Search

The widely recognised Energiewende, ("energy transition") in Germany has lost its original momentum. We therefore address the question of how the transition process to a new energy system can be reignited. To do so, we developed the "5Ds approach", which lays the groundwork for a process analysis and the identification of important catalysts and barriers. Focusing on the five major fields required for the energy transition, we analyse the effects of: (1) Decarbonisation: How can efficiency and renewable energies be expanded successfully? (2) Digitalisation: Which digital solutions facilitate this conversion and would be suitable as sustainable business models? (3) Decentralisation: How can potential decentralised energy and efficiency opportunities be developed? (4) Democratisation: How can participation be strengthened in order to foster acceptance (and prevent "yellow vest" protests, etc.)? (5) Diversification of service: Which services can make significant contributions in the context of flexible power generation, demand-side management, storage and grids? Our paper comes to the conclusion that German policy efforts in the "5D" fields have been implemented very differently. Particularly with regard to democratisation, the opportunities for genuine participation among the different social actors must be further strengthened to get the Energiewende back on track. New market models are needed to meet the challenges of the energy transition and to increase the performance of "5D" through economic incentives. [ABSTRACT FROM AUTHOR]

The emerging energy transition is particularly described as a move towards a cleaner, lower-carbon system. In the context of the global shift towards sustainable energy sources, this paper reviews the potential and roadmap for hydrogen energy as a crucial component of the clean energy landscape. The primary objective is to present a comprehensive literature overview, illuminating key themes, trends, and research gaps in the scientific discourse concerning hydrogen production and energy policy. This review focuses particularly on specified geographic contexts, with an emphasis on understanding the unique energy policies related to renewable energy in Brazil, Austria, and Germany. Given their distinct social systems and developmental stages, this paper aims to delineate the nuanced approaches these countries adopt in their pursuit of renewable energy and the integration of hydrogen within their energy frameworks. Brazil exhibits vast renewable energy potential, particularly in wind and solar energy sectors, positioning itself for substantial growth in the coming years. Germany showcases a regulatory framework that promotes innovation and technological expansion, reflecting its highly developed social system and commitment to transitioning away from fossil fuels. Austria demonstrates dedication to decarbonization, particularly through the exploration of biomethane for residential heating and cooling. [ABSTRACT FROM AUTHOR]

The sun's total radiation alone exceeds the world population's entire energy consumption by 7.500 times and ignites secondary renewable energy sources. The end energy consumption buildings use for heating amounts to 28% of Germany's total energy consumption. With the ongoing trend of digitalization and the transition of the German energy supply away from fossil fuels and the consequent political dependency, electric heat pumps and photovoltaic (PV) systems have become increasingly important to the discussion. This has led to an increasing demand for smart control strategies, especially for inert systems such as thermally activated building systems (TABS). This paper presents and analyses a weather predictive control (WPC) strategy using a validated thermodynamic simulation model. The literature review of this paper outlines that the current common control strategies are data intense and complex in their implementation into the built environment. The simple approach of the WPC uses future ambient temperature and solar radiation to optimize the control of the heating, cooling, ventilation, and sun protection system. The thermal comfort and energy demand evaluate the concept. We show that with a WPC for TABS, thermal comfort can improve without increasing the energy demand for the office building in the moderate climate of Munich. Furthermore, this paper concludes that the WPC works more effectively with more thermal mass. This simplified building control strategy promotes the European roadmap goal of climate neutrality in 2050, as it bridges the phenomenon of the performance gap. [ABSTRACT FROM AUTHOR]

In Germany, there are over 32,000 schools, representing great potential for climate protection. On the one hand, this applies to educational work, as understanding the effects of climate change and measures to reduce GHG emissions is an important step to empower students with knowledge and skills. On the other hand, school buildings are often in bad condition, energy is wasted, and the possibilities for using renewable energies are hardly used. In our "Schools4Future" project, we enabled students and teachers to draw up their own CO2 balances, identify weaknesses in the building, detect wasted electricity, and determine the potential for using renewable energies. Emissions from the school cafeteria, school trips, and paper consumption could also be identified. The fact that the data can be collected by the students themselves provides increased awareness of the contribution made to the climate balance by the various school areas. The most climate-friendly school emits 297 kg whilst the school with the highest emissions emits over one ton CO2 per student and year. Our approach is suitable to qualify students in the sense of citizen science, carry out a scientific investigation, experience self-efficacy through one's own actions, and engage politically regarding their concerns. [ABSTRACT FROM AUTHOR]

