Search

Abstract Bio-based carbon dioxide removal encompasses a range of (1) natural sink enhancement concepts in agriculture and on organic soils including peatlands, and in forestry, (2) bio-based building materials, and (3) bioenergy production with CO2 capture and storage (BECCS). A common database on these concepts is crucial for their consideration in strategies and implementation. In this study, we analyse standardised factsheets on these concepts. We find different dynamics of deployment until 2045: for CO2 removal rates from the atmosphere, natural sink enhancement concepts are characterised by gradually increasing rates, followed by a saturation and potentially a decrease after few decades; forest-related measures ramp up slowly and for construction projects and bioenergy plants, annually constant removal rates are assumed during operation which drop to zero afterwards. The expenses for removing 1 t CO2 from the atmosphere were found to be between 8 and 520 € t CO2 −1, which arises from high divergence both in capital and operational expenditures among the concepts. This high variability of expenses seems to suggest the more cost-effective concepts should be implemented first. However, aspects from economics, resource base and environmental impacts to social and political implications for Germany need to be considered for developing implementation strategies. All concepts investigated could be deployed on scales to significantly contribute to the German climate neutrality target.

With the amendment to the German Climate Change Act in 2021, the Federal Government of Germany has set the target to become greenhouse gas neutral by 2045. Reaching this ambitious target requires multisectoral efforts, which in turn calls for interdisciplinary collaboration: the Net-Zero-2050 project of the Helmholtz Climate Initiative serves as an example of successful, interdisciplinary collaboration with the aim of producing valuable recommendations for action to achieve net-zero CO2 emissions in Germany. To this end, we applied an interdisciplinary approach to combining comprehensive research results from ten German national research centers in the context of carbon neutrality in Germany. In this paper, we present our approach and the method behind the interdisciplinary storylines development, which enabled us to create a common framework between different carbon dioxide removal and avoidance methods and the bigger carbon neutrality context. Thus, the research findings are aggregated into narratives: the two complementary storylines focus on technologies for net-zero CO2 emissions and on different framing conditions for implementing net-zero CO2 measures. Moreover, we outline the Net-Zero-2050 results emerging from the two storylines by presenting the resulting narratives in the context of carbon neutrality in Germany. Aiming at creating insights into how complementary and related expertise can be combined in teams across disciplines, we conclude with the project’s lessons learned. This paper sheds light on how to facilitate cooperation between different science disciplines with the purpose of preparing joint research results that can be communicated to a specific audience. Additionally, it provides further evidence that interdisciplinary and diverse research teams are an essential factor for defining solution spaces for complex, interdisciplinary problems.

Abstract Background Policymakers are tasked with both driving the rapid expansion of renewable energy technologies and, additionally channelling the limited national potential of biomass into areas where it can provide the greatest benefit to the energy system. But do current policy instruments promote the use of biomass in these areas? As biomass is limited, its use must be sustainable without leading to further biodiversity loss or depleting forest or soil resources. In this study, short-term energy scenarios are generated using the BenOpt model, which take into account both current and alternative policy instruments under limited biomass utilisation. The results are compared with long-term, cost-optimal energy scenarios for the use of biomass. Results The analysis reveals that the instrument of a GHG quota does not promote the use of biofuels in hard-to-electrify areas of the transport sector, where they should be cost-optimally allocated according to long-term energy scenarios. Biofuels are promoted for use in passenger road transport and not in the shipping or aviation sector. In contrast, alternative policy scenarios indicate that the sole instrument of a high CO2 price is more conducive to direct electrification and could displace more fossil fuels by 2030 than the GHG quota alone. This instrument also promotes the optimal use of biogas plants in the power sector in accordance with long-term cost-optimal developments. Conclusions The instrument of a GHG quota might lead to counterproductive developments in passenger road transport, but it also helps to ramp up the biofuel capacities required in shipping and aviation in the long term. However, it does not provide the necessary incentives for the ramp-up of battery electric vehicles, which would be the cost optimal solution in passenger road transport according to the long-term scenarios. Even though alternative policy scenarios show that the sole instrument of a high CO2-price is more conducive to direct electrification, a high CO2 price alone is not enough (e.g. in the heat sector) to promote the efficient use of biomass instead of simply covering the base load demand.

Spatially and temporally resolved data on electricity production from run-of-river plants are very useful to study various aspects of this renewable energy at both the local and regional scale. In the absence of disaggregated feed-in data from such power plants in Germany, it is necessary to apply numerical simulations to determine their electricity production for a desired region and time period. We show how a simulation model can be created using publicly accessible power plant data and information from transmission system operators as model input. The developed physical model is applied to an ensemble of 7974 run-of-river plants in Germany, including those with and without water storage facilities, to simulate their electricity production for the year 2021. The resulting and spatially aggregated simulation results correlate well with the official total electricity feed-in from run-of-river plants in Germany, as well as on smaller spatial scales such as the city of Hamburg. Such disaggregated time series can be used to assess the renewable hydropower generation at different spatial and temporal levels, as each power plant is simulated with its geographical and technical data. Moreover, this study presents the electricity production landscape of run-of-river power plants in Germany as a highly resolved map and at the federal state level with related energy indicators, which enables a better monitoring of this renewable energy. The obtained results also support the expectation that the existing run-of-river plants will play an important role in the future transformation and decarbonization of the German power sector.

Abstract Background Innovations and new supply chain concepts are crucial for establishing a sustainable and circular bio-economy that reduces carbon emissions and lowers negative environmental impacts. PESTEL-based concept development provides information about positive, negative and neutral external factors of the macro-environment and their influence on supply chains. The primary data were collected at a stakeholder workshop and gaps in understanding the critical details were closed through expert interviews. The information gathered was organised using a data management software and coded by following a deductively formed system based on predefined PESTEL categories (political, economic, social, technological, ecological, legal). Stakeholders that used the method on intermediate carbon carriers (ICC) grappled with identifying the obstacles that hinder the market uptake of innovations. The workshop revealed a substantial demand for additional information. Infrastructural aspects were considered key to adequately understanding all of the segments along a supply chain. Using PESTEL alone, without taking infrastructural aspects into consideration, meant that the macro-environment that surrounds and affects the ICC supply chain remained a black box. This paper developed docking-related approaches to the basic PESTEL method in order to improve its output for the development of strategic concepts and to improve the market uptake of bio-economy-centred innovations. Results The expanded PESTEL method (hereinafter PESTEL + I) significantly shifted the emphasis of strategic decisions to the marketing of individual innovations compared to the basic method. Docking information gathering onto infrastructure (+ I) should be considered in order to expand existing strategy development concepts for bio-economy value chains. Testing the market uptake of innovations was beyond the scope of this study. Conclusions PESTEL + I not only increased the utility, but also the complexity and the time needed to analyse an entire supply chain. The expanded method, however, provides stakeholders and strategy developers with a more useful tool to support and optimise market uptake strategies in the bio-economy. Beyond this, there is a knowledge gap with regard to reducing the effort needed to collect data and evaluate such studies. Hence, follow-up research needs to find ways to digitalise major steps in the overall process to make it more efficient.

