Energy production & consumption

Energy production & consumption Data collection and presentation by Carl Denef

Energy is the physical entity indispensable for performing work. It comes in different forms: mechanical, kinetic, thermal, radiative, electric, magnetic, chemical, nuclear, gravitational and others. Energy can be transformed to different forms at various efficiencies. An energy source can also be called a fuel.

All natural energy on earth comes from the radiative energy of the sun, heat in the earth’s mantle (geothermal energy), and gravity. About 0.01% of solar energy is converted to plants. Over millions of years residues of living matter have been transformed under the soil and the sea to fossil hydrocarbon energy in the form of coal, oil and natural gas. These energy sources are limited and not renewable. Potential energy in it is transformed to usable power by burning. The rest products are greenhouse gasses, causing global warming and climate change.Energy can also be converted directly from solar radiation, gravity, the Earth crust and living plants by human technology (wind, solar, hydroelectric, geothermal and biomass power). These energy forms are renewable. In addition, the Earth crust contains uranium and thorium isotopes, that release high amounts of heat energy upon nuclear fission. Human-made hydrogen can also become a sustainable source of energy in the future.

© picture: WWF-Canon / Edward Parker

2What is energy ? Where does it come from?

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© picture: WWF-Canon / Edward Parker

One of the units of measurement of energy is the Joule (J). It is a measure of the capacity or power to generate work, such as locomotive work in a combustion motor of a car, light generation by electric power, electricity generation in a turbine by wind power etc. Another unit, called Watt (W), is the power which in one second of time gives rise to 1 joule of energy 1 W = 1 J/sec 1 kilowatt (kW) = 1000 J/sec 1 megawatt (MW) = 106 J/sec 1 gigawatt (GW) = 109 J/sec

1 terawatt (TW) = 1012 J/sec

Amounts of energy can also be expressed in terms of its flow over time during power conversion, with as unit the Watt.sec 1 W.sec = 1 J 1 kW.hour (kWh) is the energy flow with a power of 1 kW sustained during 1 hour 1 kWh = 1000 x 3600 = 3.6 x 106 J = 3.6 MJ 1 kWyear (1kWy) = 1000 x 3600 x 24 x 365 = 31 536 000 000 J or 1 J = 31.71 x 10-12 kWy = 31.71 x 10-21 TWy In the slides that follow energy capacity is usually expressed in GWy or TWy, shortened in the figures as GW and TW. In some slides energy consumption is expressed in kWh, MWh or TWh

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Energy units3

Energy density

Fuel kWh per kilogram*

Deuterium–tritium 92 400 000Uranium-235 23 279 200[3]

Hydrogen (compressed at 70 MPa) 34Natural gas 15.5Gasoline (petrol) / Diesel ~13Propane (including LPG) 13Biodiesel 12Ethanol 8.4Coal 6.7Wood 5Car battery (lead-acid) 0.7Li-ion battery 0.24 Alkaline battery 0.67Nickel-metal hydride battery 0.288

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Fuel kWh  per m3 Liquid hydrogen 2389Hydrogen, at 690 bar and 15°C 1260Hydrogen, gas[ 2.8Natural gas 10.2Gasoline (petrol) / Diesel 9600

Energy efficiency

Electricity generation EfficiencyGas turbine up to 40%Gas turbine plus steam turbine (combined cycle) up to 60%Hydropower turbine up to 90% Wind turbine up to 59% (theoretical limit)Solar cell 6–40% (technology dependent)Hydrogen Fuel cell up to 85%Geothermal power 10–23%Engine/MotorCombustion engine 10–50%[2]

Electric motors 70–99.99% (above 200W); 50–90% (between 10–200W);

Electrolysis of water 50–70%AppliancesIncandescent light bulb 0.7–5 %Electric heater 100 %Natural processPhotosynthesis up to 6% [3]

Muscle 14–27%

Energy conversion efficiency is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The useful output may be electric power, mechanical work, or heat.

