ELEC 590 Directed Study Course
Renewable Energy in Smart Grid Systems
Supervisor and instructor: Prof. Dr. Aaron Gulliver
Summer term 2014
Author: Abdullah Rehan
E-‐mail: [email protected]
1 ELEC 590 Smart Grids in Renewable Energy Technology
Acknowledgement This work has been made possible by the endless efforts and guidance of my supervisor Prof. Dr. Aaron Gulliver, Department of Electrical Engineering at University of Victoria, BC, Canada. I am thankful for his support, motivation and assistance starting from the proposal development,
continuing till the completion of the report.
Abstract
Background: The main motivation of this project is the level of greenhouse gases that has increased drastically over a period of time merely because of using conventional sources of power. Burning coal and natural gas to fulfill our energy requirements is a practice which if continued will have irreversible negative impacts on the environment. Smart grid technology is a modern system that administers the efficient delivery and management of power which when integrated with renewable energy systems can be a solution.
Objective: The main objective is to evaluate the feasibility of all renewable energy resources available so that a way to integrate them with smart grid technology can be more efficient, feasible and reliable.
Methodology: The working principle and construction procedure of each type of renewable energy and smart grid technology is studied. Then the financial and power feasibility for all renewable energy technologies and smart grid technology is analyzed.
Results: After comparing values and statistics of all renewable energy and smart grid projects, the most feasible renewable energy is figured out. A model system integrating smart grid technology and renewable energy technologies is proposed.
Conclusion: Smart grid system costs generally remain the same regardless of which renewable energy technology is integrated, but the costs are predicted to decline in the future with better technology. The cheapest renewable energy systems are wind and solar power systems. If enough capital is available, the most energy efficient and feasible systems are geothermal and biomass power stations in the long run.
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Table of Contents
Chapter 1: Introduction ............................................................................................................................... 3
Chapter 2: Smart grid technology ................................................................................................................ 5
Chapter 3: Renewable energy technologies ................................................................................................ 8
3.1 Solar power ....................................................................................................................................... 10
3.1a Construction of a photovoltaic system ....................................................................................... 12
3.1b Solar fuel cells ............................................................................................................................. 13
3.2 Wind power ...................................................................................................................................... 14
3.2a Construction of a wind farm ....................................................................................................... 16
3.3 Biomass power .................................................................................................................................. 18
3.3a Construction of a biomass power plant ...................................................................................... 19
3.4 Hydroelectric power ......................................................................................................................... 21
3.4a Construction of a hydroelectricity power plant .......................................................................... 22
3.5 Emerging renewable energy technologies ........................................................................................ 23
3.5a Geothermal energy ..................................................................................................................... 23
3.5b Ocean wave energy .................................................................................................................... 24
3.5c Tidal wave energy ....................................................................................................................... 26
3.5d Innovative renewable energy technologies ................................................................................ 26
Chapter 4: Feasibility study on renewable energy .................................................................................... 28
Chapter 5: Designing a smart grid system ................................................................................................. 30
Chapter 6: Conclusion and discussion ....................................................................................................... 32
6.1 Feasibility of renewable energy technologies ............................................................................. 34
6.2 Future of integrated smart grid technology with renewable energy .......................................... 36
6.3 An ideal system integrating smart grid and renewable energy technology ................................ 36
Chapter 7: References ................................................................................................................................ 39
3 ELEC 590 Smart Grids in Renewable Energy Technology
Chapter 1 Introduction:
The world is currently dependant on an energy infrastructure that heavily relies on fossil fuels which
have high chances of getting depleted. Such energy resources are major contributors of green house
gases and carbon dioxide. If current practices of energy generation are continued, excessive Carbon
dioxide emissions will degrade the environment. Carbon emission rates need to be maintained at
present levels by implementing carbon neutral energy resources immediately in a cost efficient manner.
Optimized energy systems with minimal production, transmission and maintenance costs are required
which provide constant energy with minimal losses. There is a huge scope for learning more about the
technicalities of how solar energy can be utilized by photovoltaic systems and solar fuel cells in addition
to biomass, wind, and other types of renewable energy resources for meeting clean energy
requirements.
Table 1: Effects of carbon economy on the environment
Source: Nathan S. Lewis and Daniel G. Nocera, “Powering the planet: Chemical challenges in solar energy utilization”, PNAS
vol.103 no.43, pages 15729-‐15735, October 24, 2006.
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According to consumption rates, 50-‐150 years of oil reserves, 207-‐590 years of natural gas and 1000-‐
2000 years of coal is left to be used as energy resources which can account to up to 25-‐30TW of energy
consumption rate worldwide for centuries to come. A more hazardous issue than depletion is the rate of
emissions by using fossil fuels as energy resources. In the next 50 years, the energy consumption rate is
expected to increase to 27.6 TW from 13.5TW which will account to an increase in carbon emission rate
to 13.5 billion metric tons GtC/yr from 6.6 billion metric tons GtC/yr. These carbon emissions tend to
accumulate between the ocean surface and the atmosphere. The mixing time between the near surface
and deep oceans varies between 400-‐ thousands of years which means that until severe intervention is
done to remove these emissions actively, these gases will stay in surplus to the new emissions. Hence,
the CO2 in the atmosphere should now be limited to 550ppm and for that entirely carbon-‐neutral
energy resources are required immediately because if the process of this shift from a “high carbon
economy” to a “low carbon economy” is even delayed by 20 years, carbon neutral power equal to the
amount of power produced by all the energy resources existing combined will be required to maintain
the level of 550ppm of CO2 in the atmosphere. [1]
It is time to reform the environment-‐degrading energy infrastructure into a sustainable and resilient
energy infrastructure that is more environmental friendly. One of the main problems that the energy
sector faces is the renewable energy transportation costs over long distances when compared to the
more conventional energy coming from resources such as the fossil fuels. Another issue that arises
when analyzing the feasibility of renewable energy production is with the generation process. Since the
primary source of such energy is nature itself, the output is not constant and the fluctuation makes it an
unstable resource of energy. An ideal solution to these particular problems would be the one that
incorporates maximum use of renewable energy resources mitigating the affects of fluctuation in its
production by the use of smart grid systems (further explained in Chapter 2).
