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Energy storage technology has broad application prospects
来源:凯信达 | Author:aokebattery | Published time: 2017-05-24 | 3483 Views | Share:
Energy storage is an indispensable supporting technology for smart grid, renewable energy access, distributed generation, microgrid and electric vehicle development. It can effectively realize demand side management, eliminate diurnal peaks and valleys, smooth load, and improve power equipment. Operating efficiency, reducing power supply costs, can also be used as a means to promote renewable energy applications, improve grid operation stability, adjust frequency, and compensate for load fluctuations. The construction of smart grids promotes the upgrading of energy storage technologies and promotes the rapid growth of energy storage demand, especially for large-scale energy storage, which leads to corresponding investment opportunities.

With the large number of applications of energy storage technology, changes will be brought about in the design, planning, scheduling and control of traditional power systems. Energy storage technology is related to the national economy and people's livelihood, and has increasingly important economic and social values. At present, the development of energy storage in China has just started. The state should study the relevant industry standards for energy storage technology as soon as possible, strengthen the investment in basic research of energy storage technology, effectively encourage technological innovation, and master independent intellectual property rights; from the initial stage of the development of large-scale energy storage technology, pay attention to environmental factors and prevent environmental pollution; Give play to the role of energy storage in energy conservation and emission reduction, and extend the incentive policy for new energy to the energy storage sector.

In recent years, the peak-to-valley difference of China's power grid has increased year by year, and the peak load of most power grids has increased by about 10% or even higher. The growth of the trough load is maintained at 5% or even lower. The increase of peak-to-valley difference is greater than the increase of load. The introduction of energy storage system in the power grid has become an urgent need to realize peak shaving.

Energy storage technology has broad application prospects, but achieving large-scale energy storage is still a worldwide problem. At present, there are about 40 energy storage demonstration projects in China, and there are not many projects with a scale of 1000 kilowatts. These energy storage projects play a demonstration and exploratory role and do not have industrial significance.

Development opportunities in the energy storage industry
Due to the large distance between China's energy center and power load center, the power system has always followed the development direction of large power grids and large motors, operating in accordance with centralized transmission and distribution mode, with the rapid development of renewable energy power generation and social power quality requirements. The continuous improvement of energy storage technology has broad application prospects. The main application directions of energy storage technology are: local area network composed of wind power generation and photovoltaic power generation complementary system, used for power supply in remote areas, power supply in factories and office buildings; uninterruptible power supply and emergency power system in communication system; wind power generation and photovoltaic power generation system Grid-connected power quality adjustment; as a means of large-scale power storage and load peaking; electric vehicle energy storage device; as a large backup power supply for important national departments. With the continuous advancement of energy storage technology, energy storage technologies with good safety, high efficiency, clean and environmental protection, long life, low cost and high energy density will continue to emerge, which will definitely drive the rapid development of the entire power industry industry chain and create huge Economic and social benefits.

The key investment areas of the smart grid recently determined by the State Grid Corporation include a large number of energy storage applications, such as energy storage technology projects in wind power generation and photovoltaic power generation, energy storage technology in power distribution, and electric vehicle charging and discharging technology. Whether it is wind power or solar power generation, it has its own random and intermittent characteristics. The rapid growth of its installed capacity will adversely affect the peaking of the power grid and system security. Therefore, reliable energy storage technology must be supported as a support. buffer. Advanced energy storage technology can largely solve the volatility problem of new energy power generation, and integrate large-scale safety of wind power and solar power into the power grid.

The grid-connected inverter is used as an interface device between the photovoltaic cell and the power grid. The DC power of the photovoltaic cell is converted into AC power and transmitted to the power grid, which plays a vital role in the photovoltaic grid-connected power generation system. Grid-connected inverter performance is critical to system efficiency, reliability, system life and cost reduction.
 
The development of energy storage technology is conducive to the promotion of wind power on-site consumption. In the context of the current industrial gradient transfer, it is possible to consider the layout of heating and energy-intensive industries near large-scale wind power bases, and accelerate the establishment of wind farms and these large power users. Coordinated operation mechanism of the power system. The key investment areas of the smart grid recently determined by the State Grid include a large number of energy storage applications: power generation areas such as wind and solar integration and energy storage projects, and power distribution areas such as energy storage technology, electric vehicle charging and distribution automation.

