分散式灵活性和可再生能源的整合——德国的经验和对中国的展望（英文版）-GIZ.pdf

Sino-German Energy Transition Project Decentralized Flexibility and Integration of Renewable Energy Experiences in Germany and Outlook for China 2 Legal Information Publisher: Deutsche Energie-Agentur GmbH (dena) German Energy Agency Chausseestraße 128 a 10115 Berlin, Germany Tel: +49 (0)30 66 777-0 Fax: +49 (0)30 66 777-699 E-mail: info@dena.de Internet: www.dena.de Authors: Tim Mennel, dena Hrvoje Brlecic Layer, dena Lisa Strippchen, dena Anders Hove, GIZ Wenyun Qian, GIZ Date: 8/2022 All rights reserved. All use of this publication is subject to the approval of dena. Please quote as: Deutsche Energie-Agentur (Publisher) (dena, 2022) “Decentralized Flexibility and Integration of Renewable Energy” The report “Decentralized Flexibility and Integration of Renewable Energy” is published by the German Energy Agency (dena) as part of the Sino-German Energy Transition Project. The project supports the exchange between Chinese government think tanks and German research institutions to strengthen the Sino-German scientific exchange on the energy transition and share German energy transition experiences with a Chinese audience. The project aims to promote a low-carbon-oriented energy policy and help to build a more effective, low-carbon energy system in China through international cooperation and mutually beneficial policy research and modelling. The project is supported by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) as part of the Sino-German Energy Partnership, the central platform for energy policy dialogue between Germany and China on a national level. From the Chinese side, the National Energy Administration (NEA) supports the overall steering. The Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH leads the project implementation in cooperation with the German Energy Agency (dena) and Agora Energiewende. 3 1 Distributed generation and decentralized flexibility in Germany 5 1.1 Development of distributed generation 2000-2022 . 6 1.2 Deployment of storage and DSM in Germany today 7 1.3 German and EU policy targets for decentralized renewable energy and flexibility 7 2 Technical challenges of electricity systems with high share of variable renewables . 9 2.1 Challenges in distribution grids . 9 3 Flexibility for grid integration of distributed renewables . 13 3.1 Flexibility as a remedy for problems on the distribution and system level . 13 3.2 Flexibility in the distribution grid 13 3.3 Aggregation of decentralized flexibility 15 4 The use of decentralized flexibility in German distribution networks 17 4.1 User-sited battery electricity storage 17 4.2 Demand side management (DSM) 20 5 Application to China . 25 5.1 Distributed generation in China 25 5.2 Distributed storage . 28 5.3 Centralized storage . 28 5.4 Demand-side management . 29 5.5 Coal plant flexibility . 30 5.6 Ancillary service markets 30 5.7 Relevance of German experience . 31 5.8 Suggestions for decentralized flexibility in China . 31 List of figures 33 List of tables . 34 References 35 Content 4 Distributed generation plays an increasingly important role in the energy transition. With Germany aiming at a renewable energy share in its net electricity consumption of 80% by 2030, up from 45% in 2021, small-scale renewable energy sources connected to the distribution grid must contribute a larger share of national energy output alongside large-scale sources such as onshore and offshore wind. So far, most of Germany’s distributed generation consists of solar PV installations, both rooftop and small-scale ground-mounted installations. Other small-scale technologies include biomass, biogas, and small-scale hydro generation. By 2021, Germany had 2 million rooftop solar PV installations, approximately 15% of the country’s total solar PV capacity. Though solar helps reduce carbon emissions by replacing electricity from fossil fuels, its variable output creates technical challenges for the distribution grid, most notably thermal overloads of network devices, violation of voltage limits, backfeed issues, and phase imbalances. Fluctuating feed-in of renewable energy can lead to general generation adequacy and stability problems on the system level, especially as Germany phases out more conventional generation that can provide firm capacity and ancillary services. Flexibility measures are the key to solving these distribution network problems and enabling distributed energy to play a full role in replacing conventional plants in the system. For the distribution grid, flexibility refers to the increased use of electricity storage, mostly batteries, and demand side management (DSM). Electricity storage: On the distribution grid level, batteries are the most relevant technology. Batteries can perform load shifting, as well as a broad range of grid services, including balancing power, spinning reserves, and blackstart capacity. Behind the meter, batteries can contribute to the increase of