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.     

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.     

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).     

Bereitstellung von Regelleistung durch Elektrofahrzeuge: Modellrechnungen für Deutschland im Jahr 2035

The German government has set ambitious goals for both the expansion of renewable energy supply and electromobility. According to its Energiewende policy, electricity supply from fluctuating renewables is supposed to further increase considerably. This will tend to require a greater provision of balancing reserves. At the same time, supply from conventional dispatchable plants, which used to provide the bulk of reserves, will decrease. Against this background, this article analyzes the scope for an assumed fleet of 4.4 million electric vehicles to supply balancing reserves in 2035. Examining two different future power plant scenarios, it explores the potentials of reserve provision with and without the option of feeding electricity from vehicle batteries back to the grid. Results from an extended open-source power system simulation model show that the assumed vehicle fleet can efficiently provide a substantial share of reserve requirements, also in case the vehicle-to-grid option is not available. Arbitrage on wholesale markets, on the other hand, is negligible under basic assumptions. Likewise, total system cost savings are minor when compared to a pure cost-optimal loading of vehicle batteries. Under alternative assumptions on the future power plant portfolio as well as on battery degradation costs, however, wholesale arbitrage, reserve provision, and system cost savings can be substantial.     

Stromspeicher für die „Energiewende“ – eine akteursbasierte Analyse der zusätzlichen Speicherkosten

Political targets for implementing the German “energy turnaround” aiming at the ambitious extension of renewable energies to generate electricity. However, a majority of the renewable supply is provided by intermittent sources, e.g. wind and solar power. For balancing the increasing supply fluctuations additional storage options are claimed beside of an enforced grid infrastructure and a more flexible demand side. Despite of the political guidelines the economics of additional flexibility measures has to be considered. For this paper we analyse the costs of large scale stationary battery storages to be operated in wholesale markets and transmission grid level. By deriving a key figure based on a life-cycle cost approach, we are able to evaluate the additional costs of electricity of selected battery technologies (lead-acid, lithium ion, sodium sulphur, redox-flow). Moreover, current and valid parameters of the cost analysis are received by scientific and industrial stakeholders of battery systems via online survey and face-to-face interviews. According to the stakeholder estimation a nationwide operation of stationary battery storages will be established at wholesale and transmission grid level until the year 2030. The life-cycle cost analysis, which also includes estimated future cost reductions, shows that lead-acid batteries remain the cost-efficient technology, assuming about 100 storage cycles p.a. In addition, a sensitivity analysis reveals the impact of increasing annual storage cycles as well as the achievable cost reduction by economies-of-scales of the power unit of the storage system.     

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.     

Elektroautos in einer von erneuerbaren Energien geprägten Energiewirtschaft

The German Federal Government wants to establish Germany as a leading market for electric mobility. Potential environmental benefits and changes in the economic framework conditions of the energy sector are described in this paper. In order to quantify the electricity split which is actually used for charging electric vehicles, two economic models for the energy sector, a model for the market penetration of electric vehicles, a vehicle model and an LCA model are brought together. Based on an assumed dynamic increase of electric vehicles to 12 million in 2030, an additional electricity demand of about 18 TWh is calculated. If the vehicles are charged directly after their last daily trip, the peak load increases by 12%—despite the small increase in electricity demand. First model calculations for the development of the European power generation system show that the direct impact on the construction of new power plants remains low even until 2030. An impact of electric mobility on CO₂ certificate prices can only be seen from 2025 onwards and is limited to an increase in certificate prices by a maximum of 8 % in 2030. An optimisation is possible with intelligent charging strategies: The peak load without demand side management can be reduced by 5 GW and about 600 GWh of additional wind energy can used which would otherwise have been throttled due to feed-in management—about 3.5 % of the total electricity demand of electric vehicles. On the other hand, demand side management leads to more coal power plants instead of gas power plants being used to meet the additional electricity demand. If additional renewable sources are installed along with demand side management, the electricity for electric vehicles is almost carbon free. This is also reflected in the life cycle balance of electric vehicles which also includes vehicle and battery production: With today’s average electricity split in Germany, the greenhouse gas emissions of electric vehicles are about comparable to vehicles with conventional combustion engines. However, the electricity split in 2030 or the use of additional renewable energy sources lead to a significant advantage in the greenhouse gas balance.     

