Chapter 2

School of EngineeringThermodynamics

Chapter 2: The World Energy System

Dr. Jorge Francisco Estela Uribe

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ThermodynamicsDr. Jorge Francisco Estela

The World Energy System

Primary energy:

Primary energy is the total energy contents of a natural resource. It is the

energy in raw form without any transformation. It is the total energy that is

available for transformation and end use.

Energy carriers:

These are forms of energy between primary energy sources, from which

they are transformed, and the end use forms, to which they are converted.

Energy consumption:

As energy is always conserved, the concept of consumption only means

the transformation of energy to the forms of end use, i.e. energy services.

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Energy flows:

Primary energy

Transformation

Final use

Energy carrier

Reserves Exports Imports

Exports Imports



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Sources of primary energy:

HydroelectricityWindOcean (waves, currents, thermal gradient)Bioenergy

Indirect

ThermalPhotovoltaic

Direct

GeothermalTidal

Uranium (nuclear energy)

Crude oil

Coal

Natural gas

Non-solar

Mineral fuels

SolarFossil fuels

Renewable sourcesNon-renewable sources



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Primary energy, energy carriers and energy systems* :

Uranium

Natural gas

Coal

Crude oil

Nuclear power plantElectricity

Fossil fuel power station

Enthalpy, mechanical work, electricity

Oil refineryLiquid fuelsNon-renewable sources

Energy systems (conversion processes)

Energy carriers

Primary energy sources

* www.wikipedia.org



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Primary energy, energy carriers and energy systems* :

Biomass power stationEnthalpy, electricityBiomass sources

Geothermal power stationEnthalpy, electricityGeothermal energy

Hydropower plant, wave farm, tidal power station

Mechanical work, electricity

Flowing water, tidal energy

Wind farmMechanical work, electricity

Wind energy

Photovoltaic power plantElectricity

Solar energy Solar power tower, solar furnace

EnthalpyRenewable sources

Energy systems (conversion processes)

Energy carriers

Primary energy sources

* www.wikipedia.org



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Who uses energy:



�Those who drink potable water and eat non-raw food.

�Those who need to preserve food and other materials.

�Those who need heating, air conditioning or ventilation.

�Those who need artificial illumination.

�Those who need to travel through long distances.

�Those who need mechanical for their work.

�And those who do not wish or can not put aside all the technological

amenities, gadgets and services of modern society.

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Historical uses of energy per capita*:

* E. Cook, The Flow of Energy in an Industrial Society, Scientific American, September 1971

92025236426440Technological

308569612828Industrial

1044284824Advanced agriculture

48161616Primitive agriculture

20812Stone age

88Primitive

TotalTransportIndustry & agriculture

Home & commerce

Food

Daily per capita consumption, MJPeriod



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International Energy Agency, Key Energy Statistics 2011

0 1 2 3 4 5 6 7 8 9

Energy supply per capita (toe/capita)

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

Hum

an D

evel

opm

ent I

ndex

Quality of Life and Energy Supply

Norway

NetherlandsNew Zeland

Mexico

Portugal

RussiaSaudi Arabia

South Africa

Spain

SwedenSwitzerland

United Kingdom

United States

Argentina

Australia

Austria

Brazil

Canada

Chile

Colombia

Denmark

Egypt

Ethiopia

FinlandFrance

Germany

JapanGreece

China

IndiaPakistan

Haiti

Mozambique

Sudan

Venezuela

Uruguay

Morocco



10/84




0 1 2 3 4 5 6

Energy Supply per capita (toe/capita)

0

10

20

30G

DP

per

cap

ita (

US

D/c

apita

)x10

00

Energy Supply and GDP 2009

OECD

Middle East

Non-OECD Europe & AsiaChina

Latin America

AsiaAfrica

World Average

Wor

ld A

vera

ge

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0 1 2 3 4 5 6

Energy Efficiency (USD/toe)x1000

0

10

20

30

GD

P p

er c

apita

(U

SD

/cap

ita)x

1000

Energy Effciency and GDP 2009

World Average

Wor

ld A

vera

ge

OECD

Middle East

Non-OECD Eurasia ChinaAsia

Latin America

Africa

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Is this really necessary? Is it an excess…?



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Are these really necessary or are they excessive wa ste of energy?



Sustainable energy: why is it so important?

�The supply of energy is essential for the well-being of society.

�The current energy systems have been built around the multiple advantages of the fossil fuels.

�The duration of the fossil fuels reserves is a highly disputed issue, but those are essentially finite and will run out completely.