self-consumption and the improvement of power quality for the customer. DSM: Typical technologies providing DSM on the distribution grid level are household appliances such as air conditioning or heat pumps or business appliances such as cold stores or chemical processes. Metered customers can use DSM in market appliances to optimize their electricity procurement strategy and reduce power bills. Moreover, distribution grid operators can engage in load control contracts with providers of decentralized DSM to manage grid congestion and reduce costs for all customers. The activation of flexibility entails changes to electricity sector regulation. In the liberalized EU electricity system, network operations are unbundled from generation and trade, and they are subject to regulatory oversight, in particular for grid investments. The EU and member states will require further regulatory changes to realize the potential of storage and DSM: First, grid regulation must enable smart grid investment such as grid company communication and control technologies, which are a prerequisite for the activation of flexibility. This should include modern smart meter technologies as well as gateways that enable all consumers and prosumers to participate in real-time load control programs enabling the use of flexibility by network operators, potentially managed by third-party aggregator companies. Second, flexibility asset owners need a suitable framework for the remuneration of flexibility. Ideally, payment for decentralized flexibility should fully reflect its value to the system in avoiding grid or generation investment. This should include the introduction of flexibility markets or innovative ancillary services that put load control and batteries at the disposal of the distribution network operator (DNO). Dynamic grid fees would incentivize the use of flexibility for congestion management. Third, regulators must further encourage aggregation of decentralized flexibility through market data transparency and market access. Independent aggregators can enable decentralized flexibility by prosumers and small business, for wholesale and balancing markets. Thus, decentralized flexibility can contribute to load shifting and system stability. Germany can offer useful lessons for China even though the regulatory regimes differ. China has seen a surge in distributed generation over the past decade, with distributed solar PV surpassing 100 GW in 2021, dominated by industrial installations. Industrial customers are ideal for decentralized flexibility given their greater sophistication compared to households and access to energy service companies. We suggest to accelerate both energy storage and DSM: grid problems such as the violation of thermal limits of network devices, voltage, and backfeed issues are likely to challenge Chinese distribution grids once localities reach high penetration rates of solar PV. Activating flexibility offers an opportunity to address these challenges. Distribution grid operators should use electricity storage as well as DSM to manage congestion problems. This will require incentivizing distributed flexibility with appropriate remuneration. Summary: harnessing flexibility can overcome VRE grid challenges 5 The role of renewable energy in the primary energy consumption of Germany is increasing, reaching 17% in 2020. Renewable energy has gained particular importance in electricity supply over the past two decades. In 2021, the renewable share of net power generation had reached about 45%, up from less than 4% in 2000. In contrast, renewables play a minor role in the consumption sectors today. In the mobility sector for example, oil and oil products provide 90% of the energy. 1 Fossil fuels also account for a large share of energy use in the industry and heating sector. With increasing electrification via heat pumps, electric vehicles, and production of hydrogen, along with improved efficiency, the consumption of fossil fuels will decrease in those sectors. In consequence, electricity consumption will rise over the next two decades, even as the variable renewable share also rises. Figure 1 Share of RE in total primary consumption and electricity generation Source: AGEB, March 2022 1 Distributed generation and decentralized flexibility in Germany Renewable energy generation based on wind and solar PV reached 45% of Germany’s electricity generation in 2021, and will likely surpass 80% by 2030, even as Germany electrifies transport, industry, and heating. Distributed generation will make a significant contribution. As the installed capacity of wind and solar PV rises, the system needs flexibility measures to balance variable renewable output. On the distribution grid level, small-scale electricity storage and DSM can contribute to the stability of the grid. Due to their increasing importance and value, recent German and EU legislation has focused on boosting both distributed generation and decentralized flexibility. 