The British Wind Energy Association (BWEA) has urged government to end uncertainty about the future of renewables beyond 2010 by bringing forward its intended review of the Renewables Obligation (RO) -- the UK's support mechanism for renewable energy sources. The RO came into effect in April 2002. It requires electricity retailers to buy a proportion of their power from green sources -- starting at 3% in 2002/03 rising to 10.4% in 2010. The government has pledged that the obligation on retailers will last until 2027, but has refused to give a firm commitment to raise the level of the obligation after 2010. Instead, it promises to hold a review in 2005/06. BWEA points out to the Parliamentary Renewable and Sustainable Energy Group (PRASEG) that the RO has stimulated the market for wind energy. Tradable renewables obligation certificates (ROCs) place a higher value on the green credentials of electricity from renewables than the price of the power itself. But until a clear decision is made on renewable energy targets beyond 2010, the uncertainty about future ROC prices makes it harder to obtain finance for wind developments, says BWEA. Large offshore wind farms could be particularly affected. The government's recent Energy White Paper set out an "aspiration" to double renewables' contribution to the energy mix to 20% by 2020. "There is no doubt that the renewables obligation is catalysing the expansion of wind energy in the UK," says BWEA's new chief executive, Marcus Rand. Britain is poised to build a new industry generating thousands of jobs, he adds. "Central to all this becoming a reality will be the renewables obligation and its ability to offer a long term stable market."