Prognose der Day-Ahead Wind- und Photovoltaikstromerzeugung – Einflussgrößen und Zuverlässigkeit

In the future, the percentage of renewable energies in the electricity generation is expected to increase continuously. Especially weather-dependent wind and solar power plays a substantial role. These energy sources are partly characterized by a fluctuating and imprecisely predictable power generation. To cover the residual load and to balance the forecast errors a rising number of flexible producers and consumers will be needed in the future. This is necessary to ensure the high security of supply of the German electricity grid.Against this background, the objective of the following investigation is to analyse the day-ahead forecasting quality of the feed-in from wind and photovoltaic systems in the control areas of Germany’s transmission system operators and in the entire area of Germany for the years 2010 to 15. The aim of this analysis is to identify the crucial parameters that influence the forecast error. Subsequently, the share of the wind and photovoltaic power forecast which can be considered as reliably predictable for the following day is estimated. In addition, the increase in this reliable prediction through a higher level of detail in the assessment of the forecast error is quantified. Based on these results, the need of flexibilities through the weather-dependent electricity supply from wind and photovoltaic systems can be estimated, and the impact on the electricity system can be evaluated.     

Ein Jahr danach: Erste empirische Ergebnisse der Ausschreibungen für Windenergie an Land gemäß EEG 2017

The sixth amendment of the German Renewable Energy Sources Act (Erneuerbare-Energien-Gesetzes [EEG]) came into force at January 1st, 2017. Especially regarding onshore wind energy, it includes fundamental changes. Having set raised market integration as well as market compatibility and cost-efficiency as the main three goals, market-based tendering shall be the instrument to reach them.Meanwhile, the first three calls have been completed. This enables the opportunity for a first evaluation of the tendering as a system to fund onshore wind energy in Germany and a comparison of the criticism which came along with the newest amendment. At first glance, several improvements can be found: Especially a—previously expected—forced competition on the market but also low bid and tender values show a massive potential of cost reduction. However, the analysis further shows that energy cooperatives are disproportionally privileged, which leads to a distortion of competition and the risk of a future non-continuous development. Additionally, the current system results in regional disparities, coming along with disadvantages especially for the southern states. 10 suggestions for improvement show possible answers concerning the main shortcomings.     

State of the German Short-Term Power Market

The paper at hand provides a comprehensive overview of the current state of the German short-term power market with focus on trading and efficiency. The pivotal question is whether current market designs are appropriate to maximise social welfare. If this can’t be confirmed, trade-offs between technical restrictions, transparency requirements, the structure of the supply side and regulators focusing mainly on consumer surplus are analysed, which prevent markets from being fully efficient. The emphasis is on Germany due to it’s central location in Europe, it’s sheer size and the rapid increase of renewable generation in recent years. This development forced the German power market into a state of transition. As a result, developments in Germany might serve as a blueprint for other European countries. The introduction of negative day-ahead prices, the implementation of a very liquid intraday trading, a quarter hourly auction and market-based systems for the procurement of Ancillary Services are just some examples of Germany’s pioneering role. On the other hand, negative effects of the rapid changes such as the excessive use of non-market based redispatch measures and system endangering imbalance price regimes shall also be explored. As a matter of course, cross-references to other European countries and harmonisation projects are included as the German market is well interconnected with neighbouring markets.     

Eine soziologische Systemanalyse und sozio-ökonomisches Review der Soziotechnik Energiewende

The transition of the energy supply system in Germany from fossil-nuclear energy resources to renewable energies is a policy issue and defines a society technics. Society technics takes responsibility for an essential societal need and should be based on an agreement between all actors in all involved systems. According to a society-technics there are benefits for encouraging research, good governance for political support, public understanding of science (PUSH), and academic consultation for politics.Positive implementation will results in optimal coordination as all systems will function and all actors will work for synergy-effects. But a sociological system analyses works out many “dyssynergies”, handling the transition only as technological challenges and failing in underlying this transformation as a socio-technical system. Using renewable energies will not only change the technological system architecture but also modifying social systems and individual attitudes.     

Techno-ökonomische Bewertung von Energie-Autarkie für die Energieversorgung von Einfamilienhäusern

Many consumers currently follow the idea of energy self-sufficiency and try to contribute to meet their energy needs in order to become independent and self-sufficient from the central power supply system. In order to achieve load-oriented energy self-sufficiency the provision of energy must cover the full energy demand at any time. Against this background, in this paper the costs and potentials of a load-oriented energy self-sufficiency of single-family homes are analysed. Thereby it is differentiated between electricity-, heat- and energy self-sufficiency. The modelling is carried out with the simulation environment ?Polysun Designer“ which allows a high temporal dynamic simulation of the annual energy demand and supply.The results show that, within the investigated supply variations, the highest levels of energy self-sufficiency can be achieved by an energy supply system completely based on electricity using a combination of PV; heat pump and battery storage. Depending on the building standard, a maximum of 45 (existing buildings) and 71?% (new buildings) of the building’s energy demand can be covered with renewable energy. The economic evaluation however has shown that under present conditions, none of the investigated supply variants can compete with conventional energy supply (public grid connection + gas condensing boiler).     

