]

3.4.4 Alkaline Fuel Cell (AFC) Alkaline Fuel Cell (AFC) was invented by the British inventor Francis Thomas Bacon and for that reason it is also known as Bacon Fuel Cell. In the 1960s, NASA used AFC in the space programs Gemini and Apollo aiding the landing on moon. AFCs use alkaline solutions, such as potassium hydroxide (KOH), as an electrolyte (see figure 9). For operations in high temperatures the content of KOH is approximately 85% per cubic weight and for low temperatures below 120 oC, ranges between 35—50% [28]. Comparatively, alkaline is the best electrolyte and its efficiency can reach even 80%, but it needs high purity of hydrogen and oxygen in order to avoid the “poisoning” of the fuel cell [14].

26

Figure 9 – Alkaline Fuel Cell (AFC) [28]

For years, it has been commonly used in space programs where the best performance at any price is preferred. Despite the high cost, the efficiency rate is the great advantage of this fuel cell. However, today, the typical operating temperature is around 70 0C and consequently the platinum catalysts can be avoided and more common and cheaper materials like nickel can be used.

3.4.5 Phosphoric Acid Fuel Cell (PAFC) PAFC is one of the most popular commercial solutions, using a 100% “pure” phosphoric acid solution as an electrolyte (see figure 10). The operation temperatures vary between 150 and 200 0C. The main advantage is the relatively good tolerance in poisoning from carbon monoxide, but the efficiency is smaller (from 37% to 42%) than other fuel cells in producing electricity production.

Figure 10 - Phosphoric Acid Fuel Cell (PAFC) [20]

It was the most popular technology before 2001 and today the PAFCs are mostly used for stationary power generations with operational capacity between 100 kW and 400 kW and for heavy transportation vehicles like buses [20].

27

3.4.6 Molten Carbonate Fuel Cell (MCFC) Molten Carbonate Fuel Cells (MCFCs) were developed for power factories, industrial purposes and military applications. They usually use biogas, natural gas, methane and coal and the electrolyte is a molten carbonate salt, which is suspended in a porous, chemically inert ceramic matrix. The operating temperature for MCFCs is high, close to 650 0C. The electrical efficiency is around 60% but if the waste of heat is captured and used, the final efficiency can reach even 85% [29].

Figure 11 - Molten Carbonate Fuel Cell (MCFC) [29]

The extremely high temperatures of operation in MCFC have as a result the internal reforming process, which is a conversion of the fuel to hydrogen in the cell, reducing the total cost. In addition, high temperatures make it less prone to carbon monoxide poisoning than the systems with low operational temperatures. One important disadvantage of this fuel cell technology is the requirement of a liquid electrolyte and the obligation to add carbon dioxide at the cathode as carbonate ions - these carbonate ions are consumed at the reaction in anode (see figure 11). Moreover, due to the high temperatures, the response time is relatively big and the need for maintenance is increased (see appendix IV).

3.4.7 Solid Oxide Fuel Cell (SOFC) Solid Oxide Fuel Cell (SOFC) has similar electrical and overall efficiency with MCFC, 60% and 80% respectively (see figure 12). The second common characteristic with the MCFC is that, because of the high operational temperatures, the fuels can be reformed into the cell and that it is more resistant in small quantities of Sulphur (S). Hence, a various number of hydrocarbon fuels can be used in this technology even coal gas. However, the high temperature has some disadvantages: i) the start-up time is longer, ii) it needs more time to reach the nominal values and iii) more funds are needed in order to construct a device more resistant in high temperatures [30].

28

Figure 12 - Solid Oxide Fuel Cell (SOFC) [30]

SOFC uses an oxide ion conducting Yttria-Stabilized Zirconia (YSZ) as an electrolyte. The cathode is made from strontium-doped lanthanum manganite, the anode from nickel/YSZ and the bipolar plate from doped lanthanum chromite or metals tolerant in high-temperatures. The SOFC operational temperature ranges from 700 to 1000 0C [31]. The applications of this technology can vary from portable devices (500 W), to automobile auxiliary units, to small residential applications (5 KW) and can even be used in distributed generator power plants (100 KW – 3 MW) [31].

3.4.8 Direct Methanol Fuel Cell (DMFC) Direct Methanol Fuel Cell (DMFC) is similar to the PEMFC but instead of hydrogen, it uses methanol as a fuel (see figure 13). It operates in temperatures between 60 and 130 0C. It also uses a polymer membrane as an electrolyte. The anode is made from platinum-ruthenium that helps to exploit the hydrogen from the liquid methanol without using a fuel reformer.

Figure 13 - Direct Methanol Fuel Cell (DMFC) [32]

It can store high-energy substance in a small volume and that is why it is used to replace batteries in forklift tracks in order to refuel the vehicle in a few minutes rather than charging for hours [32].

29

3.4.9 Comparison between Fuel Cell technologies Table 6 below is summarising all the basic information on Fuel Cell technologies presented in previews sub-chapters, making the comparison between different types of fuel cells easier.

Adv

anta

ges

1. S

olid

ele

ctro

lyte

2.

Low

tem

pera

ture

3.

Qui

ck S

tart

up

4. U

ses

pure

hyd

roge

n 1.

Fas

t cat

hode

reac

tion

2.Lo

w c

ost c

ompo

nent

s 3.

Use

s pu

re h

ydro

gen

1. In

crea

sed

tole

ranc

e in

po

ison

ing

2. U

ses

pure

hyd

roge

n

1. H

igh

effic

ienc

y 2.

Fue

l fle

xibi

lity

3. U

se v

ario

us c

atal

ysts

4.

Sui

tabl

e fo

r CH

P

1. H

igh

effic

ienc

y 2.

Fue

l Fle

xibi

lity

3. U

se v

ario

us c

atal

ysts

4.

Sol

id e

lect

roly

te

5. S

uita

ble

for C

HP

1.

Low

tem

pera

ture

s 2.

Hig

h en

ergy

sub

stan

ce

in a

sm

all v

olum

e

App

licat

ions

1. B

acku

p po

wer

2.

Dis

tribu

ted

ge

nera

tion

3.Tr

ansp

orta

tion

1. M

ilita

ry

2. S

pace

1. D

istri

bute

d

ge

nera

tion

1. E

lect

ric U

tility

2.

Dis

tribu

ted

gene

ratio

n

1.H

igh

effic

ienc

y 2.

Fue

l Fle

xibi

lity

3.U

ses

vario

us

cata

lyst

s 4.

Por

tabl

e de

vice

s 1.

Cel

l pho

ne

2. L

apto

p 3.

Bat

tery

cha

rger

4.

Mid

-siz

e ap

plic

atio

n (b

oats

, cab

ins

etc.

