In issuing its ‘request for proposals’ (RFP), the company said it would accept submissions from businesses with only 2MW of installed capacity and be generating intermittently.

It added that hydro proposals would be for new projects to be certified by the Low Impact Hydropower Institute, but incremental improvements to large plants are also acceptable.

Duke said it wanted to contract a total of 2.1GW of renewables by 2012 to both meet growing demand and statutory obligations. The projects, though, must be capable of delivering into Duke’s transmission grid, be up and running by 1 January 2012, and may be assigned a firm or dispatch rating to reflect intermittent supplies.

Separate to its renewables RFP, the company has also issued an RFP for more traditional supplies or assets to obtain up to 800MW by 2010 and 2GW of capacity by 2013.

Company president, Ellen Ruff, said the drive to obtain extra capacity in the next few years includes building new plants, greater use of renewables and boosting energy efficiency.