www.theengineer.co.uk
1 September 2010
Plans to use hydrogen fuel-cells to increase energy efficiency at carbon capture and storage (CCS) plants will be entered into a competition for government funding. A group of companies led by B9 Coal hopes to build the UK's first underground coal gasification (UCG) plant that uses alkaline fuel-cells to convert hydrogen into electricity. This process would allow upwards of 90% of the CO2 produced from the coal to be captured while generating electricity with a 60% efficiency rating at a cost as low as 4p perkWh.
This compares with between 37 and 44% efficiency for typical coal-fired power stations, according to the US National Petroleum Council. 'This is a completely new combination of technologies, with very significant advantages in terms of low cost and high efficiency,' B9 Coal's director Alisa Murphy told The Engineer. 'The capital expenditure on a turbine is considerably more than on the fuel-cells and they're much easier to operate and maintain.'
Two of the companies involved in the project, fuel-cell developer AFC Energy and Australian firm Linc Energy, completed the world's first successful trial of fuel-cells powered by hydrogen from UCG in June this year in Australia. The B9-led consortium is proposing a 500MW project located at Rio Tinto Alcan's Lynemouth Plant in Northumberland using the technology, and is supported by the North East Process Industry Cluster (NEPIC) and environmental project facilitators Renew. UCG works by injecting oxygen into the underground coal seam gas, igniting a combustion process that decomposes the coal into CO2, hydrogen and other gases.
The process makes much larger amounts of coal accessible than mining and without the conventional environmental impact, potentially opening up an extra 17 billion tonnes of coal in the UK. Typically the hydrogen produced is used to power a turbine. 'In order to get the kind of efficiencies you would want from a turbine you would have to operate flat out,' said Murphy. 'With fuel-cells you get 60% electrical efficiency whatever amount of hydrogen you're putting in.'
Using fuel-cells also allows the hydrogen to be stored and the electrical output to be increased during peak demand time, simply by turning on more cells. 'This makes it a very commercially attractive model as well,' added Murphy. The group plans to apply for funding under the next round of the Department of Energy and Climate Change's (DECC) CCS demonstration competition, which is due to open later this year. 'The government is talking about showing global leadership on CCS,' said Murphy. 'In order to do that you have to come up with something radically different that is about powering the future rather than looking back at old dirty technologies and trying to improve them.'
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