Flexible system needed make UK renewables cost-effective -report

LONDON, Feb 21 (Reuters) - Britain needs a more flexible electricity system if it is to make intermittent renewable sources as wind and solar cost-effective, an independent research report said on Tuesday, as the government tries to hit emissions targets.

The UK Energy Research Centre (UKERC) reports comes as the government is under pressure to act on rising energy costs after three of Britain's "Big Six" suppliers announced price rises over the last few months.

Britain has a legally binding target to cut emissions of harmful greenhouse gases by 80 percent from 1990 levels by 2050, and hopes to achieve this partly by increasing its renewable generation and closing coal-fired power plants.

"Without investing in greater flexibility you could end up with a system where (renewable) integration costs are almost as much as generation costs," Robert Gross, one of the report's authors and UKERC Co-Director, said during a media briefing.

If the country generated 50 percent of its electricity from intermittent renewables, the costs associated with connecting them to power grid and providing back up power when they do not run, would range between 15 and 45 pounds ($19-56) per megawatt hour (MWh), the report said.

For the cheapest figure to be realized the country would need to develop a flexible electricity system, using tools such as more power links with other countries and battery storage to better manage supply and demand, it said.

The cost of renewable electricity generation has fallen rapidly over the past few years, with offshore wind costs below 100 pounds/MWh and expected to continue falling.

As much as 20 percent of Britain's electricity can be generated by wind farms at present. ($1 = 0.8019 pounds) (Reporting by Susanna Twidale; Editing by Alexander Smith)