Coal back on the agenda

BY DAVID Adam

AS the reserves of other fossil fuels start to run out, it seems inevitable that the world will turn back to coal for its energy needs

As the world's environment ministers, NGOs, and business groups meet in Montreal this week to discuss ways of tackling climate change, most know there is a ghost at the feast. Behind the smiles and handshakes, the spectre of an old king hangs over their negotiations.

Coal is the dirtiest, least efficient, and biggest emitter of greenhouse gases of all the fossil fuels. It is also the cheapest, easiest to get hold of, and by far the most abundant.

There remain centuries worth of coal buried in the Earth's crust. If burnt, the resulting carbon dioxide would heat the planet enough to melt both the Arctic and Antarctic ice caps.

Crucially, a significant amount of this vast resource lies beneath the developing nations China and India, which plan to use it to drive their own version of the industrial revolution.

The unspoken message at Montreal is that, in a post-Kyoto world, if China and India burn all their coal, then whatever tortuous deals the developed world reach over reducing emissions, it will come to nothing.

The United States, too, has plans to increase the amount of coal burnt by some 40 per cent by 2025. It was no coincidence that these were the three countries singled out by Tony Blair when he talked last week about the need for a new worldwide agreement after 2012.

To put the quantities in perspective, a British study this year predicted that China's growing demand for coal will double its annual carbon dioxide emissions from 1,500 million to 3,000 million tonnes by 2030.

The U.K. government, meanwhile, is drawing up a review of its climate change policies aimed at saving an extra 11 million to 14 million tonnes of coal by 2010.

Does this mean global environmental disaster? Not if you believe advocates of what until recently would have been a laughable misnomer: "clean coal."

Geoff Morrison, the programme manager for the International Energy Agency's clean coal centre in London, is one such optimist. He says: "The key to clean coal is basically in the way that you burn it."

On the plus side, modern coal-fired power stations, which act as oversized kettles to boil water to drive steam turbines, are undoubtedly much cleaner.

Electrostatic devices now trap some 99 per cent of dust, and chemical scrubbers stop noxious oxides of nitrogen and sulphur escaping to cause, among other environmental problems, acid rain.

But what "clean" coal plants cannot yet tackle on a meaningful scale is carbon dioxide. Coal produces almost twice as much CO2 as natural gas to yield the same amount of energy.

Rising efficiency helps, but these meagre gains are quickly swamped by the scale of the increase in the number of new power stations. China is building about one a week.

Enter another concept, barely mentioned until four or five years ago: carbon capture and storage. If coal is ever to be truly clean, then the carbon dioxide inevitably produced has to be trapped and isolated from the atmosphere, probably underground.

Technically, the storage part is relatively simple. Cost aside, the concerns are over short-term legality and long-term safety.

Capture is much trickier, mainly because carbon dioxide is just one ingredient in the cocktail of gases that emerges from the business end of a power station. If coal is ever to be clean, the CO2 must be separated.

This can be done: a mine scrubbers that chemically isolate the carbon dioxide are fitted to several power stations in the U.S. But in that case local industries are prepared to pay for the pure gas.

Without such a customer, or some kind of a financial value placed on sequestered carbon, the economics don't add up. Pumps for the chemical scrubbers and compressors for the carbon dioxide draw electricity directly from the power station's bottom line, reducing output by up to a quarter.

A better way might be to change how the coal is burnt. The Swedish power company Vattenfall is building an "oxycoal" plant near Berlin that will use oxygen, not air, to ignite the fuel. Without the large quantities of diluting nitrogen gas in the exhaust stream, the CO2 should be easier and therefore cheaper to separate.

George Bush favours a different strategy: turning coal into hydrogen gas, a process called integrated gasification combined cycle (IGCC).

"IGCC has been around for about 20 years, but it's only really the Americans who have been pushing it," Mr. Morrison says.

(Guardian Newspapers Limited)