)

Elec

tric

al

Effic

ienc

y

40 -

60%

60 -

70%

37-4

2%

60%

50-6

0%

>40%

Typi

cal

Size

1KW

–

200

KW

10K

W –

100K

W

Mod

ule

100-

400K

W

300K

W –

3M

W

1KW

–

2MW

25W

-

5

KW

Ope

ratin

g T

(o C)

80-1

00 o C

an

d 12

0-21

0 oC

70 -1

20 o

C

150

-200

oC

600

-700

oC

700

-100

0o C

60 -1

30 o

C

Elec

trol

yte

Sol

id P

olym

er

Mem

bran

e

Pot

assi

um

hydr

oxid

e so

lutio

n in

w

ater

P

hosp

horic

ac

id s

olut

ion

Alk

ali

carb

onat

es in

a

cera

mic

m

atrix

of L

iHO

2

Sol

id c

eram

ic,

typi

cally

yttr

ia-

stab

ilise

d zi

rcon

ia (Y

SZ)

Sol

id P

olym

er

Mem

bran

e

Fuel

Cel

l Ty

pe

PEM

FC

AFC

PAFC

MC

FC

SOFC

DM

FC

Table 6* - Comparison between fuel cell technologies

*Created by the author and based on information from [26] [33]

30

4. Application Study

4.1 Aim of the case study This case study aims to examine hydrogen storage technology, a very promising sustainable technology. It has already been applied in wind, solar and hydro plants, having shown a big potential for future development, especially in rural communities. The case study further analyzes how that technology can be beneficial in assisting the grid when the existing hydro-scheme cannot satisfy the demand. Due to the lack of information, it is needed to make reasonable assumptions and to be creative in order to result in a realistic model with logical and useful results. Of course this is an effort based on the existing data, trying to present the various aspects of a potential hydrogen storage application. It is important to mention that the rural community of Knoydart is very small and therefore easily influenced by any change that happens within its everyday spectrum. The implementation of new infrastructure projects or minor population fluctuations can influence the energy and consumption character of the whole area.

4.2 Appropriate Fuel Cell Technology There are various fuel cell technologies but is it possible for any of them to be singled out as the most suitable? There is no right or wrong answer since every available fuel cell technology has advantages and disadvantages. It is imperative that every project is individually examined according to its needs and resolved via an appropriate fuel cell technology. In the examined Knoydart case, the current instantaneous power needs rarely exceed 160 KW. In order to satisfy increased future electrical needs, a fuel cell with an approximate power capacity of 200 KW is selected. Knoydart is a small, rural and at the same time isolated community, making any access to carbonate hydrogen fuel difficult. Therefore, the easiest way to provide Knoydart with energy fuel is to separate hydrogen from the water that is abundant in the area through an electrolyser. Consequently, a fuel cell that uses pure hydrogen as fuel is selected. The hydrogen fuel cell will assist the grid or it will be a back-up power source. A quick response is of crucial importance so a fuel cell, which operates in low temperatures and has a high performance / cost ratio is preferred. All these reasons lead to the selection of the Polymer Electrolyte Membrane fuel cell (PEMFC) as the most appropriate stationary solution for the specific case study.

31

4.3 Electrical demand analysis The analysis comes upon certain obstacles. There are enough properties with electric meters however the problem lies in the fact that there are no properly documented data with the readings from the electric meters. The only information concerning the electric demand comes through the data logger, which provides information for the electrical production of the hydro-turbine. There are data available which showcase the instantaneous average power for every 30 minutes coming from the hydro-scheme [8]. This average power equals the average consumption power because an economizer is regulating the water flow through the turbine in order to deliver to the grid the exact same amount of energy that is needed to satisfy the instantaneous electricity demand. Thus, the only way to create a pattern was to compare the production from the hydro-plant year by year. The comparison is made by using the instantaneous average power for the same half hours on the same dates and hours in two consecutive years. The data available are refined by using only the moments that appeared and are available in both years. Using the new data, potential consumption increase patterns are investigated. Unfortunately, no specific pattern corresponds to every year because, as mentioned, a new infrastructure project can increase dramatically the consumption and for that reason, many fluctuations appear from 2005 to 2009 (table 2, sub-chapter 2.7). The only data available that concerns a long period of time are those over the last 10 years, during which the regular peak demand has risen from approximately 100KW to 130 KW, and the average off peak load from over 50 KW to 70KW (see Appendix II). Hence, it is reasonable to account for an increase close to 30%, as being a logical increase during a 10-year period. The assumption that a steady annual increase occurs can be made, approximating a 2.66% increase rate per year. The process continues with the analysis of the 2009 data, which is the year with the most data available about the hydropower, and consequently about the electrical consumption. Usually the breakdown lasts only for a few hours. It is, therefore, easy to estimate the instantaneous average demand for any gap using the hours coming right after and before the breakdown and also from the consumption pattern of the previous and following day. For 2009 there are 379 missing half-hours, which translates to 189.5 hours or 7.9 days [8]. So it is very convenient to estimate and add manually all the missing data for this year. Figure 14 shows the estimation of the electrical demand in 2009.

32

Figure 14 - Electrical demand in 2009

4.4 Breakdowns, Extended and Scheduled Maintenance To simulate the performance of hydrogen storage technology, a model based on observation, facts and logical assumptions has to be created.

4.4.1 Facts The only predictable out of order moments are those during the Scheduled Maintenance (SM) periods because they take place every two weeks. Also there are moments in which the hydropower plant is in breakdown owing to failure or to extended maintenance. There is no specific data that can be used or any other way to distinguish between this breakdown and extended maintenance. From now on they will be jointly referenced as Breakdown Failure/Extended Maintenance (BF/EM). In addition, there are few breakdowns because of increased electricity demand. These breakdowns occur when demand exceeds a marginal demand, which is 180 KW and will be referenced as Over Marginal Demand Breakdown (OMDB). The total BF/EM moments from January 2007 until September 2010 are presented (see figure 15) and listed by date in the appendices for these four years (see appendix V).

0

10000

20000

30000

40000

50000

60000

70000

80000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Energy (KWh)

Month

33

* There is no data from Sep 2010 to Dec 2010

Figure 15- No of Breakdowns / Extended Maintenance from Jan 2007 to Sep 2010

During these forty-five months from January 2007 to September 2010 the hydro-scheme remained closed owing to BF/EM for approximately 580 hours (150 hours per year), which means an average of 12.9 hours per month. This average does not present the actual distribution during a year and a more detailed analysis to define the breakdown hours for every month was conducted (see figure 16). That decision is taken because the demand takes into account different values at any season of the year.

* There is no data from Sep 2010 to Dec 2010

Figure 16 - Breakdowns/ Extended Maintenance hours per month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 2010* 1 0 0 1 0 4 0 2 0 0 0 0 2009 1 0 3 2 0 0 2 0 2 0 0 2 2008 2 0 0 5 1 0 0 2 1 1 0 2 2007 3 4 0 1 0 2 1 1 2 1 0 2

0

1

2

3

4

5

6

No of BF/EM

0

20

40

60

80

100

120

140

160


Hours

Month

2010*

2009

2008

2007

34

4.4.2 Observations After further examination of the data, several patterns are observed. All these patterns are accumulated and taken under consideration in order to create a model for the Breakdowns Failure/Extended Maintenance (BF/EM):

• Every year the scheme is out of order from April through July at least once, with a minimum duration of 28h and a maximum duration of 60 hours per time.

