ElectraTherm Green Machine Installed at Biogas Facility in Trechwitz, Germany

April 4, 2012 - PRLog -- ElectraTherm installed its first Green Machine in Germany at a biogas power generation facility to produce additional electricity without additional fuel or emissions. The site is producing biogas through anaerobic digestion to fire an 800kWe MWM internal combustion engine that generates electricity to sell to the grid. The current output of the engine is 500kWe but with the inclusion of the Green Machine, excess engine heat will now be employed to generate approximately 7% more electricity. This is the first application in Germany where an Organic Rankine Cycle (ORC) is incorporated into a biogas facility meeting the 60% thermal requirements to qualify for Germany’s EEG 2012 bonus feed-in tariff rate. The addition of the Green Machine allows the entire site’s electrical production to quality for the higher rate which equates to a very attractive payback period.  

“Germany’s 2012 feed-in tariff rate rewards biogas facilities that utilize 60% of the thermal heat load in their processes,” said Markus Heyde, Project Manager for Etalon GmbH, and site manager. “Adding the Green Machine to this site helped us reach the 60% requirement, and the incentive enables an attractive payback.”

ElectraTherm’s Green Machine generates distributed power from waste heat in a zero emissions closed loop cycle. Hot water enters the Green Machine at 90-95°C, where it heats a working fluid into a pressurized vapor. The high pressure vapor expands through ElectraTherm’s patented twin screw power block, spinning an electric generator rated for 30-65kWe output. After turning the twin screw expander, the vapor is condensed back into a liquid through the use of an external air cooled condenser. After condensing, the working fluid flows back to the evaporator to repeat the process.

The MWM engine is equipped with an exhaust gas heat exchanger designed to combine both the heat available in the exhaust and the heat available in the jacket water into a single heat stream. The waste heat from the engine is used to heat the anaerobic digestion process, and excess heat not needed to sustain the anaerobic digestion process is utilized by the Green Machine to produce fossil-fuel free electricity 24/7.