Hydrogen Energy Storage: The Future of Renewable Energy Solutions
2024-11-26
As a low-carbon new energy and new raw material, hydrogen energy is a key carrier for realizing energy transformation and an important supplement to electric energy in the future secondary energy system. As a new energy storage method, hydrogen energy storage system has the advantages of long discharge time, large capacity, high economy, flexible storage and transportation, and environmental friendliness. It can effectively supplement the deficiencies of other energy storage and will play an important role in the construction of new power systems.
At present, the hydrogen energy storage system is in the demonstration application stage. In the future, with the development of technology and large-scale application, the cost of hydrogen energy storage system will drop significantly, which is of great significance to serving carbon peak and carbon neutrality.
1. Hydrogen energy storage system is developed by utilizing the mutual conversion of electricity and hydrogen energy.
Hydrogen energy storage system can store both electricity and hydrogen and its derivatives (such as ammonia and methanol).
The narrow hydrogen energy storage system is based on the conversion process of "electricity, hydrogen and electricity" (Power-to-Power, P2P), mainly including electrolyzers, hydrogen storage tanks and fuel cells.
The surplus new energy electricity in the off-peak period is used to electrolyze water to produce hydrogen, which is stored or used by downstream industries; during the peak period of electricity consumption, the stored hydrogen energy can be used to generate electricity using fuel cells and incorporated into the public power grid.
The broad definition of hydrogen energy storage system emphasizes the one-way conversion of "electricity and hydrogen", storing hydrogen in gaseous, liquid or solid forms (Power-to-Gas, P2G), or converting it into chemical derivatives such as methanol and ammonia (Power-to-X, P2X) for safer storage.
2. The application value of hydrogen energy storage system is extremely high and it is an important supplement to the new power system
The new power system is an important component of the new energy system. It uses new energy as the main power source. The key lies in the coordinated development of energy storage with different functional positioning, the introduction of large-scale, cross-regional emerging peak-shaving means, the realization of power and energy balance on different time scales, and the organic integration with other deeply decarbonized energy varieties to achieve the ultimate goal of carbon neutrality.
As energy storage becomes the fourth indispensable element of the new power system of source, grid, load and storage, the hydrogen energy storage system can achieve long-term, cross-seasonal storage from hours to seasons, with diversified transportation methods, not restricted by the power transmission and distribution network, and can play an auxiliary role in smoothing the fluctuation of wind and solar power output, tracking the planned output curve, providing peak-shaving auxiliary capacity, participating in power demand response, and alleviating transmission and distribution line congestion on the power supply side, grid side, and user side. It will become an important supplement to the new power system.
The hydrogen energy storage system reduces power abandonment and smoothes fluctuations on the power supply side. Since the output of new energy sources such as photovoltaics and wind power has natural volatility, the problem of abandoned light and wind has always existed in the power system. The use of hydrogen energy storage systems to convert electricity that cannot be connected to the grid into green hydrogen on site can not only solve the problem of new energy consumption, but also provide clean and cheap hydrogen energy for local industries, transportation, construction and other fields.
At the same time, the hydrogen energy storage system absorbs power when the wind farm and photovoltaic power station are at peak output, and outputs power when their output is at low. The combined power curve after adding the total wind and solar power to the power of hydrogen storage energy becomes smooth, thereby improving the friendliness of new energy and supporting large-scale new energy power transmission.
On the grid side, the hydrogen energy storage system provides peak-shaving capacity and alleviates congestion in transmission and transformation lines. The ability of the grid to receive and absorb new energy depends largely on its peak-shaving capacity. With the penetration of large-scale new energy and changes in the structure of industrial electricity consumption, the peak-to-valley difference of the grid will continue to expand, and hydrogen energy storage has the characteristics of high density, large capacity and long-term storage, which can provide considerable peak-shaving auxiliary capacity. In addition, in some areas, the growth of power transmission capacity cannot keep up with the pace of growth in power demand. During peak power demand, the transmission and distribution system will be congested and blocked, affecting the normal operation of the power system. Therefore, a large-capacity hydrogen energy storage system can act as a "virtual transmission line" and be installed downstream of the flow of the blocked section of the transmission and distribution system. Electric energy is stored in sections without transmission and distribution congestion. The hydrogen energy storage system releases electric energy during peak power demand, thereby reducing the capacity requirements of the transmission and distribution system and alleviating the congestion of the transmission and distribution system.
The hydrogen energy storage system can realize arbitrage of electricity price difference and serve as an emergency backup power source on the user side. At present, most industrial users have implemented the peak-valley electricity price system to encourage users to plan their electricity use in different time periods. With the hydrogen energy storage system, users can use hydrogen energy storage devices to store electricity during the valley period when electricity prices are lower, and use fuel cells to release electricity during peak periods, thus realizing peak-valley electricity price arbitrage.
In addition, diesel generators, lead-acid batteries or lithium batteries are the mainstream of emergency backup power systems at present, which have defects such as high noise, high pollution emissions or short service life, low energy density and poor endurance. Mobile hydrogen fuel cells are environmentally friendly, quiet and have long endurance, making them one of the most ideal alternatives. There are already practical cases, such as a single hydrogen fuel cell mobile emergency power supply with a single stack power of more than 120 kW.