• The remaining breakdowns or extended maintenance appeared every month between 0 and 4 times (usually between 1 and 3 times).

• The only month without any Breakdown Failure or Extended Maintenance in these 4 years was November.

• Every year there are breakdowns close to New Year’s Eve because of the increased domestic energy demand.

• The average total hours, during which the hydro plant was out of order, is 150 hours per year.

4.4.3 Creating a representative model All these observations are taken into consideration in order to create a model for breakdowns/extended maintenance and scheduled maintenance for the specific hydro-scheme. The representative scenario has twenty-one BF/EM with a total of 150 hours out of order and one Scheduled Maintenance (SM) having a one-hour duration every two weeks. This model will be used to simulate the performance of the hydrogen storage system.

No of

BF/EM* Hours per

BF/EM Total BF/ EM Hours

No of SM**

January 2 4 8 2 February 1 3 3 2

March 3 1 3 2 April 2 5 10 2 May 3 4 12 2 June 1 50 50 2 July 3 8 24 3

August 2 7 14 2 September 1 8 8 2

October 1 2 2 2 November 0 0 0 2 December 2 8 16 3

*BF/EM: Breakdown Failure/Extended Maintenance ** SM: Scheduled Maintenance

Table 7 - Representative model for breakdowns, extended and scheduled maintenance.

35

In the representative scenario, the total number of hours during which the scheme is out of order is kept close to the average (150 hours) and the distribution of BF/EM retains its usual annual pattern. As evidenced in the following charts (see figures 17 and 18), the numbers of representative BF/EM are similar with the collective data from January 2007 to September 2010 (see figures 15 and 16).

Figure 17 – Representative model for the No of Breakdowns Failure/Extended maintenance

Figure 18 – Representative model for the total hours of Breakdowns Failure/Extended Maintenance

4.5 Simulating the process

4.5.1 Description of the system The system can satisfy the demand when the power is below 180KW. According to the data analysed in chapter 4.3, the instantaneous average power for every half hour throughout the year 2009 is available.

0 0.5 1

1.5 2

2.5 3

3.5


No of FB/EM

0

10

20

30

40

50

60


Hours

Month

36

Assuming that a “clever” electronic system is applied, the hydro turbine can be regulated through the economiser when the demand is 125 KW or less to produce 140 KW at least, and send the remaining 15 KW or more to the electrolyser. With that “clever” electronic system, at least 7.5 KWh per half an hour can be used to store hydrogen in tanks. When the system is out of order or inefficient for any reason, a fuel cell will be using the stored pure hydrogen as a fuel to deliver the electricity needed in the rural community of Knoydart. With this renewable storage system, the hydrogen can be used in order to avoid breakdowns due to increased demand over 180 KW (OMDB) by assisting the grid, or as a stand-alone power supply during the Breakdown Failure / Extended Maintenance and Scheduled Maintenance. Of course in the future the electrical demand will rise. As a result, the periods of storing hydrogen in the system will diminish. Responding to this new situation, the 125 KW/140 KW limit can be expanded in order to improve the efficiency of the system. For the needs of the specific case study, a detailed excel simulating program is created to calculate the potentially stored hydrogen from the energy surplus in the hydro-plant along with the energy produced in order to assist the grid.

4.5.2 Parameters and Assumptions As already explained in chapter 4.3, the excel data, which shows the average half-hour power demand was filled according to the patterns related with previous and following dates with logical assumptions for every half-hour. Now the data contains the demand from the hydropower production for the full year (2009). This half-hour value is called Instantaneous Average Power Demand (IAPD) on which are based all calculations concerning hydrogen storage. In the excel that was developed the system parameters are:

1. Marginal Demand Point: which is the 180KW average instantaneous power. 2. The Annual Increase Rate: which is set at 2.66%. 3. Storage Half-Hour: for any IAPD between 0 KW and 125 KW, the economiser will

regulate the hydro turbine to produce more and the surplus of power will be delivered to the electrolyser to produce hydrogen and store it to the tank.

4. Surplus Power1: the economizer will regulate the system to give a constant power output of 140 KW when the instantaneous demand is below 125 KW. In that case the grid will consume the needed 125 KW or lower and then the rest 15 KW or more will be sent to the electrolyser to produce Hydrogen.

5. H(kg) / KWh: the kilograms of hydrogen that can be stored through an electrolyzer in the tank. In the specific application, the electrolyzer used is the PureH2 Electrolyser 16 manufactured from Pure Energy Center Ltd. The electrolyser can deliver 16 Nm3/h (or 1.346 Kg /h) at full capacity of 81 KW per hour. Thus the Hydrogen production through electrolysis could be 0.0197 Nm3 (or 0.017 kg) per KWh. (see appendix VI).

1 In the future, the limits of 3 and 4 can be modified in order to meet the future demand

37

6. LHVH: the Low Heating Value of hydrogen is 33.33 KWh per kilogram (see appendix VII) 7. n fuel cell : the efficiency rate for a fuel cell ranges between 40% and 60% [26] of the LHVH

[34]. For the calculations an efficiency rate at 60% is assumed.

4.5.3 Excel process

The excel program simulates the system during a one year period. The excel columns calculate the following data:

• The Instantaneous Average Demand Power for every year after 2009 is calculated taking

into account a steady increase of 2.66%. IADPYear = IADP2009 * 1.0266Year – 2009. For example: if the Instantaneous Average Power Demand for a specific half-hour in 2009 was 100 KW then in 2020 will be 100 * 1.02662020-2009 = 130 KW

• If the half-hour Instantaneous Average Power Demand exceeds the Marginal Demand Point (180 KW) then the half-hour will be considered, as Over Marginal Demand Breakdown (OMDB) and assisting energy from the hydrogen system will be necessary in order to avoid the breakdown.

• A binary system is created to show when the system needs assistance from the

hydrogen system. If the value is 0, the system can operate without assistance. If the value is 1, assistance from the hydrogen storage is needed.

• The number of half-hour appearances of Over Marginal Demand Breakdown in one year

is also calculated (OMDB).

• If the Instantaneous Average Power Demand (IAPD) is smaller than the limit of Storage Moment (125 KW), then the kilowatt hours (KWh) that can be sent to the electrolyser are calculated (the half-hour periods when the hydro-scheme is out of order are not calculated and consequently the hydrogen system will not be able to store any hydrogen at these periods).

• The potential stored hydrogen in kilograms is calculated for any half-hour from the

following equations: H(kg) = Surplus Power (KW) * 0.5hours * 0.017 kg/KWh

• The potential electrical energy from the stored hydrogen is calculated as: E = H(kg)* LHVH * n fuel cell = H(kg) * 33.33 KWh/ kg * 0.60.

• The necessary energy in KWh from the hydrogen system, which is needed to assist the

grid when the hydro scheme cannot satisfy the demand and the Instantaneous Average Demand Power is over 180 KW, is calculated. For example: if the instantaneous average demand power is 190 KW for 30 minutes, the hydro-scheme can satisfy only 180 KW so

38

the rest 10 KW of power needed should be delivered by the hydrogen system. In order to do that the hydrogen system should produce 10 KW x 0.5 hours = 5 KWh.

