A new method of recovering more oil from offshore fields looks set to offer a secure and greener future for the UK’s coal-fired power stations.
A report on cleaner coal technologies, published this week by the DTI, said the environmental impact of coal-fired power stations could be drastically reduced by capturing and storing the carbon dioxide they produce. This CO2 could then be used to increase the volume of oil recovery, particularly in the North Sea, the review said.
Modern coal gasification techniques mean CO2 from coal-fired power stations could be captured and piped to offshore oil reservoirs, where it makes low-pressure oil much lighter, helping it to rise to the surface. The CO2 also sweeps into the cracks in the earth where oil would otherwise be trapped and dislodges it.
The use of CO2 could increase the amount of oil recovered by 15 per cent, according to Brian Morris, a deputy director at the DTI and manager of the cleaner coal technology demonstration plant review.
In the longer term the CO2 could then be stored in the North Sea’s huge depleted oil wells, reducing emissions, he said. ‘This would be a way of radically reducing greenhouse gases, and coal-fired power stations would become more environmentally acceptable if CO2 could be captured and stored in this way.’
There are still legal and commercial issues to be resolved before the technique could be used, such as the expense and practicalities of piping CO2 between power plants and North Sea oil platforms.
Oil companies such as BP are looking into the technology, but have yet to resolve these cost issues, said Andrew Carr, senior reservoir engineer at the DTI. ‘Though the power generators and oil companies are talking, they have not yet reached a point where the generators are able to say they can capture and deliver the CO2 at a price the oil companies feel they can afford. But they are getting closer,’ he said.
The use of CO2 in oil recovery is standard practice in the oil fields of Texas, Carr said, but these do not use the gas captured from power stations. One pilot scheme, the Weyburn Project, is using CO2 piped from a gasification plant in North Dakota to recover oil at a field in Canada.
John Griffiths, senior consultant at power and gasification specialist Jacobs Consultancy, said CO2 is very effective in Enhanced Oil Recovery (EOR) schemes. ‘CO2 is a very heavy gas, and when you push it into the oil it mixes and offers very good recovery of extra oil.’
But the government must first decide whether it plans to promote the use of coal-fired electricity generation in the future, or rely on renewable energy and natural gas for the UK’s power needs, he said. ‘If the government is happy it can get enough natural gas to meet the UK’s needs at economic prices, then fine. But if we have to find an alternative, and getting enough electricity from renewable resources is going to take some time, then gasification of coal could be the answer.’