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ETW Energietechnik has built a biomethane plant in Rittershoffen in cooperation with the planning office Rytec. The processing capacity of the plant, which went into operation in February 2023, is about 700 Nm³ of raw biogas per hour. This means that up to 350 Nm³ of biomethane per hour is fed into the natural gas grid. This is roughly equivalent to the average fuel consumption of 20,000 passenger cars.
The project was initiated by three young, visionary farmers from Alsace who are committed to environmental protection and renewable energies and want to promote sustainable agricultural use in the region. Only agricultural residues from the immediate surroundings are used as substrates.
The low power consumption of 137.6 kW electric makes the plant from ETW state of the art for biomethane plants of this size class. This significantly reduces the risk of future electricity price increases. Even with a downstream high-pressure compression plant, which compresses the processed biomethane to 67.7 barg (bar gauge, overpressure) and feeds it into the natural gas grid, the power consumption of the entire plant is less than 202 kW electrical, significantly lower than comparable products on the market. This means that the entire system consumes less than 7 % of the energy provided by the biomethane.
When designing the plant technology for the fermentation of the diverse residual materials, great importance was attached to quality. The "ETW Smartcycle" biomethane plant from ETW Energietechnik is of high quality, reliable and low-maintenance. Thanks to the use of oil-free screw compressors and an intelligent plant control system, the plant has the lowest energy consumption on the market, according to the manufacturer.
For the concrete, prefabricated parts from Drössler Umwelttechnik with factory-concreted installation parts such as agitator frames were used. All built-in parts have additional sealing flanges. The sandwich construction of the tank walls is thermally insulated and already factory-fitted with integrated heating pipes that are appreciated by the concrete.
The stirring and separation technology was carried out by the Paulmichl company. The agitators are equipped with powerful external drive technology. Especially the fermenter agitator "Mammut" convinces at the Rittershoffen plant with a strong agitating performance at a high dry matter content. The infinitely variable hydraulic adjustment of the agitators allows optimal adaptation to the fermenter substrate. The panoramic sight glasses developed by Paulmichl provide operators with an insight into the monitoring of the plant operation. Reliable separation is achieved by a separator from the "PM260" series, which is specially adapted to the fermentation residue. By means of pressure control of the separator, the feed pump is controlled in its delivery rate, so that operation can take place without a feed tank and overflow pipe.
The gas storage tanks from Sattler have a high tensile strength and low permeability.
With Biog's solids feeder, more demanding residues such as straw and manure can be fed in liquid form. The system in Rittershoffen consists of a biofeeder. The downstream "Biomerge" mixing system mixes fermenter liquid with the shredded material and pumps it through an eccentric screw pump as a homogeneous mass into the fermenter. Stones as well as other foreign bodies are successfully separated in the overall system. This helps to reduce the wear and tear on the pumps as well as on the downstream technology.
Gate valves and measuring technology are each double-protected, so that the plant is equipped with Rytec's highest safety standards.
The low-energy gas processing plant from ETW, the frequency converters from Rytec and the future CO2 liquefaction generate a negative CO2 footprint on balance.
ETW Energietechnik
