Multiple energy storage technologies complement each other's strengths

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  The energy storage industry is characterised by a wide range of technological directions and a spiral of development. Each energy storage technology is suitable for different application scenarios, and the most suitable technology route must be chosen for a particular scenario. Compared with pumped storage, new energy storage technology has become the fastest growing and most promising form of energy storage due to its fast response, flexible configuration, short construction cycle and other advantages, and good matching with new energy development and consumption. China's new energy storage industry as a whole is at the stage of transition from R&D demonstration to the early stage of commercialisation. The National Development and Reform Commission and the Energy Bureau issued the "14th Five-Year Plan" for the implementation of new energy storage development, which clearly proposes to promote the development of diversified energy storage technologies, including sodium ion batteries, new lithium ion batteries, lead carbon batteries, liquid flow batteries, compressed air, hydrogen (ammonia) storage, and other energy storage technologies, Compressed air, hydrogen (ammonia) energy storage, thermal (cold) energy storage, etc. At the same time, many of the above cutting-edge technologies will be included in the demonstration, and pilot demonstrations such as the use of abandoned mine pits for energy storage will be encouraged to promote pilot demonstrations of new energy storage technologies on multiple time scales. For oil and gas companies that are accelerating their transition to new energy, the oil and gas industry is currently in a "golden period" of research and development of special energy storage technologies.

  At present, lithium-ion batteries almost occupy the monopoly position of scenic power generation supporting energy storage. In the past five years, under the promotion of the consumer digital industry and the new energy vehicle industry, the energy density of lithium-ion batteries has increased by more than one time, cycle life has increased by two to three times, and the application cost has dropped by more than 60%, making it the lowest cost means of energy storage. According to experts, it is expected that by further improving the cycle life of batteries, energy efficiency and other technical parameters, by the end of the 14th Five-Year Plan, the cost of energy storage is expected to drop to 0.1-0.2 yuan per kilowatt-hour. However, lithium-ion batteries are still facing safety problems, especially after the scale of energy storage power plants reached 100 MW level, it is urgent to further improve their safety through the optimization of the battery material system, intelligent monitoring and control, and the improvement of the standard system and other channels.

  At present, for oil and gas fields and mines to deploy large-scale energy storage supporting large-scale scenic power station, lithium-ion batteries are still relatively mature energy storage technology, will play an important role in the short term. However, in the long term, limited by the constraints of lithium metal mineral resources, security bottlenecks, lithium-ion batteries are difficult to meet the needs of the explosive growth of energy storage in the oil and gas industry. For oil and gas equipment electrification energy storage support, lithium-ion batteries with its high quality energy density, high volume energy density, will long-term as the optimal choice for distributed energy storage. Oil and gas companies have battery diaphragm, carbon materials and other key materials preparation raw materials and technical advantages, while in the gas field water has the advantage of lithium brine resources, can provide high value-added raw materials for the lithium industry.

  Liquid flow battery through the electrolyte within the valence change of ions to achieve electrical energy storage and release, compared to lithium-ion batteries, belong to the essence of safe electricity storage technology, with power and capacity can be designed independently, high security, long life, large scale and other advantages, but its low energy density, high cost, more suitable for oil and gas field large and medium-sized 4-10 hours of energy storage scenarios. China's all-vanadium liquid flow battery research is generally at the international leading level, is carrying out 100 MW level electrochemical energy storage national demonstration, iron-chromium liquid flow, zinc-bromine liquid flow and other battery technology in the small-scale demonstration application stage, the system cost, stability has become a key factor to limit its promotion and application. Oil and gas companies equipment manufacturing enterprises, refining and chemical enterprises in the liquid flow battery equipment development, piping design, fluid control, membrane materials research and development and production and other related technology accumulation, through independent research and development to tackle the liquid flow battery technology, to promote the commercialization of liquid flow battery process.

  Compressed air energy storage stores energy in the form of compressed air, including combustion and non-combustion type, with the advantages of large capacity, long life, high safety, can be applied to peak and valley reduction, load balancing, frequency modulation, distributed energy storage and power generation backup, etc. It is a long-time large-scale energy storage technology with great development potential. At this stage, compressed air energy storage is still facing problems such as high cost of above-ground storage tanks, geographically restricted underground space distribution and low system efficiency. The development of traditional compressed air energy storage, need to rely on gas storage caves, natural gas and other fossil fuels, for electricity, salt mining industry-related enterprises there is a development bottleneck, while oil and gas companies have abundant underground space resources, mature gas storage design and construction technology, mature drilling and completion engineering technology and perfect gas compressor, gas generator equipment development technology, the development of compressed air energy storage has a unique advantages.

  Thermal energy storage uses thermal storage materials as a medium to store thermal energy such as solar heat, geothermal heat, industrial waste heat and low-grade waste heat, which can be used for clean heat supply, thermal power peaking, clean energy consumption and other fields. The main thermal storage methods include sensible thermal storage, latent thermal storage (phase change thermal storage) and thermochemical reaction thermal storage, of which sensible thermal storage is more mature. The development of high-performance and inexpensive thermal storage materials and the flexible, efficient and rationalised design and development of thermal storage systems are the main research directions in the field of thermal energy storage. The oil and gas industry has a large demand for thermal energy storage in the fields of geothermal development, thick oil extraction, pipeline heating, oil refining and chemical industry, and at the same time has the ability to develop and practice equipment, so it has the significant advantage of developing thermal energy storage.

  As a chemical energy storage technology, hydrogen storage has the flexibility of electricity-hydrogen and hydrogen-electricity conversion, covering both large-scale and long-term electricity storage, as well as storage of hydrogen and its derivatives (such as ammonia and methanol). With many advantages such as high energy density, low operation and maintenance costs, non-polluting processes and long term storage, hydrogen energy storage is suitable for large scale energy storage and long term energy regulation. In the future, hydrogen energy will be coupled and complemented with electrical energy to become an important consumer of China's end-use energy system. However, there are still problems in the system cost, reliability of key materials and core components, electric-hydrogen coupling operation control, fuel cell power generation, etc., such as reliability and durability gap with foreign products, which need further research breakthrough. Oil and gas companies have long-term experience and technology accumulation in key materials, core processes and equipment systems in the fields of hydrogen production, storage, transportation and use, and have the core advantage of developing hydrogen storage.