This article refers to the German biogas market and the German law. From a technical point of view, some ideas can certainly be transferred to your country.
The expansion of renewable energies in Germany is moving forward. Renewable Energies are, according to the Bundesministeriums für Wirtschaft und Klimaschutz (2024), with about 52 % of the gross electricity consumption in the first half of 2023, one of the most important energy sources. The share of renewable energies is supposed to increase to 80 % by 2030. The Umweltbundesamt (2023) emphasizes the status of biomass as the still most important renewable energy resource. With various utilization options in several sectors, such as heat, traffic, and power generation, the share of biomass in renewable energies is about 53 %.
Furthermore, the Bundesministerium für Ernährung und Landwirtschaft (2022) underlines the essential status of biogas for future energy systems in one of its articles, which is based on the energy source’s storable, flexible, and base load-capable characteristics. For 2021, the amount of renewable energy generated from biogas takes up 12.2%; for renewable heat, it is up to 10 %. The positive development correlates with the growing number of biogas plants in Germany since 2000, which numbers about 9.600 now. The substantial force of this development was based on the compensations granted by EEG for gas supply over 20 years. This now-ending period leads to the fact that biogas plants have had to face reliable follow-up concepts from the beginning of the EEG Compensation.
An economic Operation without federal support systems (EEG) is hardly obtainable
The question of suitable follow-up concepts for a further economic operation of biogas plants is highly precarious these days. Güsewell et al. (2023) underline that to this day, the operation of biogas plants in Germany without federal support systems (EEG) is only economic under favorable conditions. By working out a guideline, Baumkötter et al. (2020) are delineating a solid framework that compares different follow-up concepts linked to the practical applicability for plant operators. The current political discussions are still not clear about the option for a continued compensation period over ten years. Plant operators have the option to choose other options besides the EEG to prevent the need for decommissioning.
Follow-up concepts besides the EEG
- Biogas Processing onsite of the biogas plant
The combined heat and power plant on-site generated sales value in former concepts. In follow-up concepts, this can be generated by processing raw biogas to biomethane and supplying it to the gas grid. Biogas processing plants are also available at more minor power scales. Operation of biogas plants with a production capacity 250 Nm³ / h and above is possible (with alternative processing systems also less). The construction of a biogas-feedin-plant is mandatory for the biogas supply and the local gas supplier’s connection to the gas grid. Furthermore the separated CO2 from the biogas processing can be processed and marketed as liquefied CO2.
There are several options can be considered if a gas grid connection is not within an economical range. If operated combined heat and power plants are decommissioned, a substitute for the heat supply (e.g., wood chips) is needed to act as digester heating.
- Centralized biomethane processing plant
For small biogas plant operators, it is not economical to build a self-operated biogas processing plant. If there are several biogas plants in a spatial correlation, a centralized biogas processing plant can be a viable follow-up concept for those plants. Therefore, the costs for constructing and interconnecting only result in the centralized plant. Modifications are mandatory for every linked biogas plant in the range of piping and controls. The raw biogas of every single plant will be transported to the centralized processing plant by raw biogas connections.
Conclusion
With the share of electricity and heat production delivered by biogas plants today, follow-up concepts at the end of the EEG compensation period are more important than ever. Otherwise, functioning production plants that generate, deliver, and store energy 365 days a year are at risk of a shutdown due to the lack of economical operation possibilities. With technical planning, necessary permitting, and financial expenses, there are manifold options for economically operating a broad range of plants, even without being compensated by EEG.
Are you operating a biogas plant and planning to implement a follow-up concept? We gladly support you with our know-how and our network. Please feel free to address further questions by contacting us by e-mail.
The authors are employed at greenValue GmbH. greenValue is a service provider in renewable energies with broad experience and comprehensive references, e.g., in project management.
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Source: 29 February 2024, www.greenvalue.de
