RWE Generation is considering investment in the 1.6GW plant to comply with tightening emissions standards and keep it open into the 2020s.
However, the European Commission has launched infraction proceedings against the UK government over the way it has applied EU regulations. The dispute, which centres on the Welsh coal burned at Aberthaw, could force RWE to close the plant by 2016.
The UK had been granted a relaxation of emissions rules to allow Aberthaw to burn locally mined coal, which is more difficult to ignite than other types of coal due to its low proportion of volatile matter.
The Commission is now challenging the interpretation of that provision, saying it was meant to apply only to coal with less than 10 per cent volatile matter. Aberthaw’s feedstock has between 6 and 15 per cent volatile content.
An RWE spokesperson said the matter needed to be “urgently clarified” so the UK could continue to benefit from the security of supply offered by the plant.
The GMB union accused the Commission of “moving the goalposts”. Regional officer Ken Barker said Aberthaw should be treated as a “special case” as closure would have a “devastating effect” on the local economy.
The Welsh Government is understood to be leading discussions from the UK side. A spokesperson said it was a confidential matter and officials were working “to bring the issue to an acceptable resolution”.
European Commission officials were not available for comment at time of publication.