Can coal come clean?

Carbon sequestration sounds like the answer to Europe’s prayers. Technologies capable of capturing greenhouse gas emissions from coal power plants could in theory make it possible to keep generating heat and light from a favourite traditional source, without adding to pollution and climate-change worries.

Carbon sequestration, or carbon capture and storage (CCS), is a term used to describe a number of processes, including the natural absorption of carbon dioxide (CO2) by forests. When describing technologies that cut emissions from coal power plants, it is also termed ‘clean coal’.

With a quarter of the world’s heat coming from coal, the world still needs to clean up coal power generation. A coal-fired power plant emits between 750 and 1,300 grams of CO2 per kilowatt hour (g/kwh), compared to about 450g/kwh for gas, up to 120g/kwh for wind power and a maximum of 60g/kwh for nuclear.

But energy interest groups are divided over how much clean coal can deliver.

The big power companies are in no doubt that emerging clean coal technologies are among the best ways to tackle global warming. Earlier this month, Shell and Statoil announced plans for a carbon sequestration project in Norway. RWE last year said it was looking at the possibility of building a clean coal power plant in south-east England. ExxonMobil, BP, Total, and Vattenfall last November joined a €15 million European Commission research project to study CCS projects in Germany, Norway and Algeria.

The French company Alstom and American Electric Power this year announced plans to install carbon capture technologies on two existing power plants by 2011 - the first time this has been attempted on a commercial scale.

"Our belief is that the number one problem is not to build clean plants, but to make existing plants clean," says Philippe Joubert, president of Alstom Power System.

Joubert says that he hopes the new technology, described as a chilled ammonia process, can eventually be transferred to existing and new coal plants around Europe.

But environmental activists say the promise of clean coal is being used as an excuse for power companies to continue investing in dirty fossil fuels, rather than looking for new, clean energy sources.

"Carbon sequestration will be economically viable too late," says Claude Turmes, a vice-president of the Greens European Free Alliance. "Too late to meet CO2 reduction targets, and too late for the reinvestment cycle of our power sector."

About two-thirds of EU power plants were built in the 1970s and will soon need to be replaced, said the Luxembourg Green MEP.

Turmes says researchers started to look for clean coal processes in the 1970s, when the problem was air pollution and not global warming. "It is a mistake to talk about clean coal in the climate change age," he said.

Turmes says that moving away from coal would also help break up EU energy market monopolies, by giving smaller companies chance to develop alternative energy technologies.

Carbon sequestration sounds like the answer to Europe’s prayers. Technologies capable of capturing greenhouse gas emissions from coal power plants could in theory make it possible to keep generating heat and light from a favourite traditional source, without adding to pollution and climate-change worries.