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ENVA Energy concerns itself with the utilization of waste heat for the generation of electricity in ways that are meaningful both economically and in energy terms. According to a study by the Fraunhofer UMSICHT Institute from the year 2006, there is a technical potential in Germany alone for the use of waste heat in a volume of 8.4 GWel. On a worldwide scale, the figure is nearly 264 GWel in terms of the following energy sources: geothermy, the combined heat and power generation sector, special gas applications, and industry.

A highly promising approach in this area is offered by ORC (Organic Rankine Cycle) technology. With this technology, instead of water, an organic medium or refrigerant is vaporized, the energy used in an expansion unit, similar to that to be found in a conventional power station, and finally condensed once more in the recooling unit. The mechanical energy produced in the process is converted by a generator into electric current, which can then be used in-house or fed into the public grid.


ORC technology has been in use for power generation for many years, e.g. in biomass power plants, and in itself, therefore, is not a newcomer to the energy market. However, utilizing the potential of waste heat with a temperature below 90 °C for the production of electricity in a way that makes both economic and energy sense is indeed an innovation ‒ one which ENVA Energy has now succeeded in bringing to market readiness in the shape of its own in-house development, the ORC Module.

At the heart of this patented system is a special rotary piston expander of the kind also used in the ENVA Energy’s Energy Module of ENVA Energy, which has the advantage compared to conventional turbines of being able to achieve a comparatively high level of internal efficiency even at very low evaporation pressures of the working medium.