DECC (UK Department of Energy and Climate Change) has identified 48 Twh/yr of industrial waste heat, which is about 17% of total UK industrial energy consumption. The first problem in recovering this heat as electricity is the inescapable low efficiency (Carnot) of exploiting small temperature differences between heat source and heat sink. With free heat available from industry, the problem for any waste heat recovery system is then how to build a low temperature generator that is cheap enough to earn the three year payback that is required for waste heat to become a no-brainer.
The current contenders - organic Rankine cycle is too expensive for really low temperature differences and thermo-electric is expensive and inefficient. Ascending Power is developing a very cheap alternative.
The Ascending Power solution proposes boiling water to produce steam under vacuum ( Technology ). Water under vacuum at low temperature is cheap and safe, with none of the pressure vessel dangers of steam under pressure. Over several years of research we have investigated various methods of heat conversion, starting with passing steam up Archimedes screw rotors, but have now settled on a novel type of rotor that is efficient, cheap to manufacture, low maintenance and has good packaging characteristics for taking advantages of higher temperatures