The Fluid used in Rankine Cycle Engines can be a “humid” fluid (such as water) or a “dry” organic fluids. The choice of the fluid depends in particular on the running temperature of the system. Researchers at Loughborough University and the University of Sussex, both in the UK, also have concluded that using waste heat from light-duty vehicle engines in a steam power cycle could deliver fuel economy advantages of between 6.3% and 31.7%, depending upon drive cycle, and that high efficiencies can be achieved at practical operating pressures.[1]