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In the modern age of today, proposals and models need to be set up in order to solve the two
bottleneck energy investment problems of transmission and fluctuation of renewable energy
development during the planning phase. These long-‐term investment planning models will be an aid for
analysts, investors and policy makers for finding out methods to make extensive use of current and
emerging renewable energy technologies in order to support the development and enhancement of
renewable energy so that the world’s energy infrastructure can be transformed into a much cleaner
system over a period of perhaps the next 40 years.
Chapter 2 Smart grid technology:
Figure 1: General layout of smart grid systems
Image source: http://www.powergenasia.com/conference/smartmeter.html.
“Smart grid” nowadays is considered as a general term that refers to a type of technology that people
use to transform utility electricity systems that are used for delivery into modern 21st century delivery
systems with the help of computer-‐based remote control and automation. These particular systems can
be made incorporated today by two way communication systems and technology along with the regular
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computer processing practices that have been used for many years in various industries. In the most
recent years, they are beginning to be used on electricity networks, from the different power plants and
wind farms all the way to the customers and consumers of the electricity for commercial, domestic and
industrial purposes. Such systems are able to offer numerous benefits to utilities and consumers mostly
in terms of higher efficiency and improvements in delivery of the electricity grid for energy users’ homes
and offices. The general idea of such a system can be seen in figure 1.
The invention of such systems has changed the nature of work that the workers of utility companies
have to do as well. For almost a century now, workers of the utility companies have had to go out and
gather much of the data needed to provide and regulate electricity. In order to do this, the workers have
to read meters, search for broken equipment and measure voltage which only covers a fraction what
they have had to do every day. Most of the devices that the utility companies use to deliver electricity
efficiently were not automated and computerized but because of the smart grid technology, many
options and products are now being made available to this industry to help modernize the electricity
generation process.
The conventional “grid” is basically the network that carries electricity from the plants where it is
generated to consumers that have a demand for it. This grid consists of wires, substations, transformers,
switches and a lot more.
Exactly like the way that a “smart” phone nowadays merely means a phone that has a computer in it, a
smart grid means the electric utility grid that has now been computerized and can entirely be controlled
by a computer system. One of the main tasks associated with it is adding a two-‐way digital
communication technology to all the devices that are associated with the grid and its functionality. The
devices are responsible for carrying out the same function designated to them as before but the means
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of collecting that information for the relative functionality is now through the use of sensors. Devices on
the network now use sensors in order to gather data from power meters, voltage sensors and fault
detectors. The whole process is made possible by a two-‐way digital communication between the devices
in the field and the utility’s network operations center from where everything is administered and
controlled. One key feature that justifies the use of smart grid systems is the automation technology
that now lets the utility adjust and control each individual device and millions of devices from one
central location now matter how remote that is.
As inferred from principal characteristics, smart grid systems are able to use digital technology in order
to improve reliability, resiliency, flexibility, and efficiency both in terms of economy and energy of the
electric delivery system. The advantages and additional options offered by smart grid systems can be
analyzed from figure 2.
Figure 2: Importance of smart grid systems and smart meter benefits
Image source: Wave 3 – SGCC consumer pulse and segmentation research. Base=Total consumers, n=1089.
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Chapter 3: Renewable energy technologies
Renewable energy is basically the energy that is generated from resources, which are naturally
replenished. These resources include sunlight, wind, rain, tides, waves and geothermal heat. By using
these renewable energy resources for energy generation, we fulfill multiple needs of the 21st century:
• Electricity generation
• Hot water/ space heating
• Fuels for motors
• Rural off-‐grid or remote areas energy services
Renewable energy is an important technology sector in the world of today because of the numerous
benefits it has to offer. The key environmental benefit attained is through the cleanliness of renewable
energy technologies because of the use of clean and green sources of energy which have a very minimal
impact on the environment. Since one is not dependant on conventional sources such as fossil fuels,
renewable energy resources will not run out and this type of energy will stay in the world for future
generations to come. Such technology is also economically feasible in the way that it creates jobs and
helps the economy. Most renewable energy investments are known to be used up on materials and
workmanship in order to construct and sustain the facilities, in contrast to costly energy imports. These
investments are mostly spent within the country of origin, often in the same state and town. This means
that the energy dollars stay at home creating employment opportunities while fueling local economies.
Meanwhile, the renewable energy technologies which are developed by each country can also be sold
overseas, in turn providing a boost to the country’s trade deficit.
Almost about 16% of the global final energy needs today are met from renewable resources, in which
10% [2] of the energy is generated from traditional biomass, (main use is for heating) and 3.4%
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from hydroelectricity. New renewable energy resources such as small hydro, modern biomass, wind,
solar, geothermal, bio-‐fuels and other emerging technologies are responsible for another 3% which are
growing rapidly [3].At country level, at least 30 countries all over the world already have a renewable
energy contribution of more than 20% of the total energy supply. The exact figures of renewable energy
contribution to the total world energy consumption can be seen in figure 3.
Figure 3: Renewable energy share of total energy consumption 2010
Image source: Renewables 2011, global status report.
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3.1: Solar power
Figure 4: Solar photovoltaic total world capacity
Image source: Renewables 2011, global status report.
The solar cell is an integral part of the PV system and its operation is based on the fact of a direct
conversion of the electromagnetic radiation from the sun which is received mainly consisting of the
visible light of the wavelength (400 nanometers to 750 nanometers) into the usable electricity with the
help of the photovoltaic effect. This photovoltaic effect is usually composed of the conversion of energy
from the incident photons that come into electrical potential energy that is transferred to charge
carriers inside a semiconductor material, which enables them to transfer in between the different
voltage bands within the material which effectively results in the accumulation of voltage between the
two electrodes that in turn represents the output voltage of the solar cell. The total capacity of solar
photovoltaic systems can be seen in figure 4.
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Various types of solar cells now exist in the market which can be integrated into photovoltaic systems
depending on their efficiency and cost. Multi-‐junction solar cells contain several p-‐n junctions and one of
each junction is tuned to a wavelength of light that is different from each other so that light is wasted.
