Building a new power system is a complex and systematic project. It needs to take into account the coordination of power security and stability, the increasing proportion of new energy, and the reasonable cost of the system at the same time. It needs to handle the relationship between clean transformation of thermal power units, orderly penetration of renewable energy such as wind and rain, the construction of power grid coordination and mutual aid capabilities, and the rational allocation of flexible resources. The scientific planning of the construction path of the new power system is the basis for achieving the goal of carbon peaking and carbon neutralization, and is also the boundary and guide for the development of various entities in the new power system.
By the end of 2021, the installed capacity of coal power in China will exceed 1.1 billion kilowatts, accounting for 46.67% of the total installed capacity of 2.378 billion kilowatts, and the generated capacity of coal power will be 5042.6 billion kilowatt hours, accounting for 60.06% of the total generated capacity of 8395.9 billion kilowatt hours. The pressure on emission reduction is huge, so it is necessary to reduce the capacity in order to ensure the safety of supply. The installed capacity of wind and solar power is 635 million kilowatts, accounting for only 11.14% of the total technological developable capacity of 5.7 billion kilowatts, and the power generation capacity is 982.8 billion kilowatt hours, accounting for only 11.7% of the total power generation capacity. The installed capacity and power generation capacity of wind and solar power have huge room for improvement, and need to accelerate penetration in the power grid. There is a serious lack of system flexibility resources. The installed capacity of flexible regulated power sources such as pumped storage and gas-fired power generation accounts for only 6.1% of the total installed capacity. In particular, the total installed capacity of pumped storage is 36.39 million kilowatts, accounting for only 1.53% of the total installed capacity. Efforts should be made to accelerate development and construction. In addition, digital simulation technology should be used to predict the output of new energy on the supply side, precisely control and tap the potential of demand side management, and expand the proportion of flexible transformation of large fire generator sets Improve the power grid’s ability to optimize the allocation of resources in a large range to deal with the problem of insufficient system regulation capacity. At the same time, some main bodies in the system can provide services with similar functions, such as configuring energy storage and adding tie lines in the power grid can improve local power flow, and configuring pumped storage power plants can replace some condensers. In this case, the coordinated development of each subject, the optimal allocation of resources, and the economic cost saving all depend on scientific and reasonable planning, and need to be coordinated from a larger scope and a longer time scale.
In the traditional power system era of “source follows load”, the planning of power supply and power grid in China has some problems. In the era of new power system with the common development of “source, grid, load and storage”, the importance of collaborative planning is further amplified. Pumped storage, as an important clean and flexible power supply in the power system, plays an important role in ensuring the security of the large power grid, serving clean energy consumption and optimizing system operation. More importantly, we should strengthen planning guidance and fully consider the connection between our own development and the construction needs of the new power system. Since entering the “Fourteenth Five Year Plan”, the state has successively issued such documents as Medium and Long term Development Plan for Pumped Storage (2021-2035), Medium and Long term Development Plan for Hydrogen Energy Industry (2021-2035), and Renewable Energy Development Plan for the “Fourteenth Five Year Plan” (FGNY [2021] No. 1445), but they are limited to this industry, The “Fourteenth Five Year Plan” for power development, which is of great significance for overall planning and guidance of the power industry, has not been officially released. It is suggested that the national competent department should issue a medium and long-term plan for the construction of a new power system to guide the formulation and rolling adjustment of other plans in the power industry, so as to achieve the goal of optimizing the allocation of resources.
Synergistic Development of Pumped Storage and New Energy Storage
By the end of 2021, China has put into operation 5.7297 million kilowatts of new energy storage, including 89.7% of lithium ion batteries, 5.9% of lead batteries, 3.2% of compressed air and 1.2% of other forms. The installed capacity of pumped storage is 36.39 million kilowatts, more than six times that of the new type of energy storage. Both new energy storage and pumped storage are important components of the new power system. The joint arrangement in the power system can give play to their respective advantages and further enhance the system regulation capacity. However, there are obvious differences between the two in function and application scenarios.