Multiple global crises are adding new elements to the discussion on securing and shaping a resilient, renewable energy system in Germany. Biomass from residues, forest wood and energy crops are major renewable energy contributors in Germany today. The role of energy crops within that system is controversially discussed for a long time and a phase-out from cultivated biomass is again in the focus. But what kind of trade-offs would be connected with such a phase-out and what would be the optimal allocation priorities of the remaining biomass potential? Through a detailed representation of biomass potentials, prices and conversion technologies in an energy system optimisation model, it could be shown in a scenario analysis that a phase-out increases the demand for energy imports by 1400 PJ per year, which is associated with on-costs of €14–25 billion annually in the long term. Finally, the results show that the decision on whether to grow energy crops in the future is directly influencing the future transformation strategy for high-temperature industrial heat applications. Solid biomass is identified as the future cost-optimal solution to fully transform this sector. However, a phase-out of energy crops changes the cost-optimal allocation priorities completely.

Abstract Background With sustainable bioenergy in the European energy mix, intermediate bioenergy carriers (IBC) become of growing importance, as they can ensure a more efficient utilisation of biomass feedstocks from agricultural and forest residues. A high potential for market uptake is foreseen for fast pyrolysis bio-oil (FPBO), one of several IBCs. While facing the chicken and egg problem in market entry, the aim of this study was the development of adequate strategies to support market implementation. The case study findings and methodological approach can provide policymakers, industry, and a broader audience with a vision for addressing similar challenges in market adoption of innovations in the bioeconomy and beyond. Therefore, we tested a new PESTEL + I approach and its practical applicability to an IBC value chain. Results With an adopted PESTEL method, we analysed a promising value chain in which FPBO is produced from sawdust in Sweden and Finland, transported to the Netherlands and upgraded and marketed as a marine biofuel. Our results show that the market uptake of IBCs such as FPBO and subsequently produced biofuels is above all driven by the European Renewable Energy Directive II (RED II). In Annex IX Part A, sawdust is listed as a feedstock for advanced biofuels, which can be double counted towards the 14% renewable energy share goal in the transport sector in 2030. To support the use of advanced biofuels in the maritime and aviation sector, the proposal for revision of RED II 2021 contains a new multiplier (1.2x) for fuels delivered to these sectors, while all other multipliers are deleted. These legal European obligations and implementation into national law of member states create strong incentives for many downstream market actors to use advanced biofuel. However, technological challenges for FPBO use still hamper fast market introduction. Conclusions Overcoming technology challenges and the creation of long-term validity of guidelines and regulatory framework will create stable market conditions, investment security and finally stimulate long-term offtake agreements between feedstock providers, technology developers and downstream customers. The approach and findings can provide a vision to overcome similar challenges in other bioeconomy innovations’ market uptake and beyond.

Abstract Soil is central to the complex interplay among biodiversity, climate, and society. This paper examines the interconnectedness of soil biodiversity, climate change, and societal impacts, emphasizing the urgent need for integrated solutions. Human‐induced biodiversity loss and climate change intensify environmental degradation, threatening human well‐being. Soils, rich in biodiversity and vital for ecosystem function regulation, are highly vulnerable to these pressures, affecting nutrient cycling, soil fertility, and resilience. Soil also crucially regulates climate, influencing energy, water cycles, and carbon storage. Yet, climate change poses significant challenges to soil health and carbon dynamics, amplifying global warming. Integrated approaches are essential, including sustainable land management, policy interventions, technological innovations, and societal engagement. Practices like agroforestry and organic farming improve soil health and mitigate climate impacts. Effective policies and governance are crucial for promoting sustainable practices and soil conservation. Recent technologies aid in monitoring soil biodiversity and implementing sustainable land management. Societal engagement, through education and collective action, is vital for environmental stewardship. By prioritizing interdisciplinary research and addressing key frontiers, scientists can advance understanding of the soil biodiversity–climate change–society nexus, informing strategies for environmental sustainability and social equity.

Abstract To reach their net‐zero targets, countries will have to compensate hard‐to‐abate CO2 emissions through carbon dioxide removal (CDR). Yet, current assessments rarely include socio‐cultural or institutional aspects or fail to contextualize CDR options for implementation. Here we present a context‐specific feasibility assessment of CDR options for the example of Germany. We assess 14 CDR options, including three chemical carbon capture options, six options for bioenergy combined with carbon capture and storage (BECCS), and five options that aim to increase ecosystem carbon uptake. The assessment addresses technological, economic, environmental, institutional, social‐cultural and systemic considerations using a traffic‐light system to evaluate implementation opportunities and hurdles. We find that in Germany CDR options like cover crops or seagrass restoration currently face comparably low implementation hurdles in terms of technological, economic, or environmental feasibility and low institutional or social opposition but show comparably small CO2 removal potentials. In contrast, some BECCS options that show high CDR potentials face significant techno‐economic, societal and institutional hurdles when it comes to the geological storage of CO2. While a combination of CDR options is likely required to meet the net‐zero target in Germany, the current climate protection law includes a limited set of options. Our analysis aims to provide comprehensive information on CDR hurdles and possibilities for Germany for use in further research on CDR options, climate, and energy scenario development, as well as an effective decision support basis for various actors.

Abstract This work assesses pathways towards a net‐zero greenhouse gas (GHG) emissions chemical industry sector in Germany until 2050, focusing on the ammonia, methanol, ethylene and adipic acid subsectors and the effect of the recycling of C embedded in chemical end products on the GHG abatement cost and primary resource demand. This was done using a bottom‐up mathematical optimization model, including the energy sectors and the chemicals sector, with electricity and biobased options considered. Results show that net‐zero GHG emissions for the considered chemicals in 2050 are attainable at a marginal cost of 640–900 €/tCO2‐eq, even with 26%–36% of demand being satisfied by fossil production routes. This is possible because renewable organic chemicals can act as carbon sinks if, at their end of life, C is permanently stored via landfilling or passed on to the next value chain via recycling. Nonetheless, considering the cost implications, the practical deployment of renewable chemicals is a challenge. The considered renewable chemicals cost 1.3–8 times more than their fossil counterparts, resulting in a marginal CO2 price of 480 €/tCO2‐eq when all primary resources (energy crops, forest residues and renewable electricity) are considered, or 810 €/tCO2‐eq when the availability of arable land is restricted. In the transition to net‐zero emissions for the chemicals under study, a circular economy is important not only for reducing demand for primary resources as is typically the case but also reduces GHG abatement costs by 13%–24% through carbon capture and utilization effects.

Spatiotemporally resolved data on photovoltaic (PV) power generation are very helpful to analyze the multiple impacts of this variable renewable energy on regional and local scales. In the absence of such disaggregated data for Germany, numerical simulations are needed to obtain the electricity production from PV systems for a time period and region under study. This manuscript presents how a physical simulation model, which uses open access weather and plant data as input vectors, can be created. The developed PV model is then applied to an ensemble of approximately 1.95 million PV systems, consisting of ground-mounted and rooftop installations, in order to compute their electricity production in Germany for the year 2020. The resulting spatially aggregated time series closely matches the measured PV feed-in pattern of Germany throughout the simulated year. Such disaggregated data can be applied to investigate the German PV power generation landscape at various spatiotemporal levels, as each PV system is taken into account with its technical data and the weather conditions at its geo-location. Furthermore, the German PV power generation landscape is presented as detailed maps based on these simulation results, which can also be useful for many other scientific fields such as energy system modeling.

