Background The German energy transition has entered a new phase and one important aspect is the question, to what degree the gas sector could be supplied with so-called “green” gases, i.e., gases from renewable sources. This paper focuses on the potential of domestic methane from biological origin (bio-CH4) until 2030 that is estimated with two different methods. The comparison of the results provides a consolidated estimate. Methods In a bottom-up approach, a GIS-based cluster analysis was undertaken to estimate the potential on bio-CH4 from the existing cogeneration biogas plant (BP) stock. In a top-down approach a meta-analysis of GHG-reduction scenarios with respect to bio-CH4 was performed. The meta-analysis was also extended to methane from renewable electricity (e-CH4) since the BP stock may play a role in the provision of CO2. Further, it included the year 2050 (the target year for most scenario studies) as well as issues like energy imports. Results The bottom-up approach yields a potential of 24.9 TWh of bio-CH4 for 2030. This is well within the range of the top-down analysis of 11–54 TWh (average: 32.5 TWh) for that year. In some scenarios values for e-CH4 where considerably higher, especially with respect to 2050, but in these studies the sources—including the CO2 sources—are either not explained at all or they are due to imports of e-CH4 in combination with direct air capture (DAC) rather than biogenic sources. Concerning the regional dispersion, the bottom-up analysis shows that the largest potentials (53% or 905 of the biogas plants) are located in the northern part of Germany, more particular in Lower-Saxony, Schleswig-Holstein, Mecklenburg-Western Pomerania. These represent 54% or 602 MW of the installed capacity of the clusters. Conclusion The consistency of the outcomes of the two methodologically very different approaches may be called the main result of this research. Therefore, it provides a consolidated analysis of the potential for domestic supply of bio-CH4 in 2030. Furthermore, the amount corresponds to 2.7–3.5% of the German natural gas consumption in 2018. Taken bio-CH4 and e-CH4 together it corresponds to 7.2–8.0%.

Background: The Paris Climate Agreement requires a rapid and efficient shift to renewable energies and a decarbonization of the energy system. Combined heat and power provision from biomass is one way to efficiently provide renewable heat. Despite this, many bioenergy plants in Germany are mainly used to generate electricity and the provision of externally usable heat still has untapped potential. In this study, we investigated gross quantities as well as the economically viable potential of Germany's current bioenergy plant stock in supplying renewable heat. Methods:We used a top-down GIS modeling approach to spatially and explicitly assess the heat demand of three different categories of heat sinks at sub-municipal level. These included residential, commercial, and industrial areas, as well as large individual heat consumers. We then calculated the plant-specific heat sales potential for two different district heating network options. In addition, we developed a method for assessing the economic efficiency of the previously identified technical heat sales volume for a set of 20 different clusters of bioenergy plants. Results:The results show that about 50% of the bioenergy plants have potential heat consumers in their immediate proximity. The overall technical heat sales potential for all three categories totals around 150 TWh th /a. However, this potential is not evenly distributed throughout Germany. Certain regions appear to be more favorable for investing in district heating networks powered by heat from biomass. The economically viable heat sales potential related to electrical energy generation ranges from − 0.128 to 0.160 €/kWh th . Conclusion:We concluded that, under certain conditions such as location or supply and demand structure, German bioenergy plants have the potential to provide a significant share to renewable energies in the heating sector. In addition, the heat sales potential is highly relevant for plant operators as the importance of heat as a business segment is set to increase. Furthermore, bioenergy plants could contribute 2.1% (16.3 TWh th /a) to the total demand for space heating in Germany (765 TWh th /a) when considering certain technical and economic constraints.