By increasing the number of junctions, higher efficiency can be achieved but with three junctions an
efficiency of about 43% can be achieved. In contrast to the multi-‐junction solar cells, single junction
solar cells are only made up of a single p-‐n junction and have a lower efficiency of about 30%. These
cells are usually 175um thick and have dimensions of 7cm by 7cm are normally weldable and solderable.
Crystalline silicon solar cells are the kind widely available and up till now the most efficient solar cells
that provide stable power. These cells have a practical efficiency of 22.5% and are the most frequent
options when designing a PV system.
The output of PV system depends on the fill factor of a solar cell. The higher the fill factor, higher the
efficiency of the solar cell. These relationships can be seen from numeric calculations below:
These relationships can be seen from equations 1 and 2.
𝐹𝐹 = !!" × !!"!!" × !!"
….(1)
ƞ = !!"×!!" ×!! !!"
….(2)
where 𝐹𝐹 is the fill factor, 𝐼!" is the current at maximum point, 𝑉!" is the voltage at maximum point, 𝐼!" is short
circuit current, 𝑉!" is open circuit voltage, ƞ is the efficiency and 𝑃!" is the input power. PV systems are capable
of producing 1000kWh/kWpeak of energy per nominal power with 20-‐30 years of proven durability with
output that can be DC or high quality AC via an inverter. Such systems are easily scalable for less than
1W to greater than 10MW of power. The maintenance costs are generally very low until hit by
hazardous storms making these systems cost marginal. With 10% efficiency and $300/m^2 along with
balanced maintenance cost of $3/W, an optimal electricity price of $0.35 kW/hr can be achieved which
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can be considered when comparing to the cost of $0.02-‐0.05 kW/hr for fossil fuels generated energies
[4].
The energy from solar power can be easily stored if inexpensive batteries become available which have
lifetimes of about 30 years. An alternative to this approach can be pumping water uphill through a
turbine powered by solar power and storing the energy mechanically but till now, a feasible system that
does not require charge and discharge every 24hours is unavailable. A third method of storing this
energy is by using an artificial photosynthesis procedure to produce a solar fuel cell in which chemical
bonds are broken and then formed.
PV power is that it is time sensitive. On a sunny day, the output power will be great but at night time, a
cloudy day or winter season when the sun is only out for a few hours, the use of PV-‐systems as source of
energy is not suggested. PV systems are also temperature sensitive since a rise in temperature accounts
to a fall in the solar cell performance; hence these systems are inefficient in extremely hot conditions.
The environmental impact of PV power is almost negligible. Crystalline solar cells make use of Cadium
which is a carcinogen and not disposable in a recycling program. PV systems are easily funded by banks
worldwide since it is the most developed form of renewable energy that exists.
3.1a) Construction of a Utility PV system
A PV system consists of a solar module, voltage converter/charge controller, a storage unit and an
inverter that converts AC into DC. The output might be connected directly to a load or to a power grid. A
solar panel consists of series and parallel connected solar cells. Typically, the cells in one panel should
match well otherwise a big difference reduces the overall efficiency and even destroys the weakest cell.
Group cells are sometimes connected in parallel so that reverse current does not become an issue
because of shadowing of a high number of cells. A solar generator will then finally have PV modules
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connected in series and parallel. Each module should be regulated actively and connected in series.
Conversion of input power to output power can be done by choosing between linear regulators, buck,
buck-‐boost, boost and fly-‐back converters. Each converter has a different power input to output ratio
and efficiency so the choice depends on each application. The storage of this power generated can be
done by using big loads of lead acid accumulators or by storing the power directly into a grid where it
can be shared from with other users immediately after generation.
For an ideal PV system, the ambient temperatures need to be lower and surveys need to be done before
the area is selected so that it is made sure that the site receives a favorable amount of sun. A practical
example of a large scale PV system can consist of 150 KVA, 98.9% efficient, 208 to 480 air cooled
transformer. The ground surface preparation can be set +/+ one inch vertical in 10 feet horizontal.
About 250 MCM of copper can installed on ground for protection from lightening equipment. A high
efficiency PV module can be set at 300 feet north-‐south by 140 feet east west on ground. The wiring
design has to be for around 0.5% drop of maximum voltage from the furthest point in the array to the
inverter. By smartly designing the system, the installation costs of such power systems can be reduced
down to $0.30 per DC watt of PV capacity. Crystalline solar cells are usually used because of a stable
performance. The capacity of such a system can generally be up to 495 MW with a renewable energy of
861,143 MWh with expected values of $30.85/MWh of energy.
3.1b) Solar Fuel Cells
In one hour, 4.1*10^20 J of energy strikes the earth which is much greater than the 4.1*10^20 J of
energy that the planet uses in one year [1]. This energy is stored by an innovative process called artificial
photosynthesis. During this process, water reduction and oxidation catalysts are combined with a light
collection and charge separation system ultimately capturing spatially separated electron hole pairs to
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make bonds of hydrogen and oxygen. This hydrogen is then combined with Carbon dioxide in the
atmosphere to produce solar fuels which can store the sun’s energy for later use as a renewable
resource of energy. This process can be performed by a solar fuel cell in which hydrogen and oxygen are
combined to generate an electron and proton flow through a membrane. Light is used to run the
electron and proton flow in reverse and the coupling of electrons and protons to photo catalysts
(Titanium dioxide doped with small amounts of iron or chromium [5]) breaks the bonds of water and
produces Hydrogen at the cathode and oxygen at the anode, effecting solar fuel production. This
process between the cathode and the anode results in a flow of electric current. A schematic diagram of
a solar fuel cell can be seen in figure 4.
Figure 4: Working principle of a solar fuel cell
Image Source: Nathan S. Lewis and Daniel G. Nocera, “Powering the planet: Chemical challenges in solar energy utilization”,
PNAS vol.103 no.43, pages 15729-‐15735, October 24, 2006.