Bioenergy is a crucial element of the future energy system with wide range of applications in electricity, heat and transport. A major challenge for the analysis and optimisation of the bioenergy system is the degree of diversity and complexity compared to wind or solar energy. A coherent database for studying the role of bioenergy in the energy system needs to cover the different entities such as bio-resources, conversion procedures and process chains. Since there is no comprehensive data collection for bioenergy so far, we develop a SQLite database by merging several existing datasets and additional information. The resulting Bio-Energy Technology Database (BET.db) provides a consistent set of 141 feedstocks as well as energy carriers, 259 conversion technologies, and 134 energy supply concepts. The proof of concept within a bioenergy system modelling a wide range of technologies for the electricity, heat and transport sectors using the BENOPT model has been successful. By providing a one-stop-shop solution for techno-economic information about on the bioenergy nexus, this blind spot can be avoided for further investigations. The current stage of development is an intermediate prototype that will be developed into a more versatile and interactive web application later on.

Abstract The bioeconomy is envisioned to play a decisive role in accelerating urban transformations towards greater sustainability and resilience. Integrating biological principles, such as metabolism, ecosystems and cycles, into urban planning and city life, and promoting a so-called “bio-principled city” provides significant potential for shaping more sustainable urban development. However, the future vision of a “bio-principled city” currently reflects more of a programmatic idea than a real political agenda. This study therefore draws attention to the existing policy mix of the city of Leipzig and evaluates in how far it already supports the city’s transformation into a bio-principled city. For this purpose, we developed a proper conceptional framework consolidating different research methods to conduct a comprehensive policy mix analysis. The analysis shows that the current policy framework for a bio-principled city in Leipzig is complex, uncoordinated and lacks in definitive actions. Our analysis offers interested policy makers and scientists an example of how an incidental and thus patchy policy mix can look like in practice. By highlighting its strengths and corresponding limitations, we provide a starting point for deliberate interventions to further promote the vision of a bio-principled city politically and thus realize its implementation.

Abstract Background Germany is highly dependent on natural gas, the availability of which has become uncertain due to Russia's invasion of Ukraine. Biogas provision in Germany is realized by more than 9500 mainly farm-side biogas plants that have the potential to increase the security of gas supply. Main text To assess the potential contribution of biogas to a secure gas supply in Germany, we combine a literature-based analysis of the current status and potentials of the biogas supply chain with calculations of the marginal costs for producing biogas under the current market conditions. Biogas provided 50 TWh of final energy in Germany in 2021, primarily in the form of power and heat. The production of biomethane, which can in principle replace natural gas when fed into the gas grid, amounted to 10 TWh in terms of the lower heating value, which corresponds to a share of about 1% of the German gas market in 2021. However, at the end of 2021, biogas significantly contributed to the provided power (13 TWh or 22% of power supply from natural gas) combined with co-generated heat (13 TWh or 2% of heat supply from natural gas). Increasing flexible power provision from biogas is promising under the current power market conditions. In contrast, the current biogas substrate mix will lead to crucial limitations: 75% of the input into German biogas are energy crops, which are limited in availability under rising agricultural prices. Conclusions and recommendations In conclusion, biogas can only make up a small share of the current natural gas consumption. An immediate programme to mobilize the use of biogenic by-products, waste, and cultivated biomass without requiring additional land is recommended. We also propose measures to increase the flexibility of power production and heat use and more greenhouse gas-related incentives of biogas supply for the medium term. Finally, we see the need for additional efforts for non-food feedstock mobilization on a European scale by realizing the envisaged tenfold increase in the contribution of biomethane to a production goal of 35 billion cubic metres by 2030 in the REPower EU Plan of the European Commission.

Solar photovoltaic (PV) is a key technology for any renewable energy system. As subsidy-free PV becomes more and more economically feasible, region-specific planning tools that define areas suitable for ground-mounted PV are needed. While many top-down studies have assessed suitable areas at a national scale, an accurate scalable bottom-up assessment of regional ground-mounted PV potentials in high spatial and temporal resolution that goes further than a mere identification of appropriate land areas is missing. This work introduces such a method based on digital landscape models that consider terrain slope, orientation, location-specific irradiation, and land use type, and combines this geoinformatical information with a PV yield model that allows to assess hourly PV generation potential on suitable areas. The method is validated with three existing ground-mounted PV plants in Germany, where a comparison of real and simulated annual electricity yields shows average deviations of 5%. Subsequently, ground-mounted PV potentials in three German counties with varying settlement structures as well as topographic and weather patterns are assessed and a comparison of yearly and hourly simulated generation potentials with regional electricity demand is performed. While the yearly analysis demonstrates the substantial overall potentials of local ground mounted-PV in all regions, with demand coverages ranging from 80% to hypothetically more than 40 times of current electricity demand according to current regulations, the hourly autarky ratio, defined as the share of hours of a year where ground-mounted PV can satisfy demand, ranges from 25% to 40%, without consideration of storage or demand side management. A subsequent investigation of the ability to export excess electricity generation from ground-mounted PV shows that the two regions with highest ground-mounted PV potentials have less-developed grid infrastructures, thus restricting excess electricity generation export potentials.

Bioenergy with Carbon Capture and Storage (BECCS) is a bio-based Carbon Dioxide Removal Technology (CDR) undergoing detailed and comprehensive screening in many countries. The latest scientific reports emphasized that net-zero targets can not be achieved globally or nationally without deploying such technologies. Germany aims to achieve carbon neutrality by 2045, and negative emissions thereafter, which means a higher demand for CDRs. Despite BECCS being the building block of net-zero policies, its implementation on a national and regional scale presents serious challenges. Therefore, in this study, we analyze the role of BECCS in the German bioenergy system with a spatially detailed bottom–up optimization model that accounts for techno-economics and political aspects of BECCS (e.g. availability of biomass and investment costs). Our analysis demonstrates that BECCS can remove almost 61 Mt CO _2 in 2050; however, the outcomes demonstrate sensitivity toward CO _2 credit and CO _2 prices, which can raise the removal as high as 69 Mt CO _2 . Additionally, results suggest that removing enough CO _2 to achieve carbon neutrality in Germany by 2045 solely through BECCS seems extremely challenging; thus, a portfolio of negative emission technologies will be necessary to contribute. Our findings provide a better understanding of BECCS feasibility and its potential to assist us in achieving climate targets in Germany. Although we apply our model to Germany, the developed tool and insights are generic and can be applied to other countries.

