The low efficiency of bioenergy with carbon capture and storage (BECCS) means that plants using the technology will require heavy subsidies, an academic has warned.
Dr Daniel Quiggin, senior research fellow at the Chatham House Institute, raised concerns about BECCS during a hearing of the House of Commons Environmental Audit Committee on Thursday (25 November).
In a BECCS plant, biomass is burnt to generate electricity and the consequent carbon emissions are captured using the heat from the same combustion process.
But pointing to figures from a report produced by consultancy Baringa for Drax, which is developing plans to build two BECCS units at its power station in North Yorkshire, Quiggin told the committee that the generation efficiency of a 630MW turbine would drop from 36% to 21% compared to one not fitted with CCS technology.
While acknowledging that this rate may improve over time as the technology develops, Quiggin said BECCS is “unlikely” to deliver the level of efficiency desired in modelling carried out by the Climate Change Committee, which estimated that the technology could meet up to 15% of the UK’s electricity needs by 2050 while simultaneously sequestering emissions.
“This lower power efficiency means it will be very expensive or risky to deliver that power into the wholesale market, which is likely to drive up subsidies required,” he said.
But Jason Shipstone, senior innovation officer at Drax, told the committee that the usual method of measuring plants’ efficiency does not work for BECCS because it has two outputs.
He said: “If you apply negative emissions technology to biomass power stations, you get two goods for one – dispatchable energy and negative emissions.”
Responding to criticism that demand for wood pellets from BECCS could increase pressure on forests to unsustainable levels, Shipstone said that Drax is investigating alternative sources of biomass.
He said that the company has tested increasing the proportion of other plants, such as energy crops, to as much as 30% of the material burnt in a plant, which is around ten times the level it normally uses.