New energy storage refers to new energy storage technologies other than pumped storage, including electrochemical energy storage, flywheel, compressed air, hydrogen (ammonia) energy storage, etc. Most of the new energy storage power stations have the advantages of short construction period and simple and flexible site selection, but the current economy is not ideal. Among them, the electrochemical energy storage scale is generally 10~100 MW, with a response speed of tens to hundreds of milliseconds, high energy density, and good adjustment accuracy. It is mainly suitable for distributed peak shaving application scenarios, usually connected to the low-voltage distribution network or new energy station side, and technically suitable for frequent and rapid adjustment environments, such as primary frequency modulation and secondary frequency modulation. Compressed air energy storage takes air as the medium, which has the characteristics of large capacity, many times of charging and discharging, and long service life. However, the current efficiency is relatively low. Compressed air energy storage is the most similar energy storage technology to pumped storage. For desert, gobi, desert and other areas where it is not suitable to arrange pumped storage, the arrangement of compressed air energy storage can effectively cooperate with the consumption of new energy in large-scale scenery bases, with great development potential; Hydrogen energy is an important carrier for large-scale and efficient utilization of renewable energy. Its large-scale and long-period energy storage features can promote the optimal allocation of heterogeneous energy across regions and seasons. It is an important part of the future national energy system and has broad application prospects.
In contrast, pumped storage power stations have high technical maturity, large capacity, long service life, high reliability and good economy. They are suitable for scenarios with large peak shaving capacity demand or peak shaving power demand, and are connected to the main network at a higher voltage level. Considering the requirements of carbon peak and carbon neutralization and the fact that the previous development progress is relatively backward, in order to accelerate the development progress of pumped storage and achieve the requirements of rapid increase of installed capacity, the pace of standardized construction of pumped storage power stations in China has been further accelerated. Standardized construction is an important measure to deal with various difficulties and challenges after the pumped storage power station enters the peak period of development, construction and production. It helps to accelerate the progress of equipment manufacturing and improve the quality, promote the safety and order of infrastructure construction, improve the efficiency of production, operation and management, and is an important guarantee for the development of pumped storage towards lean direction.
At the same time, the diversified development of pumped storage is also gradually valued. First of all, the medium and long-term plan for pumped storage proposes to strengthen the development of small and medium-sized pumped storage. Small and medium-sized pumped storage has the advantages of rich site resources, flexible layout, close proximity to the load center, and close integration with distributed new energy, which is an important supplement to the development of pumped storage. The second is to explore the development and application of seawater pumped storage. The grid connected consumption of large-scale offshore wind power needs to be configured with corresponding flexible adjustment resources. According to the Notice on Publishing the Results of the Resource Census of Seawater Pumped Storage Power Plants (GNXN [2017] No. 68) issued in 2017, China’s seawater pumped storage resources are mainly concentrated in the offshore and island areas of the five eastern coastal provinces and the three southern coastal provinces, It has a good development prospect. Finally, the installed capacity and utilization hours are considered as a whole in combination with the power grid regulation demand. With the increasing proportion of new energy and the trend of becoming the main source of energy supply in the future, large capacity and long-term energy storage will become just needed. At the qualified station site, it shall be properly considered to increase the storage capacity and extend the utilization hours, and it shall not be subject to the restriction of factors such as unit capacity cost index and be separated from the demand of the system.
Therefore, in the current situation that China’s power system is seriously short of flexible resources, pumped storage and new energy storage have broad prospects for development. According to the differences in their technical characteristics, under the premise of full consideration of different access scenarios, combined with the actual needs of the regional power system, and constrained by security, stability, clean energy consumption and other boundary conditions, collaborative layout should be carried out in capacity and layout to achieve the optimal effect.
