Scientists study carbon-capture control systems

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.