Abstract
AbstractUp to the latest versions of the German renewable energy act (EEG), there had been a constant growth of new biogas plants (BGPs). After reaching a stagnation in the last years, today the focus has shifted to improving the existing BGPs. Assuming that most plants have not reached the technical end of life, the question arises on how an operation can be realized beyond the initial EEG support period of 20 years. In addition, new legal and economic conditions require the implementation of adjustments, that is, “repowering measures.” Based on a method review, a plant‐specific model approach is presented to assess repowering measures for a wide range of BGPs differing in capacity, substrate mixture and agricultural structures. The techno‐economic model includes different performance indicators like levelized cost of electricity (LCOE) and temporal aspects like technical progress. Using a data set for BGPs in the state of Baden‐Wuerttemberg (Germany), results are illustrated for the different model modules and three repowering scenarios of an extended operation period of ten years. The scenarios regard different options to meet the requirements of the current EEG, namely the flexibilization and restrictions on energy crops, in comparison with a reference case. While in repowering scenarios, the number of plants decreases between 54% and 69% and the overall power capacity changes between −48% and 13% until 2035. The results further show a reduction potential in the specific area demand and GHG emission up to 12% and 24%, respectively. Technical progress, additional revenues and capacity premiums are shown to be an important factor for efficient substrate utilization, low LCOE and thereby the enabling of an extended operation period. The scenario results indicate that the agricultural areas for energy crop cultivation and the amount of manure used in BGPs will be reduced considerably, inducing new chances and challenges in the future.
Highlights
In the year 2000, the renewable energy act (EEG) was introduced in Germany to promote renewable energy technologies and climate protection
Beginning in 2020, the first biogas plants (BGPs) will reach the end of their initial EEG promotion period
Questions arise on how the development over the 10–20 years will look like, if operators continue the operation beyond the 20 years’ EEG period or if a large share of BGPs, forced by the economic frame conditions, will shut down
Summary
In the year 2000, the renewable energy act (EEG) was introduced in Germany to promote renewable energy technologies and climate protection. The initial support scheme of the EEG, the feed‐in tariffs for electricity, has ensured 20 years of operation and induced a steady, sometimes steep growth of newly installed biogas plants (BGPs). Today around 9,200 BGPs with an electric capacity of 4,240 MW exist in Germany (FvB, 2017). With new regulations in the latest versions of the EEG (2017), the installation of new BGPs is stagnating, showing only a negligible growth. Due to this development, the biogas sector is shifting from building new to improving the existing BGPs. Beginning in 2020, the first BGPs will reach the end of their initial EEG promotion period. The future perspective of BGPs is mainly determined by the following aspects:
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