The energy sector faces a pressing need for significant transformation to curb CO2 emissions. For instance, Czechia and Germany have taken steps to phase out fossil thermal power plants by 2038, opting instead for a greater reliance on variable renewable energy sources like wind and solar power. Nonetheless, thermal power plants will still have roles, too. While the conventional multistage axial turbine design has been predominant in large-scale power plants for the past century, it is unsuitable for small-scale decentralized projects due to complexity and cost. To address this, the study investigates less common turbine types, which were discarded as they demonstrated lower efficiency. One design is the Elektra turbine, characterized by its velocity compounded radial re-entry configuration. The Elektra turbine combines the advantages of volumetric expanders (the low rotational speed requirement) with the advantages of a turbine (no rubbing seals, no lubrication in the working fluid, wear is almost completely avoided). Thus, the research goal of the authors is the implementation of a 10 kW-class ORC turbine driving a cost-effective off-the-shelf 3000 rpm generator. The paper introduces the concept of the Elektra turbine in comparison to other turbines and proposes this approach for an ORC working fluid. In the second part, the 1D design and 3D–CFD optimization of the 7 kW Elektra turbine working with Hexamethyldisiloxane (MM) is performed. Finally, CFD efficiency characteristics of various versions of the Elektra are presented and critically discussed regarding the originally defined design approach. The unsteady CFD calculation of the final Elektra version showed 46% total-to-static isentropic efficiency. [ABSTRACT FROM AUTHOR]

Achieving national targets on renewable energy poses several challenges, especially in multi-level governance environments. Incentives and specifications on wind energy development might cause uneven progress or even discrepancies. Therefore, governments have commenced adopting 'positive planning' to combine energy targets with spatial and land-use planning. Yet detailed discussions regarding wind energy development remain scarce. In this paper, I explore three explanatory case studies in Germany and Sweden, aiming to provide policymakers and planners with essential knowledge while presenting significant challenges and key lessons learned. Positive planning appears to center on a strong energy target focus, limited space, and a balanced approach, shaped by the sociopolitical context. While Germany has recently embraced positive planning, Sweden started ambitiously but is encountering planning and policy challenges. Planning agencies play a vital role in promoting wind energy targets at mid-scale levels, yet legally binding targets matter. Striking a balance between energy targets and addressing land-use concerns without disregarding them requires managing a delicate trade-off. Early communication and inter-agency collaboration, as seen in Sweden, might facilitate identifying compromises, navigating trade-offs between species protection and renewable energy and offering municipal incentives. Nonetheless, negotiating satisfactory spatial trade-offs for a long-term proof of concept remains a challenge. [ABSTRACT FROM AUTHOR]

The expansion of renewable energy infrastructure comes with increasing conflicts at local level that significantly impede the expansion of renewable energy in Germany and impact the realization of national and international climate goals. In some conflicts, rural communities are torn apart and social relations strained beyond the energy conflict. Other projects are realized with no or only minor disruption. To researchers, project developers and local politicians alike, it seems unpredictable as to which way local energy conflicts evolve. Thus, the paper aims to shed light on conflict dynamics and identifies a number of aspects that influence local energy conflicts. The paper applies a conflict theoretical perspective on local energy conflicts. Rather than identifying energy conflicts as a sign of dysfunctionality, conflicts are seen as an important element of a democratic society struggling to find the best way through the transformation towards decarbonization. Based on qualitative research on local energy conflicts in five German municipalities the paper analyzes aspects that encourage constructive conflicts and aspects that impede such developments. With reference to Dahrendorf's conditions of conflict the categories of energy conflicts are systematized within an analytical framework according to conditions of organization, conflict and change. These categories and aspects are embedded in specific local conditions, making conflicts on the one hand typical and on the other very specific. They are also entry points for dealing constructively with the conflicts. [ABSTRACT FROM AUTHOR]

Renewables are the greener substitute for the conventional polluting sources of generating energy. For their successful integration into the power grid, accurate forecasts are required. In this paper, we report the lessons acquired from our previous works on generating time-series ARIMA-based forecasting models for renewables. To this end, we considered a consistent dataset spanning the last four years. Assuming four different performance metrics for each of the best ARIMA-based models of our previous works, we derived a new optimal model for each month of the year, as well as for the two different methodologies suggested in those works. We then evaluated the performance of those models, by comparing the two methodologies: in doing so, we proposed a hybrid methodology that took the best models out of those two methodologies. We show that our proposed hybrid methodology has improved yearly accuracy of about 89.5% averaged over 12 months of the year. Also, we illustrate in detail for the four years under study and each month of the year the observed percentage of renewables and its corresponding accuracy compared to the generated forecasts. Finally, we give the implementation details of our open-source REN4KAST software platform, which provides several services related to renewables in Germany. [ABSTRACT FROM AUTHOR]

