Investors and lenders in renewable energy projects may find themselves working alongside, or in competition with, a public sector financier which has a very modest mandate.The Clean Energy Finance Corp will target a return based on "a weighted average of the five-year Australian Government bond rate" net of operating expenses. The target return is thus around three per cent, based on the yield on a five-year bond over the last year.The treasurer, Wayne Swan, announced the target on Wednesday.By contrast, the Future Fund targets an average return of at least the consumer price index plus 4.5 per cent to 5.5 per cent. The Future Fund returned seven per cent for the six months to December 2012.The CEFC's investment mandate direction spells out its goal as being "to help mobilise investment in renewable energy, low-emission and energy efficiency projects and technologies in Australia, as well as manufacturing businesses and services that produce the required inputs."The Corporation will invest at the demonstration, commercialisation and deployment stages of innovation. "The Corporation has been established to finance Australia's clean energy sector using financial products and structures to address the barriers inhibiting investment."The mandate asserts that it is the "intention of the CEFC to apply commercial rigour when making its investment decisions [and] have regard to its potential effect on other market participants when considering investment proposals."The CEFC must also "have regard to positive externalities and public policy outcomes when making investment decisions and when determining the extent of any concessionality for an investment."