US waste-heat-to-power products maker Alphabet Energy said on Wednesday it has raised USD 23.5 million (EUR 21m) from a Series C financing round led by a new investor, oil and gas sector player Schlumberger (NYSE:SLB).

A young startup is making flexible sheets of metal covered in tiny antennas that can turn heat into electricity.

Sound like the stuff of science fiction? The company, RedWave Energy, is working on the unusual idea that could, if successfully manufactured, help turn waste heat from power plants and factories into energy.