The energy crisis in Europe in 2022 and its consequences have brought changes to approaches towards the issue of energy security, energy policy, and the ability to react to crisis phenomena in the energy market in a short period of time. European countries that are dependent on Russian fossil fuels have faced numerous dilemmas and challenges in 2022. This paper aims to analyse the instruments and energy policies introduced as the reactions of European countries, specifically with the examples of Poland and Germany, to the ongoing fossil fuel crisis in the context of a short period. Due to the specificity of the energy market, the countries' energy policies mainly concern long- and medium-term goals. In 2022, there was an unprecedented situation in which many European countries had to make significant changes to their fossil fuel imports quickly. We analyse and evaluate how two European countries that are heavily reliant on imported energy resources responded in a short time to the necessity of modifying their patterns of fossil fuel supply and demand. The results of our research are models that illustrate both countries' reactions to the disturbances in the energy market during the initial months of the energy crisis. As part of the research, we conducted an analysis of the energy mix of Poland and Germany, their import energy dependency, and self-sufficiency. We then compared them with the short-term energy policies of both countries. As a result, we elaborate on a comparative analysis of the models of Poland's and Germany's responses to the crisis. The research also assesses the similarities and differences in the response models in Poland's and Germany's short-term energy security policies. The results of our research may help, in the future, to choose the available short-term instruments in the energy policy of countries in the face of a sudden need resulting from disruptions in supply chains. The article contributes to the future discussion on renewed national and regional energy security, as well as efficiency concepts. Our research findings could be valuable in selecting appropriate short-term energy policy tools for countries during supply chain disruptions. This article provides significant input for future deliberations on enhancing national and regional energy security, and also efficiency strategies. [ABSTRACT FROM AUTHOR]

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 FROM AUTHOR]

Low-carbon energy requires more land than the non-renewable resources. This paper balances holistic assessments of the land demands for biomass heating and their ecosystem services. It is predicted that biomass will continue to play an important role in the heating sector in Germany by 2050, as it is one way to increase the use of renewable energy and reduce CO2 emissions. To balance this out, it is important to ensure that the substitution of fossil fuels with fuelwood does not result in losses in biodiversity, natural forest, and agricultural land. Based on the observed types of fuel demand, the need for space in terms of the growing area is characterized as the corresponding land under the consideration of a given land-use type. Formulas have been applied at the federal level in Germany. The area required to supply an average German household is 0.64 ha if all the wood harvested is used for energy purposes, but this is in competition with all other types of timber use. Fuelwood from thinning alone cannot meet the domestic demand. However, a sustainable supply of woody biomass is possible if residues mainly from forestry and the wood processing industry are used, causing a land demand of 2.69 ha per house, possibly in combination with smaller shares of the above-mentioned types of use. Thus, the shares of pellets and wood chips for heating purposes should be expanded, which would also bring ecological advantages. The qualitative consideration of forest ecosystem services shows that changing the forest composition or management may increase the fuelwood supply but does not necessarily decrease forest ecological services. [ABSTRACT FROM AUTHOR]

Legislative efforts for renewables-based energy decarbonisation hinge upon the support and commitment from different stakeholders holding often conflicting positions regarding disruptive processes of socio-technical transformation. However, the evolving acceptance of market actors on the policy-driven promotion of renewables over time remains under-scrutinised. Simultaneously, despite growing attention to power and politics in sustainability transitions, limited efforts remain invested for elucidating the political-economic nature of the market-based selection environments they are operationalised through, highlighting the need for a more systematic comprehension of the "politics of selection". To address these shortcomings, this paper provides a more refined understanding of the role of policy-driven markets and its participating agents in facilitating/hindering innovation diffusion and broader (system-wide) sustainability transitions. To do so, it showcases a longitudinal case study of the politics underlying Germany's evolving feed-in policy support framework for orchestrating a market-mediated diffusion of renewables (1980s–2020). Based on policy analysis and semi-structured interviews, the study traces the changing acceptance and ensuing strategic (re)actions of market actors to the emergence and evolution of Germany's market for electricity from renewable energy sources. Results show how different market participants effectively shape the selection environments they operate in by proactively contesting/deluding the design features of the support policies organising their economised relations (e.g., market entry conditions, exchange rules, remuneration levels, pricing schemes, etc.). Such efforts are undertaken through legal means and market framing strategies targeting the affordability of policy support costs, coupled with the strategic use of policy instrumentation as a vehicle to further expand/retain their market shares to the detriment of competing actors. [ABSTRACT FROM AUTHOR]

The present paper considers the problem of choosing among a collection of competing electricity price forecasting models to address a stochastic decision-making problem. We propose an event-based evaluation framework applicable to any optimization problem, where uncertainty is captured through ensembles. The task of forecast evaluation is simplified from assessing a multivariate distribution over prices to assessing a univariate distribution over a binary outcome directly linked to the underlying decision-making problem. The applicability of our framework is demonstrated for two exemplary profit-maximization problems of a risk-neutral energy trader, (i) the optimal operation of a pumped-hydro storage plant and (ii) the optimal trading of subsidized renewable energy in Germany. We compare and contrast the approach with the full probabilistic and profit–loss-based evaluation frameworks. It is concluded that the event-based evaluation framework more reliably identifies economically equivalent forecasting models, and in addition, the results suggest that an event-based evaluation specifically tailored to the rare event is crucial for decision-making problems linked to rare events. [ABSTRACT FROM AUTHOR]

