The biogas plant owned by RETERRA Freiburg GmbH, a fully owned subsidiary of REMONDIS South Region, was first commissioned in 1999. From here, RETERRA processes around 32,000 tonnes of organic waste from private households on behalf of the City of Freiburg and the District of Breisgau-Hochschwarzwald. Moreover, it also recycles small volumes of organic waste from commercial businesses. The plant uses state-of-the-art technology and produces 4.7m cubic metres of high quality biogas every year. The majority of the biogas is transported by pipe to the combined heat and power (CHP) plant run by Badenova in Freiburg-Landwasser where it is transformed into electricity. The waste heat generated by this process is captured and used to heat the district of Freiburg-Landwasser. The remaining biogas is turned into electricity and heat by the CHP plant on RETERRA’s Tullastraße site. Those living in Freiburg, therefore, have one of the most efficient organic waste digestion systems around.
All in all, the biogas produced by RETERRA-Freiburg GmbH generates approx. 10,000,000 kWh of eco-friendly, carbon-neutral electricity. This is sufficient to cover the requirements of around 3,000 homes in the city and is helping the region to achieve their goal of switching over to renewable energy. The way biogas is used in Freiburg-Landwasser is extremely energy efficient and is becoming a role model thanks to the way it combines biogas, landfill gas and bio natural gas. “RETERRA Freiburg’s ongoing supply of gas to the district of Landwasser has been an important component of the council’s strategy to reduce its carbon footprint ever since the plant was commissioned in 2011,” explained Freiburg city councillor Gerda Stuchlik who is responsible for environmental matters. The agricultural industry continues to benefit from the approx. 13,500t of liquid digestate generated by the biogas plant every year. This saves the farmers having to buy in large quantities of mineral fertiliser and helps protect the region’s soils and rivers. The additional 8,500t of compost are sold from the site to local residents, gardening and landscaping businesses as well as to farmers.
“RETERRA Freiburg’s ongoing supply of gas to the district of Landwasser has been an important component of the council’s strategy to reduce its carbon footprint ever since the plant was commissioned in 2011.”
Gerda Stuchlik, Freiburg city councillor responsible for environmental matters
Large sums of money have been invested in the site over the last few years to ensure it meets all technical and legal requirements. Besides switching a number of individual machinery components, the company has also had a new storage hall built as well as a large silo that is able to hold 4,000m3 of liquid digestate. Moreover, the work to extend the offices and staff rooms and to convert the delivery chutes has been completed as well.
Ongoing investments in the site ensure the plant reaches the highest possible levels of efficiency – and that it fully complies with the Federal Renewable Energy Act.
The latest highlight of this investment project is the completion of the new curing area including an additional tunnel composting system and new technology to process the compost. The solid material left over after the digestion stage will now be stabilised in fully enclosed, climate-controlled composting areas. Once the treatment stages have been completed, the finished product will then be processed into high quality compost using the new screening machinery. “We have, therefore, been able to further improve the quality of the compost,” commented REMONDIS managing director, Aloys Oechtering. “Soil improvers from biogas plants are rich in nutrients and are perfect for gardening and landscaping businesses.” Now that all the new technology has been installed, the site meets all of the requirements set out in the ‘EEG’ (Federal Renewable Energy Act).
RETERRA produces clean energy and top quality compost in the city itself. Our thanks go to all those living in Freiburg who have welcomed this facility as being an important part of its Green City