Influence of electricity price mechanism on pumped storage development
Pumped storage serves the whole power system, including power supply, power grid and users, and all parties benefit from it in a non competitive and non exclusive way. From an economic perspective, the products provided by pumped storage are public products of the power system and provide public services for the efficient operation of the power system.
Before the reform of the electric power system, the state has issued policies to make it clear that pumped storage mainly serves the power grid, and is mainly operated by the power grid operating enterprises in a unified or leased manner. At that time, the government uniformly formulated the on grid electricity price and sales electricity price. The main income of the power grid came from the purchase and sales price difference. The existing policy essentially defined that the cost of pumped storage should be recovered from the purchase and sales price difference of the power grid, and unified the dredging channel.
After the reform of the transmission and distribution electricity price, the Notice of the National Development and Reform Commission on Issues Related to Improving the Price Formation Mechanism of Pumped Storage Power Plants (FGJG [2014] No. 1763) made it clear that the two-part electricity price was applied to pumped storage power, which was verified according to the principle of reasonable cost plus allowable income. The capacity electricity charge and pumping loss of pumped storage power plants are included in the unified accounting of the operation cost of local provincial power grid (or regional power grid) as a sales electricity price adjustment factor, but the channel of cost transmission is not straightened out. Subsequently, the National Development and Reform Commission issued documents successively in 2016 and 2019, stipulating that the relevant costs of pumped storage power plants are not included in the permitted income of power grid enterprises, and the costs of pumped storage power plants are not included in the transmission and distribution pricing costs, which further cut off the way to channel the cost of pumped storage. In addition, the development scale of pumped storage during the “13th Five Year Plan” period was far lower than expected due to insufficient understanding of the functional positioning of pumped storage at that time and single investment subject.
Faced with this dilemma, the Opinions of the National Development and Reform Commission on Further Improving the Pricing Mechanism of Pumped Storage Energy (FGJG [2021] No. 633) was launched in May 2021. This policy has scientifically defined the electricity price policy of pumped storage energy. On the one hand, in combination with the objective fact that the public attribute of pumped storage energy is strong and the cost cannot be recovered through electricity, the operating period pricing method was used to verify the capacity price and recover through the transmission and distribution price; On the other hand, combined with the pace of power market reform, the spot market of electricity price is explored. The introduction of the policy has strongly stimulated the investment willingness of social subjects, laying a solid foundation for the rapid development of pumped storage. According to statistics, the capacity of pumped storage projects put into operation, under construction and under promotion has reached 130 million kilowatts. If all the projects under construction and under promotion are put into operation before 2030, this is higher than the expectation of “120 million kilowatts will be put into production by 2030″ in the Medium and Long term Development Plan for Pumped Storage (2021-2035). Compared with the traditional fossil energy power generation mode, the marginal cost of power generation of new energy such as wind and power is almost zero, but the corresponding system consumption cost is huge and lacks the mechanism of allocation and transmission. In this case, in the process of energy transformation, for resources with strong public attributes such as pumped storage, policy support and guidance are needed in the early stage of development to ensure the rapid development of the industry. Under the objective environment that China’s pumped storage development scale is relatively backward and the carbon peak carbon neutralization window period is relatively short, the introduction of the new electricity price policy has played an important role in promoting the development of the pumped storage industry.
The transformation of the energy supply side from conventional fossil energy to intermittent renewable energy determines that the main cost of electricity prices changes from the cost of fossil fuels to the cost of renewable energy and flexible regulation of resource construction. Due to the difficulty and long-term nature of the transformation, the establishment process of China’s coal based power production system and renewable energy based new power system will coexist for a long time, which requires us to further strengthen the climate goal of carbon peaking and carbon neutralization. At the beginning of the energy transformation, infrastructure construction that has made great contributions to promoting clean energy transformation should be policy driven and market driven, Reduce the interference and wrong guidance of capital profit seeking on the overall strategy, and ensure the correct direction of clean and low-carbon energy transformation.
