Pilot plant for renewable methane

The pilot plant is a research and demonstration platform which is being built at the DBFZ within the project "Pilot-SBG | Bioresources and Hydrogen to Methane as Fuel". Pilot SBG operates on behalf of the Federal Ministry for Digital and Transport as part of the Federal Government's Mobility and Fuels Strategy (MFS). The official start of the construction of the plant on the DBFZ site took place at the end of May 2022.

At its core, the pilot plant combines the anaerobic fermentation of selected residual and waste materials with the subsequent methanation of the resulting biogas. Innovative upstream and downstream processes increasing the resource efficiency and provide valuable by-products.

For the two campaigns, agricultural by-products in the form of straw and cattle manure as well as urban waste such as organic and green waste are sourced and processed regionally. The process chain essentially consists of the specific preparation of the raw materials, the subsequent optional pre-treatment using a hydrothermal process, the anaerobic fermentation to biogas in two parallel fermenter lines of different designs, the catalytic methanation of the CO2 in the biogas with the addition of hydrogen and the processing of the fermentation residues. Various aggregates of a separation cascade including optional hydrothermal post-treatment are available for digestate processing. As a result, renewable methane is produced as the main product at the pilot plant.


This is to be used in a subsequent tank facility in compressed form as renewable CNG in the DBFZ vehicle fleet. According to the current planning status, it can be assumed that 0.2-1.2 t of raw materials will be processed monthly in the final pilot operation and two car tank fillings of renewable CNG will be provided.

The representation of the entire process chain in one plant is unique in Germany on this scale. The pilot plant serves to gain knowledge, for example, on the interaction of components and apparatus or the influence of process parameters on its stability and yield. Its capacity has been selected to provide sufficient flexibility for research and development and to be cost-justifiable. After the operating campaigns planned from 2023, the plant will be available to actors from science and industry alike as a technology platform for research and development and is designed in such a way that different technology modules can be used flexibly. To a limited extent, it can also be used for these purposes already during the project term Pilot-SBG.


Modules pilot plant

Substrate preparation

In the substrate pretreatment module, the biomass is prepared. The primary objective is to adjust particle sizes and fiber lengths of the substrates (< 20 mm) as well as the dry matter content of the substrate mixtures such a way that the plant operation is as unobstructed as possible. Given the varying properties of the different biomasses such as cereal straw, green cuttings or biowaste - different processing steps for coarse, fine, dry and wet comminution are necessary. This module does not consist of a single plant unit, but of several aggregates that are operated in batches, as well as a central weighing station and areas for filling, transferring and mixing the substrates. The aim is to provide storable and conveyable batches for the subsequent process steps.

Anaerobic fermentation

In the anaerobic fermentation module, the processed biomasses are degraded by microorganisms in a controlled process. In this process, part of the contained organic matter is converted into biogas, a mixture of mainly methane and carbon dioxide. Two reactor lines are available for this purpose, which differ in their first process stage. One line has a continuously stirred tank reactor as the first process stage, as it is common in agricultural applications, for example. The second reactor line, in contrast, uses a plug flow reactor at this point, as is widely used in the treatment of organic waste. Common to both process lines is that the second and third process stages are each designed as continously stirred tank reactors. This allows a direct comparison of the most common reactor systems. Here, the methane yield over the process stages can be assessed as a function of varying process parameters.

Methanation and gas purification

In the methanation module, the biogas from the two digesters is mixed with externally supplied hydrogen without separating the methane. In the temperature-controlled tubular reactor, carbon dioxide from the biogas reacts with hydrogen on a catalyst to form methane and water. After the water is separated in a condensate trap, a product gas is produced with a methane content almost twice that of biogas. On approx. 500 ml of catalyst and at a process pressure of 20 bar(a), 2.5 m³/d of biogas with approx. 50 vol% methane content is converted into approx. 2.47 m³/d of synthesis product with > 95 vol% methane content. To ensure that the product gas is suitable as a fuel, unreacted residual carbon dioxide can be removed by gas scrubbing.

Digestate treatment

In the digestate treatment module, the portion of biomass that has not been fermented into biogas is treated to produce dischargeable water, a solid organic farm fertilizer rich in nitrogen and phosphorus, and a liquid inorganic farm fertilizer rich in nitrogen and potassium. In addition, a recirculate can be provided from the liquid phase of the digestate for mixing in the biogas process. The first step of digestate treatment consists of separating the solid phase from the liquid phase by means of a press screw separator and decanter centrifuge or chamber filter press with the addition of flocculants. For further treatment or concentration of the liquid phase, the membrane technologies ultrafiltration and reverse osmosis are available. With the separation cascade, an average of 0.1 - 0.5 m³ of digestate can be processed per day with the aim of achieving a volume reduction of at least 50%. The quantity and quality of the recovered nutrients or farm manure depends on the biomass used and the process conditions in the anaerobic fermentation. During processing, all relevant process parameters are recorded for monitoring the separation processes and for determining mass and energy balances.

Hydrothermal pretreatment and upgrading

In the pilot plant context, the module "Hydrothermal Processes" (HTP) covers processes for the digestion, treatment or upgrading of biomasses and residual materials, in particular those with a high water content, under elevated pressure and temperature. The processes typically run at temperatures of 150-280 °C and pressures of about 5-65 bar for between thirty minutes to a few hours. Part of the pilot plant is a 0.5m³ reactor, which can be operated up to 240°C and 39bar. This is used in the lower temperature and residence time range for the pre-treatment of difficult to access biomasses for fermentation. In the course of digestate treatment, higher temperature and pressure levels can be operated in the same plant technology in order to convert aqueous digestate into so-called hydrocarbon as well as to effect a shift of nutrients between the aqueous and solid phases. Taking phosphorus as an example, the portion bound in the solid phase can be transferred to the liquid phase and thus made accessible so that it can be recovered in downstream processes via a precipitation reaction.

Guided tours

Are you interested in a guided tour of the pilot plant for renewable methane on the premises of the German Biomass Research Center (Deutsches Biomasseforschungszentrum gemeinnützige GmbH)?

More information


We produce biogas! In the course of commissioning a pilot plant for the production of renewable methane at DBFZ German Biomass Research Center gemeinnützige GmbH, valuable biogas is obtained in the first step from straw and cattle slurry.

Since May 2022, the modules of the pilot plant for the production of renewable methane have been successively installed so that, after commissioning, the feasibility of the process chain can be demonstrated in the form of stable plant operation.

On May 31, 2022, the starting signal was given for the construction of the pilot plant on the DBFZ site in Leipzig. The start of construction was ceremoniously accompanied by the DBFZ project team as well as participating companies.

» To the press release

Official start of construction of the pilot plant at the DBFZ
(Photo: Paul Trainer, DBFZ)

Official start of construction with Ronny Bonzek (management) and the project management
(Photo: Paul Trainer, DBFZ)

Project team Pilot-SBG
(Photo: Paul Trainer, DBFZ)