Schools play an important role in achieving climate protection goals, because they lay the foundation of knowledge for a responsible next generation. Therefore, schools as institutions have a special role model function. Enabling schools to become aware of their own carbon footprint (CF) is an important prerequisite for being able to tap the substantial CO2 reduction potential. Aiming at the direct involvement of students in the assessment process, a new assessment tool was developed within the Schools4Future project that gives students the opportunity to determine their own school's CF. With this instrument the CO2 emissions caused by mobility, heating and electricity consumption as well as for food in the school canteen and for consumables (paper) can be recorded. It also takes into account existing renewable energy sources. Through the development of the tool, not only a monitoring instrument was established but also a concrete starting point from which students could take actions to reduce Greenhouse Gas (GHG) emissions. This paper presents the tool and its methods used to calculate the CF and compares it with existing approaches. A comparative case study of four pilot schools in Germany demonstrates the practicability of the tool and reveals fundamental differences between the GHG emissions. [ABSTRACT FROM AUTHOR]

This paper identifies socioeconomic factors that are supposed to impact the investment decision of private households in Germany regarding small-scale solar PV (photovoltaic) systems. In 2022, the last nuclear power plant will phase out and the end of coal-fired power plants is fixed for 2038. Thus, the legislator is mandated to foster the addition of renewable energy capacities to close the gap fossil fuels and nuclear power leaves. Some share of the renewable energies could be from private households that mainly invest in small-scale solar PV systems. To stimulate investments, it is necessary to identify factors that are important for the investment decisions of private households. Within this paper, secondary socioeconomic data for the period from 2009–2018 was compiled. In order to identify the latent variables, a factor analysis was conducted. The results state five factors that are supposed to impact the investment decisions of the prosumer in Germany. [ABSTRACT FROM AUTHOR]

The intensive electrification of the automotive sector means that the energy system must be able to adapt to the current market situation. The increase in energy demand is a major factor associated with electric vehicles. The study analyzed the operation of a grid-connected facility operating a vehicle fleet providing transport services in the region Halle/Saale, Germany. Measurement data were used in the analysis, including global positioning system data of the vehicles and technical data, including average fuel consumption on a given route section, daily load demand of the industrial facility, and energy generation from photovoltaics. This paper shows the impact of using a battery electric vehicles (BEVs) fleet in the load distribution for the industrial facility considered. The NEDC energy consumption profile for the Nissan e-NV200 were used in this study. Furthermore, the paper presented simulation results allowing one to determine the usage potential, energy demand, and consumption of EVs using real data, reliably representing the processes related to EV daily use. The measurement data were captured using available specialized equipment: Dako-Key (GPS data), PV power generation (Siemens 7KM PAC4200), and load (Janitza UMG 604-Pro) in September, 2018. On this basis, it is possible to identify the effects and variations in load on the power grid during the replacement of combustion vehicle fleets used currently by EVs for the provision of transport services. Three models were presented, making it possible to calculate changes in energy demand for each scenario. In the first model, EVs were charged exclusively from the distribution network. In the second, the energy generation from a renewable source was considered and the possibility of compensating the energy demand of the vehicles from this source was demonstrated. In the third model, the daily load profile and the period of maximum load in the electricity grid were considered. The results are presented in graphical and tabular form. Finally, the potential of using an EV fleet to increase the functionality of a modern industry object was determined and discussed. Based on data for the adopted scenarios, electrification of transport can increase demand for energy by 40.9% for individual enterprises. The electrification of the automotive sector will increase the instantaneous energy demand of businesses, forcing the integration of renewable energy sources during designing new invests. [ABSTRACT FROM AUTHOR]

The shift to electric transportation is crucial to fighting climate change. However, Germany's goal of 15 million electric vehicles (EVs) by 2030 remains distant. Therefore, enhancing their economic viability is essential to promoting EV adoption. One promising option to increase the economics for the user is PV self-consumption optimization using smart charging EVs. Yet, more research is needed to explore the use case's impacts on the German/European energy systems. Therefore, PV self-consumption optimization using EVs is integrated into an energy system model, assessing its impact on the energy system in 2030. For this purpose, the use case is modeled for different groups of people—personas—which are defined in a way that creates a diverse set of personas reflecting the distribution of different statistical values within Germany. The modified (dis)charging profiles are then aggregated and integrated into the energy system model. With a high implementation of PV self-consumption optimization in Germany in 2030, a positive system effect (with a system cost reduction of 53 million EUR/a) can be observed with a lower need for further storage and less curtailment of renewable energies (RES). Furthermore, the market values for RES increase by 0.7%, which fosters the integration of RES. [ABSTRACT FROM AUTHOR]

