Solar and wind energy are not always available in equal quantities. At the same time, energy demand fluctuates throughout the day and year. To better align local energy production with energy consumption, the “biovolatil” joint research project is investigating the interaction between biomass gasifiers, combined heat and power (CHP) plants, geothermal energy, and existing energy systems. The goal is a climate-neutral, as self-sufficient as possible, and at the same time flexible municipal energy supply.

The focus is on design and process engineering adjustments that enable demand-driven operation of the biomass gasification CHP plants. The project partner Burkhardt GmbH, a manufacturer of biomass power plants, is testing these approaches on a gasification system under real-world conditions. “The results lay the groundwork for integrating such flexible plants into real-world energy systems in the future,” says project manager Johannes Voß from the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT.

New Reactor Insert Tested Under Real-World Conditions

The geometry of the reactor insert in the gasifier influences how much fuel the plant converts and how much electrical and thermal power it generates. The project team has therefore developed an alternative reactor insert and tested it in a demonstrator. It is designed to specifically adapt the output of the biomass gasification CHP plant to lower heat demand. The design is such that the reactor insert can be retrofitted into existing plants with minimal effort. An initial version has already been in operation for approximately 3,000 operating hours. An optimized version is currently being tested. The focus is particularly on system behavior, operational safety, and long-term durability. In the future, plant operators could adapt their existing plants seasonally to medium-term demand as part of regular maintenance intervals.

Product gas recirculation expands the operating range

Another approach involves recirculating product gas: In this process, a part of the gas generated during the process is fed back into the gasification reactor. Initial test series show that this can specifically influence operating behavior and reduce the minimum plant load. The next tests are intended to clarify the extent of the potential for increased flexibility and what operating strategies can be derived from it.

Overall Concept Based on Real Data

The findings to date are being incorporated into a comprehensive operating strategy. “We are currently discussing various concepts for coupling biomass gasification CHP plants with geothermal energy,” says Johannes Voß. Real, location-specific data from the energy grids of the municipalities of Oberhausen and Zittau form the basis for the evaluation. The project team will then compare the concepts based on environmental and economic criteria.

Project partners and funding

The “biovolatil” joint research project is funded by the German Federal Ministry for Economic Affairs and Energy (BMWE). In addition to the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT, the following partners are part of the project consortium: Burkhardt GmbH, EnProCo Berlin GmbH, the Fraunhofer Research Institution for Energy Infrastructures and Geotechnologies IEG, Zittau/Görlitz University of Applied Sciences, and the ifeu Institute. Associated partners are Energieversorgung Oberhausen AG and Stadtwerke Zittau GmbH.