3.2 Wind power The main operating principle lies in the fact of converting the wind energy into a useful form of energy
known as the electrical energy. We use wind turbines to make electrical power, windmills for the
mechanical power and wind pumps for water pumping or drainage. Wind generators have a capacity of
500-‐2000 kW with larger units having a capacity of up to 5000kW or more in off shore areas. Such
systems have high capital costs because of expensive equipment and also a very large maintenance cost
since the generators are complicated to fix, once undergone defects. The operating costs for wind
power generators tend to be low though [4].
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Typical wind generating power systems are capable of an output of 2000 kWh/kWpeak with scalability
problems for systems with output under 50kW. This power is proportional to a third power of wind
speed which is not as good as the power from PV. Power from wind generators is AC and is of variable
frequency. The theoretical maximum efficiency of such systems is about 59% although conversion
efficiency comes at a price. In order for this to be a primary renewable energy resource, the price per
kWh needs to be minimized. Practical efficiencies of modern wind generators vary from 25-‐30% in
contrast to the traditional wind mill’s 5% [4]. This is a very effective form of energy because it produces
no green house gases and uses very little land. Ideally wind generators should have a large diameter and
should be installed in places with high wind speeds and high probability of wind. Their height should be
as much as possible and the temperature of the surroundings should be lower since the density of wind
decreases in such conditions. The numerical relationship between the power and these factors is shown
in equation 3.
𝑃𝑜𝑤𝑒𝑟 = !!×𝜌×𝐷!×𝑣! …..(3)
Where 𝜌 is density (Kg/𝑚!), 𝐷 is diameter (m), 𝑣 is velocity (m/s).
A typical drawback of this technology lies in the faulty gear box of a wind generator. Fast torque changes
cause untypical compression of the gearbox in the axis direction, reducing the lifetime of wind
generators to 7 from the projected number of 15 years. This typical problem is a major topic under
research now. Environmentally, wind generators shed ice in the winter, cause shadowing and noise and
also spoil the pristine looks of the countryside. The exact figures of global wind power capacity and its
growth can be seen in figure 5 and 6.
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Figure 5: Wind power capacity 2011
Image source: Renewables 2011, global status report.
Figure 6: Wind power capacity growth by country Image source: Renewables 2011, global status report.
3.2a) Construction of a Wind farm
Constructing and planning the development of a wind farm requires the successful completion of
several steps listed below.
1) Municipal consultations in which the residents and community of the area around the potential
wind farm are taken into dialogue and kept in constant contact throughout the process.
2) Wind assessment in which engineers and experts use meteorological masts to measure wind
speed and climatic conditions so that an estimation of energy potential can be calculated.
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3) Wind farm design in which engineers are able to model wind flow, turbine performance, sound
levels, design access roads, turbine foundations, local electric network, and connection to the
electricity or smart grid.
4) Environmental study in which assessments mitigate the negative environmental impacts on the
surroundings.
5) Land acquisition in which developers negotiate terms in order to use the land.
6) Permitting and public consultation in which federal requirements and permissions are sought.
7) Economic and financial analysis in which the economic viability of the project is demonstrated.
8) Manufacturing of the wind turbine parts.
9) Site preparation and construction.
10) Commissioning in which the electrical collection network is installed and connected to the
regular or smart grid system.
11) Operation and maintenance
The tower construction is done not only regarding the weight of the nacelle and rotor blades, but also
with regard to the absorption of large static loads which are caused by the different power of the wind.
Examples of tower heights:
• hub height 40-‐65 m: approx. 600rated power and approx. 40 to 65 m rotor diameter
• hub height 65 to 114approx. 1.5 to 2rated power and approx. 70 m rotor diameter
• hub height: 120 to 130approx. 4.5 to 6rated power and approx. 112 to 126 m rotor diameter
18 ELEC 590 Smart Grids in Renewable Energy Technology
Figure 7: Working principle of a wind turbine Image source: “Wind Energy”, EcoPlanetEnergy Renewable Energy Resources, http://www.ecoplanetenergy.com/all-‐about-‐eco-‐
energy/overview/wind/.
For wind turbines with higher power, doubly-‐fed asynchronous generators are the ideal choice. The
operating rotation speed can be changed, unlike when using the more conventional asynchronous
generators. Another option could be using the synchronous generators. A connection to the smart grid
system of synchronous generators is only made possible with the help of transformers, because of the
behavior of fixed rotation. The control system is complicated but it is offset by the overall efficiency and
better grid compatibility.
3.3 Biomass power
By using thermal and chemical conversion processes, biomass can be converted into bio fuels and other
forms used as a resource of renewable energy. Biomass is usually used for the production of power
and/or heat, and a part of it is transformed into liquid bio-‐fuel which is used for transportation. The
technologies that are used for generating electricity from biomass include direct firing or co-‐firing (with
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coal or natural gas) of solid biomass, municipal organic waste, bio-‐gas, and liquid bio-‐fuels. Typical
sources of bio-‐mass energy are ethanol, pulp and residues of paper industry, wood and forest residues.
The global production of ethanol and biodiesel can be analyzed from the plots below in figure 8.
Figure 8: Production of ethanol and biodiesel Image source: Renewables 2011, global status report.
3.3a) Construction of a Biomass Power plant Biomass energy is generated by a properly defined method hence outlining a general map of a biomass
power plant. Typically when constructing a biomass power plant, a few process and sections need to be
defined:
• Fuel feeding systems
• Combustion technology
• Boiler systems
• Plant control
A biomass power plant will only be efficiently put to use if there is mechanism of constant supply of fuel.
After a thorough analysis of the available fuel by looking at its moisture content, grain size and specific
20 ELEC 590 Smart Grids in Renewable Energy Technology
density is it decided which feeding system is to be used. Typically, underfeed stoker, multiple shaft
screws, flap-‐gate locks, hydraulic fuel feed and pneumatic blow in equipment are a few choices. The
next step is to decide on which combustion technology is to be used because this determines efficiency
and effectiveness of the plant, its performance and longevity, its emission levels and profitability. The
efficiency of the combustion system is determined by the fine-‐tuning of combustion chamber by
designing its outer surfaces (cool or uncool), optimized position of the fuel feeding system and burning
gate, the delivery and regulation of the combustion air and safe an regular removal of ash. The options
of combustion methods are usually in feed grate combustion, ring burner, under-‐freed and blow in
combustion. Boiler systems are application specific. Various types of boiler systems using water, steam
or thermal oil as the heat transfer medium are usually the options. Control and error analysis of the
power plant is done with the help of field devices that can be placed throughout the plant for the
execution of command functions, taking measurements and reporting on conditions. There are also
cabinet devices which are integrated in a central electric control box for receiving measurement
information, making and processing system queries and sending out commands [6].