Energiewende: Alles eine Frage der Partizipation? Governance-Herausforderungen zwischen Zentralität und Dezentralität

The interaction of centralised and decentralised elements is not only a challenge for the technical und functional implementation of the energy transition, but also for the political and social assignment of developing adequate governance strategies for future energy systems. While “participation” is of capital importance for all governance approaches mediating centralising and decentralising trends, it is far from clear, how participation is to be realized in order to promote energy transition and avoiding pitfalls and flaws of participative decision making processes. Against the backdrop of a multi-dimensional understanding of “participation” comprising procedural, factual, legitimatory and meta-reflective functions, the paper considers the tense relations of participation and efficiency, legitimacy and professionalized expertise, thereby identifying structural challenges for participation in democratic societies. Finally, some suggestions are made, how the governance of the energy transition can be shaped in the future.     

Behavioral and Attitudinal Customer Loyalty in the Power Sector

The emergence of smart grids changes the customer-utility relationship. To facilitate the transition towards a sustainable, reliable and economically viable energy system, utilities need to develop smart grid products and services that have strong customer acceptance and enable different customer segments to engage in energy efficiency. Thus, integrating customer feedback on innovative smart grid services early in the innovation process is of crucial importance. Further, energy providers need to increase customer loyalty and invest in relationship marketing in order to survive and be successful in a competitive market environment.This article presents the findings of a five-month field experiment that investigated the effectiveness of different reward programs in increasing customer loyalty and customer feedback provision in the energy sector. The results demonstrate that reward programs have a positive effect on behavioral (customer feedback provision) and attitudinal (e.?g. satisfaction with the energy provider) aspects of customer loyalty. The reward type matters, however. While monetary reward programs are effective in increasing customer feedback provision, only social reward programs can improve attitudinal aspects of customer loyalty. Energy providers should therefore consider tailoring the reward type to meet their program objectives when employing reward programs.     

Grosse Stadtwerke – theoretische und empirische Exploration eines besonderen Akteurs in der Energiewende Deutschlands und der Schweiz

Urban utility companies are key players in the Swiss and German energy sector. Due to the federalist and subsidiary governance structure of the two countries’ energy sector, they perform highly system relevant tasks, as e.?g. managing the distribution grids or ensuring the public services for “their city”. In the public and scientific discourse on the role of different actor groups in the energy transition, however, not much attention is paid to urban utility companies. This contribution aims at a theoretical and empirical exploration of these particular actors by analysing their characteristics, specific challenges and strategic answers in the context of the energy transition. For this purpose, the article derives analytical dimensions for the analysis of urban utility companies from scholarly literature on transition studies, network industries and public corporate governance and empirically analyses characteristics and the current situation of urban utility companies in Germany and Switzerland. Methodologically, this article is based on an explorative, qualitative study, which synthesises results from a literature analysis, a document analysis, 38 expert interviews in both countries (in 2017) and two expert workshops conducted in Switzerland (in 2018). The study shows, how the characteristics of urban utility companies can be explained based on public corporate governance and network industries literature. This also allows to identify and understand their particular challenges, as e.?g. the fields of tension among public and private interest in the firms and the multi-dimensional relationship of owner or the particularities of network industries. Finally, this article points out, that the role of urban utility companies in the Swiss and German energy transition is neither just “inhibitor” nor pure “innovator”, but can be labelled as “intelligent follower” and “engineer of the energy transition”.     

When Public Utilities <Emphasis Type="Italic">Like</Emphasis> to Talk on Facebook

As the leading social media tool, Facebook is increasingly becoming an important channel for two-sided stakeholder communication in the energy sector. Even though public utilities more and more all relying on such virtual communication, little is known regarding the communication-related factors and their interdependencies. This study aims to reduce this research gap by analysing correlations between a public utility’s specifications, communication interactivity, the resources spent and the outcome of the Facebook conversation. In 2016, an online questionnaire was sent to German, Austrian and Swiss utility companies. The empirical data of the 139 utilities that responded fully support relationships between the communication interactivity and the invested resources as well as the outcomes of a communication. In this way, the results provide new insights for scholars and practitioners into the Facebook conversations of public entities.     

