The government is planning to set up a multi-billion dollar sovereign wealth fund to invest in energy assets overseas."The plans are at a very initial stage. A decision on this would be taken after the budget. The fund would invest in overseas energy assets like Temasek of Singapore does," Planning Commission member Surya Sethi said here.Asked about the need to set up such a fund, a top Planning Commission official said the proposed fund would be one way to earn higher returns as compared to those investing in domestic projects."We have large (forex) reserves... which have associated costs. Up to a certain level, costs are justified in minimising the risk of fluctuations and any kind of shocks," he said. "Beyond a point, costs cannot be justified and you need to find ways to earn revenue," the official said.