Abstract Rapeseed is the dominant feedstock for biodiesel production in Germany; however, significant decline in crop yields observed during the 2018 drought in Europe poses economic and environmental risks for its sustained use as a fuel crop. Many Life Cycle Assessment (LCA) studies were conducted to quantify the potential environmental impacts of biodiesel production; however, only a few studies have considered the spatial and temporal heterogeneities of the studied regions. Furthermore, previous studies have usually only focused on the greenhouse gas (GHG) savings of biodiesel and have ignored the environmental burden and economic profits of biodiesel production. For the first time, we combined the Regional Environmental LCA model with an economic analysis to evaluate both the environmental impact and the economic benefits of biodiesel production in Central Germany (CG). Our results showed that emissions from rapeseed cultivation were the largest contributor to both global and regional environmental impact categories. In our study region, we found that GHG emissions were around 56%–71% lower for rapeseed‐based biodiesel than for fossil fuels. Due to the drought in 2018, we also observed that the regional rapeseed supply could not meet the demand of biodiesel production in CG. An economic analysis of biodiesel production found significant economies of scale effect in the biodiesel industry. In addition, none of the studied biodiesel plants were able to operate at their designed installed capacities without causing indirect land‐use change. Furthermore, the profitability of biodiesel production was closely related to the feedstock cultivation cost. Based on these findings, we concluded that a regionalized LCA model would be able to more accurately evaluate the environmental influence of biodiesel production by taking site‐specific conditions into consideration. We also suggest that potential biodiesel plant operators take the regional biodiesel production density and feedstock cultivation conditions into account when deciding on plant size.

Limiting global warming to well below 2°C and pursuing efforts to limit it to 1.5°C, as agreed in the 2015 Paris Agreement, requires global carbon neutrality by mid-century at the latest. The corresponding carbon budget is decreasing steadily and significantly. To phase out carbon emissions in line with the specified temperature target, countries are formulating their mitigation efforts in their long-term low greenhouse gas emission development strategies (LT-LEDS). However, there are no standardized specifications for preparing these strategies, which is why the reports published to date differ widely in terms of structure and scope. To consider the multiple facets of reaching net-zero from a systemic perspective as comprehensively as possible, the authors propose the Net-Zero-2050 System: A novel, transferrable systems approach that supports the development of national endeavors toward carbon neutrality. The Net-Zero-2050 System is defined by three interconnected components: The Carbon-Emission-Based System, the surrounding Framing System and a set of system boundaries. For both systems levels, IPCC approaches were used as a basis and were then adjusted and supplemented by Net-Zero-2050. We suggest applying the Net-Zero-2050 System—beyond the project environment—in carbon emission based contexts at different levels. Especially at the national level, this would improve the comparability of the different national strategies to achieve carbon neutrality.

Abstract Background The availability of underexploited agricultural residues in Thailand opens up the opportunity to supply second-generation bioethanol production. The national implementation of residues-to-biofuel can potentially boost the bioeconomy and greenhouse gas mitigation but requires the involvement of multiple stakeholders in the development of effective policy recommendations. This study aims to optimize the implementation of the national strategy through the use of a multi-criteria approach that involves participatory prioritization by current stakeholders in order to evaluate certain aspects and important indicators for second-generation bioethanol development. Methods The Delphi-AHP technique was used to analyze the degree of importance of different criteria. The evaluation process was conducted with various stakeholders and used a pairwise comparison of 4 dimensions (main criteria) and 12 indicators (sub-criteria). Participants were asked to rate factors related to technical feasibility, environmental impacts, economic feasibility and social impacts in terms of importance. Results Bioethanol stakeholders in Thailand from five different sectors (industry/business, NPO/NGOs, the governmental sector, academic/research institutes and financial institutions/banks) participated in the Delphi survey. The 20 experts’ evaluation of the four dimensions ranked economic feasibility (32.7%) highest in terms of level of importance, followed by environmental impacts (25.1%), technical feasibility (24.9%) and social impacts (17.3%). When assessing the sub-criteria, the participants selected ‘final price per liter’, ‘added value of input materials’ and ‘net energy balance’ as the top three most important indicators among the 12 sub-criteria. In terms of a link between the preferred criteria and the participants’ expertise, the results encouraged taking different backgrounds and affiliations into account in the policy planning phase. Conclusions The stakeholder survey indicated the importance of economic aspects, highlighting the need to take governmental driven policy into consideration. However, implementation scenarios have to be embedded in a broader range of aspects because all the dimensions were rated as being highly impactful. For future sustainable bioenergy, the inclusion of stakeholders’ opinions can result in multifaceted scenarios that can be linked to social acceptance and benefits for all relevant players when developing policy recommendations for advanced bioenergy.

In its latest assessment report the IPCC stresses the need for carbon dioxide removal (CDR) to counterbalance residual emissions to achieve net zero carbon dioxide or greenhouse gas emissions. There are currently a wide variety of CDR measures available. Their potential and feasibility, however, depends on context specific conditions, as among others biophysical site characteristics, or availability of infrastructure and resources. In our study, we selected 13 CDR concepts which we present in the form of exemplary CDR units described in dedicated fact sheets. They cover technical CO2 removal (two concepts of direct air carbon capture), hybrid solutions (six bioenergy with carbon capture technologies) and five options for natural sink enhancement. Our estimates for their CO2 removal potentials in 2050 range from 0.06 to 30 million tons of CO2, depending on the option. Ten of the 13 CDR concepts provide technical removal potentials higher than 1 million tons of CO2 per year. To better understand the potential contribution of analyzed CDR options to reaching net-zero CO2 emissions, we compare our results with the current CO2 emissions and potential residual CO2 emissions in 2050 in Germany. To complement the necessary information on technology-based and hybrid options, we also provide an overview on possible solutions for CO2 storage for Germany. Taking biophysical conditions and infrastructure into account, northern Germany seems a preferable area for deployment of many concepts. However, for their successful implementation further socio-economic analysis, clear regulations, and policy incentives are necessary.

Peat is the major constituent of horticultural growing media. Due to its high climate footprint, its extraction and use are controversial and the need to limit its use is widely recognised. The Peat Use Reduction Strategy of the German government aims to phase out its use and replace it with renewable materials. Despite large potential, stakeholders consider the availability of peat substitutes in sufficient quantity and quality as a critical issue. The goal of this research is to systematically investigate the challenges and opportunities for substituting peat in the resource base of the growing media industry. Based on deep-dive interviews with German growing media producers, the factors determining the supply and use of the main growing media constituents—peat, green compost, wood fibres, composted bark and coir products—were analysed. The results show the critical role of the processing infrastructure on transportation distances and the quality and quantity of the market supply. Additionally, competition with other sectors affects the availability of materials for the growing media industry. Moreover, peat is still economically advantageous compared with its substitutes. Even if this advantage declines due to consumer awareness and the end of domestic extraction, the end of peat use would probably imply new policy measures.

While storytelling and visualization have always been recognized as invaluable techniques for imparting knowledge across generations, their importance has become even more evident in the present information age as the abundance of complex data grows exponentially. These techniques can simplify convoluted concepts and communicate them in a way to be intelligible for diverse audiences, bringing together heterogeneous stakeholders and fostering collaboration. In the field of energy and climate research, there is an increasing demand to make sophisticated models and their outcomes explainable and comprehensible for an audience of laypersons. Unfortunately, traditional tools and methods may be inefficient to provide meaning for input and output values; therefore, in this study, we employ a storytelling tool, the so-called Academic Presenter, to digest various datasets and visualize the extended BioENergy OPTimization model (BENOPTex) outcomes in different online and offline formats. The developed tool facilitates communications among collaborators with a broad spectrum of backgrounds by transforming outcomes into visually appealing stories. Although this study focuses on designing an ideal user interface for BENOPTex, the developed features and the learned lessons can be replicated for other energy system models.

