A Pilot Project for the Heat Transition

With two large-scale heat pumps and a biomethane CHP plant, EWE subsidiary TEWE generates renewable heat for the Brandenburg town of Erkner while also reducing the strain on the power grid. We are pleased to be able to make an important contribution to this forward-looking project with our energy solutions. We are all the more delighted to congratulate the project on being named “CHP Project of the Month” by the energy magazine Energie & Management.

The Oldenburg-based energy provider EWE has implemented a pilot project for the heat transition in Brandenburg: EWE’s subsidiary TEWE commissioned the new heat generation system at the Erkner heating plant in mid-September 2025. After just over a year of construction, the combination of large-scale heat pumps and a biomethane combined heat and power plant is supplying climate-neutral district heating to the small town of Erkner (Oder-Spree district in Brandenburg).

“With the plant technology now fully operational, we are putting our goal into practice: to make the district heating supply in Erkner more efficient, climate-friendly and future-proof,” explains Andreas Saadhoff, TEWE Managing Director. Until now, TEWE operated three natural gas-fired combined heat and power plants and a three-part district heating network in Erkner. These have been partially modernised and converted. Following the conversion of the first heating plant, the share of renewable energy in the connected district heating network now exceeds 50 per cent. This is due, on the one hand, to the use of
biomethane as fuel for the CHP plant and, on the other hand, to the installed heat pumps. Previously, heat at the central heating plant was generated exclusively using natural gas boilers. 

Its largest customers include the town of Erkner itself, an education centre and the Erkner Municipal Housing Association (WGE), the largest landlord in this town of 12,000 inhabitants. A detached house, the Protestant nursery at the church tower, a cinema, sports halls, a retirement home and a medical centre are also already connected.

Stable heat production costs

The overall system in Erkner is designed as a hybrid energy system: heat pumps and CHP units respond to electricity price signals. If electricity prices are low due to a surplus of electricity on the market, the heat pumps take over heat supply; when electricity prices are high, the CHP unit is given priority and simultaneously generates revenue from electricity production. This allows heating costs to be stabilised, price risks to be mitigated and the efficiency of the overall system to be increased. The use of heat storage further enhances flexibility. The project arose from the collaboration between TEWE and the CHP and heat pump manufacturer 2G Energy. The new generation plant consists of a biomethane CHP plant for the base load and a two-stage heat pump system. The installed agenitor 408 CHP plant from the manufacturer 2G Energy generates energy with an electrical output of 360 kW and a thermal output of 400 kW.

The electricity generated in this process in turn powers the heat pump system with an output of 530 kW. Thanks to intelligent sector coupling, there is no additional strain on the electricity grid. In this system design, the heat pump system consists of a series connection of an afilia air AEK-R290 air-to-water heat pump and a afilia water R717 water-to-water heat pump, both from 2G Energy.

The system enables water to be heated to up to 80 degrees Celsius by utilising environmental heat and incorporating a heat storage tank. According to the manufacturer, only natural substances such as propane and ammonia are used as refrigerants. The heat pump system operates for around 3,500 full operating hours per year. The operating hours are determined by forecasts and market prices. The total heat output of around 10,000 MWh per year is supplied to customers via the district heating network. The electricity generated in the CHP plant is fed entirely into the public grid. Since commissioning in June 2025, around 2,400 MWh of electricity has been generated to date.

Technology for plant operation

EWE uses the old gas boilers to cover peak loads. In winter, an existing natural gas boiler also supports the supply. To ensure sufficient flexibility, a buffer tank from the manufacturer Dehoust with a capacity of 2 × 31 cubic metres was also installed. TEWE has invested around 2.5 million euros in the new plant, of which around 600,000 euros came from the Federal Funding Scheme for Efficient Heating Networks (BEW). Planning and construction supervision were handled by EWE as a shareholder of TEWE. For the implementation, regional partners were deliberately enlisted. The two other energy centres in Erkner (Buchhorst and Flakensee), which still run on natural gas, are also to be gradually converted to climate-friendly technology.

Translation of magazine article "Energie & Management" written by Heidi Roider