Figure 9: Biomass power plant Image source: http://www.lambion.de/en/biomasse-‐kraftwerke/anlagenbau/waermeverteilung-‐kwk.html.
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3.4 Hydroelectric power Hydroelectricity is a form of renewable energy that generates electricity from hydropower. It uses the
principle of the gravitational force of the falling or flowing water. It accounts for almost 16% of the
global Generation processes and it’s also expected to increase by 3.1 % each year for the next 25 years
[3]. Hydropower is converted into electricity by different ways and some include:
• Conventional hydroelectric systems in hydroelectricity dams
• Run of the river hydroelectricity that uses the kinetic energy of the rivers and streams
• Small hydro projects having no artificial reservoirs (Typical output is 10 MW)
• Micro hydro projects supply electricity to homes, villages or isolated industries
• Conduit hydroelectricity projects which use the water that has already been directed for use
elsewhere
• Pumped storage hydroelectricity that stores water pumped in times of low demand in order to
be used for power purposes when the demand is high
All the projects of generating electricity mentioned above follow a simple mathematical formula of
which states the amount of power available from falling water and this relationship can be described by
the equation:
𝑃 = ƞρ𝑄𝑔h P is the power in watts ƞ is the efficiency of the turbine ρ is the density of water in kilograms per cubic meter Q is the flow in cubic meters per second g is the acceleration due to gravity h is the height difference between inlet and outlet
22 ELEC 590 Smart Grids in Renewable Energy Technology
3.4a) Construction of a hydroelectric power plant
Figure 10: Hydroelectric power plant and a wind turbine Image source: http://en.wikipedia.org/wiki/File:Hydroelectric_dam.svg
Image source: http://ga.water.usgs.gov/edu/graphics/hydroturbine.jpg
The typical layout of a hydroelectric dam and a wind turbine can be seen in figure 10. The main
components of a hydro electricity power plant are:
• Area • Dam • Reservoir • Penstock • Storage tank • Turbines and generator • Switchgear and protection
The area chosen to build the power plant has sufficient and unimpeded flow of water with suitable
topography to build a dam. The main function of the dam is to control the flow of water in a way that it
can be reserved for power purposes in the reservoir. The reservoir saves the water for the turbines to
generate electricity of it. The penstock is a pipe that connects the dam and turning blade and its main
23 ELEC 590 Smart Grids in Renewable Energy Technology
job is to increase the kinetic energy of the water by maintaining a high pressure. A storage tank is only
used in an emergency situation when the pressure of water is lower and it is directly connected to the
penstock. After this, the water falls onto the turbines which convert kinetic energy of the water into
mechanical energy which is converted into electrical energy with the help of the generator. The control
equipment of the power plant includes circuits, instrumentation for warning, control devices connecting
to the main board. After the generation of electricity at low voltage, a step up transformer is used to
provide a voltage of 132KV, 220KV and 400KV as per requirement.
3.5: Emerging renewable energy technologies
3.5a) Geo-‐thermal energy
Figure 11: Geothermal power plant Image source: http://www.geothermie.de/
The Geothermal energy is generated and stored in the earth. Geothermal energy originates from the
formation of the planet itself and from the radioactive decay of the minerals and works by the principle
of the geothermal gradient. In flash geothermal conversion process, higher temperature geothermal
sources (>180°C) are used. Because of the pressure difference between the subsurface environment and
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the Earth’s surface, water exists as a liquid at higher temperatures. The water with high temperature
and pressure is brought to surface, entering a low pressure chamber ultimately flashing into steam. The
pressure created by the steam channels through a turbine, spinning to generate electrical power. Also,
when a liquid is heated into a vapor, the pressure drives a turbine. When temperatures are too low for
‘flash’ water in a binary system, the heat of water needs to be transferred to a separate liquid having a
lower boiling temperature called the ‘working fluid’. When hot geothermal water comes up to surface
from deep underground, it runs through a ‘heat exchanger’ transferring the heat from the geothermal
water to the liquid working fluid. Because this working fluid has low boiling point, it vaporizes rapidly
with less geothermal heat, and the vaporization in turn produces enough pressure to drive a turbine.
3.5b) Ocean wave energy
Ocean wave is used as a resource of renewable energy when the energy transported by ocean surface
waves is captured for generating electricity. There are several modern methods that are used for
converting this energy into electricity mainly named as:
• Point absorber buoy
• Surface attenuator
• Oscillating water column
• Overtopping device
When using point absorber buoys, the device floats on the surface of the ocean attached to cables
which keep it in place by a connection to the seabed. These buoys mainly make use of the rise and fall of
swells for driving hydraulic pumps in order to generate electricity. The surface attenuator acts in a
similar fashion to point absorber buoys, but it has multiple floating segments which are connected to
each other oriented perpendicularly to incoming waves. The swells then create a flexing motion that
25 ELEC 590 Smart Grids in Renewable Energy Technology
drives hydraulic pumps in turn generating electricity. The oscillating water column devices can be either
be located on shore or in deeper waters offshore with an air chamber incorporated into the device in
which the swells compress air in the chambers ultimately forcing air through an air turbine to generate
electricity. Overtopping devices are longer and use wave velocity to fill a reservoir to a higher water
level when compared to the surrounding ocean. The potential energy in the reservoir height is then
captured with low-‐head turbines. These devices can be either on shore or floating offshore.
