A Norwegian outfit says waste heat recovery is the “hidden jewel” in the drive for renewable energy.

Viking Development Group's Viking Heat Engines (VHE) has developed a so-called CraftEngine that transforms low-temperature waste heat into electricity.

Based on a piston expander developed in collaboration with German engine design company AVL, VHE claims fuel savings of up to 5% can be achieved — and NOK 400m ($48m) is said to have been spent on developing its product.