Die Verteilung der Kosten des Ausbaus der Erneuerbaren

Germany’s private and industrial consumers have to bear electricity prices that are among the highest in Europe, a major reason being the massive subsidization of green electricity via feed-in tariffs. To dampen future electricity cost increases, numerous suggestions were published recently. They differ substantially with respect to their distributional impacts, transaction costs, political feasibility, and their impact on the cost-effectiveness of the future promotion of renewable technologies. This article’s qualitative evaluation of the most prominent proposals indicates that, more or less, they all fall short with respect to these evaluation criteria. In conclusion, decision-makers would be well advised to reconsider Germany’s renewable energy goals. Consideration should be given to either abolishing these ambitious goals or to improving the cost-effectiveness of the future expansion of renewable energy technologies to dampen the likely continued increase in electricity prices.     

Gleichzeitigkeit als Leistungsgröße: Inter- und Intra-Klassen-Leistung volatiler EE-Einspeiser

The energy transition focuses on the expansion and enhancement of distribution grids and the integration of decentralized renewable generation plants. The integration of decentralized plants presents a major challenge for distribution system operators in particular. The planning and dimensioning of energy grids requires knowledge of all integrated generating units and power consumers, as well as their power ratings. Furthermore, knowledge about the diversity of renewable power plant types enables distribution system operators and scientists to selectively or cumulatively assess the maximum feed-in capacity. This is particularly important for the assessment of case studies or border scenarios. The purpose of this article is the evaluation of the maximum simultaneous feed-in power of PV and wind power plants. Furthermore, the ratio of the installed power to the maximum power generated by renewable power plants is also investigated. The diversity factor describes the ratio of the sum of all individual load’s maximum powers to the number of loads. This simultaneity can also be adapted to renewable power plants. However, it is differentiated here between simultaneous power within one renewable power plant type (intra-class performance) and simultaneous power of different renewable power plant types (inter-class performance). In cooperation with one of the largest national distribution network operator, regression lines are approximated by statistical analyzes, in order to determinate the diversity of the Central German area.     

The Impact of PV on the German Power Market

During the last months, the discussion on feed-in tariffs (FiT) for photovoltaic (PV) installations in Germany has gained new momentum. On the one hand, the issue of over-subsidisation due to the fact that module prices have been decreasing faster than feed-in tariffs was discussed. On the other hand, increasing costs to the consumers of power were put on the agenda after the unprecedented increase in new PV capacity in Germany in 2009. After the general election in September 2009 this discussion lead to different proposals for adjusting the FiT scheme. In summer 2010 a bill was passed amending the current FiT. Both, in the discussion and in the bill, an important aspect has been neglected so far: the impact of the massively increasing PV capacities on the economics of conventional power plants. The present study fills this gap. In the first part, it is qualitatively shown how the power price and the equilibrium quantity on the power exchange change with increasing PV capacities. These findings can be directly translated into shrinking revenues for operators of conventional power plants. In the second part, a quantitative analysis of the German power market is provided. The effects of different PV scenarios on the wholesale power price and the total revenues (i.e., price multiplied by quantity) of all conventional power plants are calculated. For an incumbent operator of a coal-fired power plant, the contribution margin may decrease by more than 25% and for a new, yet to build gas-fired combined cycle power plant it may drop by more than 30%. The study concludes that the PV support scheme can be understood as the accelerator pedal for the structural change in the German power sector. Implementing the changes in the feed-in tariffs as presented in the bill will require more and faster changes in the overall design of the power market to provide sufficient incentives for backup capacities when the sun is not shining. It would also be accompanied by additional acceleration costs. Absolute caps on the added capacity, rather than further cuts in the tariffs, could buy some time for a careful redesign of the market and may reduce resistance from incumbent operators.     

蓄能调温负荷与光伏的智能化互动运行策略

为了充分利用蓄能调温负荷的调节资源,节约调温负荷的用电成本,并有效消纳光伏电量,提出了"光伏+调温负荷"的智能化互动运行策略。首先,建立了基于户型参数和天气信息的房屋冷、热需求模型;其次,以运行成本最小为目标,结合光伏出力和用冷、用热需求,在优先使用谷电电量的原则下,提出蓄能负荷与光伏供用电互动逻辑和运行策略;第三,以全年天气数据为驱动,按互动逻辑关系进行了全年运行累积计算的年运行成本分析。结果表明,互动运行模式相比于光伏与蓄能调温负荷独立模式的运行成本有很大降幅,"光伏+调温负荷"策略有效解决了光伏消纳和调温负荷电费的问题。这不仅有利于减少环境污染,还能够实现政府与用户的双赢。     