According to the national plan for the new energy industry, it is estimated that by 2020, the state will invest a total of 3 trillion yuan to develop renewable energy. By then, China's renewable energy will reach 15% in all energy consumption. According to the general market expectation, China's power installed capacity will reach 1500GW in 2020, and wind power accounts for 10%, or 150GW. The power of the supporting energy storage device is calculated according to 15% of the installed capacity of the wind power, which is about 22.5 GW. If the energy storage unit unit kilowatt cost is calculated at 4,000 yuan/kW, the energy storage market will be about 90 billion yuan in the 10 years to 2020.

According to data provided by the China Renewable Energy Association, as of the end of 2011, China had 47,000 MW of wind power installed. Currently, only about 20% of wind turbines have solved the problem of grid connection, but if they are fully equipped with 20% of the energy. Need to install 9400MW of energy storage, even if calculated according to the engineering cost of 20 million yuan per megawatt, a one-time investment of 188 billion yuan.

This is a huge investment, but this investment must consider its economy anyway. The current life of lithium-ion batteries is generally 5 years, and the annual investment is close to 40 billion yuan. If the ratio of this equipment is increased by 10 percentage points, the annual investment will be 60 billion yuan, which is not the annual increase of wind power scale units and other renewable energy sources.

The role of energy storage technology in smart grid
Quality, self-healing, safety, cleanliness, economy and interaction are the set goals of China's smart grid. The energy storage technology, especially the large-scale energy storage technology, has many characteristics that can be widely used in power generation, transmission, distribution and power consumption. Application, energy storage technology is one of the key technologies to build a smart grid and achieve its goals.

The role of energy storage technology in the stability of power systems. The application of energy storage technology can change the thinking mode of traditional power system stability control, understand the stability problem of power system from a new perspective, and seek a method that may completely solve the stability of power system. In a traditional power system, the dynamic unbalanced power caused by any small disturbances will cause oscillations between the units, and as long as the energy storage device is large enough and the response speed is fast enough, the system power can be fully balanced under any circumstances. It is an idea of actively stabilizing the power system. Since the stabilization control device associated with the energy storage technology does not have to interact with the excitation system of the generator, it is convenient to use the most effective portion in the system for suppressing the oscillation. At the same time, since the control quantity generated by the stable control device can directly act on the source that causes the system to oscillate, and accurately compensate the unbalanced power, the influence of the system operation state change on the control device control effect can be less or even not considered. Therefore, the parameter setting of the device is very easy, and the robustness to the change of the operating state of the system is also very good.
 
The role of energy storage technology in new energy generation. The lack of fossil energy supply has become a bottleneck for global economic development. At the same time, the problem of environmental pollution caused by the use of fossil energy has been highly valued by the world. Actively developing new energy and energy storage technologies and reducing human dependence on fossil energy has become a hot topic in the industry and the scientific and technological community. Among renewable energy sources, wind energy and solar energy are caused by abundant, inexhaustible, inexhaustible sources, and there is no concern about environmental pollution or pollution during use. However, wind energy and solar energy are intermittent and unstable. Defects such as sex and uncontrollability, in order to ensure the balance and continuity of power supply, energy storage devices become key components of wind power generation and photovoltaic power generation systems. Therefore, while using solar energy and wind energy, we must pay attention to the development of energy storage technology. In recent years, especially in! Renewable Energy Law of the People's Republic of China? After the introduction, China's wind power and photovoltaic power generation industry has developed rapidly, but there are still technical bottlenecks in the large-scale development of new energy sources, mainly the grid-connected technology of wind power generation and photovoltaic power generation, and the intermittent problems of power generation require mature energy storage technology to solve. Therefore, while the installed capacity of new energy sources is increased, it is necessary to simultaneously increase the energy storage capacity and effectively improve the power output quality.

The role of energy storage technology in distributed generation. In today's society, the quality and safety and reliability requirements of power supply are getting higher and higher. The traditional large-grid power supply mode cannot meet this requirement due to its own defects. At present, the combination of large power grid and distributed power generation is recognized by many energy and power experts in the world as the main method to save investment, reduce energy consumption, improve power grid safety and flexibility, and is the development direction of the power industry in the 21st century.

Distributed generation refers to a smaller set of generators that are placed directly in the distribution network or distributed near the load to meet the needs of a particular user or to support the economic operation of an existing distribution network. Distributed generation includes microturbine power generation, fuel cell energy storage, and renewable energy sources such as solar and wind power. Based on grid stability and economic considerations, distributed generation systems store a certain amount of electrical energy to cope with emergencies. Modern energy storage technology has been developed to a certain extent, and has played an important role in distributed power generation, which can improve power quality and maintain grid stability; provide power to users during distributed power generation.

