Search Results (14)

The implementation of photovoltaic and home storage systems in multi-family houses (MFHs) in Germany lags significantly behind their development in single-family houses. The Landlord-to-Tenant (L2T) power supply model is meant to reduce this gap, yet few projects have been implemented to date. In this model, the landlord must fulfill the tenants’ power demand through a combination of photovoltaic generation and storage and electricity from the grid, for which the landlord pays an auxiliary electricity price that greatly influences the financial viability of a project. Our contribution focuses on the impact of electricity price variations and recent policy changes on the financial viability of small-scale L2T concepts. We considered component investment costs, building sizes, photovoltaic yields, and future developments. Recent policy changes have improved the financial viability of L2T projects, increasing the maximal auxiliary electricity price for which an investment is viable by 13 ct/kWh for a four-party MFH. Minimal auxiliary electricity prices justifying the installation of home storage systems (HSSs) decreased by 9 ct/kWh from 2020 to 2023. Autarky rates are substantially different across the considered scenarios, with the autarky rate being defined as the percentage of consumption of self-generated energy relative to the total energy consumption. For a 22-party MFH the autarky rate decreases by 17% compared to a 4-party MFH. HSSs have the potential to increase autarky rates while maintaining the financial viability of L2T projects. Full article

The applicability of Hybrid Energy Storage Systems (HESSs) has been shown in multiple application fields, such as Charging Stations (CSs), grid services, and microgrids. HESSs consist of an integration of two or more single Energy Storage Systems (ESSs) to combine the benefits of each ESS and improve the overall system performance. In this work, we propose a novel power management controller called the Hybrid Controller for the efficient HESS’s charging and discharging, considering the State of Charge (SoC) of the HESS and the dynamic supply and load. The Hybrid Controller optimises the use of the HESS, i.e., minimises the amount of energy drawn from and discharged to the grid, thus utilising and prioritising the provided Photovoltaic (PV) power. The performance of our proposal was assessed via simulation using various evaluation metrics, i.e., Autarky, charge/discharge cycle, and Self-Consumption (SC), where we defined 24 scenarios in different locations in Germany. Full article

The significant expansion of renewable energies has led to an increased importance of storage systems. Decentralized storage solutions, including Home Battery Energy Storage Systems (HBESSs) and District Battery Energy Storage Systems (DBESSs), play a crucial role in this context. This study compares individual HBESSs with a community-used DBESS regarding the grade of autarky and self-consumption, specifically focusing on a planned residential area consisting of 36 single-family houses. A simulation tool was developed to conduct load flow simulations based on household electricity consumption, wallbox profiles for electric vehicle charging, and photovoltaic generation data across various battery capacities and system boundaries. The results demonstrate that the DBESS, compared to individual HBESSs with equivalent cumulative battery capacities, can achieve a maximum increase in the grade of autarky of up to $11.6$%, alongside an $8.0$% increase in the grade of self-consumption for the given use case. In terms of capacity, the DBESS allows for a saving of up to 68% compared to HBESS to achieve similar results for the studied neighborhood. Full article

The behavior and reactions of prosumers play a key role in the development of sustainable energy and green transformation, as it is the result of their individual decisions that determines the scope of use of renewable energy sources. For these reasons, the main goal of this article is to determine whether and to what extent autarky influenced prosumers’ decisions about the use of solar energy in households, and which promotional channels play the most important role in these decisions. An assessment of the role of autarky and promotion from the prosumer perspective on the photovoltaics market is carried out on the example of Poland as a developing economy, based on the dominant share of coal in energy production. The implementation of this goal will enable recognition and better understanding of prosumers’ intentions and attitudes, and thus more effective stimulation of the green transformation. Surveys in this area were carried out on a representative sample of 754 Polish prosumers, and were analyzed using descriptive statistics and non-parametric statistical tests. The obtained results demonstrate a strong need for energy independence among prosumers (50%) and confirm the role of this motive in the green transformation process. Respondents consider the Internet (a score of 3.8793 on a 5-point suitability scale) and information from companies installing photovoltaic installations (a score of 3.6645 on a 5-point suitability scale) to be the most effective sources of promoting photovoltaics. The example and opinion of family and friends are also important to them. Government campaigns (a score of 2.8647 on a 5-point suitability scale), television and the press play a much smaller role in the popularization of solar energy. Respondents, therefore, prefer numerous and dispersed marketing sources, that allow them to confront and verify the information obtained. Full article

To expand the potential of renewable energies, energy storage is required to level peaks in energy demand and supply. The aim of the present study was to examine and characterize the energy consumption of a milk production system to find possibilities and boundaries for a self-sufficient energy system. A detailed quantification of energy production of the test farm and the consumption of the milk production system showed, that the total energy production could cover the energy consumption of the production process. However, the temporal distribution of energy production and consumption requires energy storage in the production process. Though ice bank milk cooling and water heating have the potential to cover parts of this storage capacity, battery storage is mandatory to enable full autarky. The consideration of different seasons leads to different optimal dimensions of the energy system. The energy price is decisive for profitability, both in the purchase and in the sale. Smaller energy systems are generally at an advantage due to the higher self-consumption quota. Full article