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The ratio of energy returned/energy invested

• Energy returned on energy invested (EROEI); or energy return on investment (EROI), is the ratio of the amount of usable energy acquired from a particular energy resource to the amount of energy expended to obtain that energy. Determining the EROEI is often complex, resulting in wide variations in the data. In the asesment the whole life cycle should be envisaged.

• The more difficult to extract energy from a source, the more energy is to be invested to extract it, lowering the EROEI and increasing the price. For example, when oil was originally discovered, it took on average one barrel of oil to find, extract, and process about 100 barrels of oil. That ratio has declined steadily over the last century to about three barrels gained for one barrel used up in the U.S.

• If an energy source can flow to different tracks, its EROEI will increase. For example in Europe rapeseed is used to produce biodiesel. The EROEI is around 1.5 but a side product, pure plant oil, is used as a protein-rich animal food, with an EROEI of 16.

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Energy source ERoEI[1]

Crude oil (per 2007) 10

Oil sands (per 2007) 2 - 4

Natural gas 5 – 10Coal 1 – 10Nuclear 2,7 - 4Hydroelectric 10Wind 3 – 10Solar panels 1 – 10Biofuels

Soy biodiedel 5.5Sugar cane ethanol 4 - 8Rapeseed biodiesel 1,5

Corn ethanol 0,8 - 1,5Maize ethanol 1,1

Biomass 0,8Hydrogen 0,5

Energy capacity factor

• The net capacity factor of a power plant is the ratio of its actual output over a period of time, to its potential output if it were possible for it to operate at full nameplate capacity indefinitely. The capacity factor is highest for nuclear and geothermal power plants and lower for wind and solar energy as the latter are not continuously available. Fossil energy power stations work at full capacity only during peak hours in the day and les at night during lower demand.

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Coal

Natural gas

Nucle

ar

Geothermal

BiomassHyd

roWind

Solar P

V

85 87 90 9283

53

3425

Capacity factor

Capa

city

(%)

Land surface occupied for energy production

The figure shows the huge differences between energy types, solar and wind facilities occupying much smaller land area than bio- and fossil fuel facilities. Both low and high estimates (depending on the study) are given.

Wind

Solar

colle

c...

Photo

volta

ics

Biofue

ls

Foss

il fue

ls0

200

400

600

800

1000

1200

3 9 16

1000

900

LowHigh

Glo

bal h

ecta

res

/ MW

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Water use for energy productionTotal

• Total use in billion m3 (bcm)(in 2010 and prospected). Water withdrawal is water that is taken from the natural environment and after use redistributed in nature, for example to feed an electric turbine in the form of steam, to cool the reactor in a nuclear power plant or to irrigate biomass crop land. Often that water is warm and polluted. Consumption is water that is consumed during energy production, for example water taken up by biomass crops.

From IEA

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Water use for energy productionPer energy unit

• Withdrawal and consumption of water in gallons (Gal) per MWh (1 gallon=3.8 liter)

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How much energy do we consume today?Total and by energy type

• World total energy consumption in 2010 was 17.8 terrawatt (TW). Most is extracted from conventional fossil (coal, oil, natural gas) and nuclear (uranium) reserves. Renewable energy (wind, solar, hydroelectric, geothermal and biomass) is growing rapidly in recent years, now reaching 12 % of the world total energy consumption, which is more than double of nuclear energy consumption (5.3 %).

coal oil gas

nuclear

renewable

0

1

2

3

4

5

6

7

4.9

5.9

3.9

0.950000000000001

2.17

World energy consumption 2010

TW

coal27%

oil33%

gas22%

nuclear5%

renewable 12%

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Consumption by energy type and country

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Coal 19%

Oil35%

Gas24%

Nu-clear14%

Renewables8%

EU

Coal 21%

Oil37%

Gas25%

Nuclear9%

Renewables8%

USA 2010 (EIA)

Coal 22%

Oil43%

Gas18%

Nuclear13%

Renewables4%

Japan 2010 (EIA)

Coal 70%

Oil19%

Gas4%

Nuclear1% Hydro

electric6%

China 2009 (EIA)

