RWE npower has announced plans to close two major power stations in the UK by the end of March 2013.

The 2000 MW coal-fired Didcot A power plant and the 1000 MW oil-fired Fawley plant will be shut down in line with the requirements of the EU Large Combustion Plant Directive.

Both plants are more than 40 years old.

The announcement came as npower, RWE’s UK subsidiary, prepared to formally open the 2000 MW Pembroke power station in Wales.

The new combined cycle gas-fired power plant represents a £1 billion investment by RWE and comprises five 400 MW generating units. The company says the plant is the largest and one of the most efficient combined cycle gas turbine plants in Europe.

Didcot A and Fawley power plants were both opted out of the Large Combustion Plant Directive, which requires power plants to meet strict emissions criteria. The two facilities were therefore required to stop operating by the end of December 2015 at the latest, or once a set number of operational hours were completed.

“Both of these stations were built more than 40 years ago, and have been the unsung heroes of our economy ever since, helping to keep the lights on and Britain working 24 hours a day, 7 days a week,” said Volker Beckers, CEO of RWE npower.

The new Pembroke power station was constructed by Alstom. Each 400 MW unit is a KA26-1 single-shaft combined cycle block comprising a GT26 gas turbine, triple-pressure heat recovery steam generator, a compact reheat type STF30C steam turbine and a hydrogen cooled generator.

Fawley and Didcot A Power Stations’ open cycle gas turbines will remain operational until further notice.

The UK is likely to need 15-25 GW of new generating capacity by 2020 as old plants are closed, according to RWE, which earlier this year abandoned plans to construct new nuclear power capacity in the UK in conjunction with E.On.