�The reserves of fossil fuels are concentrated on a relatively few countries, which leads to instability, crises and conflicts.

�The exploitation of fossil fuels entails significant threats to human health due to their extraction, distribution and final use.

�The combustion of fossil fuels produces enormous amounts of greenhouse gases.

Sustainability 14/84

G. Boyle, B. Everett, J. Ramage, Energy Systems and Sustainability: Power for a Sustainable Future, Oxford University Press, 2003.



�There is a sound scientific consensus about the connections between the anthropogenic emissions of greenhouse gases and the unprecedentedincrease in ambient temperatures since the last ice age.

�The increase in global temperatures will severely disrupt agriculture, all ecosystems and the economic system in a generalised scale.

�Nuclear energy does not emit greenhouse gases but its development has been limited by high operating costs and the public concern about the release of radioactive materials, catastrophic accidents, the disposal of radioactive wastes and the proliferation of materials for nuclear weapons.

�The efficiency of the conversion of energy from resources down to the energy services is very low and the cost of those services is very low.





�The above two circumstances make the environmental and social effects

of the energy systems larger than what those should really be.

�The renewable energy sources are based on energy flows, not on energy

stocks, and are expected to play a much larger role in the future.

�The environmental and social impacts of the renewable energy sources

are, in general, smaller than those from the conventional sources.

�However, there are other constraints for their widespread use such as

their intermittence and limited availability, the lack of a global infrastructure

for their distribution and use and the high costs for the end user.




2136

Transport: 2284

3 70 52 23 11 644 186 690 433 147 618 1000

Industry: 2282 Res., Comm., Agr.: 3040

Oil: 3987

Coal:3300

Natural Gas:2540

Nuclear:703

Hydraulic:280

Biofuels, Waste: 1238

Others:102

Liquid fuels: 3874

31 236 2139 1006 703 280 94

Consumption for electricity/heat: 4591

Conversion losses: 2641 1950

102

37

553

Non

-ene

rgy:

747

Total Primary Energy Supply and Consumption by Sect ors 2009TPES: 12150 Mtoe; TFC: 8353 Mtoe; Total Losses: 379 7 Mtoe

842441310

136

330

20

51

206

26964 237


The World Energy System 17/84


Primary Energy Energy in Carriers Consumption by Sectors0

2000

4000

6000

8000

10000

12000

Mto

eTotal Primary Energy Supply and Total Final Consumption 2009

Oil

Coal

Natural Gas

Nuclear

Biofules/WasteH

ydra

ulic

Oth

ers

Liquid fuels

Electricity/Heat

Losses in

conversion and

transmission

Transport

Industry

Residential,Commercial,Agricultural

12150

8353

3797

Coal

Biofuels/Waste

Natural Gas

Non-energy



Petroleum:

1. www.wikipedia.org

2. G. Boyle, B.Everett, J. Ramage, Energy Systems and Sustainability, Power for a Sustainable Future, Oxford University Press, Oxford, 2003.

Petroleum is a naturally occurring complex flammable liquid mixture of hydrocarbons and other organic compounds [1].

Petroleum was formed by the decomposition, under high temperature and pressure in sedimentary rocks, of marine organisms, i.e. zooplankton and algae [2]. Thus, petroleum is currently found in sedimentary basins where marine sediments accumulated over time (the Middle East, the Gulf of Mexico or the North Sea).

Petroleum is converted into useful products by distillation (fractioning), i.e. separation by differences in boiling points of the liquid components. Those products are complex blends suited to particular commercial uses.




Broad composition by fractions and uses*:

* www.wikipedia.org

Waxes, asphalts26 – 35Asphaltenes

Fuel oil, lubricating oil, marine diesel

17 – 25Heavy distillate

Diesel fuel, kerosene, jet fuel

Nonane -Hexadecane

9 – 16Medium distillate

GasolinePentane - Octane5 – 8Light distillate

Gaseous fuels, petrochemicals

Methane - Butane1 – 4Petroleum gases

UsesHydrocarbonsCarbon atoms

Fractions



Conventional and non-conventional petroleum*:

* G. Boyle, B.Everett, J. Ramage, Energy Systems and Sustainability, Power for a Sustainable Future, Oxford

University Press, Oxford, 2003.

Petroleum that is obtained by the natural pressure of an underground reservoir is called conventional oil. Conventional oil is extracted by two methods and applies to roughly half of the petroleum reserves:

�Primary recovery: applies when the pressure of the reservoir is sufficient to drive the crude oil to the surface.