This paper investigates the voltage and reactive power control problem in low voltage grids with connected prosumers and bulk loads. The X(U) local control, which maintains the voltage at the feeders’ ends within a predefined band, and its combination with Q-Autarkic customer plants are the most effective and reliable strategies in grids with high prosumer share. However, these strategies may need adaptations to guarantee voltage limit compliance when bulk loads, such as electric vehicle parking garages and community-owned photovoltaic systems, are connected to the low voltage feeders. This paper extends the X(U) local control concept to involve bulk loads in Volt/var control and investigates the resulting load flows in different real low voltage grids. The results show that the extended control arrangement reliably removes all voltage limit violations by deteriorating the effectiveness of the original X(U) local control arrangement: reactive power flows and equipment loading within the low voltage grids are increased. Full article

The increasing share of distributed energy resources aggravates voltage limit compliance within the electric power system. Nowadays, various inverter-based Volt/var control strategies, such as cosφ(P) and Q(U), for low voltage feeder connected L(U) local control and on-load tap changers in distribution substations are investigated to mitigate the voltage limit violations caused by the extensive integration of rooftop photovoltaics. This study extends the L(U) control strategy to X(U) to also cover the case of a significant load increase, e.g., related to e-mobility. Control ensembles, including the reactive power autarky of customer plants, are also considered. All Volt/var control strategies are compared by conducting load flow calculations in a test distribution grid. For the first time, they are embedded into the LINK-based Volt/var chain scheme to provide a holistic view of their behavior and to facilitate systematic analysis. Their effect is assessed by calculating the voltage limit distortion and reactive power flows at different Link-Grid boundaries, the corresponding active power losses, and the distribution transformer loadings. The results show that the control ensemble X(U) local control combined with reactive power self-sufficient customer plants performs better than the cosφ(P) and Q(U) local control strategies and the on-load tap changers in distribution substations. Full article

The transition towards a reliable, sustainable, low-carbon energy system is a major challenge of the 21st century. Due to the lower energy density of many renewable energy sources, a future system is expected to be more decentralized, leading to significant changes at the regional scale. This study analyzes the feasibility of the energy transition in the Swiss canton of Aargau as an illustrative example and explores different strategies to satisfy the local demand for electricity, heat, and fuel by 2035. In particular, we assess the potential contribution of biomass. Four scenarios demonstrate what energy demand proportion could be covered by bioenergy if different priorities were given to the provision of heat, electricity, and fuel. The impact of improved conversion technologies is also considered. The results show that the sustainably available renewable energy sources in canton Aargau will probably not be sufficient to cover its forecasted energy demand in 2035, neither with present nor future biomass conversion technologies. At best, 74% of the energy demand could be met by renewables. Biomass can increase the degree of autarky by a maximum of 13%. Depending on the scenario, at least 26–43% (2500–5700 GWh) of total energy demand is lacking, particularly for mobility purposes. Full article

New business models and digital infrastructures, in the form of ‘energy platforms’, are emerging as part of a transition towards decarbonised, decentralised, and digitised energy systems. These energy platforms offer new ways for householders to trade or exchange energy with other households or with energy system actors, but also bring along challenges. This paper examines how householders engage with potential environmental, social, and economic opportunities and risks of energy platforms. We convened two serious-game style workshops in which Dutch frontrunner householders assumed the role of platform members and were challenged to deliberate about different scenarios and issues. The workshop results, while explorative in nature, are indicative of a willingness to pursue energy system integration rather than autarky or grid defection. The idea of energy platforms as vehicles for energy justice appealed less to the householders, although the participants were moderately interested in sharing surplus renewable energy. Finally, environmental motivations were of key importance in householders’ evaluation of different platform types. This shows that in the role of energy platform members, householders can engage with both the community and the grid in new and different ways, leading to a diversity of possible outcomes for householder engagement. Full article