Abstract Background The German energy transition strategy calls for a reform of the German energy sector. As a result, the German Renewable Energy Sources Act (EEG) passed in 2000 is widely regarded as successful legislation for promoting bioenergy development. More than 1000 biogas plants were constructed in Central Germany (CG) between 2000 and 2014. Despite this, few studies have been conducted for this period, which systematically investigate how environmental, social and economic factors, as well as various EEG amendments have impacted biogas production or what the environmental consequences of biogas production development in CG have been. Methods The impacts of environmental, social and economic factors and different EEG amendments on biogas production decisions in CG were quantified using a multivariate linear regression model and the event study econometric technique. A GIS-based spatial analysis was also conducted to provide insight into the changes to agricultural land use that resulted from the development of biogas plants during the EEG period. Results The main finding was that the income diversification effect resulting from biogas production was the most important factor in a farmer’s decision to adopt biogas production. In addition, all of the EEG amendments had a significant influence on the adoption of biogas production; however, EEG III and IV, which tried to promote small-scale plants, were unable to reduce the average size of the plants constructed in these two amendment periods. From a landscape perspective, there was a striking increase in the cultivation of silage maize in CG from 2000 to 2014. Silage maize was intensively cultivated in regions with a high installed biogas plant capacity. Since the first EEG amendment, permanent grassland area slightly increased while arable land area declined in CG. Conclusions The adoption of biogas production in CG was strongly driven by economic incentives for the farmers, more precisely, by the incentive to diversify their income sources. In addition to increase the subsidy, future EEG amendments should find new measures to encourage the adoption of small-scale biogas plants, which had been unsuccessful in EEG amendments III and IV.

Abstract 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%.

Abstract Background By 2030, the German transport sector needs to achieve additional greenhouse gas savings of 67 million tonnes CO2-eq. and further progress requires swiftly implementable solutions. The fermentation of cereal straw is a promising option. Returning the digestate to the farmland can close agricultural cycles while simultaneously producing biomethane. The world's first large-scale, mono-digestion plant for straw is operational since 2014. The temporal and spatial biomass availability is a key issue when replicating this concept. No detailed calculations on this subject are available, and the strategic relevance of biomethane from straw in the transport sector cannot be sufficiently evaluated. Methods To assess the balance of straw supply and use, a total of 30 data sets are combined, taking into account the cultivation of the five most important cereal types and the straw required for ten animal species, two special crops and 12 industrial uses. The data are managed at district level and presented for the years 2010 to 2018. In combination with high-resolution geodata, the results are linked to actual arable fields, and the availability of straw throughout the country is evaluated using a GIS. Results During the analysis period and based on the assumption that in case of fermentation up to 70% of the straw can be utilised, the mobilisable technical biomass potential for future biomethane production is between 13.9–21.5 Tg fm a−1. The annual potential fluctuates considerably due to weather anomalies. The all-time maximum in 2014 and the minimum for the last 26 years in 2018 are separated by just 4 years and a difference of 7.6 Tg fm. However, large parts of the potential are concentrated only in a few regions and biomethane from straw could provide 57–145 PJ of a low-emission fuel, saving 3–12 Tg CO2-eq. in case of full exploitation. Conclusion Despite the strong fluctuations and high uncertainties, the potential is sufficient to supply numerous plants and to produce relevant quantities of biomethane even in weak years. To unlock the potential, the outcomes should be evaluated and discussed further with stakeholders in the identified priority regions.

Abstract Background Since the steady growth of the German biogas sector, its sustainability is subject to constant scrutiny, especially economic and environmental sustainability. Public concerns about sustainability of biogas started with the issue of energy crop cultivation in the 2010s. To steer sustainability in the biogas sector, a broad variety of regulations and acts were enacted, mainly via top-down legislation making. But in order to govern sustainability in every step of the value chain, involvement of numerous stakeholders in the biogas sector is necessary. This paper will address the question: What are the perceptions of the relevant stakeholders in the biogas sector regarding various sustainability issues and what are their expectations? Methods Following an instrumental approach, three steps were initially undertaken for the systematic analysis of the stakeholder landscape, namely (1) stakeholder identification, (2) stakeholder categorization, and (3) investigation of stakeholder relationships. In addition, a theoretical mapping was performed to identify those actors, who most likely impact the implementation of biogas value chains, or are strongly affected by this implementation. These were then subject to surveys via questionnaires and semi-structured interviews to gather information on their sustainability governance perception. Results Results indicate that key players are farmers and biogas associations due to anchoring in agricultural sector, along with environmental non-governmental organizations (NGOs) and policy makers. Furthermore, the surveyed stakeholders agree on regulating sustainability at national level, while tending toward neutral or even disagreeing for the regulation of sustainability at local and international level. They also agree that certification and standards can be an effective tool for compliant sustainability governance. Conclusions This study revealed a clear expectation gap regarding the transfer of the current energy legislation in a bio-economy and how sustainability shall be steered then (mandatory/voluntary and local (national) level/international level). The surveyed stakeholders expect transparent and clear rules from the government to steer sustainability that they currently do not perceive with regard to the expectation gap. In order to integrate the different stakeholders in the bio-economy development instead of confronting them with opaque legislation making, it is important to clearly communicate not only the opportunities but also the requirements that come along with the implementation of a bio-economy.

Abstract Background The high number of bioeconomy (BE) policies and strategies indicates the interest in the BE in many nations. The development of the BE holds opportunities but also risks for sustainability. Thus, the future development of a sustainable BE should be based on coherent policy frameworks. There are already links between private governance approaches and public policy frameworks that might support each other for this purpose. The aim of this study was to evaluate how the current EU BE policy frameworks consider sustainability aspects and if non-governmental governance approaches could support their enhancement. Methods An inventory of BE policy documents on EU and EU member state levels relevant to sustainability was conducted applying desktop research. Major sustainability risk perceptions in the BE sectors were identified. We provide a list of sustainability risks within different BE sectors, based on an expert survey. In a qualitative evaluation, most commonly identified sustainability requirements in policy documents were benchmarked against most important sustainability risk perceptions. Results Sustainability requirements have been identified in 56% of the policy documents. The influence of the policy frameworks on the industry was found to be rather low. Specific targets and goals are included in 72% of the analysed BE policy documents, but only 50% are quantifiable. Identification of major sustainability risks revealed that in the biomass production stage, mostly environmental risks are most relevant. A “hot spot sector” with accumulated sustainability risk perceptions or a tendency to higher risk levels was not identified. Most important sustainability risk perceptions matched with requirements in policy documents, but requirements were mostly stated in a noncommittal way. Discussion and conclusions Coherence amongst the sustainability criteria included in the various BE frameworks should be increased. Groundwork developed by non-governmental governance approaches should be picked up by policy makers for more harmonised terminologies of sustainability requirements, BE definitions, etc. BE monitoring approaches should take policy targets, sustainability requirements and sustainability risks into account and should adjust them in a dynamic way.

Several energy system optimization models are used to identify solutions for the German energy transition. Most of them lack of detail in regard to the representation of the heterogeneous heat sector and the manifold bioenergy options. Benopt-Heat closes the gap and several research questions related to the future use of bioenergy in the German heat sector could be addressed. Based on the model results and novel methods to address uncertainty, policy insights with a high level of detail and confidence are generated. This software publication provides a basis to further investigate the manifold identified research questions in this field.