546 562 44% 40% 17% 480 500 520 540 560 580 600 620 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2016 2018 2020 Gross Electricity Consumption Share RE of Gross National Electricity Generation Share RE of Primary Energy Consumption TWh6 Current gross annual electricity consumption in Germany is about 500 TWh. According to the 2021 government coalition agreement, Germany’s electricity load may rise to 750 TWh in 2030 due to the contribution of electrification. 2 Meeting a large fraction of this increased electricity consumption with renewable sources entails a major expansion of renewable energy installed capacity. As of 2021, Germany had 138 GW of renewable capacity installed capacity: 64 GW of onshore and offshore wind power and 59 GW of solar PV. The most common technologies for PV are rooftop solar systems and open field solar. Both wind and solar are variable energy sources, and their fluctuating feed-in poses challenges to the grid, such as overload or voltage problems. In contrast, dispatchable renewable energy sources such as hydroelectricity or biomass offer lower variability and easier dispatch without supplementary energy storage. Yet hydro and biomass have limited growth potential in Germany. In 2021, biomass and hydroelectricity contributed around 11% of Germany’s generation, or 65 TWh. Biomass and hydro solutions will not be able to cover the exit and replacement of conventional sources. Most future renewable growth will come from variable wind and solar, necessitating greater focus on flexibility measures. 34 1.1 Development of distributed generation 2000-2022 Much of the renewable expansion of the past was due to large-scale installations connected to the transmission grid, which Germany defines as long-distance transmission at voltages above 220 kV. In a future low- carbon electricity supply system, more generation will be decentralized and used where it is produced. Private households and small businesses already operate renewable energy generation units, connected to the distribution network, the low- and medium voltage grid. Prosumers are a class of distributed energy resource owners that both consume energy from distributed resources and feed a portion of output into the grid. The energy community is a similar concept, where neighbors nearby directly consume the generated electricity. There is no universal definition of small-scale PV. In this report, installations with a capacity of up to 1 MW are considered small-scale. Distributed generation already makes up a major part of total capacity of renewable energy in Germany, most of which was solar PV. In 2021, Germany had roughly 59 GW of solar PV, located at roughly 2 million systems, 60% of which were smaller than 10 kW. 5 In 2019, Germany had 7.1 GW of PV below 10 kW, or almost 15% of the total installed PV capacity. The capacity of small-scale PV between 10 and 20 KW was about 4.7 GW in total, or a further 10% of the total. Open field PV contributes only small amounts to the installed capacity of small-scale PV. 6 Figure 2 Installed capacity of PV in Germany by size Source: Bundesnetzagentur, 20207 To use full the full potential of PV generation, innovative and integrative technologies such as floating PV or building-integrated PV will play a bigger role in the future. Besides solar PV, a variety of other small-scale renewable energies are connected to the grid on low voltage levels. These include small-scale hydro, biomass, and biogas. 7 The role of biomass and biogas differs from distributed PV generation. Biomass is mainly used for flexibility. Biogas can not only generate electricity, but can also be fed into the regular gas network for heating. There are also decentralized generation systems based on fossil fuels, such as combined-heat-and-power (CHP) systems, often using methane gas. 1.2 Deployment of storage and DSM in Germany today The transition from controllable electricity generation on high voltage level towards an energy system with variable generation both on the transmission and distribution grid level poses new challenges to the grid, especially on the distribution level. Short-term variation in renewable feed- in can cause network issues, such as overload, voltage problems, phase imbalance, and backfeed issues. These may compromise the thermal limits of grids. Additionally, new load patterns arising from increasing electrification, may cause new demand peaks, which can lead to grid congestion. It is critical that prosumers assume a constructive role, contributing to the efficiency and stability of electricity supply, and reducing congestion costs or avoiding unnecessary investments in grid or generation assets. The key to achieving this role is the activation and provision of flexibility, investigated in this report. The two technical flexibility options are demand side management (DSM) and electricity storage. DSM can help balance production and demand fluctuations by switching demand loads on a