Grid Load Contributions Through Electric Vehicles and Their Uncertainties

With the numbers of electric vehicles on the increase, their additional electricity demand can no longer be neglected. From a power systems’ perspective, it is the time dependent electricity consumption that matters. In particular, the peak demand is increased in the case of uncontrolled charging, imposing additional stress on the system. Unfortunately, since there is an absence of representative electric vehicle driving patterns, a quantification of such temporal charging requirements is challenging. To overcome this problem, we developed a detailed model, which maps combustion engine vehicles onto electric vehicle equivalents. The model’s main strengths are the consideration of the diversity within the vehicle fleet as well as the differentiation into the boundary cases of pure battery electric vehicles and plug-in hybrid electric vehicles. Applied to a German traffic study, load curves for these two cases were generated. In addition, the existing uncertainty in between was quantified using Monte Carlo method. We show that the peak energy demand through electric vehicles is much greater on working days than on weekend days. Moreover, we find that the distinction between pure and plug-in-hybrid electric vehicles matters, at least for the time being. Apart from the numerical results, the model is well suited to generate input for more sophisticated investigations of charging strategies within energy system simulations.     

Die Auswirkungen des EEG auf das Energiesystem Deutschlands – Eine Betrachtung mit dem Energiesystemmodell TIMES-D

In Germany, the electricity generation from renewable energy has been promoted since the year 2000 by a feed-in tariff system, the Renewable Energy Sources Act (EEG). This article evaluates the long-term impact of the German feed-in tariffs on the development of the German energy system with the help of the energy system model TIMES-D. In the model-based analysis, both the payment side (i.e. the tariffs) and the cost side (i.e. the EEG apportionment) are taken into consideration. Through the promotion of the feed-in tariff system—in combination with the European Emission Trading Scheme (ETS)—the use of renewable energies in electricity generation in Germany rises considerably such that renewable energy sources account for almost 40% of total gross electricity consumption in 2030. Accordingly, until 2020 total EEG fee payments as well as the EEG apportionment increase significantly. The impact of the feed-in tariff system on final electricity demand is, however, relatively small. Alternative scenario settings show that the expansion of the renewable electricity generation through the feed-in tariff system clearly exceeds the development which would occur when trying to reach the reduction targets of the ETS in a cost-efficient way.     

Integration erneuerbarer Energien in die deutsche Stromversorgung im Zeitraum 2015�C2020 mit Ausblick auf 2025

The dena grid study II examines the integration of renewable energies into Germany??s electricity supply up to the year 2020 and gives a qualified outlook up to 2025. The study develops geographically differentiated scenarios for installed wind power capacity, on the basis of which time series of the wind power feed-in into high and extra high voltage nodes and offshore wind farms are generated. Future requirements for the transmission grid and grid extension options are analysed. Opportunities to introduce more flexibility in the power system in terms of supply and demand are examined. The study gives a conceptual perspective of the need for grid extension in inner Germany in order to fully integrate renewable energies, whilst operating power stations at optimum cost and exchanging electricity with other countries in response to market demands within the scope of the specified transmission capacities.     

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.     

电池储能技术在电力系统中的应用评价及发展建议

随着智能电网时代的到来,世界各国电力系统正在从传统型向现代型转变,而储能技术的应用将成为这场变革的重要环节。对新型储能电池的技术经济特性和发展应用现状进行了介绍,构建了电池储能技术综合评价指标体系,针对储能技术在不同领域的具体应用进行了综合评价,分析了新型储能技术的发展前景并提出了相关建议,以期为政府主管部门、能源电力企业、产业界及行业专家提供参考。     

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.     

Stromspeicher im Quartier

Electricity storage is a possible flexibility option to increase the share of fluctuating electricity sources from renewable energies in the electricity system. In the past, most attention was paid to household and large storage facilities. Community storage solutions at the meso level have so far been largely neglected. It is only in the context of the change in legislation for the electricity supply of tenants that neighborhood solutions have recently been increasingly discussed.In essence, this article examines the challenges currently arising in the context of the implementation of electricity storage facilities at community level in Germany. To this end, the term “community storage” is first being discussed and outlined. Subsequently, economic-legal and socio-cultural challenges are presented and discussed as central challenges in the implementation of neighborhood storage solutions in Germany. Based on the discussion of current challenges, possible business models for the implementation and operation of district storage facilities in Germany will then be derived.     

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.     

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.