Removal of carbon dioxide from the atmosphere will be required over the next decades to achieve the Paris Agreement goal of limiting global warming to well below 2°C aiming at not exceeding 1.5°C. Technological and ecosystem-based options are considered for generating negative emissions through carbon dioxide removal (CDR) and several nations have already included these in their Long-Term Low Greenhouse Gas Emission Development Strategies. However, strategies for development, implementation, and upscaling of CDR options often remain vague. Considering the scale at which CDR deployment is envisioned in emission pathways for limiting global warming to 1.5°C, significant environmental, social, and institutional implications are to be expected and need to be included in national feasibility assessments of CDR options. Following a multi-disciplinary and comprehensive approach, we created a framework that considers the environmental, technological, economic, social, institutional, and systemic implications of upscaling CDR options. We propose the framework as a tool to help guide decision-relevant feasibility assessments of CDR options, as well as identify challenges and opportunities within the national context. As such, the framework can serve as a means to inform and support decision makers and stakeholders in the iterative science-policy process of determining the role of CDR options in national strategies of achieving net-zero carbon emissions.

Temporally and spatially resolved data on wind power generation are very useful for studying the technical and economic aspects of this variable renewable energy at local and regional levels. Due to the lack of disaggregated electricity data from onshore and offshore turbines in Germany, it is necessary to use numerical simulations to calculate the power generation for a given geographic area and time period. This study shows how such a simulation model, which uses freely available plant and weather data as input variables, can be developed with the help of basic atmospheric laws and specific power curves of wind turbines. The wind power model is then applied to ensembles of nearly 28,000 onshore and 1500 offshore turbines to simulate the wind power generation in Germany for the years 2019 and 2020. For both periods, the obtained and spatially aggregated time series are in good agreement with the measured feed-in patterns for the whole of Germany. Such disaggregated simulation results can be used to analyze the power generation at any spatial scale, as each turbine is simulated separately with its location and technical parameters. This paper also presents the daily resolved wind power generation and associated indicators at the federal state level.

Abstract Germany 2050: For the first time Germany reached a balance between its sources of anthropogenic CO2 to the atmosphere and newly created anthropogenic sinks. This backcasting study presents a fictional future in which this goal was achieved by avoiding (∼645 Mt CO2), reducing (∼50 Mt CO2) and removing (∼60 Mt CO2) carbon emissions. This meant substantial transformation of the energy system, increasing energy efficiency, sector coupling, and electrification, energy storage solutions including synthetic energy carriers, sector‐specific solutions for industry, transport, and agriculture, as well as natural‐sink enhancement and technological carbon dioxide options. All of the above was necessary to achieve a net‐zero CO2 system for Germany by 2050.

Abstract Biomass is an integral part of the energy system being not only used in the chemical industry, but also as a basic raw material for the bio-economy sector, which is promoted worldwide. However, its potential can only be exploited sustainably if biomass is cultivated and governed appropriately. Consequently, governance systems are needed to ensure sustainability throughout the bioenergy value chain to maximise the benefits and minimise possible negative impacts. This study investigates how sustainability is put into effect in the German biogas market, the largest biogas market worldwide. The development of Germany’s biogas market is described according to the structure of a four-phase market model of Heuss: the introduction, expansion, maturing, and stagnation phase. Within each of these market phases, the most important German legislation for development of the biogas market was analysed, namely the Renewable Energy Act and legislation addressing associated sustainability issues. The development of the biogas market was controlled and steered by the adaptive Renewable Energy Act, particularly by incentivising cultivation of energy crops. Efforts to promote sustainability started during the transition from market expansion to market consolidation. The effects of these efforts on greenhouse gas emission reductions have been monitored and reported for more than 15 years, but assessment of other aspects of sustainability has varied. In general, legislation regulating the agriculture sector was changed to address new sustainability concerns with some delay. Sustainable development of the agricultural biogas market requires elements of governance, including adaptive legislation within the energy sector as well as monitoring and regular reporting of environmental impacts and related developments in areas of the agriculture sector, such as meat production. Rapid growth of capacity in the biogas sector combined with a significant increase in meat production, dependent on increased fodder production, created risks to sustainability. It can be concluded that the sustainable development of biogas requires additional instruments, possibly national regulation, in addition to legislation applied to the broader agricultural sector.

Information on geo-locations of renewable energy installations is very useful to investigate spatial, social or environmental questions on their impact at local and national level. However, existing data sets do not provide a sufficiently accurate representation of these installations in Germany over space and time. This work provides a valid approach on how a data set of wind power plants, photovoltaic field systems, bioenergy plants and hydropower plants can be created for Germany based on a data extract from the Core Energy Market Data Register (CEMDR) and publicly available data. Established methods were used (e.g., random forest, image recognition), but new techniques were also developed to fill data gaps or locate misplaced renewable energy installations. In this way, a substantial part of the CEMDR data could be corrected and processed in such a way that it can be freely used in a GIS software by any scientific and non-scientific discipline.

The 2015 Paris Agreement aims to strengthen the global response to climate change, and to maintain an average global temperature well below 2°C, with aspirations toward 1.5°C, by means of balancing sources and sinks of greenhouse gas emissions. Following this, the importance of carbon dioxide removal in global emission pathways has been further emphasized, and Negative Emissions Technologies (NETs) that capture carbon from the atmosphere and remove it from the system have been put in the spotlight. NETs range from innovative, engineered technologies, to well-known approaches like afforestation/reforestation. These technologies essentially compensate for a shrinking carbon budget coupled with hard-to-abate future emissions, and a historical lack of action. However, none has been deployed at scales close to what is envisioned in emission pathways in line with the Paris Agreement goals. To understand the potential contribution of NETs to meet global emission goals, we need to better understand opportunities and constraints for deploying NETs on a national level. We examine 17 Long-Term Low Greenhouse Gas Emission Development Strategies (LT-LEDS), and discuss them in the context of available NETs feasibility assessments. Our mapping shows that most countries include NETs in their long-term strategies, and that enhancement of natural sinks is the most dominating type of NET in these strategies. In line with many feasibility assessments, LT-LEDS focus on technical and biophysical considerations, and neglect socio-cultural dimensions. We suggest that feasibility assessments at the national level need to be more holistic; context-specific and comprehensive in terms of aspects assessed.

In 2019, the German government agreed on a Climate Protection Program intended to deliver its 2030 climate targets. Concrete measures, such as a carbon price, will be put in place as early as 2021. But how to plan beyond 2030? Scenarios can be powerful tools to envision the world in 20, 30, or 50 years, to describe pathways toward different visions of the future, and ultimately to investigate technology portfolios and policy options against their performance toward the achievement of a decarbonized future. This is why scenarios are especially popular with energy and climate scholars. In particular, scenarios with biomass-based carbon removal options (BCO2) can help to highlight how we may reach a net negative emission world. Hence, in this study, 66 energy and decarbonization scenario studies are systematically reviewed for Germany from the years 2002 to 2019 to assess how inclusive they are with regard to BCO2 concepts. The portfolio of BCO2 concepts within those scenarios is studied over time and a qualitative analysis of the scenario documentation is performed to identify the rationales for their inclusion or exclusion. The results indicate “blind spots” of the scenarios with regard to bioeconomy aspects, as biomass for material use is only sparsely covered. Likewise, only about 10% of the studies provide a framework for land use changes and corresponding emission accounting to adequately represent biomass-based negative emission technologies (NETs) in their assessments. The analysis for carbon capture and storage (CCS) further reveals the necessity of revisiting the public acceptance argument which has previously served so far for many studies as the ultimate, though not well-grounded deal-breaker. Based on the detected gaps and shortcomings in the current German scenario landscape, recommendations for a more transparent and holistic representation of BCO2 in the scenario framework are given.