Renewable energy production is one of the most important strategies to reduce the emission of greenhouse gases. However, wind and solar energy especially depend on time-varying properties of the environment, such as weather. Hence, for the control and stabilization of electricity grids, the accurate forecasting of energy production from renewable energy sources is essential. This study provides an empirical comparison of the forecasting accuracy of electricity generation from renewable energy sources by different deep learning methods, including five different Transformer-based forecasting models based on weather data. The models are compared with the long short-term memory (LSTM) and Autoregressive Integrated Moving Average (ARIMA) models as a baseline. The accuracy of these models is evaluated across diverse forecast periods, and the impact of utilizing selected weather data versus all available data on predictive performance is investigated. Distinct performance patterns emerge among the Transformer-based models, with Autoformer and FEDformer exhibiting suboptimal results for this task, especially when utilizing a comprehensive set of weather parameters. In contrast, the Informer model demonstrates superior predictive capabilities for onshore wind power and photovoltaic (PV) power production. The Informer model consistently performs well in predicting both onshore wind and PV energy. Notably, the LSTM model outperforms all other models across various categories. This research emphasizes the significance of selectively using weather parameters for improved performance compared to employing all parameters and a time reference. We show that the suitability and performance of a prediction model can vary significantly, depending on the specific forecasting task and the data that are provided to the model. [ABSTRACT FROM AUTHOR]

Renewable energy sources, encompassing wind, solar, hydro, and geothermal options, are assuming an increasingly crucial role in the global energy landscape. They present a sustainable substitute for fossil fuels, effectively reducing greenhouse gas emissions and significantly contributing to the ongoing efforts against climate change. The widespread adoption of renewable energy technologies has undergone rapid expansion on a global scale, propelled by governmental policies, technological advancements, and decreasing costs. Despite their numerous advantages, renewable energy sources encounter challenges such as intermittent energy supply, storage solutions, and integration into existing power grids. Nevertheless, with sustained investment and innovation, renewable energy sources have the potential to become the predominant energy source of the future. This article conducts a bibliometric analysis of research on renewable energy sources in Poland and Germany. The analysis is grounded in publications catalogued in the Web of Science database, spanning the years from 1990 to 2023. The investigation delves into research topics related to renewable energy sources and scrutinizes the most frequently cited publications authored by individuals from these two countries. This bibliometric analysis stands out through its unique value proposition compared to other similar studies by placing a distinctive emphasis on critical research gaps, such as energy storage, smart grid technologies, and renewable energy in transportation. Additionally, the study's focus on the specific trajectories of Poland and Germany in renewable energy adoption, coupled with the identification of key institutions with the highest centrality index, provides unparalleled insights into the evolving landscape of sustainable energy research. The findings from this study can serve as a valuable source of information for policymakers, researchers, and other stakeholders interested in promoting the advancement and utilization of renewable energy sources. [ABSTRACT FROM AUTHOR]

In the face of global challenges related to climate change and sustainable development, comparing attitudes and infrastructure in the field of electromobility and renewable energy sources in different countries becomes crucial. The question of differences and similarities between Poland and Germany in these areas sheds light on the unique challenges and opportunities that the two countries present to each other. The aim of the study is to understand these dynamics, which can contribute to the shaping of more effective policies and strategies for green energy and sustainable mobility. This study was conducted through a review of Polish and foreign literature, the use of the method of tabular comparisons, and the analysis of a questionnaire that was used. These complex methods combined both quantitative and qualitative analysis, which allowed for an in-depth understanding and comparison of attitudes and infrastructure related to electromobility and renewable energy sources in Poland and Germany. The study revealed significant differences and similarities between Poland and Germany in terms of electromobility and renewable energy sources. Germany shows a higher level of urbanization, a higher share of electric car ownership, and better charging infrastructure, while in Poland there is a strong belief in the key role of renewable energy sources. These findings may have implications for future green energy initiatives and policies in both countries. The study presents a complex picture of electromobility and renewable energy sources in Poland and Germany, showing clear differences in awareness, infrastructure, and attitudes. Germany seems to be more advanced in these areas, while Poland shows a strong commitment to renewable energy sources. These conclusions do not exaggerate the differences, but underline the need for a case-by-case approach to green energy strategies in both countries. [ABSTRACT FROM AUTHOR]