Figure 12: Idea of ocean wave energy Image source: http://www.seabased.com/
26 ELEC 590 Smart Grids in Renewable Energy Technology
3.5c) Tidal energy
Tidal power is a type of hydropower in which the energy from the tides is converted into power that is
used for generating electricity and other useful forms. This is an important form of renewable energy
because tides are more predictable and provide a more stable resource of energy, currently at a high
cost because of limited choices of sites that offer high tidal ranges and flow velocities, tidal energy is
expected to be more readily available as this technology matures with time. There a number of
methods to generate tidal power:
• Tidal stream generator • Tidal Barrage • Dynamic tidal power • Tidal lagoon
In a tidal stream generator, the kinetic energy of the tides is used to power a turbine which generates
electricity. The tidal barrage uses the potential energy in the difference of height between high tides and
low tides. The potential energy is stored by the use of specialized dams and then converted to
mechanical energy which is then turned into electrical power with the help of generators. Dynamic tidal
power, a relatively new method is still untested and is based upon the idea of using interaction between
kinetic and potential energies of tidal flows. A tidal lagoon consists of circular walls that are embedded
with turbines which capture the potential energy of tides and convert it into electrical power. The only
difference between this system and tidal barrages is the absence of an already existing ecosystem.
3.5d) Innovative renewable energy technologies
Tidal energy can be divided into two main techniques; generating energy from tidal stream and tidal
range. Tidal stream uses fast flowing tidal currents generally found in constrained channels. Tidal range
uses high and low tides found in estuarine areas. In energy generated from marine biomass, we use
micro-‐algae cultures to produce bio fuels.
27 ELEC 590 Smart Grids in Renewable Energy Technology
Figure 13: Working principle of Reverse Electro Dialysis
Image source: “Reverse Electrodialysis technology”, REAPower, http://www.reapower.eu/project-‐scope/reverse-‐electrodyalisis-‐technology.html
Salinity gradient energy can be produced by Reverse Electro Dialysis (RED) and Pressure Retarded
Osmosis (PRO). The processes can be seen in figure 13 and figure 14 respectively. In RED, fresh water
and saline water is kept separate using a selective ion membrane in the presence of alternating cathode
and anode exchange membranes.
Figure 14: Working principle of Pressure Retarded Osmosis
Image source: http://newenergyandfuel.com/http:/newenergyandfuel/com/2008/12/05/osmotic-‐energy-‐potential/ .
The chemical potential difference between the salt and fresh and water then generates a voltage over
each membrane and the system has a total potential equal to the sum of all the potentials. PRO has a
28 ELEC 590 Smart Grids in Renewable Energy Technology
similar working principle but in this case the difference between water potential of fresh water and salt
water corresponds to a pressure of 26 bars which is equivalent to a hydraulic head 270 meters high and
electricity is produced from it [7]. The Geothermal energy is also a form of renewable energy resource in
which electricity is generated and stored in the earth. Geothermal energy originates from the formation
of the planet itself and from the radioactive decay of the minerals and works by the principle of the
geothermal gradient.
Chapter 4: Feasibility study on renewable energy technologies
Power Plant Type
Nominal Capacity
kW
Overnight Capital Cost
($/kW)
Fixed O&M Cost
($/kW) Plant Life
Construction Time (Years)
Fuel Cost Per
MWH Capacity Factor
Advanced PC Single Unit* Coal 650,000 $3,167 $35.97 40 4 2.44 80% Conventional
NGCC* Natural Gas 540,000 $978 $14.39 30 3 3 55%
Dual Unit Nuclear
Uranium
2,236,000 $5,335 $88.75 60 7 3.00 94%
Biomass CC* Biomass
20,000 $7,894 $338.7
9 30 4 0 80%
Biomass BFB* Biomass
50,000 $3,860 $100.5
0 30 4 0 80% Onshore Wind Wind 100,000 $2,000 $28.07 20 1 0 30% Offshore Wind Wind 400,000 $4,500 $53.33 20 1 0 40% Solar Thermal Solar 100,000 $2,500 $64.00 25 1 0 25%
Small Photovoltaic Solar 7,000 $2,500 $26.04 25 1 0 15%
Large Photovoltaic Solar 150,000 $1,600 $16.70 25 1 0 17% Geothermal – Dual Flash
Geothermal 50,000 $5,578 $84.27 40 4 0 80%
Geothermal – Binary
Geothermal 50,000 $4,141 $84.27 40 4 0 80%
Hydro-‐electric Hydro 500,000 $3,076 $13.44 80 4 0 50% Pumped Storage Hydro 250,000 $5,595 $13.03 80 4 0 60%
Table 2: Characteristics of power plants [17]
• Advanced PC single unit stands for Pulverized coal power plant.
29 ELEC 590 Smart Grids in Renewable Energy Technology
• NGCC stands for National Gas Combined Cycle plant
• Biomass CC stands for Combined Cycle plant
• BFB stands for Bubbling Fluidized Bed
The values recorded suggest that wind power stations normally have the ability to supply the highest
nominal capacity available followed by hydro power stations. In terms of nominal capacity, geothermal
stations are the least feasible option because of the way the technology operates. The overnight capital
costs depict that Biomass power stations are the most expensive to build followed by geothermal power
stations. The cheapest overnight capital costs make large photovoltaic systems the most feasible option.
Overnight capital costs are usually just a factor of comparison since this cost does not include any
possible interest rates and money value. The operation and maintenance costs follow a trend that is
very similar to the overnight capital costs. Biomass and geothermal power stations have the highest
operation and maintenance costs whereas solar and hydro power stations have the least. This cost plays
a great role in the decision making process of selecting which renewable energy technology might be
the most feasible option. Hydro and geo thermal power stations are recorded to have the highest plant
life whereas solar and wind power stations have the lowest plant life.
The plant life of a power station normally does not play a huge part in the feasibility of a renewable
energy technology unless there is a drastic difference to its counterpart’s because usually the typical
energy costs and operation and maintenance costs are able to offset this value. Photovoltaic and wind
power plants are the fastest to construct when compared to other construction times. This is a huge
advantage because associated project costs are kept to a minimum as well. When compared to
conventional power plants, all renewable energy power plants provide the advantage of having no fuel
costs based on the working principle which becomes the main reason of a shift from conventional to
renewable sources of energy. The capacity factor values suggest that biomass and geothermal power
30 ELEC 590 Smart Grids in Renewable Energy Technology
stations are the most feasible options because solar and wind power stations provide a very low value.
