Scientists study carbon-capture control systems
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Researchers in Scotland are investigating methods for controlling carbon dioxide capture equipment on fossil power plants as their loads compensate for the variability of energy output from renewable sources.
The 3.5-year project dubbed ‘COMCAT - Control, Optimisation and Measurement in CO2 Absorber Transients’ is receiving £100,000 from power generation service provider Doosan Babcock, the Energy Technology Partnership and Edinburgh University.
A PhD student will take part in the investigation led by Prof Jon Gibbins and Dr Martin Crapper from Edinburgh University into the practical aspects of CO2 capture using post-combustion amine capture. This is where CO2 is scrubbed out of the flue gas from a power plant using a reversible reaction with a liquid solvent.
Other methods for capturing CO2 include pre-combustion. In this process the fossil fuel is converted into CO2 and hydrogen gas, which are separated, creating a hydrogen-rich gas that can be used as fuel. Another carbon-capture method, oxyfuel, sees the fuel burnt in oxygen to get a mixture of CO2 and water vapour. With all of these methods, CO2 is taken away and stored in porous rocks under an impermeable sealing layer underground.
The COMCAT project will take into consideration the UK’s future energy infrastructure, which will include not only fossil power plants with carbon-capture equipment but also less constant renewable energy sources such as wind, wave and tidal turbines.
The PhD student will help Prof Gibbins and Dr Crapper develop new instruments and control strategies and then try them out on actual post-combustion capture plants.
Gibbins said the team will be working with Doosan Babcock at the Ferrybridge Power Station in Yorkshire, where Scottish and Southern Electricity was granted planning permission to trial carbon dioxide capture technology with a capacity of 100 tonnes per day.
Gibbins added that one of the factors the team will look at is controlling the flow of the liquid solvent used to capture the CO2 in response to changing loads. He estimated this could help improve performance by a few per cent, which could lead to significantly better economics for the technology.
The ultimate goal, Gibbins said, will be to make the cost of carbon-capture technology as competitive as flue gas desulphurisation (FGD). While in limited use before the 1970s, it was only then that political pressure forced industry to increase its uptake of large-scale FGD units, which are used to remove sulphur dioxide from flue gas.
‘Nobody these days, in most places, makes any fuss at all about having flue gas desulphurisation,’ he added. ‘The only sensible way you can tackle climate change is to introduce a carbon-capture technology that works and is not too expensive so it would be unthinkable to put CO2 in the atmosphere. Why would you do that when you have a perfectly workable alternative?’
The importance of Edinburgh’s work on carbon capture and storage was highlighted by prime minister David Cameron in his first official visit to India last month.
Speaking in Bangalore, he said: ‘We believe we can have a technology leadership on this, developed through some of our best universities, such as Edinburgh… that are doing incredible work on carbon capture and storage. That’s the sort of technology we can then share, export and invest with other countries.’
A key technology in the fight against climate change, carbon capture and storage also offers big opportunities for British industry. Click here to read more.
Readers' comments (4)
Chris Dieterle | 11 Aug 2010 3:33 pm
Rather than sequester/store the captured CO2 – at a huge expense – turn it in to a feedstock for carbon fiber, polycarbonate materials, and carbohydrates.
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Ankur Barua | 13 Aug 2010 8:06 am
I am a part of the design team of the post carbon capture projects in the Ferrybridge power station. The succesful implementation & testing of this demo plant is crucial for all future coal fired power plant in the UK as well in entire Europe. As on today, govt are not giving permission for a coal fired plant without a CO2 capture plant.
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Justin Gudgeon | 13 Aug 2010 5:57 pm
Chris is totally right. Any scientist knows that the best and easiest way to 'capture' CO2 is to plant a heavy yielding crop like Rye Grass and turn it into pellets. That will 'capture' about 15 tons of dry biomass per acre. Every ton of dry biomass which grows, sequesters about seven tons of CO2 from the atmosphere which means the 15 tons of pellets has removed 105 tons of CO2 from the atmosphere. If people are foolish enough, and want to permanently remove this amount of CO2 from the atmosphere, then the pellets can be bagged and and dumped down a dry mineshaft where it will stay for hundreds of years.
Better still, instead of paying farmers to grow nothing on their set-aside land, ensure they all sow Rye grass and at the end of the growing season, cut the overgrown grass, turn it into hay by drying it in the sun, bale it, and throw THAT down the dry mineshaft. That too would stay there for hundreds of years.
If the whole of Europe followed suit and sowed their set-aside land in the same way, (approx 10 million acres), then the total amount of dry biomass produced and baled-up would be in the region of 150 million tons, representing about 1.05 billion tons of CO2 removed from the atmosphere - every year. Unfortunately, I don't think there would be enough dry mine-shafts in the world in which to dump all this stuff but by simply piling the hay-bales into one enormous haystack, governments would be satisfied that at least 90% of the carbon would remain locked-up for many generations to come. This zero-cost carbon capture has the added benefit of complementing other government projects by also being wasteful, stupid and unnecessary.
The amount dry biomass photosynthetically created every year across the entire planet is calculated to be just over one trillion tonnes, necessarily removing about seven trillion tonnes of atmospheric CO2 in the process. Fortunately, 98% of this huge amount of CO2 returns to the atmosphere via the various forms of oxidation (including respiration) but this still leaves about 2% (20 billion tonnes) permanently removed from the carbon cycle through oceanic carbonate sedimentation and terrestrial detritus including the incremental increase of top-soils, bogs, peat-marshes, guano, sediments etc, plus all the timber used in building construction and the huge amount of organic matter thrown into land-fill sites. The existence of this 20 billion tons of 'captured' carbon represents a permanent removal of over 140 billion tons of atmospheric CO2.
In order for the level of atmospheric CO2 to increase, the amount of CO2 added to the atmosphere by burning fossil fuel needs to exceed the amount of CO2 permanently removed from it by oxygenic photosynthesis. Since we only produce about 65 billion tonnes annually of CO2 from burning fossil fuels against the 140 billion tons NET, taken from the atmosphere by biological processes, it must a CO2 shortage which is destabilizing the climate.
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Simon Martin | 15 Aug 2010 12:08 pm
There has been some innovative designs and practical uses for carbon captured emissions, notably that of food production. In one scheme it was pumped from a site to growing sheds which grew salad vegetables to aid them to grow, this worked well and also provided heat for the immense greenhouses. Considering its success, and its associated benefits of home grown food at reasonable prices, thus no transportation of foreign raised crops, it must be looked at seriously.
Having free heat and gas from other industries waste is essential to such industries where providing heat is the greatest cost which raises the products price, and such schemes could be implemented elsewhereto provide more of our home grown food.
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