In August 2020, Germany and Ukraine launched an energy partnership that includes the development of a hydrogen economy. Ukraine has vast renewable energy resources for "green" hydrogen production and a gas transmission system for transportation instead of Russian natural gas. Based on estimates by Hydrogen Europe, Ukraine can install 8000 MW of total electrolyser capacity by 2030. For these reasons, Ukraine is among the EU's priority partners concerning clean hydrogen, according to the EU Hydrogen strategy. Germany plans to reach climate neutrality by 2045, and "green" hydrogen plays an important role in achieving this target. However, according to the National Hydrogen Strategy of Germany, local production of "green" hydrogen will not cover all internal demand in Germany. For this reason, Germany considers importing hydrogen from Ukraine. To govern the production and import of "green" hydrogen, Germany and Ukraine shall introduce legal regulations, the initial analysis of which is covered in this study. Based on observation and comparison, this paper presents and compares approaches while exploring the current stage and further perspectives for legal regulation of hydrogen in Germany and Ukraine. This research identifies opportunities in hydrogen production to improve the flexibility of the Ukrainian power system. This is an important issue for Ukrainian energy security. In the meantime, hydrogen can be a driver for decarbonisation according to the initial plans of Germany, and it may also have positive impact on the operation of Germany's energy system with a high share of renewables. [ABSTRACT FROM AUTHOR]

Citizen energy in general and renewable energy communities (RECs) in particular are becoming key vehicles for decentralisation, but also for the democratisation of the energy system. These initiatives are now more diverse than ever and are likely to continue to act as incubators for significant projects in the transition to a renewable energy system. Beside the legal, regulatory, and financial challenges, there are several socio-economic and regulatory barriers that hinder the implementation of community energy projects. For this reason, policy learning and the dissemination of good/best practices that are transferable also to other contexts are important. This is an aspect that has not yet attracted much investigation, and only a few studies have explored the importance of transfer activities for the implementation of REC initiatives and their motives. This article aimed to address this knowledge gap by focussing on the transfer processes of best practices initiated in a particular region and discusses how these can be adapted and transferred to other contexts. We analysed the transfer case of a community renewable energy initiative, the multifunctional energy gardens, from the Netherlands to the German federal State of Thuringia, and extracted lessons with an overall validity for the transferability of drivers and success factors. We show how examples from other contexts with similar enabling conditions can represent significant foundations on which to build an effective strategy and what framework conditions are necessary to enhance the uptake of pervasive community energy initiatives in regions with low community energy development. [ABSTRACT FROM AUTHOR]

The massive installation of renewable energy sources together with energy storage in the power grid can lead to fluctuating energy consumption when there is a bi-directional power flow due to the surplus of electricity generation. To ensure the security and reliability of the power grid, high-quality bi-directional power flow prediction is required. However, predicting bi-directional power flow remains a challenge due to the ever-changing characteristics of power flow and the influence of weather on renewable power generation. To overcome these challenges, we present two of the most popular hybrid deep learning (HDL) models based on a combination of a convolutional neural network (CNN) and long-term memory (LSTM) to predict the power flow in the investigated network cluster. In our approach, the models CNN-LSTM and LSTM-CNN were trained with two different datasets in terms of size and included parameters. The aim was to see whether the size of the dataset and the additional weather data can affect the performance of the proposed model to predict power flow. The result shows that both proposed models can achieve a small error under certain conditions. While the size and parameters of the dataset can affect the training time and accuracy of the HDL model. [ABSTRACT FROM AUTHOR]

The development and implementation of public policies towards renewable energies are crucial in order to address the contemporary challenges faced by humanity. The 3Rs (reduce, reuse, and recycle), as a circular economic practice, are often cited as one of the best solutions for sustainable development. Therefore, this study analyzed public policies for renewable energy from the perspective of the circular economy. Accordingly, a systematic review of the literature was carried out with respect to the beneficiaries and convergences of circularities, with a focus on public policies for renewable energies. The sample had public policies classified into three types (distributive, redistributive, and regulatory policies). The results showed that the first studies began in 1999, with a significant increase in publications during the 2010s, in which Germany was the country with the greatest contribution. The analyses associated with space showed the countries committed to the use of renewable energies and the 3Rs of the circular economy to reduce greenhouse gas emissions. The economic analyses revealed that the circular economy for the generation of renewable energy has a positive economic return in terms of social well-being and the mitigation of environmental degradation. There is a barrier to the circular economy's development posed by the cost of its implementation in the private sector and the resistance to raising awareness in society, requiring strong public sector engagement in decision making and the constant evaluation of public policies. It is concluded that the circular economy facilitates more efficient, productive structures and public policies, promoting alternatives for energy security and sustainability for the world energy matrix. [ABSTRACT FROM AUTHOR]

Renewable Energy Communities (RECs) have been defined as modes of collective prosumership under the Renewable Energy Directive (RED II). We evaluate the benefits offered by RECs and the barriers and enablers impacting their uptake. Germany is taken as a case study for a novel multi-disciplinary assessment of a potential REC intended as a climate-neutral, mixed-use district. We found that energy cooperatives may not be suited to form RECs, but the future may see an uptake of innovative organizational structures such as the Consumer Stock Ownership Plan. It has been shown that a high degree of prosumership can provide technical and economic benefits with maximum greenhouse gas savings of 35% and a maximum self-consumption share of 61% compared to no prosumership. The REC has a negative Net Present Value (NPV) after 25 years of operation and lacks financial attractiveness. A positive NPV is only possible by using the cost savings from prosumership to recoup the investments faster. RECs are a promising mode of citizen participation in the energy transition; however, for their application in Germany, together with the currently missing regulatory allowance of sharing energy between small-scale parties over a public grid, dedicated subsidies, one-time grants or price support for operators are needed. [ABSTRACT FROM AUTHOR]