Cascade use has been identified as a key concept towards the sustainable use of bio-based products aiming at the hierarchical utilization of biomass, first as materials; secondly recycled into new materials; and finally used energetically. This principle is plausible in theory. However, the quantification of economy-wide GHG savings due to the increased cascade use is scarce. Furthermore, another option to reduce GHG emissions – the extension of product lifetime – is not taken into consideration by this concept. This article aims at analyzing the potential of increasing the cascade use of wood products in Germany and contrasting the results with the extension of product lifetime. In doing so, we combine a disaggregated input–output model with a cumulative lifetime model. Results show that increased cascade use of wood products may reduce the current total GHG emissions in Germany at about 0.19% (1.68 ± 0.34 Mt CO2eq.). Lifetime extension seems not to have such a high reduction potential at about 0.04% (0.35 ± 0.06 Mt CO2eq.). Despite limited GHG reduction potentials of increased cascade use and lifetime extension, nevertheless, these concepts should be addressed by policy makers.

Abstract Background With wind power and photovoltaics, volatile renewables have emerged as central pillars of the energy transition. This increases the demand for flexibility options to compensate fluctuations in power generation. Focussing on the role of bioenergy as a renewable flexibility option, this article seeks to address two questions. The first is whether there is an option value of bioenergy as a provider of low-carbon flexibility in a future power system, which might justify continued technology-specific deployment support. The second question is whether existing market and policy incentives are effective in activating flexibility potentials, and what perspectives exist for increasing flexibility incentives. Methods The article follows an interdisciplinary approach. First, technical potentials for flexible bioenergy plants and potential systemic contributions are examined. This is followed by an economic assessment of what flexibility incentives are provided by relevant market and policy framework conditions. Findings Power from biomass can be well suited to provide flexible generation for grid stabilisation and residual load balancing. Biogas plants require an increase of nominal power over rated power, whereas the technical flexibilisation potential of solid biomass plants depends on specific technologies. Particularly, small-scale combined heat and power systems can deliver fast responses. For existing biogas plants, the Renewable Energy Sources Act’s (EEG) flexibility premium and balancing market revenues have incentivised some changes in the production behaviour and investments in plant flexibilisation. However, decreasing spot market price levels and decreasing price variance reduce incentive strength. This also limits flexibilisation incentives for solid biomass plants. For new biogas plants, the EEG’s remuneration rules set effective flexibility incentives, but 2014 reductions in remuneration rates have significantly slowed down the expansion. Conclusions Given high technical potentials for flexibility provision, there is an option value of keeping bioelectricity in the technology mix until more is known about its future competitiveness with other low-carbon flexibility options. To maintain this option value, there is a case for setting policy incentives in a way that continued technological development remains possible. A stringent climate policy could accelerate structural change in the electricity sector, to allow for market price signals which incentivise low-carbon flexibility provision.

The use of sustainable biofuels in the aviation sector with correspondingly high reduction in specific GHG emissions will make an important contribution to reducing GHG emissions from air traffic. It is expected that airports in Europe will be supplied with JET A-1 blends that also contain various types of sustainable aviation fuels (SAF) in variable proportions (“multiblend”). This article presents the results of a study assessing the environmental impact of various sustainable aviation fuels (SAF) and multiblends, including all relevant parts of their value chains, starting from SAF production to mixing of different SAF with conventional JET A-1 and finally the use of the produced multiblend. The results of the life cycle assessment indicated that the production of some SAF caused less GHG emissions than others due to the use of waste or residues as SAF feedstock or the use of by-products to meet the internal process energy demand. A detailed assessment of GHG emissions of the studied multiblend JET A-1 showed a reduction in greenhouse gas emissions of up to 35% compared to fossil JET A-1.

In recent years, electricity production from wind turbines and photovoltaic systems has grown significantly in Germany. To determine the multiple impacts of rising variable renewable energies on an increasingly decentralized power supply, spatially and temporally resolved data on the power generation are necessary or, at least, very helpful. Because of extensive data protection regulations in Germany, especially for smaller operators of renewable power plants, such detailed data are not freely accessible. In order to fill this information gap, simulation models employing publicly available plant and weather data can be used. The numerical simulations are performed for the year 2016 and consider an ensemble of almost 1.64 million variable renewable power plants in Germany. The obtained time series achieve a high agreement with measured feed-in patterns over the investigated year. Such disaggregated power generation data are very advantageous to analyze the energy transition in Germany on a spatiotemporally resolved scale. In addition, this study also derives meaningful key figures for such an analysis and presents the generated results as detailed maps at county level. To the best of our knowledge, such highly resolved electricity data of variable renewables for the entire German region have never been shown before.

An amendment to this paper has been published and can be accessed via the original article.

A quantitative assessment of food-water-energy interactions is important to assess pathways and scenarios towards a holistically sustainable regional development. While a range of tools and methods exist that assess energetic demands and potentials on a regional scale, the same is not true for assessments of regional food demand and potential. This work introduces a new food simulation workflow to address local food potential and demand at the regional level, by extending an existing regional energy-water simulation platform. The goal of this work is to develop a GIS-based bottom-up approach to simulate regional food demand that can be linked to similarly GIS-based workflows assessing regional water demands and energetic demands and potentials. This allows us to study food-water-energy issues on a local scale. For this, a CityGML land use data model is extended with a feed and animal potential raster map as well as a soil type map to serve as the main inputs. The workflow simulates: (1) the vegetal and animal product food potentials by taking climate, crop type, soil type, organic farming, and food waste parameters into account; (2) the food demand of vegetal and animal products influenced by population change, body weight, age, human development index, and other indicators. The method is tested and validated in three German counties with various land use coverages. The results show that restricting land used exclusively for energy crop production is the most effective way to increase annual food production potential. Climate change by 2050 is expected to result in annual biomass yield changes between −4% and 2% depending on the region. The amount of animal product consumption is expected to rise by 16% by 2050, while 4% fewer vegetal products are excepted to be consumed.

The German Renewable Energy Sources Act (EEG) has been deemed successful in promoting German biogas production. However, the German state-level biogas production development (BPD) under the EEG has not been systematically studied and compared. This research aimed to study the German state-level BPD using the multivariate linear regression model with a dummy variable, and to spatially quantify the environmental and agricultural consequences using the geographic information system (GIS) technique to identify the necessities of regional-based analysis on Germany’s BPD. The empirical results indicated that Saxony-Anhalt was advanced in BPD, while farmers’ response from Bavaria to EEG was the weakest. The reason behind could be the differences in farmers’ personality traits and risk cognitions toward the biogas production investment. The spatial analysis indicated that Saxony-Anhalt had more severe environmental problems caused by the biogas production expansion than Bavaria. Therefore, to promote BPD in states such as Bavaria, an increase in the nationwide unified subsidy might lead to an overreaction of the EEG strong response states, e.g., Saxony-Anhalt, leading to more serious environmental problems. In the end, there is a need for more regional-based research on studying the BPD in Germany in the future to avoid the ambiguity of large-scale studies.