• A second binary system is created when hydrogen (kg) is needed to assist the grid in

order to satisfy the demand. The Breakdown Failures/ Extended Maintenances is set in one column and the Scheduled Maintenances is set in a different column.

• A third binary system is created according to which when the value is 0, the hydro

turbine works and when the value is 1 the hydro turbine is out of order either due to Breakdown Failure / Extended Maintenance or due to Scheduled Maintenance. When the system is out of order for any of these reasons the hydrogen works as a stand-alone power supply.

• A final binary system is created, through the combination of the three binary systems.

The new system shows when hydrogen is used to assist the grid or as a stand-alone power supply.

• The total need of hydrogen (Kg) for any half-hour and correspondent total value is

estimated.

• Various tank sizes are tested in order to find the optimal size of the tank. This column does not exceed the maximum tank storage and thus the storing half-hour periods when the tank is full are not taken into account. Obviously, the storage tank cannot take negative values.

• Finally, the simulating program calculates the half-hour periods when the tank is empty

(0 kg) and the grid needs energy from the hydrogen storage system (final binary system). These half-hours are the moments when the diesel generator is used.

4.6 Simulation results

4.6.1 Demand The electricity demand is a key factor and further analysis of the current and future electrical needs is crucial for any proposal and application like this one. Unfortunately, there is no totally sure way to predict the annual increase rate of the demand. However, previous data over long time periods can be considered and examined for predicting future behaviors. The demand as mentioned, increased by 30% during a 10-year period. In this case study the annual increase is considered to have a steady rate of 2.66%, which can be translated to 30% in a 10–year period. The average power demand is shown below (see figure 19). The average power demand in 2013 is expected to be close to 90 KW and in 2030, according to the assumptions, is estimated to be around 140 KW (see appendix VIII).

39

Figure 19 - Average power demand per year based on steady annual increase of 2.66%

4.6.2 Over Marginal Demand Breakdowns The only predictable breakdowns are these that occur when the average power needs surpass the marginal demand of 180 KW. In this type of breakdown (OMDB), the hydrogen storage system will be able to assist the grid in order to avoid the breakdown. It is logical for these breakdowns to increase with time, following the constantly augmenting electrical demand. Using the average increase demand rate that we assumed before (2.66% per year) the number of the breakdowns will grow exponentially. Figure 20, shows the number of breakdowns caused due to the increasing demand from 2013 to 2030.

Figure 20 - Estimated No of breakdown half-hour periods caused in Over Marginal Demand (OMDB) in

the following years

These breakdowns (OMDB) raise significantly in number (see figure 20) and after 2026, there are more than one thousand breakdown half-hour periods caused due to high electricity demand (1,157 half hours). Hence, hydrogen will then be very important not only for the breakdowns

0 20 40 60 80 100 120 140 160

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and (KW)

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No of breakdown half-‐hours

Year

40

owing to component failure or maintenance but also for the breakdowns because of high electrical demand. This is an extra factor of the energy problem that the Knoydart peninsula will face in the distant future. It is very important that this representative model be used to simulate the performance of a hydrogen storage system. In the simulation, BF/EM and SM are predefined from the representative model (see table 6, sub-chapter 4.4.3) and OMDB are automatically calculated when the instantaneous average power exceeds 180 KW.

4.6.3 Annual total hydrogen needs In this part, the total annual needs of hydrogen in kilograms are examined for the representative model that is created. These needs are enough to respond to any situation and use only the hydrogen system as an alternative power supply. This is not a reliable solution for the future because the main problem in this technology is the storage and the size of the tank.

Figure 21- Annual total needs of hydrogen (kg) per year

It is obvious that the total annual needs of hydrogen (see figure 21) are growing exponentially in a similar way to the number of Over Marginal Demand Breakdowns (see figure 20). This is logical because both of them are based on the electricity demand and are influenced from its increase.

0

500

1000

1500

2000

2500

3000

Hydrogen needs (Kg)

Year

41

4.7 Hydrogen Storage The main problem in this project is the tank and specifically the size of the tank that is needed. The storage pressure is a very important factor and affects the final size of the storage tank. Especially, in this case study, a tank that can store over 1.5 tonne of hydrogen is needed to satisfy the demand until 2030 only by using the hydro-scheme and the hydrogen storage system, without using the diesel generator. Obviously, this storage capacity is too high and, therefore, unreliable. Consequently, it was necessary to test the system with various storage tank capacities of 300Kg, 200kg and 150kg and try to find the most reliable and economically desirable solution. Hydrogen can be treated as an ideal gas [35]. Thus, in order to convert the kilograms of hydrogen to volume the equation of the ideal gas law can be used:

𝑷 ∗ 𝑽 = 𝒏 ∗ 𝑹 ∗ 𝑻 Where:

• P: is the pressure of storage (kPa) • V: is the volume of the gas (litres) • n: moles of gas, for H: 1g = 0.99212 mol [36] • T: is the Temperature in Kelvin • R: is the ideal gas constant which is R=8.314 J*K-1 [37]

4.7.1 Low pressure hydrogen storage (buffer tank) Since the hydrogen coming out of the electrolyser is of low pressure, the produced hydrogen can be stored without further process in a low-pressure storage tank with a 15-bar maximum pressure [38]. These tanks are bulky but very simple and they are the best and cheapest solution when space is not an issue (see figure 22). This storage system can easily be connected to the hydrogen system and in addition, the low pressure minimizes the danger of explosion.

Figure 22 - Low Pressure Hydrogen Storage Tank [38]

42

4.7.2 High pressure hydrogen storage (K-‐Type cylinders) When the space is limited, the use of cylinders that can store hydrogen in high pressure is necessary. One commercial system, which can provide high-pressure storage, is the K-Type cylinders that are manufactured by Pure Energy Centre Ltd. The K-type is a steel based cylinder, which can individually store 50 litres of hydrogen in a 200-bar pressure and ambient temperature (see appendix IX). The storage system will consist of multiple manifold hydrogen cylinder packs of 49 cylinders (see figure 23) [38].

Figure 23 - K-type cylinders [38]

However, for this type of storage the presence of a compressor, which will compress the hydrogen into the desired levels of pressure, is necessary. So, an additional parasitic electric load will be needed. Also, there are extra safety regulations and obligations due to the high pressures. Hence, additional requirements are needed like a 24-hour monitoring system and gas leakage sensors [39].

4.7.3 Dimensioning tank storage The ideal gas equation can be used for the dimensioning of the hydrogen storage tank. For the dimensioning, the commercial systems from Pure Energy Centre Ltd are taken into account and the ambient temperature is assumed to be 293.15 K (20 oC).

K- type cylinder at 200 bar Low Pressure storage tank at 15 bar

Stored H capacity

Litres No of Cylinders

Litres m3

300 kg 36,270 725 483,609 484 200 kg 24,180 484 322,406 323 150 kg 18,135 363 241,804 242

Table 8 - Dimensioning the tank in high and low pressure for various capacities (300kg, 200kg and 150kg)

43

It is obvious that the K-type cylinders require significantly less space to store the same amount of hydrogen because of their tolerance of high pressures. However, the danger of explosion is higher because of these high pressures. On the other hand, the low-pressure tank is safer and requires a simpler connection. The bulky construction is usually the main obstacle but in the specific project there is plenty of space in the area, allowing this kind of construction. For the specific project, a combination of the two systems would be the optimal solution.