The role of energy storage technology in electric vehicles. Electric vehicles are powered by electric energy, which can achieve zero emissions and low noise during operation. It is an important means to solve energy and environmental problems. The construction of a strong smart grid will greatly promote the development of electric vehicles, including the establishment of a complete electric vehicle charging and discharging infrastructure network, forming a scientific and rational layout of electric vehicle charging and discharging stations, and the charging and discharging station infrastructure to meet the development of electric vehicle industry and consumers. The need for efficient interaction between electric vehicles and the grid is fully applied. Compared with traditional fuel vehicles, electric vehicles also have a series of problems such as long charging time, short driving range and high cost of use. Among them, energy storage technology is the main bottleneck hindering the development of electric vehicle industry. The development of energy storage technology will definitely drive the development of electric vehicle industry.

Energy storage technology principle and operation mode
The basic principle of energy storage is that the energy storage technology passes the power conversion device to perform active/reactive power throughput in time, which can maintain the balance of instantaneous power within the system, avoid large power imbalance between load and power generation, and maintain system voltage and frequency. And the stability of the power angle, improve the reliability of power supply; can improve the power quality, meet the user's multiple power needs, reduce the loss caused by the reliability of the power grid or power quality; can use the peak and valley electricity price to effectively balance the load peaks and valleys, reduce the rotation Standby, realize the economical efficiency of energy use, and improve comprehensive benefits; in addition, energy storage can also help the system to restart and recover quickly after a disaster, and improve the self-healing ability of the system.

As far as the current level of energy storage technology is concerned, it is difficult for a single energy storage technology to meet performance indexes such as energy density, power density, energy storage efficiency, service life, environmental characteristics, and cost. If two or more performances are complementary, The combination of energy storage technology and composite energy storage can achieve good technical and economic performance. Based on this belief, some experts have proposed that the combination of flywheel energy storage and pumped storage power station may solve the future energy storage problem.

Although a variety of energy storage modes have emerged, flywheel energy storage and pumped storage seem to have been widely accepted by the industry if economic efficiency is not considered. Among various energy storage technologies, flywheel energy storage is a kind of energy storage technology with excellent combination of energy density, power density, and service life. It has advantages in many applications.

Flywheel energy storage refers to the energy storage method that uses the motor to drive the flywheel to rotate at high speed, convert the electric energy into kinetic energy, and use the flywheel to drive the generator to generate electricity when needed. The research on flywheel energy storage focuses on the development of composite materials technology and superconducting magnetic levitation technology to improve energy density. Among them, superconducting magnetic levitation is the main method to reduce loss, and composite materials can increase energy storage density and reduce system volume and weight. As of 2012, there is no flywheel energy storage motor of 100 kW or more in China.
 
Flywheel energy storage technology is an emerging energy storage technology. Like superconducting energy storage technology and fuel cell technology, it is a storage technology with great development prospects in recent years. Although chemical battery energy storage technology has been developed very mature, chemical battery energy storage technology has problems such as limitation of charge and discharge times, serious pollution to the environment, and high requirements on working temperature. This makes the emerging energy storage technology more and more people's attention. In particular, flywheel energy storage technology has begun to be used more and more widely in many industries at home and abroad.

The pumped storage power station uses the electric energy when the power load is low to pump water to the upper reservoir, and then releases the water to the hydropower station that generates electricity from the lower reservoir during the peak period of the electric load. Also known as energy storage hydropower stations. It can convert excess electric energy when the grid load is low into high-value electric energy during the peak period of the power grid. It is also suitable for frequency modulation, phase modulation, stabilization of the cycle and voltage of the power system, and should be used for accident backup, and can also improve the system in the thermal power station. And the efficiency of nuclear power plants.

Pumped storage power station is the most mature and widely used large-scale energy storage technology. It has large capacity and long service life (economic life expectancy is about 50 years). It can provide peaking, valley filling, frequency modulation, accident backup and other services for the power grid. Its good regulation performance and fast load change response capability are of great significance for effectively reducing the instability caused by new energy power generation input into the power grid.

However, the disadvantages of the pumped storage power station are also undoubtedly exposed. The site selection requires topographic conditions with small horizontal distance and high height difference between the upper and lower reservoirs. High rock strength, good geological conditions for seepage prevention, and sufficient water source to ensure power generation. Demand. In addition, there are problems in the reservoir area flooding of the upper and lower reservoirs, changes in water quality, and soil salinization in the reservoir area.