3. Hydrogen energy storage system has obvious advantages and disadvantages, and the industry is in the demonstration application stage
The hydrogen energy storage system has obvious advantages in storage capacity, discharge time and other performance indicators, but there is a certain gap in investment cost and conversion efficiency. The energy density of the hydrogen energy storage system can reach 140MJ/kg, which is more than 100 times that of electrochemical energy storage such as lithium batteries. It can store more energy in a smaller volume, effectively avoiding the phenomenon of energy waste.
In terms of calorific value, the calorific value of hydrogen can reach 120MJ/kg, which is 3-4 times that of traditional fossil energy such as coal, natural gas, and oil. The advantages of hydrogen energy storage system in discharge time (hours to quarters) and capacity scale (hundred gigawatt level) are obvious compared with other energy storage. In terms of conversion efficiency, the energy conversion efficiency of pumped storage, flywheel energy storage, lithium batteries, sodium sulfur batteries and various electromagnetic energy storage is above 70%.
The hydrogen production efficiency of alkaline water electrolysis, PEM water electrolysis and solid oxide (SO) water electrolysis in the "electricity-hydrogen" conversion process of the hydrogen energy storage system is 63%-70%, 56%-60% and 74%-81% respectively, while the fuel cell power generation efficiency of the "hydrogen-electricity" conversion process is only 50%-60%, and the energy loss is higher than other commonly used energy storage technologies. Large-scale application still needs technical improvement. In terms of cost, the cost of hydrogen energy storage system is about 1850USD/kW, which is much higher than other energy storage methods such as pumped storage (1000USD/kW) and electrochemical energy storage (286USD/kW).
4. There is still a long way to go before the large-scale application of hydrogen energy storage system, and technology and cost are the biggest limitations
The hydrogen energy storage system mainly includes three parts: hydrogen production system, hydrogen storage system, and hydrogen power generation system. This requires the integration of the entire hydrogen energy industry chain to realize the energy flow through the two paths of the electric energy chain and the hydrogen industry chain.
Although the hydrogen energy storage system is the mainstream path for large-scale energy storage in the future, the cost of hydrogen production system and power generation is high, the mainstream automobile transportation method is costly and inefficient, high-pressure hydrogen storage bottles are in urgent need of iteration and upgrading, and processing equipment such as carbon fiber materials, carbon fiber winding equipment and high-pressure tanks are highly dependent on imports. The technical problems of long-distance hydrogen transportation and hydrogen storage have also become an important factor restricting the further development of the industry at this stage. With the exploration of integrated hydrogen production and hydrogenation stations, light hydrogen oil integrated energy stations, or through the peak-shaving coal-fired power plants next to photovoltaic wind power bases to generate electricity by mixing hydrogen with combustion, the hydrogen energy industry is developing towards integrated energy stations, and the development model of nearby consumption may be able to solve the current dilemma and achieve cost reduction and efficiency improvement.
The adaptability of hydrogen energy storage systems to wide power fluctuations of wind farms needs to be improved. Due to the strong uncertainty of wind and solar energy, the power output fluctuation range is very large. Random changes lead to frequent changes in the input power of the alkaline water electrolysis device, resulting in changes in asbestos diaphragm pressure and alkali solution concentration, affecting the water electrolysis efficiency and the life and operation safety of the electrolysis device. At the same time, water electrolysis requires a stable DC power supply to provide sufficient power to drive the electrolysis reaction. Frequent power fluctuations will have a great impact on the operating life of the equipment and the purity and quality of hydrogen.
Therefore, it is necessary to conduct in-depth research on the adaptability of hydrogen production equipment to power fluctuations, develop high-power, low-cost, and efficient industrial alkaline water electrolysis hydrogen production technology, and develop proton exchange membrane water electrolysis hydrogen production technology that can quickly respond to power fluctuations, so as to improve the adaptability of water electrolysis hydrogen production equipment to intermittent power fluctuations.
5. Future Outlook of Hydrogen Energy Storage System
In the past two years, the number of hydrogen energy storage system projects has gradually increased, cultivating a new integrated application model of "wind and solar power generation + hydrogen energy storage + pumped storage", developing the wind power industry while building hydrogen energy storage system power stations, and using hydrogen energy to achieve peak load regulation and conversion of power grid electricity in areas with suitable resource conditions.
In the context of carbon neutrality and energy storage, as the technology of key components such as the "eight major parts" (the eight major parts refer to catalysts, diffusion layers, proton exchange membranes, membrane electrodes, bipolar plates, fuel cells, air compressors, and hydrogen circulation pumps) in fuel cells gradually improves, the overall cost of the hydrogen energy industry chain will continue to decrease, the upstream will be coupled with wind and solar hydrogen production, and the downstream will explore zero-carbon applications in multiple fields, and the hydrogen energy storage system will usher in a blue ocean market.
What is a flow battery?
Thermal energy storage system: a new direction for future energy utilization