4.7.4 Performance with various storage tanks The storage capacity to cover all the demand until 2030 and make the hydrogen system capable of being the only back-up power supply is over 1.5 tonne and is consequently an unreliable scenario. For that reason, the simulating program is run using three different storage capacities in order to find the most sustainable solution. The three capacities whose performance is tested are 300 kg, 200kg and 150 kg. In every case, the diesel generator is also an alternative power supply whenever the hydro scheme is out of order and the hydrogen system is unable to assist the grid. The figure below (see figure 24) presents the hours that the diesel generator is used each year in these three storage scenarios. A fourth scenario is also presented if no intervention is made in the current situation (see appendix VIII).

Figure 24 - Hours of diesel generator usage in various storage tanks

As shown in figure 24, as the storage of the hydrogen tank becomes larger, the hours of diesel generator usage are reduced. This reduction always happens in a similar exponential manner. The hours of diesel generator usage do not vary significantly between the three hydrogen storage scenarios but the difference with the current situation is more than evident. Therefore, an intervention to the current situation has to be made in order to reduce the use of the diesel generator, which is one of the basic aims of this project.

0

200

400

600

800

1000

1200

1400

1600

Hours

Year

Without Hydrogen Storage Hydrogen Storage 150 Kg Hydrogen Storage 200 Kg Hydrogen Storage 300 Kg

44

4.7.5 Diesel usage The efficiency rate for a diesel generator is given from the equation:

𝜼 =𝑬𝒆𝒍

𝒎𝒇 ∗ 𝑳𝑯𝑽𝒅𝒊𝒆𝒔𝒆𝒍

Where • η is the efficiency rate (dimensionless) • LHVdiesel is the Lower Heating Value of diesel, assumed at 45,000 KJ/Kg [40]. • Eel is the electrical energy in KJ • mf is the mass of diesel (Kg)

Using the average power demand from chapter 4.6.1, the electrical energy that is needed from the diesel generator is estimated. By assuming a reasonable efficiency rate of 35% for the diesel generator, the diesel mass can be found by solving the above equation. Then, by setting the diesel density equal to 0.835 kg/l [41], the annual consumption from the diesel generator can be calculated (see table 8).

Year No Hydrogen storage

Hydrogen storage 150 kg



2013 4417 L 0 L 0 L 0 L 2014 4783 L 0 L 0 L 0 L 2015 5022 L 28 L 0 L 0 L 2016 5258 L 72 L 0 L 0 L 2017 5647 L 429 L 0 L 0 L 2018 6130 L 713 L 0 L 0 L 2019 6855 L 981 L 0 L 0 L 2020 7808 L 1248 L 638 L 0 L 2021 9170 L 1578 L 1315 L 0 L 2022 10948 L 2851 L 1839 L 0 L 2023 13560 L 4485 L 2684 L 364 L 2024 16839 L 5672 L 4285 L 3361 L 2025 21767 L 7061 L 6276 L 4488 L 2026 27470 L 8601 L 7926 L 5640 L 2027 35327 L 12962 L 10808 L 9596 L 2028 44621 L 20602 L 19121 L 15703 L 2029 54883 L 28080 L 26276 L 23924 L 2030 62765 L 40019 L 38666 L 35336 L

Table 9 – Equivalent annual diesel consumption for various storage tanks

4.8 Financial Assessment The financial assessment is a very crucial part of every renewable energy project and the most important piece in a feasibility report. Whenever a new project is found to be viable from an energetic, environmental and technological point of view, usually the economical feasibility is the last barrier.

45

Many different techniques are used to assess the economical feasibility of a project. It is usually based on the payback period for each project and tries to estimate the potential profits. In this case study, any profit is more than welcome but the most important aspect is a sustainable solution in order to address the energy problem of the Knoydart community with a regional payback period for the project as an additional benefit. In fact, every project that aims at the energy improvement of a rural community should prioritize the community’s sustainability reinforcement over profitability aspects. Hydrogen technology is a new energy storage technology that is still relatively more expensive than other energy storage technologies. However, it is constantly developing and undergoing a continuous reduction in price. Unfortunately, the prices are not usually made public unless significant interest is expressed for such an endeavor. Nevertheless, general estimations of final costs are within a range of 2,000$ - 3,000$ per 1 Kilowatt of installed capacity [42].

4.8.1. Future diesel expenditures The only back-up power supply at the moment is the diesel generator. Hence, the stand-by solution is unsustainable, not only environmentally but also financially, especially because of the combustible future diesel price. Additionally, the use of diesel enhances the energy dependency on other countries, which of course is something not desirable in the energy agenda. In addition, the satisfaction of the electrical demand depends on the diesel price, which is one of the most fluctuated and hardly predictable markets. Consequently, any trial to predict the future diesel price or savings due to reduced diesel consumption cannot be substantiated. A general and simplified way to approach the subject would be to examine the increase in diesel price from 1996 to 2013. On January 1996, diesel price was 0.574 £/litres while on July 2013 the price was 1.398 £/litres (see appendix X) [43]. The increase rate from 1996 to 2013 is 2.4355, which can be translated into an average annual increase of 1.05376. This average annual increase will be considered stable for the next 17 years in order to estimate the future diesel prices and the expenditures for each storage tank scenario (see figure 25).

Figure 25 - Expenditures (£) for Diesel per year in various H storage tanks

0

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Without Hydrogen Storage

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Hydrogen Storage 200Kg

Hydrogen Storage 300 Kg

46

4.8.2. Balance between project cost and savings from diesel In this part, a balance is sought between the total project cost and the savings that can be made from the reduced diesel usage in the 200kg hydrogen storage scenario. In the previous sub-chapter, it has been stated that the cost per KW for this kind of projects is estimated between 2,000 and 3,000 $. It is assumed that the price per KW is 2,500 $, the installed capacity is 200 KW. The currency rate as checked up on 21/08/2013 is 1$ = 0.64 £ [44]. Hence, the overall cost can be estimated close to 320,000 £. An additional factor that is taken into account is the inflation. During the last years, inflation fluctuates between 1% and 5%, so a stable inflation of 2.5% is assumed for the next 17 years (2013 – 2030). The diesel price estimation has already been referenced in 4.8.1., having an annual increase rate of 1.05376. Consequently, the balance between project cost and savings from diesel is shown in the following figure (see figure 26).

Figure 26 - Balance between project cost and diesel savings

In this figure it is evident that the payback period is estimated to happen after 15 years and that is only because during the first years, diesel usage is very rare due to the still low energy demands. This would be the case if the project were set in operation today. Such projects usually have a long waiting period until final decisions from the community are made and substantial funding is assured. If this project is set in motion after two or three years, the payback period will not be 15 years but less, owing to the decreased diesel usage. After 2025 the savings from that decrease in diesel usage are significant.