PV modules tilted and oriented toward east and west directions gain gradually more importance as an alternative to the presently-preferred south (north in the Southern Hemisphere) orientation and it is shown to become economically superior even under the reimbursement of feed-in tariff (FIT). This is a consequence of the increasing spread between the decreasing costs of self-consumed solar power and the costs for power from the grid. One-minute values of irradiance were measured by silicon sensors at different orientations and tilt angles in Hannover (Germany) over three years. We show that south-oriented collectors give the highest electrical power during the day, whereas combinations of east and west orientations (E-W) result in the highest self-consumption rate (SC), and combinations of southeast and southwest (SE-SW) orientations result in the highest degree of autarky (AD), although they reduce the yearly PV Power by 5–6%. Moreover, the economic analysis of PV systems without FIT shows that the SE-SW and E-W combinations have the lowest electricity cost and they are more beneficial in terms of internal rate of return (IRR), compared to the S orientation at the same tilt. For PV systems with FIT, the S orientation presently provides the highest transfer of money from the supplier. However, as a consequence of the continuing decline of FIT, the economic advantage of S orientation is decreasing. E-W and SE-SW orientations are more beneficial for the owner as soon as FIT decreases to 7 Ct/kWh. East and west orientations of PV modules do not only have benefits for the individual owner but avoid high costs for storing energy—regardless who would own the storage facilities—and by avoiding high noon peaks of solar energy production during sunny periods, which would become an increasing problem for the grid if more solar power is installed. Furthermore, two types of commonly used PV software (PVSOL and PVsyst) were used to simulate the system performance. The comparison with measurements showed that both PV software underestimate SC and AD for all studied orientations, leading to the conclusion that improvements are necessary in modelling. Full article

The concept of an autarky has a long history and meaning related to its negation and unpopularity. In liberal schools of economics, autarky is usually considered from the perspectives of economic trade protectionism, closed economies, and threats to welfare. Nevertheless, the concept of autarky has gained a new meaning, understood as the local utilization of renewable energy resources from the perspective of their inter- and intragenerational distribution. Local action is shaped by the global perspective. This research consists of three steps. First, a model of energy autarky has been offered based on the system theory. The model shows the variety of the structures and features of energy systems offered in today’s debates on energy autarky. Second, the key postulates of sustainable development have been presented to define an autarkical sustainable energy system. Finally, the concept of bioenergy villages in Germany has been presented to illustrate the approach to energy autarky. The research shows that the concept of autarky and single solutions, such as the use of renewable resources, are not themselves a success from the perspective of sustainable development; this misunderstanding is well illustrated by the evolution of the German concept of bioenergy villages into smart villages. Full article

The purpose of the research on which this article reports was to investigate how renewable energy forms part of the strategy of a local government, and to evaluate how participatory processes are utilised in the development and communication of this municipal strategy. The research was conducted with Hessequa Municipality, a local authority situated in the Western Cape Province of South Africa. A new aspect of the research was an attempt to consider renewable energy options as part of the municipal strategy, and not as a standalone project. Action research was undertaken and the resulting qualitative data were analysed using thematic analysis. Cognitive mapping was used to display the data and to analyse the causal relationships between different strategic themes. The causal relationships explicitly show that many opportunities for renewable energy solutions are evident in the form of: biomass-to-energy, low-carbon local economic development, small-scale embedded generation, waste-to-energy, and feed-in tariffs. The barriers for implementation are aging infrastructure and financial and legislative constraints. Participatory processes formed an integral part of the strategy formulation, and a unique visualised strategy was developed for communication with local citizens—a first for a local municipality in South Africa. Full article

Supplying power to remote areas may be a challenge, even for those communities already connected to the main grid. Power is often transmitted from long distances, under adverse weather conditions, and with aged equipment. As a rule, modernizing grid infrastructure in such areas to make it more resilient faces certain financial limitations. Local distribution may face stability issues and disruptions through the year and—equally important—it cannot absorb significant amounts of locally-produced power. The European policy has underlined the importance of energy production in local level towards meeting energy security and climate targets. However, the current status of these areas makes the utilization of the local potential prohibitive. This study builds on the observation that in the vicinity of such mountainous areas, irrigation dams often cover different non energy-related needs (e.g., irrigation, drinking water). Transforming these dams to small-scale hydropower (SHP) facilities can have a twofold effect: it can enhance the local energy portfolio with a renewable energy source that can be regulated and managed. Moreover, hydropower can provide additional flexibility to the local system and through reservoir operation to allow the connection of additional solar photovoltaic capacities. The developed methodological approach was tested in remote communities of mountainous Greece, where an earth-fill dam provides irrigation water. The results show a significant increase of renewables’ penetration and enhanced communities’ electricity autarky. Full article

Regional initiatives pursuing self-sufficiency through the use of renewable energy sources (RESS-initiatives) aim at contributing to broader transitions towards more sustainable energy systems. As such, they have raised high expectations among local activists and are increasingly supported by diverse funding schemes such as national programs. How can the social dynamics entangled in these initiatives be understood and assessed? A discourse analytical perspective, such as the Argumentative Discourse Analysis developed by Hajer, can bring valuable insights in this regard. This approach highlights the formation of discourse coalitions and processes of discourse structuration and institutionalization. In order to illustrate my conceptual and methodological considerations, I present an analysis of discursive dynamics observed in the alpine district of Murau, Austria, where the vision of reaching ‘energy autarky’ by the year 2015 has influenced regional development plans since 2003. The chosen discourse analytical approach has been very helpful in guiding the analysis of this case. Specific local conditions can explain why certain visions gained discursive hegemony. Full article