The organic Rankine cycle (ORC) is a process in which steam turbines are operated with a working fluid other than steam. Organic liquids with low evaporation temperatures are used as the working fluid. The ORC process is used when the available temperature gradient between the heat source and heat sink is too low or the available heat output is too small to operate a steam turbine. This is often the case with electricity production using combined heat and power generation at small sites. ORC plants make it possible here to generate electrical energy from waste heat or associated with small heat outputs.
Wood is used much more efficiently
For the Fuhrberg waterworks, Fraunhofer UMSICHT developed a tailor-made and so far unique ORC process, which uses the waste heat at the ORC condenser for heating purposes on site and improves efficiency when using the renewable energy source wood. The successful pilot application of this ORC process on the small wood chip furnace near Hanover increases the benefit and efficiency of the decentralized energy supply by generating the required heating heat using combined heat and power generation – especially at lower heat outputs.
The electricity generated locally using cogeneration gives people greater independence from rising and fluctuating electricity prices. The pilot application, therefore, allows smaller wood and biomass heating plants to be converted to CHP operation in an economically profitable manner and represents an option for introducing cost- and resource-efficient combined heat and power generation, particularly with regard to retrofitting existing plants.