Projektinfo – Detailed information on energy research

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ORC technology uses low-temperature heat
Projektinfo 13/2011
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Transforming waste heat into electricity

Anyone generating electricity or operating high-temperature industrial processes produces waste heat. This waste heat is often not utilised, since its economic use does not seem viable. Small plants using the Organic Rankine Cycle (ORC) promise help here: they make the waste heat usable in the form of electricity, improve the cost-effectiveness and reduce CO2 emissions. Researchers from Saarland have developed an engine that uses low-temperature heat to generate electricity very efficiently for a large range of uses.

Engines convert around one third of their fuel into usable energy. Two thirds are transformed into waste heat. Usually, this heat energy vanishes unused through the exhaust or the chimney. Researchers from Saarbrücken want to change that. Since 2004, a spin-off company from Saarland University of Applied Sciences (HTW) has been working on this aspect on behalf of the automotive industry.


Major German manufacturers want to feed the heat from car exhaust gases through mobile steam circuits in order to reduce the fuel consumption by around a tenth. In 2007, graduate engineer Michael Schmidt came up with the idea of using the technology in industry to increase electricity yields. “Many components of our steam expansion engine are mass produced and can be easily modified to utilise heat flows from small power plants.” Since 2009 a demonstration plant has been connected to a coalmine gas engine at the nearby Fenne power plant. In the meantime 12 members of staff are now working in Saarbrücken on steam circuits for engines and are testing new components for at least one thousand operating hours in the demonstration system.


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Steam expansion engine
DeVeTec GmbH

Working fluids
Evonik Industries AG

Heat exchangers