The higher energy yield means that Stadtwerke Gross-Gerau can supply some 360 more people with electricity. At Friday’s official opening of the ORC system, which has been operational since the end of 2012, Lucia Puttrich, the Environment Minister of the state of Hesse, declared: “It is important, when expanding decentralized energy production, to invest in the efficiency of the systems and in the sensible utilization of waste heat. That is why the Environment Ministry is providing grants of up to 150,000 euros for the use of ORC technology in generating electricity from the unused waste heat from biogas or sewage gases. Generating electricity from the waste heat which would otherwise not be used enables the overall efficiency of a biogas plant to be significantly increased.” In Hesse grants of up to 40% of the eligible investments costs have been available since October 2012 for ORC projects for electricity generation from renewable waste heat.
In Gross-Gerau Heinz Dürr, Chairman of the Supervisory Board of Dürr AG, called for more support for energy-efficient technologies: “The energy transition won’t happen without energy efficiency. Too much emphasis is being placed on new energy sources, yet saving energy is much simpler – for example with ORC systems. In Germany it costs on average three times more to produce one kilowatt-hour than to avoid consuming it. More efficient technologies and smart energy management would enable German industry to cut its energy consumption by up to 30%.”
ORC stands for Organic Rankine Cycle, a steam turbine process which uses the waste heat from combustion processes to generate electricity. In Gross-Gerau, Dürr has installed its innovative high-temperature ORC system as part of a combined-heat-and-power plant. This has made it possible for the first time to incorporate ORC technology in CHP plants with a low power output range from 50 kW.
Since its installation, the ORC system in Gross-Gerau has completed over 3000 hours of operation. With a feed-in tariff of 20.3 cents per kilowatt-hour and 7,500 equivalent-full-power hours, the payback time is around five years.
In addition to ORC, Dürr also offers other technologies for the efficient use of heat and waste heat. These include heat pumps, heat exchangers, latent heat storage systems and the Dürr Compact Power System, which provides electricity and heat at the same time. “Dürr offers cost-effective solutions for different forms of heat and waste heat use. ORC is a core element of our product portfolio in the energy efficiency field,” stated Dürr’s CFO Ralph Heuwing, who heads up Dürr’s energy efficiency activities. Dürr’s Clean Technology Systems division, which brings together the company’s energy efficiency and environmental technology business operations, has set itself the target of achieving sales of around €200 million by 2015.