�Secondary recovery: the pressure of the reservoir has to be increased by the injection of natural gas or water.

Non-conventional petroleum applies to oil extracted by tertiary recovery (with high-pressure natural gas or CO2 to recover the remaining crude in the reservoirs) or from all other sources, i.e. shale oil, tar sands and heavy oil.



The World Energy System - Petroleum 22/84







Coal:


Coal is a combustible black or brownish-black sedimentary rock usually

occurring in layers called coal beds or coal seams [1]. Coal is composed

primarily of carbon, hydrogen, oxygen, nitrogen and sulphur.

Coal was formed by the decomposition, under high temperature and

pressure and in the absence of oxygen, of dead vegetation. This is why

coal deposits are widely spread in the world.

According to its heating value (heat released in combustion) and contents

of volatiles, coal is classified in ranks. In ascending order of heating value,

these are: peat, lignite, sub-bituminous, bituminous and anthracite.




The World Energy System - Coal 27/84





Natural Gas:


Natural gas is a naturally occurring hydrocarbon mixture, primarily

composed of methane, other hydrocarbons (ethane up to octane), nitrogen,

carbon dioxide and hydrogen sulphide [1].

Natural gas is found in deep underground formations or associated with

coal seams and petroleum deposits. Natural gas is created either by two

processes: a biogenic process (decomposition) of organic material in

shallow sediments, or by thermogenic process at great depths.

Before use, natural gas has to undergo extensive treatment to remove

undesirable components, such as nitrogen, carbon dioxide and hydrogen

sulphide.




The World Energy System – Natural gas 31/84




The World Energy System – Natural gas





Nuclear energy:


Nuclear energy results from the sustained use of the energy released by

nuclear fission to generate electricity and heat [1].

In nuclear fission, the nuclei of heavy atoms (i.e. Uranium-235) split into

lighter nuclei and free neutrons. As the combined mass of the fission

products is slightly smaller than that of the original nucleus, the mass

defect is converted into energy in the form of photons (gamma radiation)

and kinetic energy of the products. The kinetic energy is transformed into

thermal energy, which is then used to generate electricity in a power cycle.

The released neutrons hit other nuclei causing their fission. Thus, a chain

reaction is established so that a sustained nuclear energy operation is

possible in practice.



Nuclear energy:


Nuclear energy has always been a controversial issue. Its is an important

component of the world energy system for it produces about 7 per cent of

the world primary energy supply and about 14 per cent of the electricity [1].

The advocates of nuclear energy claim it is a sustainable form of energy for

it does no release greenhouse gases, but the processing of uranium

minerals do have important environmental impacts. The opponents sustain

that nuclear energy poses serious threats to human health and the

environment. Those threats come from the accidental release of

radioactive materials and from the very important issue of the disposal of

used nuclear fuels. There are also the security concerns as nuclear

reactors can be used to produce radioactive materials for weapons use.



Nuclear reactors:


About 80 per cent of reactors use light water as moderator. Three quarters

of those are pressurised water reactors [1].

Pressurised water reactors (PWRs): the reactor core is in a high-pressure

vessel is cooled by a primary circuit of pressurised water. The primary

water transfers heat to a secondary circuit in a steam generator. Then, the

secondary water drives the power cycle.

Boiling water reactors (BWRs): they are PWRs but water boils directly in

the pressure vessel. Therefore, these are simpler and safer than PWRs.

Other technologies include the pressurised heavy water reactor (PHWR),

the gas cooled reactors (GCR) and a number of experimental designs.




The World Energy System – Nuclear energy 38/84





Hydroelectricity:


Hydroelectricity is electricity generated by hydropower, i.e. from the potential energy of water falling through a difference of elevation. This is the second largest source of renewable energy, accounting for about a sixth of the world’s electricity generation [1].

The technologies are: the conventional dams; pumped storage (at times of low demand, water is pumped to higher elevations to be used at times of high demand) and run-of-the-river (it does not use a dam and the water is taken directly from the river to the generator).

Hydroelectricity is cheap and does not release carbon dioxide. But it has important environmental impacts because of the disruption of habitats (by the areas that have to be inundated) and the decay of vegetation under water releases methane (a more powerful greenhouse gas than carbon dioxide).




The World Energy System – Hydroelectricity 42/84


The World Energy System – Hydroelectricity 43/84

Renewable energy:


Renewable energy rely on natural processes that are continuouslyreplenished [1]. Apart from the comparatively very small amount of geothermal and tidal energy, ultimately almost all renewable energy forms are transformations from solar energy.

