The body that promotes international trade in renewable energy certificates, Renewable Energy Certificate Systems (RECS), based in the Netherlands, has called on the European Commission to issue guidelines to countries for implementing the Guarantee of Origin (GoO) requirement as a first step towards a pan-European market for renewable energy. The call by RECS International comes a month before the Commission is expected to report that it is premature to create a single competitive market for renewable energy under a single European support system by "harmonising" the very different national support systems. The different systems currently prevent trade of wind power across national borders. A GoO certificate verifies the greenness of a renewable electricity supply. A method for assessing eligibility and granting GoO certificates should have been introduced in each EU member state two years ago. But RECS International finds that ten EU countries still have not introduced GoO legislation. It also finds that the GoO is put to different uses in the countries where it is in place and in most cases its function is not clear. This could allow the greenness to be sold twice, or to account for the greenness in more than one country, RECS warns. "Since the implementation of the GoO, governments have not co-ordinated the use of the GoO," says Claes Hedenstrom from RECS International. "This leads to double selling and double counting and in the end to confusion and therefore lack of support by consumers." A standardised system of GoOs would help create a transparent and reliable European market for renewable electricity, he says, and urges governments and the Commission to take the international market more seriously.