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Generating Electricity from a Fuel


Here's how most of our electricity is generated. The fuel: gas, coal, oil or nuclear produces heat as it reacts or burns; the heat is used to drive a turbine / generator; this spins and generates electricity. The turbine exhaust gives out some waste heat which ends up in the atmosphere. There have been attempts to use heat like this in "district heating" schemes, but none of them have been very cost effective.


fuel to electricity and waste heat

Now- let's look at some numbers. What's the efficiency? How much of the energy is lost in converting it to electricity?



fuel to electricity and waste heat

Newcomers to energy statistics may find this surprising. Over half the energy is lost as heat. Nothing much can be done about it. If it's any comfort, an ordinary light bulb loses about 95% of its energy as heat, and we've used them happily for years.

Early turbine efficiencies were in the low 30%s; with better technology the figure has crept up, and 40% is achievable; sometimes higher, but not much higher. When you burn a fuel to produce electricity, at least half of the energy is lost.


FUELS USED IN GENERATING ELECTRICITY, UK:
unit: millions of tons of oil equivalent; rounded to nearest million
source: DTI website, Energy Stats, DUKES, section 5.1.1, Jan 2011.

There are no easy answers to energy problems, but looking at these figures, you'd never guess that reserves of gas are lower than those of oil or coal.


1997: COAL 28,.. GAS 22,.. NUCLEAR 22,.. OIL 1
1998: COAL 30,.. GAS 23,.. NUCLEAR 23,.. OIL 1
1999: COAL 26,.. GAS 27,.. NUCLEAR 22,.. OIL 1
2000: COAL 29,.. GAS 28,.. NUCLEAR 19,.. OIL 1
2001: COAL 31,.. GAS 27,.. NUCLEAR 21,.. OIL 1
2002: COAL 30,.. GAS 28,.. NUCLEAR 20,.. OIL 1
2003: COAL 32,.. GAS 28,.. NUCLEAR 20,.. OIL 1
2004: COAL 31,.. GAS 29,.. NUCLEAR 18,.. OIL 1
2005: COAL 33,.. GAS 28,.. NUCLEAR 18,.. OIL 1
2006: COAL 36,.. GAS 27,.. NUCLEAR 17,.. OIL 1
2007: COAL 33,.. GAS 30,.. NUCLEAR 14,.. OIL 1
2008: COAL 30,.. GAS 32,.. NUCLEAR 12,.. OIL 2
2009: COAL 25,.. GAS 31,.. NUCLEAR 15,.. OIL 2
2010 figures not yet released

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