-‐350000

-‐300000

-‐250000

-‐200000

-‐150000

-‐100000

-‐50000

0

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Cumulative savings from

diesel (£)

Year

47

Conclusion Energy storage is a crucial issue in the energy agenda in order to store the surplus of energy and use it when is needed. Especially for the rural communities, energy surplus is very important and any efficient way of storage can prevent them from using pollutant sources for producing energy In this dissertation, the hydropower scheme in Knoydart peninsula is analysed along with the energy production coming from that scheme, the head losses in the pipeline, the backup power plan with the diesel generator and current and future energy demand. It is without question that further analysis for the efficiency will be very important for the hydropower plant. Any possible actions in order to improve its performance and electricity production will be beneficial and could lead to a better demand satisfaction and better potential hydrogen storage. The analysis of the hydro-scheme’s current production is showing that the implementation of an energy storage system is essential. This storage system can be beneficial to the energy demand not only by minimising the diesel generator usage but also by assisting the grid for the increased demand in the near future. This application study is presenting a hydrogen storage solution with a fuel cell of a 200 KW installed capacity for the moments that the demand is not high (below 125 KW). This can be materialized with the presence of a “clever” electronic system. With that system, the economiser will regulate the hydro turbine to produce more energy when the demand is not high and the occurring surplus of energy will be used to store hydrogen. The stored hydrogen will then serve as an energy source when needed to produce electricity through the fuel cell. Definitely, the hydrogen system cannot replace the diesel generator, especially due to the annually increased electrical demand. However, depending on the storage tank size, the hydrogen system can significantly help in order to minimise (even to nullify during the first years) the usage of the diesel generator. Hydrogen storage and fuel cells is a developing technology in need of further efficiency development and cost reduction. Unfortunately, there is not many information available concerning the exact finances but only rough evaluations about the price per installed capacity (2,500$ / KW). Estimations on financial savings from this application show a reasonable payback period, 15 years, from the savings from diesel purchases. In addition, the Knoydart Foundation can promote devices that are able to run on hydrogen, such as hydrogen cookers or hydrogen vehicles. This could be practical especially during the summer months when the hydrogen tank is full and the surplus of energy remains unused. Furthermore, the fuel cell could be used to co-produce electricity and heating, reaching a total efficiency of 80%, and could be used in the future for distributed heating. Finally, there is a high possibility that in the near future the carbon footprint will affect financially each area, as is already happening today between countries with the emission trading system. This solution is preparing the Knoydart community to face not only local future demand but also

48

possible global changes in a more renewable way. Only if future needs are considered in a more spherical manner starting from the local and rural communities, can a more sustainable future be ensured for the next generation, both environmentally and financially.

49

References [1] Knoydart Foundation. (2013) Knoydart Foundation. [Online]. http://www.knoydart-foundation.com/about/about-the-foundation/ (viewed 2013 August 10)

[2] Knoydart Renewables. (2013) Knoydart Foundation. [Online] http://www.knoydart-foundation.com/home/knoydart-renewables/ (viewed 2013 August 10)

[3] Flensburg University, "Assessment and future Scenario of Knoydart Electricity System," Flensburg University, Tema Project 2013.

[4] Gowans, "Draft Report on the Existing 270 KW Hydro Electric Istallation," Dr I. G. Gorans & Partners - Civil & Structural Engineers, 2000.

[5] Wikipedia. (2013, March) Water turbine. [Online]. http://simple.wikipedia.org/wiki/Water_turbine (viewed 2013 August 12)

[6] Caledonian Energy Ltd, "Inverie Hydroelectric Scheme - Review Report For Highlands and Islands Enterprise," Review Report 1999.

[7] Dimitrios E. Papantonis, Small Hydroelectric Schemes, 2nd ed. Athens, Greece: Simeon, 2008. [8] Knoydart Renewable Ltd, "Hydrology Data," Knoydart Foundation, Excel Data [9] Daniel Aklil, "Energy Analysis overview fro Knoydart Renewable Ltd," Pure Energy Centre, Energy Analysis 2008.

[10] Webelements. (2012) Webelement. [Online]. http://www.webelements.com/hydrogen/ (viewed 2013 August 13)

[11] S.H. Najjar Yousef , "Hydrogen Safety: The road toward green technology," International Journal of Hydrogen Energy, no. XXX, pp. 1-13, May 2013.

[12] Stelios Psomas. (2003, Novemeber) Energy, Enviroment & Entrepreneurship.[Online].http://www.aegean.gr/environment/eda/Envirohelp/greece/processes/documents/Energy_Environment.pdf

[13 ]Laura Stewart, "Energy Analysis Overview for Knoydart Renewables Ltd," Pure Energy Centre Ltd, Energy Analysis 2008.

[14] Aggeliki Sagani, "The Need of Energy Storage - Methods and Applications," MSc Project 2009.

[15] Powertech Inc. (n.d) Powertechlabs. [Online]. http://www.powertechlabs.com/temp/20112426/HARP_DataSheet_Feb_4_2011web.pdf

[16] R de Levie, "The electrolysis of water," Journal of Electroanalytical Chemistry, no. 426, pp. 92-93, August 1999.

[17] Marcelo Carmo, David L. Fritz, Jurgen Mergel, and Detlef Stolten, "A Comprehensive Review on PEM water electolysis," Journal of Hydrogen Energy, no. 38, pp. 4901-4934, January 2013. [18] Engscience Wordpress. Hydrogen fuel. [Online]. http://engscience.wordpress.com/hydrogen-fuel/ (viewed 2013 August 14)

[19] Fuel Cell Today. (2013) History. [Online].http://www.fuelcelltoday.com/about-fuel-cells/history (viewed 2013 August 14)

50

[20] Fuel Cell Today. (2013) PAFC. [Online].http://www.fuelcelltoday.com/about-fuel-cells/technologies/pafc (viewed 2013 August 14)

[21] Tom Fuller. (n.d.) how stuff works? [Online]. http://auto.howstuffworks.com/fuel-efficiency/4836-how-fuel-cells-work-video.htm (viewed 2013 August 16)

[22] Texas Hydrogen 101. (2013) Texas Hydrogen 101. [Online]. http://hydrogen.harc.edu/Hydrogen101Curriculum/H101FuelCells/tabid/516/Default.aspx (viewed 2013 August 16)

[23 ]Wikipedia. (2013, August ) Fuel Cell. [Online].http://en.wikipedia.org/wiki/Fuel_cell (viewed 2013 August 17)

[24] H. Ibrahim, A. Ilinca, and J. Perron, "Energy Storage Systems - Charteristics and Comparisons," Renewable and Sustainable Energy Reviews, no. 12, 2008, pp. 1221-1250, January 2007.

