Coal was king for at least two centuries, for heating, cooking, railways and then for electricity production.

The Clean Air legislation and the dash for gas after the closure of most deep mines saw a decline in the UK, though there is a proposed new power station in Kent, using imported coal.

Coal is a dense source of energy and a bonus as it represents extra solar energy from the past, stored for our use. Unfortunately it's beset with difficulties.

Digging it up is dangerous, with 5,000 miners killed each year in China, the biggest producer, and as it is mainly carbon it burns to produce CO2, the most common climate change gas.

It produces twice as much CO2 as oil and gas, per unit of energy, and it is the worst way of producing electricity in terms of climate change. It's just a pity that it is the easiest, and 75 per cent of the six billion tonnes of coal mined each year is used in power stations.

China, the USA and Australia are the biggest world producers of coal, with China mining one-third and the USA one-sixth. Australia and Indonesia export the most.

This explains why the US and Australia were the only countries not to sign the Kyoto climate change agreement. France, on the other hand, has closed its coal industry completely and relies heavily on nuclear power for its electricity.

Unfortunately more than half the world's electricity comes from coal-fired plants that convert about one-third of the energy in the coal to electricity with the rest being dispersed as heat - hence the cooling towers and wasted heat that really should be put to better use.

It's not surprising, therefore, that it takes a third of a tonne of coal, producing almost a tonne of CO2, to keep a 100 watt light bulb shining for a year. Hence the need for low-energy bulbs.

The industry hopes to use the energy more efficiently and perhaps gasify or liquefy the coal, but such developments still produce serious amounts of CO2. The main hope for the future is developing Carbon Capture and Storage, though it could be two decades before it is proven to work on a large enough scale.

Current coal-fired stations can't be retrofitted and at the moment there is only a small-scale operation in Norway where some CO2 is collected and stored in emptied North Sea oil rocks, and there are plans for a pilot scheme in Illinois. Talk of pumping it into the sea is unrealistic as not only could it escape but it will make the seas even more acidic.

Whatever happens, electricity is going to cost much more in the future, so we all need to use less of it, even though it will be the only way to keep the wheels turning when oil runs out.