Energy Minister Chris Bowen’s expanded green energy underwriting scheme could end up costing future taxpayers “tens of billions” of dollars, says a top energy economist who predicts $59 billion in new solar, wind and batteries will eventually erode earnings from renewable power.

“The bulk of the cost of this investment is ultimately going to lie on the public purse,” Bruce Mountain told AFR Weekend. “And it would be entirely reasonable that the government gets back some or all of that from electricity customers in due course.”