Drax revisits carbon capture

Drax is revisiting CCS but this time it is post combustion applied to biomass, rather than the coal fuelled oxyfuel concept proposed as part of the cancelled White Rose project. The company is expected to begin a pilot project shortly aimed trialling a technology called BECCS (bioenergy carbon capture and storage), thought to be the first of its kind in Europe. If successful, adding carbon capture to its biomass fuelled units would have the effect of making the electricity produced carbon negative.

Drax say BECCS is “vital to global efforts to combat climate change because the technology will mean the gases that cause global warning can be removed from the atmosphere at the same time as electricity is produced”, meaning that “power generation would no longer contribute to climate change, but would start to reduce the carbon accumulating in the atmosphere.” A 2016 report by the Energy Technologies Institute suggested that by the 2050s, BECCS could deliver roughly 55 million tonnes of net negative emissions a year in the UK – approximately half the nation’s emissions target. The UK government’s Clean Growth Strategy recently identified BECCS as one of several greenhouse gas removal technologies that could remove emissions from the atmosphere and help achieve long term decarbonisation.

The demonstration project will see Drax partner with C-Capture, a spin-out from the department of chemistry at the University of Leeds, established through funding from IP Group Plc, and invest in what could be the first of several pilot projects to be undertaken at Drax to deliver a rapid, lower cost demonstration of BECCS.

Drax says its “power station became the largest decarbonisation project in Europe by upgrading its existing facilities” – with half of the station’s six 660 MW units converted to run on compressed wood pellets instead of coal, and a fourth conversion underway. It has, says Drax become “Europe’s biggest decarbonisation project – and the UK’s largest single site renewable power generator”, and, if the pilot is successful, “it will examine options for a similar re-purposing of existing infrastructure to deliver more carbon savings.”

The first phase of the BECCS project, starting in May, focused on assessing whether the “low cost, high energy efficiency” solvent C-Capture has developed is compatible with the biomass flue gas emitted by the converted units at Drax. A laboratory scale study was also initiated into the feasibility of repurposing the flue gas desulphurisation (FGD) absorbers at the power station and to assess potential capture rates.

The flue gas desulphurisation equipment has become redundant on three of the generating units at Drax that have been converted to use biomass because the wood pellets used produce minimal levels of SOx.

Depending on the outcome of a feasibility study, the C-Capture team could proceed to the second phase of the pilot in the autumn, when a 1 tCO2/d demonstration unit would be installed to capture the carbon dioxide produced by the biomass combustion.

Will Gardiner, CEO, Drax Group, said: “This pilot is the UK’s first step, but it won’t be the only one at Drax. We will soon have four operational biomass units, which provide us with a great opportunity to test different technologies that could allow Drax, the country and the world, to deliver negative emissions and start to reduce the amount of carbon dioxide in the atmosphere.”

Chris Rayner, founder of C-Capture and Professor of Organic Chemistry at the University of Leeds, said: “We have developed fundamentally new chemistry to capture CO2 and have shown that it should be suitable for capturing the carbon produced from bioenergy processes. The key part is now to move it from our own facilities and into the real world at Drax. Through the pilot scheme we aim to demonstrate that the technology we’ve developed is a cost-effective way to achieve one of the holy grails of CO2 emissions strategies – negative emissions in power production, which is where we believe the potential CO2 emissions reductions are likely to be the greatest.”

In the shorter term and at smaller scale, one possible beneficiary of the carbon dioxide produced by the BECCS programme at Drax might be the UK beer industry, which has recently been suffering from a much publicised carbon dioxide shortfall. Drax has recently been in discussions with the British Beer & Pub Association.

• Steam turbine upgrades. Drax has recently signed a new £40 million contract with Siemens for steam turbine upgrades on its three already converted biomass units.

The upgrades will deliver improved efficiencies as well as maintenance savings, which will cut the cost of biomass electricity production, says Drax.

The work, which will start in 2019, will take three years to complete, with one biomass unit being upgraded each year as part of its planned major overhaul. The efficiency gains will be achieved by fitting new pipework and valves, with new high efficiency blading and long life seals installed within the turbines on biomass units 1, 2 and 3.