The reason or this is the resource that is being used. Wind and solar power can vary greatly from initial
predictions but biomass and geothermal resources remain rather constant. This is a very important
factor in the decision making process as it shows the actual operating capacity of a power plant as
opposed to its predicted or theoretical counterpart.
Chapter 5: Designing a smart grid system
The main purpose of installing smart grid projects is to manage, monitor and control the generation,
transmission and distribution of electrical energy. These systems are able to distribute power generation
from renewable sources of energy and maximize profits from asset utilization and an efficient
management system. Driving forces of developing smart grid projects all over the world include
reliability and improved power quality, asset management, renewable energy, customer satisfaction,
energy efficiency, and emissions reduction. Smart grid projects are best suited for provinces that have
economic importance and have a high electricity demand for example industrialized cities with a
customer base consisting of households, businesses, industries, hotels and offices.
A large scale project can be divided into three stages. The first stage (approx. 4 years) usually consists of
planning and launching a pilot project. During the phase, conceptual designs are improved and
implemented followed by feasibility studies to create pilot projects for demonstration. The second stage
(approx. 4 years) is composed of large scale expansion. During this phase, renewable energy systems are
developed and upgraded and the old equipment is moved to other areas for possible usage. The new
systems are implemented and connected for smooth transition and operation of the new smart grid
technology. The third stage (approximately 4 years) is power quality and service efficiency
31 ELEC 590 Smart Grids in Renewable Energy Technology
improvement. During the phase, a large scale expansion to cover all the areas in the plan is carried out
in order to ensure the optimization of service efficiency.
Equipment required for the completion of the project [8]:
• Installation of the Smart meter 116,308 Sets
• Installation of the Energy Storage System 2 Units
• Installation of the Mobile Workforce 1 Unit
• Installation of the Solar Rooftop 3 Units
• Installation of the Substation Automation 3 Stations
• Installation of the IT Integration System 1 System
• Installation of the Electric Vehicle Charging Station
- Quick charging 3 Units
- Normal charging 3 Units
- For EV 1 Unit
• Procurement of the electric vehicle 3 units
- EV Car 2 Units
- EV Bus 1 Unit
32 ELEC 590 Smart Grids in Renewable Energy Technology
Figure 14: Smart grid project
Image source: http://www.fujitsu.com/global/Images/outlook-‐img01_tcm100-‐916953.jpg
5.1 Outcomes of integrating renewable energy and smart grid systems
The cost of meter reading, connecting and disconnecting is reduced. Since there is electricity’s
transgression, reduced non technical Loss, low cost of current coil, loss of voltage coil and reduced non
technical loss, there is reduced loss of revenue. The investment requirements of additional electrical
capacity are also significantly lower since the overall system’s peak load is reduced. The power would be
sold more readily and there would be lower outage costs since the reason and fault for electricity failure
can be immediately spotted with the help of the new system. This way there is also reduced cost of
operation and maintenance.
33 ELEC 590 Smart Grids in Renewable Energy Technology
Because of such projects, installations will get a better insight into how the energy storage and testing
strategies can be improved along with providing opportunities for supplying other services such as the
energy information services. Since the new system is more automated and easily accessible, customers
will be able to keep track of their electricity usage by themselves in order to help them economize and
also enabling the state departments of electricity to introduce systems such as prepaid metering.
Project location Operational Since Comments
Enel, Italy 2008 378,000 energy customers are
catered for. [9]
Pecan Street Inc. Austin, Texas 2003 Caters 1 million consumers and
43000 businesses. [10]
Xcel Energy, Boulder, Colorado 2008 Installed 23,000 smart electric
meters. [11]
Hydro One, Ontario 2008 Serves more than 1.3 million
customers. [12]
Model city of Mannheim 2012 Uses Broadband Power Lines.
[13]
Adelaide, Australia -‐ 7000 electricity smart meters.
[14]
Evora, Portugal 2010 Supports an entire world
heritage site. [15]
Amsterdam smart city 2012 -‐ 2013 10,000 inhabitants of
Amsterdam are supported. [16]
Table 4: Current smart grid projects
34 ELEC 590 Smart Grids in Renewable Energy Technology
Chapter 6: Conclusion and discussion
6.1 Feasibility of renewable energy technologies
Table 3: Typical energy costs
Image source: http://www.ren21.net/Portals/0/documents/Resources/GSR2011_FINAL.pdf
35 ELEC 590 Smart Grids in Renewable Energy Technology
Analyzing the data from both the table 2 in chapter 4 it can be seen that renewable energy power plants
offer the advantage of having no fuel costs. The most viable renewable energy technologies include
solar and wind power since they do not require a lot of capital and there is enough research and
technology that already exists to provide a ready source of technology in association with smart grids.
According to the values recorded as per North America, Biomass and geothermal power plants have the
highest capacity factor which independently would make them the most feasible choices. Photovoltaic
power plants have the least capacity factor. On the contrary to the capacity factor values, photovoltaic
and hydroelectric power plants have the lowest operation and maintenance costs and with biomass
power plants having the highest costs. Since biomass, geothermal and hydroelectric power plants have
complicated and large equipment involved, the construction time for them is about the same and about
4 times longer than that of photovoltaic and wind farms. The overnight capital costs are recorded to be
the highest for geothermal and hydroelectric stations whereas they are the lowest for photovoltaic
power plants. Drawing a conclusion from these feasibility figures, wind and solar power stations will be
the cheapest and fastest options as renewable energy resources. If enough capital was available,
geothermal and hydro power stations would be the ideal solutions.
As it can be seen from table 3 above, biomass and geothermal power plants provide excellent power
capacity and hence would be the most efficient ones if connected with a smart grid. Since the initial
capital required for these power plants is very high and relatively less related technology is available,
these resources can only be used if economies are strong enough and can spare the capital to erect
biomass and geothermal power plants. If that is the case, the power capacity produced would be
significantly higher and the power plants used in collaboration with the smart grids would last much
longer. This can be proven by the typical energy costs in table 3. The energy costs for geothermal and
36 ELEC 590 Smart Grids in Renewable Energy Technology
biomass power are recorded to be the least while for solar and wind power they are recorded to be the
highest.