Verlustwärme von Offshore-Gleichstrom-Seekabelsystemen – Entstehung und Übertragung

In Germany heat dissipation of subsea cables for power transmission from offshore wind farms into the sea floor is regulated. The precautionary value to be adhered to is a maximum temperature increase of 2?K in 20 to 30?cm sea bed depth. Such a temperature increase is defined by a number of influencing factors and boundary conditions and is extremely difficult to physically measure. Thus the purpose of this paper is to simulate the heat generation of DC submarine cables and the dissipation into the surrounding sea floor using the Finite Element Method (FEM). Herewith crucial parameters and influencing factors can be identified. The results show that the strongest influencing factors on the sediment temperature in 20 to 30?cm sea floor depth are the average load or longer-term preload of the cable, the burial depth and the thermal resistance of the sediment. Overall, during standard operation of wind farms and the corresponding cable systems the 2?K limit is adhered to safely. In general, this also applies to special wind and load situations.     

Dezentrale Steuerung eines Pools von Wärmepumpen auf Basis spieltheoretischer Methoden

An intelligent coupling of the power and the heat sector offers huge possibilities for the integration of electric energy from fluctuating, renewable energies. In this regard heat pumps depict a highly efficient way of power-heat-coupling. However, for a pool of heat pumps this potential can only be exploited effectively with a suitable control methodology. Such a control methodology makes it possible to enforce – depending on the specific case of application – a system-compatible behavior of the pool of heat pumps. In this respect a decentralized control approach offers a higher scalability compared with a centralized control approach. Thus a decentralized control approach based on game-theoretic methods is developed and presented here. For this purpose three game-theoretic optimization algorithms are examined. Their performance is analyzed and evaluated for two specific cases of application (reduction of peak load and tracking of a predefined load profile) by means of simulation. The results of both case studies illustrate, that game-theoretic control is easily applicable and can effectively be used to control a pool of heat pumps. Furthermore the developed control methodology can principally be adapted and utilized for all other electric loads with inherent storage functionality.     

Efficient Grid Extension for Strongly Fluctuating Energy Sources

The statistical distribution function of the yield of a source of strongly varying output is usually presented as a ‘power-duration-curve’. We show that the decisive economic curve representing the marginal benefit of such fluctuating sources like wind energy can be derived directly from this distribution function. This may allow to determine the optimum investment in renewable energy systems. As one application we determine the economic optimum limit power of high voltage lines devoted to long distance transmission of wind energy as the intersection of the marginal-benefit-curve of the energy produced and the marginal-cost-curve of the transmission line.     

影响公众对核电接受度的因素分析

公众参与是核电环境影响评价中的一个重要组成部分,而居民对核电的接受度已成为许多国家发展核电面临的最主要的问题之一。通过分析中国公众和外国公众对核电的接受度现状,总结了一些影响公众对核电接受度的因素,提出了加强宣传、研究公众对风险的认知规律、努力提高核电清洁水平和安全水平、提高核废料处置水平以及加强核电企业的形象建设等改善公众接受度的途径。     

Kurzfrist-Lastprognose für die Day-Ahead- und Intraday-Stromnachfrage bei sich systematisch ändernden Lasten

Load forecasts are used in various fields of the German energy economic to plan and to optimize the schedule of the power generation or the purchase of power from the markets based on the results of the forecasts. Therefor accurate load forecasts are necessary. But many load forecasting models reach their limits when dealing with systematic changes in the profile of the energy demand, since the model is usually calibrated by historic data so the relation between the load and the input parameters are estimated. Due to changes in the load profile the load level is moving to another level compared to the historic one. While the forecasting model is still calibrated on the old level, this can lead to higher forecasting errors and these can in turn have negative consequences on the following optimization steps. That is why a methodological approach is presented so that the forecasting model is able to adapt a systematic change in the load profile. Therefor the presented approach is at first applied to a case of application, before it is applied to two more extreme variations of the load profile to identify possible limits of the presented approach.     

Die Berücksichtigung von Spitzenkappung in der Anreizregulierung

The model of temporary disconnection of renewable energy in case of high energy injection and low demand is thought to be an effective method for reducing investments in electricity networks. However, plant owners need to be reimbursed for foregone sales. According to the currently discussed draft of the Amendment of the German Incentive Regulation Ordinance, these costs can be rolled over to the consumer on a yearly basis, but are part of the cost benchmark with their base year values. This paper shows that this model sets incentives for optimal investments in electricity networks, but violates the participation constraint: Net operators will be exposed to a severe risk of worsening their position in the cost benchmark. In expectation, they will generate losses and investors have no incentive to invest in electricity networks. This problem can be solved by allowing net operators to roll over costs to customers, while considering average reimbursement fees in the cost benchmark.     

