A plant‐specific model approach to assess effects of repowering measures on existing biogas plants: the case of Baden‐Wuerttemberg

Up 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

Seasonal flexibilisation: A solution for biogas plants to improve profitability

It has been shown that the power demand-oriented operation of biogas plants contributes to the challenges of future energy systems with high shares of fluctuating renewable energies. This flexibilisation is usually short-term and can improve profitability. Long-term seasonal flexibilisation could further overcome present low heat utilisation rates due to the low heat demand of district heating in summer and constant biogas production across the year. To assess the benefits of seasonal flexibilisation for different biogas plants, we apply an existing model approach for analysing biogas repowering and optimising the combined heat and power (CHP) despatch. Plant-specific constraints and historical spot market data are used to determine power revenues, heat utilisation rates, greenhouse gas emissions and the profitability of the biogas plants. For different setups of CHP units and heat demand levels, the seasonal operation mode is compared with the non-seasonal reference mode. The economic benefit of seasonal flexibilisation is on average 10 €/MWhel when comparing the same rated power output and varies with plant size and CHP-setup. Increases in the heat utilisation rate are the main driver. Benefits increase with additional installed CHP capacities and rising heat prices. As gas production changes over the year, higher CHP capacities increase flexibility in winter and align the power market revenues of seasonal and non-seasonal operation. Very high heat prices even offset economies of scale. However, seasonal flexibilisation does not allow economic operation in Germany under current market conditions. The dependence on other sources of revenues and extended support schemes therefore remains

AuRaSa - BIOGAS: Auswirkungen von veränderten energie- und umweltrelevanten Rahmenbedingungen und Technologiefortschritt auf die Entwicklung sächsischer Biogasanlagen – AuRaSa

Bis zum Jahr 2030 entfällt für viele sächsische Biogasanlagen die garantierte Vergütung nach dem Erneuerbare-Energien-Gesetz. Jeder Anlagenbetreiber muss dann ein Konzept des betriebsindividuellen wirtschaftlichen Weiterbetriebes entwickeln. Für den Biogasanlagenbestand wurden mit EEG-Förderung drei Folgekonzepte/Zukunftsstrategien als wirtschaftlich tragfähig und nachhaltig identifiziert. Auch Eigenenergienutzungs- und Gasaufbereitungskonzepte wurden betrachtet. Analysiert wurden u.a. die Kosten bei einer Reduzierung der Bemessungsleistung, ein erhöhter Gülle-Input mit besseren Konditionen sowie eine Flexibilisierung. Die Veröffentlichung richtet sich an sächsische Biogasanlagenbetreiber und Landwirtschaftsbetriebe mit Tierhaltung. Redaktionsschluss: 13.08.202

AuRaSa - BIOGAS: Auswirkungen von veränderten energie- und umweltrelevanten Rahmenbedingungen und Technologiefortschritt auf die Entwicklung sächsischer Biogasanlagen – AuRaSa

Bis zum Jahr 2030 entfällt für viele sächsische Biogasanlagen die garantierte Vergütung nach dem Erneuerbare-Energien-Gesetz. Jeder Anlagenbetreiber muss dann ein Konzept des betriebsindividuellen wirtschaftlichen Weiterbetriebes entwickeln. Für den Biogasanlagenbestand wurden mit EEG-Förderung drei Folgekonzepte/Zukunftsstrategien als wirtschaftlich tragfähig und nachhaltig identifiziert. Auch Eigenenergienutzungs- und Gasaufbereitungskonzepte wurden betrachtet. Analysiert wurden u.a. die Kosten bei einer Reduzierung der Bemessungsleistung, ein erhöhter Gülle-Input mit besseren Konditionen sowie eine Flexibilisierung. Die Veröffentlichung richtet sich an sächsische Biogasanlagenbetreiber und Landwirtschaftsbetriebe mit Tierhaltung. Redaktionsschluss: 13.08.202

A life cycle assessment of biomethane production from waste feedstock through different upgrading technologies

Upgrading consists of a range of purification processes aimed at increasing the methane content of biogas to reach specifications similar to natural gas. In this perspective, an environmental assessment, based on the Life Cycle Assessment (LCA) method, of different upgrading technologies is helpful to identify the environmental characteristics of biomethane and the critical steps for improvement. The aim of this work is to conduct an LCA of biomethane production from waste feedstock, using the SimaPro software. The study focuses on the comparison of several upgrading technologies (namely, membrane separation, cryogenic separation, pressure swing adsorption, chemical scrubbing, high pressure water scrubbing) and the on-site cogeneration of electricity and heat, including the environmental benefits deriving from the substitution of fossil-based products. The results show a better environmental performance of the cogeneration option in most of the impact categories. The Fossil resource scarcity is the impact category which is mainly benefited by the avoided production of natural gas, with savings of about 0.5 kg oil eq/m 3 of biogas for all the investigated technologies, with an average improvement of about 76% compared to conventional cogeneration. The results show that the membrane upgrading technology is slightly more environmentally convenient than the other upgrading technologies