6.2 Future of integrated smart grid technology with renewable energy
The installation of smart grid systems is a perfect solution to the world energy crisis. The new system is
efficient, automated, more reliable and most of all, capable of integrating all renewable energy
resources together. Since such projects improve the prospect of these resources to be used more
efficiently, the energy costs of each renewable resource are likely to decrease as well. For example, the
solar energy costs are predicted to decrease to 6-‐25c/kWh from 25-‐125 c/kWh, biomass costs are likely
to decrease to 4-‐10 c/kWh from 5-‐15 c/kWh. Similarly, wind energy costs are likely to come down to 3-‐
10 c/kWh from 5-‐13 c/kWh with geothermal energy costs reducing to 2-‐8 c/kWh from 2-‐10 c/kWh.
These systems are likely to become more main-‐stream in the near future as the investment trends
suggest. In 2010, 211 billion dollars was the global investment in renewable energy which shows a 32%
growth from the investment in the previous year. Wind power showed a growth of investment of 30%,
solar power showed a growth of 52% and geothermal a growth of 44% in just one year with Europe and
North America taking the lead.
6.3 An ideal system integrating smart grid and renewable energy technology
The working principle of smart grid technology can be seen in chapter 2. Now that the technology is
receiving more attention, the number of applications that can be used on the smart grid after the data
communications technology is instilled and deployed is increasing with growth as fast as inventive
companies are capable of creating and producing them. The advantages of using the smart grid
technology includes improved cyber-‐security and handling sources of electricity coming from wind, solar
power, biomass, hydro and other forms of renewable energy. The companies and corporations that are
37 ELEC 590 Smart Grids in Renewable Energy Technology
making smart grid technology offering the services mentioned above include long term technology
giants, established communication firms and even fresh technology firms. Due to the incorporation of
smart gird technology into the electricity network, we have several things to gain out of it and some of
them are listed below:
• Self-‐recovery from events causing power hindrance
• Enabling active participation by consumers in demand response
• Resilience of operation against physical and cyber attacks
• Delivering improved power quality to meet the needs of 21st century
• Introducing and accommodating numerous generation and storage options
• Mitigating the effects of power fluctuation of various renewable energy resources
• Combining the output and renewable and nonrenewable resources of energy
• Enabling new products, services, and markets
• Optimizing assets and operating efficiently
The construction requirements and procedure of each type of renewable energy power station can be
seen in chapter 3. Solar power in combination with all the other forms of renewable energy that exist
today can result in feasible energy systems. Integration of major renewable energy resources through
the use of smart grid systems utilizes the topography of earth efficiently and cuts transmission costs and
losses of electricity. Such systems can compose of PV systems in areas where sun is abundant,
hydroelectric power in areas that can support dams, wind power in regions where the wind speed and
probability is high, geothermal and biomass power where the resources are enough to operate and
maintain the technology. Chapter 5 describes and explains a model system that integrates renewable
energy technologies and smart grid system together successfully. As it can be seen from table 4 in
38 ELEC 590 Smart Grids in Renewable Energy Technology
chapter 5, this technology has already been implemented in certain parts of the world. This table also
highlights who leads the current projects.
39 ELEC 590 Smart Grids in Renewable Energy Technology
Chapter 7: References
[1] Nathan S. Lewis and Daniel G. Nocera, “Powering the planet: Chemical challenges in solar energy utilization”, PNAS vol.103
no.43, pages 15729-‐15735, October 24, 2006.
[2] IEA publications, “World energy outlook 2006”, Chapter 15 energy for cooking in developing countries, 2006.
[3] REN21 publications, “Renewables 2011 Global Status Report”, 2011.
[4] Prof. Dr. Werner Bergholz, “Expansions from PV systems in 2 dimensions”, Lectures Energy Systems, Jacobs University
Bremen, Fall 2012.
[5] Akira Fujishima, Tata N. Rao, Donald A. Tryk, “Titanium dioxide photocatalysis”, Journal of Photochemistry and
Photobiology C: Photochemistry Reviews, Volume 1, Issue 1, 29 June 2000, Pages 1-‐21.
[6] Lambion energy solutions, “Energy from Biomass”, http://www.lambion.de/en/biomass-‐plants/bio-‐residue-‐technology.html,
retrieved on June 7th 2014.
[7] Statkraft, “OsmoticPower”,http://www.statkraft.com/energy-‐sources/osmotic-‐power/default.aspx, retrieved on 28th Nov
2013.
[8] Power gen-‐Asia, “Smart grid project”, http://www.powergenasia.com/conference/smartmeter.html, retrieved on June 8th
2014
[9] Enel, “Smart cities in Italy”, http://www.enel.com/en-‐GB/innovation/smart_grids/smart_cities/italy/, retrieved on 14th June
2014.
[10] "Building for the future: Interview with Andres Carvallo, CIO — Austin Energy Utility". Next Generation Power and Energy
(GDS Publishing Ltd....) (244). Retrieved 2008-‐11-‐26.
[11] Betsy Loeff (March 2008). "AMI Anatomy: Core Technologies in Advanced Metering". Ultrimetrics Newsletter (Automatic
Meter Reading Association (Utilimetrics)).
[12] Betsy Loeff, Demanding standards: Hydro One aims to leverage AMI via interoperability, PennWell Corporation
40 ELEC 590 Smart Grids in Renewable Energy Technology
[13] "E-‐Energy Project Model City Mannheim". MVV Energie. 2011. Retrieved May 16, 2014.
[14] “Solar city Adelaide”, http://www.sgiclearinghouse.org/Oceania?q=node/2571&lb=1, retrieved on 14th June 2014.
[15] “Evora Smart City”, http://www.inovcity.pt/pt/Pages/homepage.aspx, retrieved on 14th June 2014.
[16] “Amsterdam Smart City”, http://amsterdamsmartcity.com/, retrieved on 15th June 2014.
[16] “US Energy Information Administration”, http://www.eia.gov/, retrieved on 16th June 2014.