The UK government has published further details* of how it intends to bring about an end to “unabated” coal generation by 2025. Rather than mandating the retrofitting of carbon capture and storage, unabated units will be required to meet a new carbon dioxide intensity limit of 450 g CO2 per kWh. This approximates to the carbon dioxide intensity of a natural gas fuelled combined cycle plant.
The new limit, which will apply to units with a thermal capacity of over 300 MWt, will come into force from 1 October 2025, “to align with the beginning of the 2025/26 capacity market delivery year”, meaning that unabated coal will not be able to bid into auctions for delivery of capacity in 2025/26 and beyond.
Emissions from co-fired fuels, eg biomass, will be taken into account, but the limit will not apply to units that convert fully. The government recognises that co-firing with biomass is one way generators couldmeet the new limit, and would attract subsidies under the current renewables support scheme. It is looking at ways of controlling costs to electricity consumers of new biomass co-firing or conversion.
Largely driven by the UK’s carbon price support scheme and the growth in low carbon electricity, coal’s share in UK power generation fell to 9% in 2016, down from 22% in 2015. In the second quarter of 2017 it fell to a record low of 2%, and in April 2017 the UK experienced the first 24 hour period without coal on the system since the first coal fired power station opened in 1882.  
*Department for Business, Energy & Industrial Strategy, Implementing the end of unabated coal by 2025, Government response to unabated coal closure consultation