In addition, there are battery energy storage. The energy storage battery mainly refers to the storage battery used for solar power generation equipment and wind power generation equipment and renewable energy storage energy. Energy storage not only ensures that the new energy power connected to the most upstream power generation is continuous and stable; at the end of the energy use, the huge demand difference between day and night also requires energy storage to cut peaks and fill the valley; and the newly added electric power In the car, some experts said that if all the existing vehicles in China are converted into electric vehicles, it would be equivalent to rebuilding a national grid system, which is a catastrophic investment. In the most ideal state, the electric vehicle should not only be used as a suction side of energy, but also can be transmitted back to the grid to regulate the peaks and valleys, which can greatly reduce the excessive construction of the grid in order to balance the load. In the ultimate energy landscape, energy storage will become the cornerstone of a distributed, intelligent and controllable energy landscape. Now, energy storage is only less than 2% of the total installed capacity. This obviously means that in the above three aspects, energy storage contains this huge business opportunity.

The root cause of the economic problems of energy storage projects lies in the lack of research and development technology for key materials of energy storage batteries, resulting in high cost of energy storage batteries. With domestic mainstream energy storage batteries such as lithium batteries and all-vanadium flow batteries, the core materials rely on a large number of imports, and the price is high. Lithium battery separator import dependence is more than 80%, and the import dependence of lithium hexafluorophosphate, the core material of electrolyte, is as high as 80% to 90%. The core component of all vanadium redox flow battery is imported by fluorine ion exchange membrane. Once accounted for 50% of the cost of vanadium batteries.

Obviously, achieving technological breakthroughs in the processing and utilization of energy storage materials and reducing the cost of energy storage batteries are the key to the industrialization of energy storage. In this regard, the author has two suggestions: First, relevant research institutions and enterprises should pay attention to the research and development of key technologies for energy storage materials, strengthen basic research on energy storage technology, and master core technologies; second, the state should increase the intellectual property rights of energy storage technologies. The protection of the strength, the introduction of corresponding preferential policies, and more importantly, the formulation of a clear medium and long-term industrial development plan.

The challenges facing the energy storage industry
As a key link in the development of smart grids, electric vehicles and renewable energy, the development of the energy storage industry has attracted the attention of investors. At present, China's energy storage technology "many sects" is in the initial stage of industrialization.

However, China's energy storage is in the primary stage of development and cannot be applied on a large scale. First, various energy storage technologies are numerous, most people do not know how to use and choose; second, the related technologies and performance are not mature; third, the price is high. Compared with the more advanced countries in the world, China's energy storage market has not established a relevant industrial chain, and is still in a state of “a swarm of bees”. At the national policy level, there is insufficient investment in energy storage.

From the perspective of short-term development, there is no perfect answer to the energy storage materials themselves. From the perspective of power grid dispatching and energy storage, there are problems in capacity and energy storage areas. Therefore, there is a need for breakthroughs in energy storage development routes, materials, and technologies, and breakthroughs in efficiency, cost, and safety issues are needed.

One is the economic problem. Energy storage itself is an industry, but the current high cost is also a major factor affecting the large-scale development of energy storage. At present, most of the energy storage projects in the demonstration project are replaced by social ones, and the problem of promotion is inevitable. The key materials, manufacturing processes and energy conversion efficiency are also common challenges faced by various technologies.
 
The second is the application of the problem. Due to the short application time of energy storage in power systems, especially the large-scale application of power grid systems, its pumped storage power stations are only experimental demonstration projects. The power industry has high requirements for product reliability. Traditionally, it requires at least 5 years of field reliability testing and trial use to pass the minimum standards of power users, resulting in long productization period before production scale. The design of the energy storage products is mature and reliable. Sex is directly related to a certain scale. Based on the above-mentioned reality, it is not realistic to promote large-scale storage of energy in the short term, but the smart grid that is currently in full swing is in urgent need of solving the key problem of energy storage, so the application is the first test.

The third is the policy problem. The energy storage benefits from the power system links such as power generation, transmission, distribution and electricity sales. However, there is no leading link at present, which will inevitably lead to unfair distribution of benefits. Since the economic value of energy storage is difficult to calculate, if it is led by the government, its implementation enterprises will have various problems such as low enthusiasm. Therefore, how to choose the applicable energy storage technology, how to scale application in the power system, and how to establish the industry mechanism is also the core issue that the relevant competent authorities and enterprises should jointly consider when formulating the energy storage industry policy.

Zhang Huamin, a researcher at the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences, also pointed out that with the popularization and application of renewable energy, the development of the electric vehicle industry and the construction of smart grids, various energy storage technologies are facing enormous challenges and unprecedented development opportunities.