Abstract
For the existing biogas plants (BGP) in Germany, the period of the public support scheme begins to end in 2021. From a technical point of view, essential components have an operational life span of more than 20 years and allow for an extended operation. However, a profitable extension would require suitable follow-up concepts and depends on the underlying plant-specific setup, the regional conditions, as well as the regulatory and economic framework. Based on an expert evaluation, four promising follow-up concepts were identified in a multistage process consisting of expert interviews, workshops, and an online survey. These follow-up concepts are “Basic flexibilization,” “Substrate change,” “Seasonal flexibilization,” and “Biomethane upgrading.” They were assessed with a plant-specific biogas repowering model for a heterogeneous data set of 2,508 BGPs and were compared in three scenario frameworks to derive robust development paths. To capture the heterogeneity of the existing BGPs in Germany, the model was developed further regarding regional parameters such as power output, substrate mix, and emission factors. Across all the scenarios, “Seasonal flexibilization” proves to be the most promising follow-up concept for more than 50% of the BGPs. This is followed by “Substrate change,” which is particularly suitable for larger BGPs with high shares of energy crops and no heat utilization. Biomethane upgrading is usually the second choice compared to participation in extended public support schemes for electricity production. However, it is the only concept that is profitable under current market conditions due to the high CO2-quota prices in the German fuel sector. The development pathways also show a significant potential to increase the net GHG reduction, which on BPG average can be nearly doubled. Our approach shows that the interplay of the heterogeneous BGP structure, the applied economic decision variable, and the nonuniform framework conditions in different energy markets is of crucial importance when assessing similar biogas markets, identifying robust follow-up pathways, or designing framework policies.
Highlights
In the early 2020s, the first generation of renewable energy plants in Germany reaches the end of their 20 years’ support period by the German Renewable Energy Sources Act (EEG)
The plant-specific results are shown for the reference biogas plants (BGP)
Since BGP4 is affected by the corn cap, the substrate mix slightly changes in the concept “Flex Base.”
Summary
In the early 2020s, the first generation of renewable energy plants in Germany reaches the end of their 20 years’ support period by the German Renewable Energy Sources Act (EEG). The German electricity system is in a crucial phase of its energy transition Conventional, dispatchable capacities such as nuclear and coal power plants are phased out or starting to be phased out. The share of renewable electricity is targeted to rise from 38 to 65% in 2030% (CDU, CSU, and SPD, 2018). Of this electricity, 14%, equivalent to 31.46 GWhel, is produced in biogas plants (BGPs) including the biomethane conversion pathway. 14%, equivalent to 31.46 GWhel, is produced in biogas plants (BGPs) including the biomethane conversion pathway The majority of these BGPs were built in the agricultural sector (Daniel-Gromke et al, 2018)
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