New Biomethane plant with a processing capacity of approximately 700 normal cubic meters of raw biogas per hour

ETW Energietechnik, in collaboration with the planning office Rytec, has successfully constructed a biomethane plant in Rittershoffen, Alsace. This state-of-the-art facility, operational since February 2023, has a processing capacity of approximately 700 normal cubic meters of raw biogas per hour. As a result, up to 350 normal cubic meters of biomethane can be injected into the natural gas grid every hour, which is equivalent to the average fuel consumption of 20,000 passenger cars.

The project was initiated by three environmentally conscious farmers from Alsace who are dedicated to promoting sustainable agricultural practices in the region. The plant exclusively utilises agricultural residues from the immediate surroundings as substrates, further emphasising its commitment to local resources.

One notable feature of ETW's plant is its remarkably low power consumption of only 137.6 kilowatts electric, setting a new standard for biomethane plants of its size. This significantly reduces the risk of future electricity price increases. Even with a high-pressure compression plant integrated into the system, which compresses the biomethane to 67.7 barg (bar gauge) before feeding it into the natural gas grid, the total power consumption remains below 202 kilowatts electrically. This efficiency is significantly better than comparable products available on the market, with the entire plant consuming less than 7 percent of the energy provided by the biomethane.

Efficient planning and streamlined construction processes played a crucial role in the rapid progress of the project. Initial considerations for the plant began in 2016, followed by concrete design and planning work in 2019. Rytec, responsible for the approval, funding applications, construction financing, and earthworks, ensured a seamless workflow by minimising interfaces. As a result, the biogas plant has created three job opportunities in the region. Although concerns were initially expressed by residents of the neighboring village of Rittershoffen, the project developers invested significant effort and resources to integrate the plant harmoniously into the landscape.

FERME SCHARRENBERGER, a family business known for growing fine crops like asparagus and horseradish, considers the sustainable development of the region a top priority. Denis Scharrenberger, Managing Director of FERME SCHARRENBERGER, emphasises the importance of aligning the biogas plant with their company philosophy while providing environmental benefits to the entire region. To address local residents' concerns, the biomethane plant was strategically located away from the road, surrounded by a wall and adorned with high-quality native trees and hedges. Extensive earthworks, as well as the installation of longer power lines and pipelines, were undertaken to accommodate the community.

Great attention was given to ensuring the highest quality in the plant technology designed for fermenting diverse residual materials. ETW Energietechnik's SmartCycle® biomethane plant is renowned for its reliability, low maintenance requirements, and exceptional energy efficiency. By employing oil-free screw compressors and an intelligent plant control system, the facility boasts the lowest energy consumption in the market.

During construction, prefabricated parts from Drössler Umwelttechnik were utilised, including factory-concreted installation components such as FF pieces and agitator frames. All built-in parts feature additional sealing flanges, and the tank walls are thermally insulated with a sandwich construction and integrated heating pipes protected by concrete.

Paulmichl was responsible for the stirring and separation technology, employing powerful external drive technology in the agitators. The Mammut fermenter agitator particularly excels at Rittershoffen plant, delivering strong agitation performance even with high dry matter content. With the ability to hydraulically adjust the agitators, optimal adaptation to the fermenter substrate is achieved. The panoramic sight glasses developed by Paulmichl provide operators with visual insight and monitoring of the plant's operation. The separation process at the Rittershoffen plant is carried out by a specially adapted PM260 series separator, which ensures reliable operation. Pressure control of the separator facilitates flow rate control of the feed pump, eliminating the need for a feed tank and overflow pipe.

For gas storage, SATTLER's tanks were chosen due to their exceptional tensile strength and extremely low permeability.

The implementation of the BioG solids dosing system allows for the introduction of more demanding residues, such as straw and manure, in liquid form. The Rittershoffen system includes a 190 cubic meter BioFeeder and a subsequent BioMerge mixing system that homogeneously blends the fermenter liquid with shredded material. The resulting mixture is pumped into the fermenter using an eccentric screw pump, successfully removing stones and other foreign bodies in the process. This significantly reduces wear and tear on the pumps and downstream equipment.

The plant's gate valves and measuring technology are double-protected, ensuring the highest safety standards as per Rytec's specifications.

With the integration of ETW Energietechnik's low-energy gas processing plant, Rytec's frequency converters, and future CO2 liquefaction, the biomethane plant generates a negative CO2 footprint, making a significant contribution to environmental sustainability.