With the full development of renewable energy and gradually becoming the main power supplier, the construction of China’s power market is also constantly improving and maturing. Flexible regulation resources will become the main demand in the new power system, and the supply of pumped storage and new energy storage will be more sufficient. At that time, the construction of renewable energy and flexible regulation resources will be mainly driven by market forces, The price mechanism of pumped storage and other main bodies will truly reflect the relationship between market supply and demand, reflecting full competitiveness.
Correctly understand the carbon emission reduction effect of pumped storage
Pumped storage power station has significant energy saving and emission reduction benefits. In the traditional power system, the role of pumped storage in energy conservation and emission reduction is mainly reflected in two aspects. The first is to replace thermal power in the system for peak load regulation, generating power at peak load, reducing the number of startup and shutdown of thermal power units for peak load regulation, and pumping water at low load, so as to reduce the pressure load range of thermal power units, thus playing the role of energy conservation and emission reduction. The second is to play the role of safety and stability support such as frequency modulation, phase modulation, rotary reserve and emergency reserve, and to increase the load rate of all thermal power units in the system when replacing thermal power units for emergency reserve, so as to reduce the coal consumption of thermal power units and achieve the role of energy conservation and emission reduction.
With the construction of a new power system, the energy saving and emission reduction effect of pumped storage shows new characteristics on the existing basis. On the one hand, it will play a greater role in peak shaving to help large-scale wind and other new energy grid connected consumption, which will bring huge emission reduction benefits to the system as a whole; On the other hand, it will play a safe and stable supporting role such as frequency modulation, phase modulation and rotary standby to help the system overcome the problems such as unstable output of new energy and lack of inertia caused by high proportion of power electronic equipment, further improve the penetration proportion of new energy in the power system, so as to reduce emissions caused by fossil energy consumption. The influencing factors of power system regulation demand include load characteristics, the proportion of new energy grid connection and regional external power transmission. With the construction of a new power system, the impact of new energy grid connection on power system regulation demand will gradually exceed the load characteristics, and the carbon emission reduction role of pumped storage in this process will be more significant.
China has a short time and heavy task to achieve carbon peak and carbon neutralization. The National Development and Reform Commission issued the Plan on Improving the Dual Control of Energy Consumption Intensity and Total Amount (FGHZ [2021] No. 1310) to assign emission control indicators to all parts of the country to reasonably control energy consumption. Therefore, the subject that can play a role in emission reduction should be correctly evaluated and given due attention. However, at present, the carbon emission reduction benefits of pumped storage have not been correctly recognized. First, the relevant units lack the institutional basis such as carbon methodology in the energy management of pumped storage, and second, the functional principles of pumped storage in other areas of society outside the power industry are still not well understood, leading to the current carbon emission accounting of some carbon emission trading pilots for pumped storage power plants according to the guidelines for enterprise (unit) carbon dioxide emission accounting and reporting, and taking all pumped electricity as the emission calculation base, The pumped storage power station has become a “key discharge unit”, which brings a lot of inconvenience to the normal operation of the pumped storage power station, and also causes great misunderstanding to the public.
In the long run, in order to correctly understand the carbon emission reduction effect of pumped storage and straighten out its energy consumption management mechanism, it is necessary to establish an applicable methodology in combination with the overall carbon emission reduction benefits of pumped storage on the power system, quantify the carbon emission reduction benefits of pumped storage, and form an offset against the insufficient quota internally, which can be used for external carbon market transactions. However, due to the unclear start of CCER and the 5% limitation on emissions offset, there are also uncertainties in methodology development. Based on the current actual situation, it is recommended that the comprehensive conversion efficiency be explicitly taken as the main control indicator of the total energy consumption and energy conservation objectives of pumped storage power plants at the national level, so as to reduce the constraints on the healthy development of pumped storage in the future.
Post time: Nov-29-2022
