Non-renewable Electricity

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Converting existing power stations
New power stations
    Natural gas-fired
    Nuclear
    The choice
Conservation
Conclusion
Further reading

Throughout the world, the great majority of electricity is generated by burning fossil fuels. These may be natural gas, coal or oil. All are responsible as major contributors to greenhouse gas emissions, natural gas being the worst (this apparent anomaly is discussed in the essay on Natural Gas), and oil the least bad. Renewable sources are discussed in the essay on the subject. Other non-renewable methods include nuclear fission, which have the great advantage of being responsible for a minute fraction of all the man-made greenhouse gas emissions, even when viewed holistically. In fact, the modern nuclear power station is probably the only large-scale generating method with acceptably low levels of environmental harm.

Converting existing power stations

Some countries, in the mistaken belief that natural gas is less polluting than other fossil fuels, are proposing to convert oil- and coal-fired to this method. The ability to convert existing power stations is very limited; at the best, the more modern plants could be modified. This would reduce the carbon dioxide emissions by up to about 20 percent per kWh, while increasing methane emissions. However, major changes to the thermal design of the plant would be necessary; gas is not a "drop-in" substitute for oil or coal. Notably, the stack gases would contain much higher levels of water vapour. Other infrastructure changes would be the provision of high-pressure, insulated, liquid gas reservoirs at -164°C and the means of filling them from ships, pipelines and from biological methane. It must be noted, however, that most natural gas is a fossil fuel that contributes to climate change. Worse, it requires considerable energy to liquefy the natural gas and to transport it from the producer to the power station, all of which will also come from fossil fuels and will contribute to carbon dioxide emissions.

New power stations

New power generating capacity must be built. The big question is what type?

Natural gas-fired

This is the obvious and easy method, but there are four serious disadvantages that must be taken into consideration:

natural gas combustion produces carbon dioxide emissions, responsible for climate change. For each kilogram of natural gas burnt, nearly 2.5 kilograms of carbon dioxide is emitted.
the supply of natural gas is limited, the bulk coming from politically volatile Middle Eastern countries and Russia: supply is therefore impossible to guarantee and the price is sure to rise drastically as reserves dwindle
supply is dependent on special tanker ships, which are limited in number
natural gas emissions are about 35 times worse than carbon dioxide ones for causing climate change:
- as tankers ship liquid natural gas, the reservoirs have to be vented, causing some gas to escape.
- compressors, valves, and other components in pipelines cause fugitive emissions
- "pigging" and maintaining pipelines cause emissions
- well-head emissions are considerable
- concomitant gases and vapours are separated at the well-head and are used as fuel or flared, with some methane emission

There are two kinds of gas-fired stations: conventional thermal types with a boiler driving a steam turbine and direct-fired gas turbines. The latter has the advantage that, in the event of a breakdown elsewhere in the grid, a loss of wind or sun from renewable sources, or a sudden increase in demand, they can be brought on line in a very short time: this makes for the ideal back-up method without the need to idle conventional thermal systems. Their capacity is smaller, but their efficiency is better.

Nuclear

This also suffers from disadvantages:

the psychological problem of convincing the people (and consequently, elected representatives) that nuclear power is safe and beneficial and means neither Hiroshima nor Chernobyl; the biggest problem is that ecopolitical NGOs are inclined to greatly exaggerate the danger with anti-nuclear propaganda founded on half-truths and even untruths.
the very small quantity of highly radioactive waste left over from recycling the fuel rods need to be safely disposed of. Some countries do not have the means of doing this and must rely on third party countries.
the USA has a legal barrier to prevent recycling nuclear fuel.
externalised costs (security issues, inspections, insurance and decommissioning) must be factored in to the estimated calculation.

However, there are also great advantages:

although current supplies of uranium are limited, known reserves are sufficient for centuries of world-wide potential demand
with the modern Euro-pressurised water reactor, 96% of the spent fuel can be recycled, reducing the volume of radioactive waste.
safety levels of modern reactors are very high and are constantly monitored by internal and external bodies, such as the IAEA.
the holistic level of greenhouse gas emissions (including transport and recycling of fuel) is about 2 per cent that of a fossil-fuel power station of equal power.

The choice

Taking the long term view, I believe that the most economical, environmentally sensitive and reliable choice is with nuclear power stations. The recycling of the fuel for most countries is mostly within the European Union (France and the UK) with easy means of transport. The actual cost of nuclear-generated electricity is typically towards the top of the same range as fossil-fuel-fired systems, so should not entail any great adjustment of prices, especially as fuel prices rise. The holistic carbon dioxide emissions, including mining, purification and transport of the fuel is typically about 2 - 3 per cent of that from even the best fossil fuels (note that this chart does not include emissions due to the leakage of natural gas, but only the carbon dioxide resulting from its combustion):

Of course, this should be complemented by renewable sources, to a maximum possible. This maximum of variable methods is generally about 18 - 20 percent of the grid capacity, for any one type, and an aggregate of about 24 per cent for all types, to ensure stability. At all times, the electricity from these sources should be used to a maximum and the shortfall be filled in, initially, by nuclear, then fossil-fuel fired, if the demand still exceeds the supply.

In my opinion, this kind of scenario provides the best possibility for the future.

If the hydrogen-fuelled or electric car becomes the norm, then a doubling or tripling of generating capacity will be required (see the essays on Cars and Hydrogen).

Conservation

Of course, electricity should not be wasted. If it is, it is costly and polluting. It therefore behoves every user to use this source of energy as economically as possible. There are various ways of doing this:

use low-energy light bulbs
switch off lights when not required for more than 3 minutes
switch off all appliances not in use
keep constant room and water temperatures but switch off at night
set the thermostat of immersion heaters to 50 - 55°C
ventilate rooms minimally
for electric room heating, use the air conditioner in 'heat' mode to rapidly bring a room up to a comfortable temperature, rather than a fan convector or heater
consider night-storage heaters rather than fan convectors or other heaters (these have the advantage that they 'burn' electricity when the supply is much greater than the demand and the power stations are producing their background levels of emissions; the extra load makes almost no difference to the pollution. The cost of energy is also reduced in most countries)
run irrigation pumps at night (this also conserves water)
use thermostatted electric heating to a maximum of 20°C in living rooms and 18°C in bedrooms
use thermostatted air-conditioning to 28°C in summer for only a minimum time
improve house insulation
purchase low-consumption appliances
switch off computers not in actual use (this is a major waste of energy; the average computer and monitor will consume, at rest, the same amount of electricity as is necessary to light 6 - 10 workspaces).

Conclusion

Future electricity supplies are a thorny problem that cannot be resolved by half-measures. All parties, including the public, must take the bull by the horns. Conservation is important, as are renewable supplies, where these are feasible. Demand will, however, foreseeably rise, especially in developing countries. Decisions must be made as to how this will be done, even if they are unpopular.