Coal 41%

Oil23%

Gas8%

Nu-clear5%

Waste & Re-newables28%

India 2011 (EIA)

Oil13% Gas

4%

Hydroelectric

1%

Tradi-tional

biomass & waste

82%Nigeria 2010 (EIA)

Coal 2%

Oil47%

Gas28%

Hydroelectric

23%

Venezuela 2010 (EIA)

Coal 3%

Oil & bioethanol

39%

Gas7%

Nuclear1%

Hydroelectric

29%

Biomass21%

Brazil 2010 (EIA)

How much energy do we consume per capita?• Energy consumption per capita is highly variable in different areas of the world,

developing countries consuming much less. Values range between 0.2 kW/person (Eritrea) and 22 kW/person (Iceland) sustained for 1 year. In Belgium it is 7.4 kW, ranking 7th highest.

• There are also striking differences between cities in the same country, for example in electricity consumption in U.S. cities.

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Per capita electricity use in kWh/capita

• The striking differences between developed and developing countries is also reflected in the number of people (> 1.6 billion) without access to electricity in 2002 and predicted to have only slightly improved in 2030. This is due in part to the strong population growth in this part of the world. It clearly shows that dealing with energy issues cannot be disconnected from the inequality problem between people.

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In India 2009

How much energy did we consume in the past?• Energy consumption grew spectacularly, both in total and per capita, since the industrial

revolution, as a consequence of the population explosion (click here to see population growth animation) and of human scientific and technical development. Since then we have already consumed about 800 TW of fossil energy. Fossil fuels are still dominant in the global energy mix, supported by $ 523 billion subsidies in 2011, up almost 30% in 2010 and six times more than subsidies to the renewable energy sector[4 ., an alarming situation, considering that the fact that fossil energy combustion is the cause of global warming and climate change .

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Predominant energy types over history

• The dominant energy source changed over time from wood to coal to oil. At present there is a transition in motion to a renewable energy age, named by Greenpeace the ‘Energy Revolution’.

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(1 Quad.Btu (british thermal units) = 33.45 × 10- 3 TW)

Energy consumption by sector

• Energy supplies are used for >50 % in industry, for > 25 % in transportation, and for 22 % in residential and commercial facilities. The type of energy differs widely among these sectors. Oil is used for 96 % in transportation, while coal and nuclear energy feed electricity generation.

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Industry52%

Transportation27%

Residential14%

Commercial8%

World 2012 (EIA)

Transp

ortation

Industrial

Residential+co

mmercial

Electr

icity

0

20

40

60

80

100

120

Sector energy consumption by energy type

CoalOilGasNuclearRenewable

Perc

ent

World total electricity production = 2.3 TW (~20 000 TWh)

• Energy type used by sector differs widely among countries

Industry 77%

Transporta-tion 8%

Residential 11%

Commercial 4%

China 2009 (EIA)

Industry31%

Transportation28%

Residential22%

Com-mercial

19%

U.S. 2008

10b

Deadly accidents due to energy generation

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The table underneath shows the number of people killed by electricity generation systems worldwide per year, as collated by the IEA from different studies (lowest and highest numbers are given). Coal is responsible for a much higher number of deaths than other energy sources, while nuclear fatalities are lowest. In the Chernobyl disaster there were 56 direct deaths and 4000 people died from cancer. Recent estimates on the hazards caused by the Fukushima nuclear accident predict a total of 130 cancer deaths over lifespan.[22] Some 230 000 people were killed in a dam failure of a hydroelectric power station in China in 1975.

However, it is astonishing to note that the number of people killed in road accidents worldwide was 1,230,000[2] in 2007. It is even more astonishing that the annual death toll due to fossil energy-related climate change is 400 000 and that this will increase to 700 000 by 2030 if a drastic change in our fossil energy economy is not implemented.

Average number of people killed/year due to electricity generation

Low estimates High estimatesCoal 2296 26814

Hydroelectric 320 512Natural gas 126 672

Nuclear 52 312