In this work, we investigate the economic viability of demand response (DR) as a balancing option for variable renewable energies, such as wind and solar. Our assessment is based on a highly resolved national energy system model for Germany coupled with a regional DR optimisation model. First, this allows us to determine the spatially resolved flexibility demand, e.g., for avoiding transmission grid congestion. Second, a high number of DR technologies from the residential, commercial and industrial sector, as well as sector coupling, can be considered to cover the regional flexibility demand. Our analysis is based on a scenario for 2035 with a 66 % share of renewable energy sources in the power generation. The results show that the largest DR capacity is being installed in the west of Germany, an area with a high density of population and industry. All DR units have an aggregated capacity below 100 MW per transmission grid node. For the economic assessment, we further differentiate between two cases. In the first case with full DR cost consideration, the optimisation selects only large-scale technologies with low specific investment costs. The second case assumes that the required communication components are already installed. Here, we consider only variable costs and disregard the investment costs. As a result, several small-scale DR technologies are used, such as e-mobility. We publish the developed methodology as an open-source model, which allows reuse for other scientific purposes. [ABSTRACT FROM AUTHOR]

The large-scale storage of hydrogen in salt caverns, modelled on today's natural gas storage, is a promising approach to storing renewable energy over a large power range and for the required time period. An essential subsystem of the overall gas storage is the surface facility and, in particular, the compressor system. The future design of compressor systems for hydrogen storage strongly depends on the respective boundary conditions. Therefore, this work analyses the requirements of compressor systems for cavern storage facilities for the storage of green hydrogen, i.e., hydrogen produced from renewable energy sources, using the example of Lower Saxony in Germany. In this course, a hydrogen storage demand profile of one year is developed in hourly resolution from feed-in time series of renewable energy sources. The injection profile relevant for compressor operation is compared with current natural gas injection operation modes. [ABSTRACT FROM AUTHOR]

Potential analyses identify possible locations for renewable energy installations, such as wind turbines and photovoltaic arrays. The results of previous potential studies for Germany, however, are not consistent due to different assumptions, methods, and datasets being used. For example, different land-use datasets are applied in the literature to identify suitable areas for technologies requiring open land. For the first time, commonly used datasets are compared regarding the area and position of identified features to analyze their impact on potential analyses. It is shown that the use of Corine Land Cover is not recommended as it leads to potential area overestimation in a typical wind potential analyses by a factor of 4.7 and 5.2 in comparison to Basis-DLM and Open Street Map, respectively. Furthermore, we develop scenarios for onshore wind, offshore wind, and open-field photovoltaic potential estimations based on land-eligibility analyses using the land-use datasets that were proven to be best by our pre-analysis. Moreover, we calculate the rooftop photovoltaic potential using 3D building data nationwide for the first time. The potentials have a high sensitivity towards exclusion conditions, which are also currently discussed in public. For example, if restrictive exclusions are chosen for the onshore wind analysis the necessary potential for climate neutrality cannot be met. The potential capacities and possible locations are published for all administrative levels in Germany in the freely accessible database (Tool for Renewable Energy Potentials—Database), for example, to be incorporated into energy system models. [ABSTRACT FROM AUTHOR]

Biogas production is a process with great potential. It uses the biodegradable raw materials of animal, vegetable and municipal waste. The amount of municipal as well as agricultural waste is increasing every year. This waste is an unmanaged and nuisance waste, and using it in biogas plants reduces the amount of waste. Biogas production is part of the EU's policy to reduce dependence on fossil fuels and use energy from renewable sources (diversification of energy sources). Its importance is certain to increase in the future as energy demand increases. This article deals with the economical use of biodegradable waste for biogas production in Poland and Germany. Both countries have a similar agricultural and municipal waste structure. An agricultural biogas plant is one way of obtaining energy based on renewable energy sources (RES). Energy production from agricultural biogas will allow Poland to meet the 32% obligation imposed by the EU and Germany to continue to be the market leader in biogas plants. The biogas market in Poland is growing, while in Germany, there is a decline in biogas installations. The article indicates what changes need to take place in agriculture and the use of municipal waste in these countries to sustain the development of biogas plants. Both countries should maintain animal husbandry to ensure continuous access to substrate and use waste for production rather than growing maize or other mixtures only for biogas plants. Due to the high price of chemical fertilisers, pulp from biogas plants should be an alternative to chemical fertilisers in both countries, which will contribute to greener crops. The governments of both countries should support such measures. [ABSTRACT FROM AUTHOR]