Modellgestützte Bewertung des Kraft-Wärme-Kopplungsgesetzes 2016 anhand ausgewählter Anwendungsfälle in Wohngebäuden

Cogeneration is a promising technology in the energy transition amongst other things in view of its energy efficiency and its broad applicability in the household, tertiary and industry sectors. For the promotion of cogeneration technologies, support schemes are in place in German energy policy. Amongst other things the Combined Heat and Power (CHP) Act serves as the main instrument for the promotion since 2002. In the new version of the CHP Act of 2016 the German Federal Government strives towards a more market-oriented design resulting in significant amendments featuring inter alia a highly case-dependent tariff design with modified levels and durations of remuneration. It is therefore the aim of the present study to assess these modifications with respect to technical, economic and ecological aspects in a model-based approach by means of selected use cases at different levels of spatial aggregation for residential buildings. Results point to an economic advantageousness for cases of the medium energy consumption level (streets and blocks of houses) under the new regime as well as the reversal of this attractiveness for objects of high consumption (neighbourhoods, districts). Particularly, CHP plants tend be dimensioned comparatively smaller with a greater number of full-load hours under the new regime. Furthermore, implications with regard to technical and ecological aspects are shown in this contribution.     

Bioenergie – Beitrag zum heutigen und zukünftigen Energiesystem

The introduction and establishment of renewable energies is still discussed intensively with the focus on climate-neutral coverage of the global energy demand. In this regard it is a valid option to use biomass as a feedstock. Already today biomass contributes significantly to cover the energy demand in the global energy system. Therefore, the present and future global bioenergy potentials are investigated in the following and compared to the respective biomass use. The results show, amongst others, that the share of biomass for heat, electricity and fuel production will increase worldwide until 2030, although the availability of biomass for energy production is likely to decline in the future.     

Germany’s Energy Supply

Germany has only very limited domestic energy resources. Seventy percent of primary energy needs must be covered by imports. The markets for energy are marked by a wide diversity and a large number of providers. The oil market has been intensely competitive for decades now. Lignite and hard coal are subjected to fierce substitution competition, especially with natural gas. The natural gas and electricity markets were fully liberalized in 1998. Consumers can freely choose from a vast number of suppliers. Since the beginning of this century, however, state interference particularly in the electricity market has increased. The expansion of renewables has been promoted since the year 2000 by feed-in priority and feed-in remunerations regulated by the state. The energy transition initiated in 2011 is characterized by ambitious energy and climate policy targets. Key pillars include the conversion of electricity generation from production on the basis of conventional energy sources to a system based mainly on renewable energies combined with stringent requirements designed to enhance energy efficiency and what are probably the most ambitious climate protection targets worldwide. As regards the expansion of renewables and the phase-out of nuclear energy, Germany is keeping to its target path. By contrast, there are no signs yet that the objectives formulated in terms of the lowering of primary energy consumption and the reduction in greenhouse gas emissions will be achieved.     

Can Lignite Take a Back Seat?

Transmission grid extension is a central aspect of the future energy system transition in Germany. This stems from the diverging occurrence of renewable energy feed-in and consumption as well as the targeted nuclear and currently discussed carbon phase-outs. After realizing the retirement of the domestic nuclear energy fleet by 2022, a next policy objective could be the phase-out of domestic lignite generation. The German electricity grid was not designed to accommodate these emerging challenges. Hence, the following paper addresses the impact of decommissioning lignite power plants on the most cost-effective grid extensions by 2030. To determine the optimal transmission grid design, efficient methods for techno-economic analysis are required. The challenge of conducting an analysis of grid extensions involves lumpy investment decisions and the non-linear character of several restrictions in a real-data environment. The following paper introduces the application of the Benders Decomposition, dividing the problem into an extension and a dispatch problem to reduce the degree of computational complexity. The results show that lignite phase-out can significantly increase the number of grid extensions in Germany. All scenarios simulating a lignite phase-out by 2030 lead to higher overall system costs but lower CO\({}_{2}\) emissions.     

Markt- und Systemintegration von erneuerbaren Energien im Rahmen der Systemtransformation – Ein Beitrag zur definitorischen Abgrenzung

The reconstruction of the electricity system is one of the main challenges of the German energy transition (Energiewende). The expansion of renewable electricity generation should enable the phase out of nuclear and fossil power generators in the long run. The Renewable Energy Sources Act (Erneuerbare Energien Gesetz) aims at increasing renewable generation up to a share of at least 80?% in gross electricity consumption by the year 2050. There are many possible ways to reach this target. Today, the characteristics of the future energy systems become apparent through the legal framework and long term energy scenarios.Economic, social and regulatory hurdles will need to be overcome to enable the transition of the electricity system. In this context, specific measures are evaluated with respect to their contribution on the system transformation, system integration and market integration. Up until now a consistent framework for evaluating political actions and scientific that should effectively support the energy political objectives is not present. The concepts of power system transformation, power system integration and market integration are differentiated and defined to close this gap. Based on this framework, a practical example is evaluated. The exact definitions will help to objectify the political and scientific debate. Furthermore, it contributes to develop regulatory and market mechanisms.