Renewable energy accounts for around 16 per cent of the total primary energy supply and participates with about 19 per cent in the generation of electricity.

Climate change awareness, high oil prices and peak oil are driving a very rapid expansion in investment, development and commercialisation of renewable energy technologies. Those markets are growing at rates far exceeding 20 per cent per annum.

Renewable energy technologies are expected to play quite significant a role in power generation, space heating and transport fuels.



Advantages of renewable energy sources:


�The very fact that they are continuously replenished by natural processes.

�The fact that they are fluxes and not stocks of energy.

�They are considerably more benign in environmental and health impacts

than fossil fuels and nuclear energy.

Disadvantages of renewable energy sources:

� They are intermittent, so that storage technologies are needed.

� Their distribution and availability is very limited because the infrastructure

for distribution and commercialisation is, so far, very limited.

� They remain to be expensive to the end user.




The World Energy System – Solar energy 46/84












The World Energy System – Wind energy 52/84


The World Energy System – Geothermal energy 53/84


The World Energy System – Ocean energy 54/84


The World Energy System – Bioenergy 55/84


The World Energy System – Bioenergy 56/84


Oil and natural gas: why are they so special?

Oil and natural gas comprise half of the world primary energy supply and

consumption because of the following undisputable advantages:

�The are cheap and easily available.

�They are less contaminant than coal.

�They are convenient and easy to use.

�They are easy to distribute, store and transport.

�For many countries, the supply is ensured from domestic production.



British Petroleum, BP Statistical Review of World Energy, June 2011

Oil Natural Gas Coal0

10

20

30

40

50

60

70

80

90

100

Per

cent

age

Regional Distribution of Fossil Fuel Reserves

North America

S&C America

Europe/Eurasia

Middle East

Africa

Asia/Pacific


North America

South & Central America

Europe & Eurasia

Middle East

Africa

Asia Pacific

World Average

0 50 100 150 200 250

Years

Reserves/Production Ratios of Fossil Fuels 2009

Oil Natural Gas Coal

Average Middle East and Africa

British Petroleum, BP Statistical Review of World Energy, June 2011




Environmental and social impacts associated with en ergy sources*:

Effects on landscape and biodiversity, ground water pollution due to fertilisers, use of scarce water, competition with food production.

Biomass

Radioactivity (routine release, risk of accidents, waste disposal), misuse of fissile and other radioactive materials, proliferation of nuclear weapons, land pollution by mining, health effects on uranium miners.

Nuclear power

Global climate change, acid rain, environmental spoliation by open-cast mining, land subsidence due to deep mining, ground water pollution, mining accidents, health effect on miners.

Coal

Global climate change, methane leakage from pipes, methane explosions, gas rig accidents.

Natural gas

Global climate change, air pollution by vehicles, acid rain, oil spills, oil rig accidents.

Oil

Potential impacts and concernsSource

* G. Boyle, B.Everett, J. Ramage, Energy Systems and Sustainability, Power for a Sustainable Future, Oxford University Press, Oxford, 2003.



Environmental and social impacts associated with en ergy sources*:

Sequestration of large land areas (centralised plants), use of toxic materials in manufacture of PV cells, visual intrusion.

Solar energy

Release of polluting gases (SO2, H2S, etc.), ground water pollution by chemicals including heavy metals, seismic effects.

Geothermal energy

Visual intrusion and destruction of wildlife habitat, reduced dispersal of effluents (apply only to tidal barrages).

Tidal power

Visual intrusion in sensitive landscapes, noise, bird strikes, interference with telecommunications.

Wind power

Displacement of communities, effects on rivers and ground water,dams (visual intrusion and risk of accidents), seismic effects, downstream effects on agriculture, methane emission from submerged biomass.

Hydroelectricity

Potential impacts and concernsSource

















CO2 Emissions by Fuel 2009Oil 10643

36.7%

Coal 12470

43%Natural Gas 5771

19.9%

Renewables 116

0.4%

OECD 1204 43%

Middle East 1509 5%

Non-OECD Eurasia 2497 9%

China 6877 25%Asia 3153 11%

Latin America 975 3%Africa 928 3%

28999 x 10 6 ton

CO2 Emissions by Region

28999 x 106 ton



0 1 2 3 4 5 6

Energy Supply per capita (toe/capita)

0

5

10

15C

O2

Em

issi

ons

per

capi

ta (

ton/

capi

ta)