Wind power has risen continuously over the last 20 years and covered almost 25% of the total German power provision in 2019. To investigate the effects and challenges of increasing wind power on energy systems, spatiotemporally disaggregated data on the electricity production from wind turbines are often required. The lack of freely accessible feed-in time series from onshore turbines, e.g., due to data protection regulations, makes it necessary to determine the power generation for a certain region and period with the help of numerical simulations using publicly available plant and weather data. For this, a new approach is used for the wind power model which utilizes a sixth-order polynomial for the specific power curve of a turbine. After model validation with measured data from a single wind turbine, the simulations are carried out for an ensemble of 25,835 onshore turbines to determine the German wind power production for 2016. The resulting hourly resolved data are aggregated into a time series with daily resolution and compared with measured feed-in data of entire Germany which show a high degree of agreement. Such electricity generation data from onshore turbines can be applied to optimize and monitor renewable power systems on various spatiotemporal scales.

The assessment of regional bioenergy potentials from different types of natural land cover is an integral part of simulation tools that aim to assess local renewable energy systems. This work introduces a new workflow, which evaluates regional bioenergy potentials and its impact on water demand based on geographical information system (GIS)-based land use data, satellite maps on local crop types and soil types, and conversion factors from biomass to bioenergy. The actual annual biomass yield of crops is assessed through an automated process considering the factors of local climate, crop type, soil, and irrigation. The crop biomass yields are validated with historic statistical data, with deviation less than 7% in most cases. Additionally, the resulting bioenergy potentials yield between 10.7 and 12.0 GWh/ha compared with 13.3 GWh/ha from other studies. The potential contribution from bioenergy on the energy demand were investigated in the two case studies, representing the agricultural-dominant rural area in North Germany and suburban region in South Germany: Simulation of the future bioenergy potential for 2050 shows only smaller effects from climate change (less than 4%) and irrigation (below 3%), but the potential to cover up to 21% of the transport fuels demand in scenario supporting biodiesel and bioethanol for transportation.

Photovoltaics, as one of the most important renewable energies in Germany, have increased significantly in recent years and cover up to 50% of the German power provision on sunny days. To investigate the manifold effects of increasing renewables, spatiotemporally disaggregated data on the power generation from photovoltaic (PV) systems are often mandatory. Due to strict data protection regulations, such information is not freely available for Germany. To close this gap, numerical simulations using publicly accessible plant and weather data can be applied to determine the required spatiotemporal electricity generation. For this, the sunlight-to-power conversion is modeled with the help of the open-access web tool of the Photovoltaic Geographical Information System (PVGIS). The presented simulations are carried out for the year 2016 and consider nearly 1.612 million PV systems in Germany, which have been aggregated into municipal areas before performing the calculations. The resulting hourly resolved time series of the entire plant ensemble are converted into a time series with daily resolution and compared with measured feed-in data to validate the numerical simulations that show a high degree of agreement. Such power production data can be used to monitor and optimize renewable energy systems on different spatiotemporal scales.

Humans’ activities in urban areas put a strain on local water resources. This paper introduces a method to accurately simulate the stress urban water demand in Germany puts on local resources on a single-building level, and scalable to regional levels without loss of detail. The method integrates building geometry, building physics, census, socio-economy and meteorological information to provide a general approach to assessing water demands that also overcome obstacles on data aggregation and processing imposed by data privacy guidelines. Three German counties were used as validation cases to prove the feasibility of the presented approach: on average, per capita water demand and aggregated water demand deviates by less than 7% from real demand data. Scenarios applied to a case region Ludwigsburg in Germany, which takes the increment of water price, aging of the population and the climate change into account, show that the residential water demand has the change of −2%, +7% and −0.4% respectively. The industrial water demand increases by 46% due to the development of economy indicated by GDP per capita. The rise of precipitation and temperature raise the water demand in non-residential buildings (excluding industry) of 1%.

Solid biofuels have the potential of making a major contribution to achieving the objectives of the Paris Climate Agreement if they are used more extensively for covering the heat demand of the industry and the trade, commerce, and service (TCS) sector. To unlock this potential, a holistic analysis of the supply chain from producer to end customer was performed, involving consultants, planners, and financial institutions. The focus is on the deployment of larger biomass heating boilers (with heat loads spanning several 100 kW to several MW). The study identifies the most important barriers for expanding the use of solid biofuels for heat in the German TCS sector as well as in the industry sector. Nine sets of measures were identified for overcoming the most critical barriers, among others, by drawing on best practice approaches and solutions from other German and European contexts. Based on these measures, political recommendations were derived to shape the regulatory framework conditions accordingly. These recommendations can in turn offer a stimulus for other countries to foster a more efficient and climate-effective use of biomass.

With the Renewable Energy Directive 2018/2001 (RED II), adopted in December 2018, the EU is continuing the political framework for the use of renewable energy sources in the transport sector for the period from 2021 to 2030. At the same time, the German federal government has set a target of reducing greenhouse gas (GHG) emissions in the transport sector by at least 40% to 42% by 2030 compared to the 1990 GHG level. To investigate the possible effects of the European and national requirements on the German GHG quota, cost-optimal fuel mixes were modelled to achieve the GHG targets of 26 fuel options in each of the nine different scenarios. The results show clear differences between the scenarios that implement the RED II targets (including 14% renewables in transport by 2030) and those that implement the climate protection target (40–42% GHG reduction compared to 1990 by 2030). If only the minimum requirements of RED II are met, the German climate protection target is clearly missed without further measures. In order to achieve the climate protection target, a significant reduction in the final energy consumption in transport is required, as well as a very high GHG quota of 34.5%, meaning a high proportion of renewables of ca. 40% and using almost all the fuel options considered.

Bioenergy contributes significantly towards the share of renewable energies, in Europe and worldwide. Besides solid and liquid biofuels, gaseous biofuels, such as biogas or upgraded biogas (biomethane), are an established renewable fuel in Europe. Although many studies consider biomethane technologies, feedstock potentials, or sustainability issues, the literature on the required legislative framework for market introduction is limited. Therefore, this research aims at identifying the market and legislative framework conditions in the three leading biomethane markets in Europe and compare them to the framework conditions of the top six non-European biomethane markets. This study shows the global status and national differences in promoting this renewable energy carrier. For the cross-country comparison, a systematic and iterative literature review is conducted. The results show the top three European biomethane markets (Germany, United Kingdom, Sweden) and the six non-European biomethane markets (Brazil, Canada, China, Japan, South Korea, and the United States of America), pursuing different promotion approaches and framework conditions. Noteworthy cross-national findings are the role of state-level incentives, the tendency to utilise biomethane as vehicular fuel and the focus on residues and waste as feedstock for biomethane production. Presenting a cross-country comparison, this study supports cross-country learning for the promotion of renewable energies like biomethane and gives a pertinent overview of the work.