[25] Fuel Cell Today. (2013) PEMFC. [Online] http://www.fuelcelltoday.com/about-fuel-cells/technologies/pemfc (viewed 2013 August 16)

[26] Fuel Cells 2000. (2103) Types of Fuel Cell. [Online] http://www.fuelcells.org/base.cgim?template=types_of_fuel_cells (viewed 2013 August 22)

[27] Je Seung Lee et al., "Polymer Electrolyte Membranes for Fuel Cells," Journal of Industrial and Engineering Chemistry, vol. 2, no. 12, pp. 175-183, 2006, REVIEW. [28] Fuel Cell Today. (2013) AFC. [Online] http://www.fuelcelltoday.com/about-fuel-cells/technologies/dmfc (viewed 2013 August 18)

[29] Fuel Cell Today. (2013) MCFC. [Online ] http://www.fuelcelltoday.com/about-fuel-cells/technologies/mcfc (viewed 2013 August 19)

[30] Fuel Cell Today. (2013) SOFC. [Online] http://www.fuelcelltoday.com/about-fuel-cells/technologies/sofc (viewed 2013 August 19)

[31] Ngyen Q. Minh, "Solid Oxide Fuel Cell Technology - Features and Applications," Solid State Ionics, no. 174, pp. 271-277, July 2004.

[32] Fuel Cell Today. (2013) DMFC. [Online] http://www.fuelcelltoday.com/about-fuel-cells/technologies/dmfc (viewed 2013 August 20)

[33] Fuel Cell Today. (2013) Technologies. [Online] http://www.fuelcelltoday.com/about-fuel-cells/technologies (viewed 2013 August 20)

[34] James Larminie and Andrew Dicks, Fuel Cell Sustem Explained, 2nd ed. England: John Wiley & Sons Ltd, 2003.

[35] Yunus A Cengel and Michael A Boles, Thermodunamis: An Engineering Approach, Fourth edition ed.

[36] Endmemo. (2013) Chemical mole gram calculator. [Online]. http://www.endmemo.com/chem/mmass.php (viewed 2013 August 21)

[37] Easycalculation. (2013) Ideal Gas Low Calculator. [Online] http://easycalculation.com/chemistry/ideal-gas.php (viewed 2013 August 21) [38] Pure Energy Centre. (2013) Hydrogen Storage. [Online] http://www.pureenergycentre.com/pureenergycentre/Hydrogen/Hydrogen_Storage/Hydrogen_Storage.php (viewed 2013 August 21)

51

[39] Amraa Shanzbaatar, "Comparing Hydrogen Storage Methods for Efficient Hydrogen Power Backup Systems," H Bank Technology Inc, n.d.

[40] The Engineering ToolBox. (2013) Fuels - Higher Calorific Values. [Online]. http://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html (viewed 2013 August 21)

[41] European Commission, "Well-to-wheel analysis of future automotive fuel and powertrains in the european context," Directoral General - Jont Research Centre, 2007.

[42] Fuel Cell Today, "Hydrogen + Fuel Cells 2103," Fuel Cell Today, Event Report 2013.

[43] Bolton Paul, "Petrol and Diesel Prices," Department of Energy & Climate Change , SN/SG/4712, 2013.

[44] Currency.me.uk. (2013, August) Convert dollars to pounds(USD to GBP). [Online] http://www.currency.me.uk/convert/usd/gbp (viewed 2013 August 21)

[45] Brunopolletresearch.com. (n.d.) Thr pollet PEM fuel Cell group. [Online] http://www.brunopolletresearch.com/Energy_Data.pdf (viewed 2013 August 22)

[46] Wikipedia. (2013, July) Wikipedia. [Online] http://en.wikipedia.org/wiki/Hydrogen(viewed 2013 August 22)

52

Appendices

Appendix I. Inverie Hydro Investigation comments (email) Email by Ed Carrick Wallace Stone LLP

53

40506070

Head

Loss

@ 9

6 l/

s

loss

es

Plas

tic P

ipe

Stee

l Pip

e

Head

Los

s (m

)

Disc

repa

ncy

~ 20

m Lo

ss

Aver

age

Loss

108.

7mm

/m

0102030

070

145

335

467

567

647

747

834.

594

4.5

1174

.5

Aver

age

Loss

52.4

mm

/m

Aver

age

Loss

15.8

6mm

/mCh

aina

ge

from

Dam

(m)

Turbine

Dam

54

Appendix II. Brief Description of the demand (email) Email by Jim Brown Maintenance Manager Knoydart Foundation Ltd

55

Appendix III. Safety in application for hydrogen

Table 10 - Safety in application for hydrogen [11]

56

Appendix IV. Information about fuel cell technology (email) Email by Sean Allan, P.Eng. Project Engineer, Smart Utility & EV Infrastructure Powertech Labs Inc.

7/31/13 RE: North Scotland H2 isolated Grid - Outlook Web Access Light

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RE: North Scotland H2 isolated Grid

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You forwarded this message on 23/07/2013 22:18.

Sent: 23 July 2013 21:31

To: Nikolaos Karamitsos

Dear Nikolaos, [you wrote:]>The daily load profile is :> Peak load =130 KW> Off Peak load = 70-‐80 KW This very small load, and very small peak would be easy to provide electrical service with fuel cell generator. I understand that this electrical load is already serviced by anexisting diesel generator, rather than completely replacing this generator the hydrogen fuel cell generator would allow this system to work as a diesel hybrid system. Actually, the diesel engine is required to set the frequency (60Hz here in North America) and then the fuel cell generator would be a "grid tied" machine. This means the fuel cell generator needs to have an existing grid to sync up with. It is possible to have a "Black Start" fuel cell generator, however this would use a different powerelectronics setup. For the Bella Coola HARP project the fuel cell generator was a "Grid Tied" generator, and it would match up frequency with the existing running dieselgenerator. >This project is a theoretical proposal for the community. Consequently the >budget is not specific but of course a reliable economical solution is more>than welcome. Okay. When and if this project does become a reality, I can provide some more detailed cost estimates. The more effort that is put into a cost estimate the more accurate itwill be. However, I normally get paid to come up with cost estimates, that's what engineering consulting is all about! Also it would be very helpful if you have any specific information about the following issues: • Does the hydrogenics Electolyzer use the PEM technology or another (like PAFC,Molten Carbonate)? The Hydrogenics Electrolyzer uses PEM tech. An abundance of info on their website www.hydrogenics.com. Molten Carbonate is ridiculously hot, and takes forever to gethot and is not practical from an ongoing maintenance perspective. • Which is the minimum electrical load which can feed the electrolyzer (maybe a proportion of the nominal load)? You can purchase an electrolyzer sized to any process. I have seen electrolyzers that are packaged into a 40ft ISO container, and I have seen small appliances about the sizeof a dishwasher. Therefore the minimum electrical load is as low as you desire it to be. • The efficiencies of the electrolyzer and the fuel cells in full and partial load. Electrolyzer efficiency = 75-‐80% this means that of the available electrical energy that is put into the electrolyzer approximately 20-‐25% is lost as heat, noise, inefficiency inthe system. Most of the energy loss is heat. Both the product H2 gas is cooled, and the electrolyte is cooled. Fuel cell efficiency = 80-‐85%. Again, the loss is due to heat. • Any drawing of the system and dimensions See attached.