CO2 Emissions and Energy Supply 2009

OECD

Middle East

Non-OECD Eurasia

China

Latin AmericaAsia

Africa

World Average

Wor

ld A

vera

ge




Emissions scenarios:

-0.51.5CO2/TPES

2.00.5TPES/cap

1.00.5Population

Growth scenarios28,99916,95412,045Emissions, Mton/year

12,1506,5825,238TPES, Mtoe

2.3872.532.300Intensity CO2, Mton/Mtoe

1.971.2494.276TPES/cap, toe/cap6,7615,5361,225Population, million

Base line 2009

TotalRest of the world

OECD



Emissions scenarios:

1,650,0231,204,731445,292Released CO2, Mton

3,771,541Accumulated CO2, Mton

482Concentration CO2, ppm

56,52946,7729,757Emissions, Mton/year

3,029,031Stock CO2, Mton

31,30223,4187,885TPES, Mtoe

1.8061.971.237Intensity CO2, Mton/Mtoe

3.852.8135.246TPES/cap, toe/cap9,8288,3251,503Population, million

Projections 2050

TotalRest of the world

OECD



Strategies for the control of atmospheric carbon di oxide*:

•Install CCS systems in 800 large power stations.

•Install CCS systems in carbon gasification plants.

•Install CCS systems in hydrogen production plants for 1500 million vehicles.

Capture and storage of CO 2 (CCS)

•Increase the thermal efficiency from 40 to 60 per cent in 1,600 large power stations (> 1 GW).

•Replace 1,400 large power stations with CCGT.

Power generation

•Increase the fuel economy of 2000 million automobiles from 48 km/gallon to 96 km/gallon.

•Reduce the use of 2000 million automobiles from 16,000 km/year to 8,000 km/year at and average 50 km/h.

•Reduce in 25 per cent the electricity consumption in residentialand commercial uses.

Efficiency of end uses and conservation

Technologies and patterns of useStrategies

*R.H. Sokolow, S.W. Pacala, A Plan to Keep Carbon in Check, Scientific American, September (2006, 28-35.



Strategies for the control of atmospheric carbon di oxide*:

•Stop all deforestation.

•Extend conventional agriculture practices to the whole cultivable land.

Agriculture and forestry management

•Double the generation of nuclear energy to displace carbon consumption.

•Multiply by 40 the generation of wind power to displace carbon consumption..

•Multiply by 700 the generation of solar energy to displace carbon consumption..

•Multiply by 80 the generation of wind power to produce hydrogen for automobiles.•Power 2000 million automobiles with ethanol produced from 1/6 ofthe total cultivable land and biomass with yield of 15 ton/ha.

Alternative energy sources

Technologies and patterns of useStrategies

*R.H. Sokolow, S.W. Pacala, A Plan to Keep Carbon in Check, Scientific American, September (2006, 28-35.



Renewables Share of World TPES 2009

CombustibleRenewables and waste:

10.6%

Hydroenergy:2.2%

Others: 0.5%

Geothermal:0.414%

Solar: 0.039%

Wind: 0.064%

Tide: 0.0004%

Oil

34.3%

Coal

25.1%

Natural Gas

20.9%

Nuclear

6.5%

Renewables

13.1%




Potential resources of renewable energy*:

>2,800

TPES (2009): 500 x 1018 J. TPES (2100): 510 – 2700 x 10 18 J.

Total renewable sources:

>1,600Solar: 10 per cent efficiency of conversion solar radiation.

>20Geothermal: potential of the most promising locations.

>20Tidal: potential of the most promising locations.

>630Wind: 35 per cent of the potential in continental areas and coastal waters.

70Hydroelectricity: equivalent to half of the energy of all the rivers in the world.

>440Biomass: equivalent of 35 x 109 ton/year.

Potential, 10 18 J/yearSource

* Intergovernmental Panel on Climate Change, Third Assessment Report, 2001



Renewable energy scenarios:

As of 2009, all renewable sources (hydroelectricity, biofuels, waste and others) accounted for 13.3 per cent of the world TPES.

International Energy Agency: Scenarios to 2030

�Current Policy Scenario: All renewable sources would increase to 14.2 per cent.

�450 Policy Scenario: All renewable sources would increase to 22.1 per cent.

British Petroleum: Scenario to 2030

It foresees the doubling of the percentage of renewable energy in the TPES.

US Energy Information Administration: Scenario to 2035

It also foresees the doubling of the share of renewable energy in the TPES.

Royal Dutch Shell: Scenario to 2050

It foresees that renewable energy would account around 25 to 30 per cent of TPES.



