Frankfurt, February 20. At the Preußner farm in Friedberg, north of Frankfurt in Germany, the Energor company uses biogas from food waste to fuel local homes – generating heat and electrical power using two mtu gas-powered 8V 4000 GS CHP modules, each with 800 kW output.
Since the company’s creation in 1995, farmer Gerd Preußner and his son Matthias have turned the farming business into a food waste recycling enterprise. Each year, they produce three million cubic meters of biogas from 18,000 tons of food waste. That biogas is used in their twin mtu CHP modules to generate a total of 7.5 million kWh – enough to fuel a village of almost 2,000 households.
The process of circular economy
Each morning, a fleet of trucks collects food waste from within a 50 km radius from schools, nurseries, hospitals, care homes and restaurants. For their customers, it’s a convenient means of waste disposal with a positive output.
The biomass collected is then subjected to a sanitation process taking one hour at 70°C. Non-organic substances are removed and then it is transported to the fermenter where carbohydrates, proteins and fats are converted to methane by means of micro-organisms. Iron hydroxide is also added during fermentation to eliminate hydrogen sulphide.
It takes around another 100 days in the fermenter before the food waste begins to produce biogas. This is then transported via active carbon filters to one of the two mtu CHP modules which uses it to deliver 800 kW of heat and electrical power – and with great reliability.
Engineering excellence and a long-term partner
Energor has benefited not only from the technical excellence the plant provides, but from the Rolls-Royce service teams as well. When a chemical leak caused damage to the CHP plant in early 2023, we were able to provide a replacement within six weeks, allowing energy production to get back into full swing quickly.
For the Preußners, this is particularly important as they not only feed electrical power into the public utility grid but use it themselves to heat water. Thermal energy is also harnessed for sanitising the waste, drying maize crops and wood on the farm, and melting fats. The latter is another pillar in the Preußner business which collects fats alongside food waste to be purified, processed and sold on to be made into other alternative fuels like HVO (Hydrotreated Vegetable Oil).
In autumn 2023, we launched a new mtu CHP module that sets new standards in efficiency, power density and life-cycle costs. The 12-cylinder version boasts over 1,500 kW output, peak efficiency of 44.1% and overall efficiency of 90%.