• Typical size of the tank, pressure and temperature of storage. There were two elements of hydrogen storage: 1) Buffer Tank: 20 Type 3 cylinders make by Dynetek Industries in Calgary each was 174L by volume, 10bar nominal pressure, ambient temp (which varies from -‐25°C to+30°C in Bella Coola) 2) Storage bank: 40 x 2 = 80 type 3 Dynetek cylinders each 174L by volume, 200bar nominal pressure, ambient temp same as above. • Any information about the parasitic electricity consumption for the hydrogen storage. Is this included in the efficiency of the electrolyzer referree above? The electrolyzer has a few Parasitic loads: including chiller systems, water purification systems, and the product hydrogen gas purification systems. • Rough cost estimations of the system (storage tank, electrolyzer, fuel cell) Electrolyzer for Bella Coola HARP = 1million CND$$$Fuel Cell for Bella Coola HARP = 1 million CND$$$Storage systems plus compressor systems = 1 million CND$$$ But your system is smaller. >Sorry for the barrage of questions but the information on the internet>varies and is not always reliable. Not many people have practical real world experience with this type of technology. >I believe your experience can clarify better some of these issues. Also any documents>(reports, data, manuals etc) related to the above questions which can support my final>project would be more than welcome.

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Appendix V. Breakdown Failure/Extended Maintenance (BF/EM)

2010 Hours 2009 Hours 2008 Hours 2007 Hours 6-‐Feb 9.5 18-‐Jan 8 10-‐Jan 1 1-‐Nov 2 5-‐Apr 1 16-‐Mar 6 18-‐Jan 1 19-‐Jan 1.5 8-‐Jun 1 17-‐Mar 7 10-‐Apr 1.5 20-‐Jan 0.5 16-‐Jun 28 19-‐Mar 1.5 10-‐Apr 48 6-‐Feb 2 24-‐Jun 8.5 27-‐Apr 5 12-‐Apr 48 8-‐Feb 0.5 29-‐Jun 9 29-‐Apr 64 15-‐Apr 14.5 10-‐Feb 6 16-‐Aug 7 1-‐Jul 60 24-‐Apr 32 22-‐Feb 4.5 17-‐Aug 1 30-‐Jul 2 6-‐May 60 21-‐Apr 3.5

25-‐Sep 9 6-‐Aug 10 28-‐Jun 1 26-‐Sep 9 23-‐Aug 7 28-‐Jun 2 9-‐Dec 6 15-‐Sep 2.5 28-‐Jul 35 10-‐Dec 1 4-‐Oct 3 21-‐Aug 3 10-‐Dec 1 30-‐Dec 1 11-‐Sep 1 11-‐Dec 0.5 31-‐Dec 3 13-‐Sep 9 11-‐Dec 1 2-‐Oct 8.5 30-‐Dec 1 27-‐Dec 7 31-‐Dec 1 31-‐Dec 4

Table 11 - Breakdown Failure/Extended Maintenance dates from Jan 2007 to Sep 2010

2010 2009 2008 2007 No BF/EM 8 Breakdowns 17 Breakdowns 14 Breakdowns 17 Total hours 65 Total hours 183 Total hours 232.5 Tota hours 91

AV Hours per Breakdown

8.1 AV Hours per Breakdown



5.3

Min 1 Min 0.5 Min 1 Min 0.5 Max 28 Max 64 Max 60 Max 35

Table 12 – Number of total hours and average hours per month of Breakdown Failure/Extended Maintenance

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Appendix VI. Electrolyser Model: PureH2 Electrolyser 16 Manufactured by Pure Energy Centre Ltd

AN-005 Page 1 of 1

16Nm3/h Onsite hydrogen production alkaline electrolysis

Main Features & Options Available

Water purification system 200L Purified water buffer storage tank Alkaline electrolysis system Integrated Hydrogen purification system

o Deoxygenation to achieve up to 99.995% o Drier to achieve up to -45oC average dew point

Power conditioning and control Multipoint active hydrogen detection Integration into complete turn-key solution

TECHNOLOGY & SYSTEM LAYOUT Hydrogen is produced using state of the art alkaline electrolysis of water to produce hydrogen & oxygen gases through the use of electricity. Equipment is provided with all necessary auxiliary items to provide safe reliable onsite hydrogen production ELECTROLYSIS TECHNICAL SPECIFICATIONS Maximum Hydrogen Production 16 Nm3/hour Maximum Electricity consumption / supply 81 kW @ 400VAC 50Hz Transformer position Internal Control panel position Internal Production variation range 20% to 100% of maximum capacity Deionised water consumption at full power 13.6 litre/hour Hydrogen purity (before purifier) 99.3%-99.8% Outlet gas dew point (before drier) Saturated at ambient temperature Outlet gas Pressure up to 12 bar Environment temperature range 5-35oC Valves actuation Pneumatic Cooling system Air or Liquid Dimensions (Length X Depth X Height) 1650 mm X 2400 mm X 2150 mm Weight 2450 kg Certification CE approved Additional Configuration Options Parallel connection of several units to increase production capacity remote surveillance control system through Internet full service contract compression & buffer storage allowing for flexible supply independent from production purchase of ‘green’ electricity to eliminate CO2 emissions from the production process Disclaimer: This Note is for advice only. Please note that legislation, guidance and practical methods are continually subject to change. Please take note of prevailing legislation and guidance, as amended, whether mentioned here or not. Where legislation and documents are summarised, this is for general advice and convenience, and must not be relied upon as a comprehensive or authoritative interpretation. It is the responsibility of the person/company involved in the assessment, development and operation of potential installations to ensure up to date working practices are applied to determine the status of a site and the requirements needed. Note: Technical specifications are subject to change

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Appendix VII. Hydrogen Data

Table 13 - Hydrogen Data [45]

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Appendix VIII. Hours of future diesel generator use per year in various storage tank capacities and average demand power Year No Storage

(hours) 150 Kg Storage (hours)

200Kg Storage (hours)

300Kg storage (hours)

Average Power Demand (KW)

2013 166 0 0 0 91.8 2014 175 0 0 0 94.3 2015 179 1 0 0 96.8 2016 182.5 2.5 0 0 99.4 2017 191 14.5 0 0 102 2018 202 23.5 0 0 104.7 2019 220 31.5 0 0 107.5 2020 244 39 20 0 110.4 2021 279 48 40 0 113.4 2022 324.5 84.5 54.5 0 116.4 2023 391.5 129.5 77.5 10.5 119.5 2024 473.5 159.5 120.5 94.5 122.7 2025 596.5 193.5 172 123 125.9 2026 733 229.5 211.5 150.5 129.3 2027 918.5 337 281 249.5 132.7 2028 1129.5 521.5 484 397.5 136.3 2029 1353.5 692.5 648 590 139.9 2030 1508 961.5 929 849 143.6 Table 14 - Hours of future diesel generator use per year in various storage tank capacities and average power demand

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Appendix IX. High pressure tank (K-‐type cylinders)

Table 15 - K-type cylinder technical characteristics [38]

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Appendix X. Diesel price from Jan 1990 to Jul 2013

Table 16 - Diesel Price from Jan 1990 to Jul 2013 [43]

Hydropower for isolated rural communities Analysis of the Knoydart community system in Scotland

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