Renewable energy production will require large areas of land; production sites should be designed to include biodiversity conservation. Guidance for decision-makers on reasonable coexistence is needed. We use time-series data alongside a meta-study on birds in solar parks, utilizing succession theory to indicate which bird groups can thrive in solar parks. Using an evidence-based and interdisciplinary approach, we documented biodiversity and conditions at a 6 ha site in the newly created post-mining landscape of Lusatia, Germany, for 16 years, grouping avian species depending on the ecosystem state in which they were observed. In a key mid-period of early succession lasting eight years, the avifauna was characterized by successional groups 2, herbaceous plant-preferring, ground-breeding species; and 3, open shrub-preferring species. The preceding and following groups were: (1) pioneer bird species that prefer open ground; and (4), pre-forest species. Comparison of these data with available bird monitoring in solar parks showed that bird species of groups 2 and 3 can also successfully settle in open-space solar parks that have some natural habitat attributes, whereas this is hardly possible for the preceding and following groups. Using this information, opportunities for habitat improvement are facilitated, and potential conflicts can be addressed more purposefully. [ABSTRACT FROM AUTHOR]

(1) The German energy system transformation towards an entirely renewable supply is expected to incorporate the extensive use of green hydrogen. This carbon-free fuel allows the decarbonization of end-use sectors such as industrial high-temperature processes or heavy-duty transport that remain challenging to be covered by green electricity only. However, it remains unclear whether the current legislative framework supports green hydrogen production or is an obstacle to its rollout. (2) This work analyzes the relevant laws and ordinances regarding their implications on potential hydrogen production plant operators. (3) Due to unbundling-related constraints, potential operators from the group of electricity transport system and distribution system operators face lacking permission to operate production plants. Moreover, ownership remains forbidden for them. The same applies to natural gas transport system operators. The case is less clear for natural gas distribution system operators, where explicit regulation is missing. (4) It is finally analyzed if the production of green hydrogen is currently supported in competition with fossil hydrogen production, not only by the legal framework but also by the National Hydrogen Strategy and the Amendment of the Renewable Energies Act. It can be concluded that in recent amendments of German energy legislation, regulatory support for green hydrogen in Germany was found. The latest legislation has clarified crucial points concerning the ownership and operation of electrolyzers and the treatment of green hydrogen as a renewable energy carrier. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Deep learning (DL)—in particular convolutional neural networks (CNN)—methods are widely spread in object detection and recognition of remote sensing images. In the domain of DL, there is a need for large numbers of training samples. These samples are mostly generated based on manual identification. Identifying and labelling these objects is very time-consuming. The developed approach proposes a partially automated procedure for the sample creation and avoids manual labelling of rooftop photovoltaic (PV) systems. By combining address data of existing rooftop PV systems from the German Plant Register, the Georeferenced Address Data and the Official House Surroundings Germany, a partially automated generation of training samples is achieved. Using a selection of 100,000 automatically generated samples, a network using a RetinaNet-based architecture combining ResNet101, a feature pyramid network, a classification and a regression network is trained, applied on a large area and post-filtered by intersection with additional automatically identified locations of existing rooftop PV systems. Based on a proof-of-concept application, a second network is trained with the filtered selection of approximately 51,000 training samples. In two independent test applications using high-resolution aerial images of Saarland in Germany, buildings with PV systems are detected with a precision of at least 92.77 and a recall of 84.47. [ABSTRACT FROM AUTHOR]

The main objective of the cultivation of energy crops is the production of renewable energy, the substitution of fossil energy resources, and a substantial contribution to energy supply. Thus, energy yield and energy efficiency are the most important criteria for the assessment of energy crops and biomass-based renewable energy chains. Maize is the energy crop with the highest cultivation acreage in Germany because of its high energy yields, but is the subject of controversial debate because of possible detrimental effects on agro-ecosystems. This raises the question as to which energy crops and production systems could be used instead of maize, in order to increase crop diversity and lower environmental impacts. We examined yields, energy inputs, energy outputs, and energy efficiency of alternative energy crops (combinations of catch crops and main crops) compared to maize in four-year field experiments at three southern German sites by means of process analyses. Maize showed moderate energy inputs (11.3–13.2 GJ ha−1), with catch crops ranging from 6.2 to 10.7 GJ ha−1 and main crops ranging from 7.6 to 24.8 GJ ha−1. At all three sites, maize had the highest net energy output compared to the other crops ( x ¯ = 354–493 GJ ha−1), but was surpassed by combinations of catch and main crops at some sites (winter rye/maize: x ¯ = 389–538 GJ ha−1). Although some combinations yielded higher net energy outputs than maize, no other crop or combination of crops outperformed maize regarding energy use efficiency (energy output/energy input: x ¯ = 32–45). [ABSTRACT FROM AUTHOR]