The EPS (Echogen Power Systems, USA) heat engine uses industrial grade liquid CO2 as the working fluid, which does not have practical temperature or pressure working limits. It ranges from 6-32 MWe. The turbomachinery pumps the liquid CO2 to high pressure and passes through a combination of recuperators and waste heat exchangers (without using a secondary oil loop) before entering the turbo-expander, which drives the shaft that in turn drives a generator. Effluent CO2 exits the turbine, and passes through a series of recuperators to exchange more heat, and finally enters the condenser where it is converted back to liquid CO2. Exiting the condenser, the liquid CO2 re-enters the pump to repeat the cycle.
This engine might be applicable at many industrial plants, renewable energy plants, like geothermal, solar or biomass stations.
It was invented in 1816 by Robert Stirling. The Stirling engine was originally known as a hot air engine. It was the first closed cycle hot-air engine and produces power by repeatedly heating and cooling a fixed amount of gas sealed inside the engine. It is intended as safer alternative to the steam engine. Its maximum efficiency is 66,4%
Its advantage that it can be also used in small sizes at a household level, the new development is with solar applications. Some expectations are that it may revolutionize the renewable energy applications.