The hydrogen economy:

It means the proposed extensive use of hydrogen as an energy carrier. Hydrogen does not occur freely in nature. Therefore, hydrogen is not a primary energy source, it is an energy carrier.

Hydrogen is produced basically by reforming of natural gas. It is also produced by electrolysis of water and by biotechnological processes involving algae and micro organisms.

Hydrogen is currently used for: petroleum refining (hydrocracking), the production of ammonia, methanol and hydrochloric acid, the hydrogenation of vegetable oils, the reduction of minerals, the treatment of metals, welding in reducing atmosphere, cooling of generators and for rocket fuels.

As the production of hydrogen is an energy expensive process, the feasibility of the hydrogen economy depends on coupling it with a zero- or low-emission energy source.



Technological challenges for the hydrogen economy:

Production:

If it is produced by reforming of hydrocarbons, it has to be coupled with CCS systems. If it is produced by electrolysis of water, the electricity must come from zero-emissions sources.

Storage in vehicles:

The mass energy density of hydrogen of 120 MJ/kg is much higher than that of gasoline (46 MJ/kg). But, due to its very low molar mass, the hydrogen volume energy density (10 MJ/m3) is much smaller than that of gasoline (35000 MJ/m3). Therefore, it has to be used either as compressed gas (∼70 MPa) or as cryogenic liquid (∼-253°C), but both processes would consume up to 30 per cent of the carried energy. The use as metallic hydrides, that solve the problem of volume storage, would otherwise impose heavy penalties in terms of weight and cost.



Hydrogen economy based on fossil fuels:

Fuel cells

Gas turbines

Liquefaction

Hydrogen from reforming ofnatural gas

CO2 capture

Geologic storage

Gas turbines

Homes,industry,transport

Gaseous hydrogen

Liquid hydrogen

Natural gas

CO2

Electricity

Reforming: CH4 + 2H2O → CO2 + 4H2


Natural gas wells


Solar and nuclear hydrogen economy:

Fuel cells

Gas turbines

Liquefaction

Homes,industry,transport

Gaseous hydrogen

Liquid hydrogen

Electricity

HydroelectricityWindPhotovoltaicWavesNuclear

Hydrogen from electrolysis



Energy sustainability: how to achieve it*:

To achieve a sustainable world energy system, the following is needed:

To develop much improved technologies for the exploitation and use of

fossil and nuclear fuels with much lower environmental and social impacts.

To significantly develop and implement renewable energy technologies in a

significantly greater scale.

To significantly improve the efficiency of the conversion, distribution and

end use of energy and change the patterns of use of energy.




More sustainable fossil fuels*:

Improve the efficiency of combustion:

�Highly efficient combined-cycle gas turbines (CCGT, IGCC).�Combined use of heat and power (co-generation).�Improved heating systems and appliances.�More efficient internal combustion engines.

Reduce the combustion emissions:�Removal of sulphur dioxide.�Smaller emissions of nitrogen oxides and particulates.�Capture and storage of carbon dioxide (CCS).

Non-combustion conversion of energy:�Fuel cells.




Technology perspectives for energy sustainability*:

Transforming the energy services:

�Improved energy efficiency in buildings, industry and vehicles.

Transforming the energy supply:

�Advanced combustion and CCS.

�Generation of electricity from natural gas and nuclear energy.

�Generation of electricity from renewable sources.

�Use of biofuels and hydrogen fuel cells in vehicles.

Transforming the electric system:

�Advanced storage technologies for intermittent renewable sources.

�Integration of power transmission and telecommunications.

* International Energy Agency, Energy Technologies Perspectives; Energy Technologies for a Sustainable Future, 2005 .



Conclusions:

�The world energy system is the largest and most complex industrial operation in the world. This is so because energy is essential for our civilisation.

�Although we cannot dispense with the energy supply, the world energy system has significant environmental impacts and threats to human health.

� Due to the undeniable conveniences of fossil fuels, about 80 per cent of the world energy system relies upon the use of these fuels. Climate change results from the carbon dioxide emitted by combustion of coal, oil and natural gas. The increase in temperatures, the raise of sea level and changes in rain patterns will affect all aspects of human life by the second half of the century.

�A shift to extensive use of low-emissions renewable energy sources is the only solution to mitigate in the medium term the effects of climate change. A number of promising technologies are well identified, but much more research and investment is needed to progress towards the extensive commercialisation of renewable energy.


Chapter 2

Technology

supply of energy

energy carriers

energy consumption

energy services

flow of energy

world energy system784

world energy system584

world energy system1284