Recent Advances in Energy Storage Technology

 As the research programs of various Top BESS Manufacturers continue to advance, the technologies of various energy storage systems (ESSs) have also developed rapidly. These technologies play an important role in many industries such as manufacturing, service, renewable energy and portable electronics. The current focus of technology development is to improve energy storage capacity to ensure the stable operation and cost-effectiveness of power systems. The main development trends of energy storage systems include the shift from traditional lithium-ion batteries to new chemical batteries with greater stability, higher density and longer life. Another focus is to develop energy storage solutions for large-scale renewable energy projects. In addition, energy storage systems are shifting towards more flexible and mobile distributed systems. Energy storage systems apply a range of technologies to capture, store and release energy to meet actual needs.

Pumped Storage

Pumped storage is a mature grid-level energy storage technology that can provide storage capacity on the scale of millions of kWh. There are three main types of pumped storage: fixed speed, variable speed and ternary hydraulic short circuit. Fixed speed pumped storage represents the most widely used and mature technology in the world, and its motor/generator rotation is always synchronized with the grid frequency. In contrast, variable speed pumped storage uses power electronic converters to enable the motor/generator to operate at a speed independent of the grid frequency, which is more advantageous in improving the pumping efficiency.

Ternary pumped storage is a newer technology that combines the advantages of the hydraulic short circuit concept to better adapt to rapid changes in power generation and pumping power levels. One of the significant advantages of pumped storage for the grid is that it can store energy for more than 6 hours and can achieve a million-kilowatt-level power generation capacity. Operators are proficient in this technology, especially fixed-speed pumped storage, and can integrate it seamlessly into the grid. In addition, pumped storage technology also has advantages in natural inertia, voltage support, black start capability, and impact on short-circuit current. In terms of cost, the average storage cost of pumped storage technology is also quite competitive, at about Rs. 35,000 per kW and Rs. 3.91 per kilowatt-hour (excluding pumping power costs). However, capital costs may vary depending on specific site requirements and conditions.

Compressed Air Energy Storage

Compressed air energy storage is also a grid-scale energy storage technology that can provide long-term energy storage on a megawatt to gigawatt scale. This technology first compresses air into large natural salt caverns, and then uses the compressed air to generate electricity through specialized gas turbines. However, a major challenge facing compressed air energy storage technology is the lack of suitable caverns to store compressed air. It is precisely because of the limited number of suitable caverns that compressed air energy storage projects are at a disadvantage in global development.

Solid Gravity Energy Storage

Solid gravity energy storage technology uses electromechanical equipment to move heavy objects vertically in a gravity field, thereby converting electrical energy into gravitational potential energy, and then converting the potential energy back to electrical energy when the electricity is used. Solid gravity energy storage technology uses high-density solids to enhance environmental adaptability in different geographical locations, improve energy density, speed up cycle efficiency, and have better economic feasibility. Solid gravity energy storage, like pumped storage and compressed air energy storage, shows a supporting role for the power grid. But despite its potential, solid gravity energy storage technology is still in the research and development stage, and small-scale pilot projects are being launched around the world. In India, Gravitricity has conducted a pilot project in partnership with Indian power company NTPC. However, many countries lack specific policies and engineering incentives for solid gravity energy storage, as the technology is still in its early stages of development and there is a lack of large-scale pilots and projects compared to pumped hydro.

Flywheel Energy Storage

Flywheel energy storage is based on the principles of conservation of momentum and energy. When a flywheel reaches rated speed and rotates in a vacuum, its momentum remains constant (under ideal conditions). When this energy is converted into electrical energy, the conservation of energy causes the kinetic energy to be converted into electrical energy. Advanced flywheel energy storage systems have the advantages of high energy density, high energy conversion efficiency and low energy losses, making them suitable for medium and short-term energy storage. When the system is in operation, the flywheel rotates at high speeds ranging from 10,000 rpm to 100,000 rpm. Currently, grid-scale flywheel energy storage systems are mainly used in electric vehicles and isolated grids. For larger grids, the inertia generated by rotating components in coal-fired power plants and thermal power plants is expected to be sufficient to meet grid requirements.

Batteries

Among the existing battery technologies such as lithium-ion batteries, all-vanadium flow batteries, molten sodium batteries and lead-acid batteries, lithium-ion batteries and all-vanadium flow batteries are considered the best choices for grid-level energy storage technologies due to their cost-effectiveness, performance, cycle life and technical maturity. Lithium-ion batteries and all-vanadium flow batteries with energy storage capacity of several hundred megawatts have been deployed in grid-level battery energy storage systems. These technologies play a vital role in balancing grid loads by simplifying renewable energy generation, providing grid backup capacity, enhancing grid resilience, facilitating load shifting, providing ancillary services and ensuring continuous power supply. The deployment strategy for battery-integrated grid-level energy storage devices should consider multiple factors such as grid demand, levelized cost analysis, reliability, environmental impact, battery pack design, safety, maintenance and grid integration. However, many countries face the challenge of scarce lithium and cobalt resources. Although large lithium reserves have been discovered in some regions, the production of other raw materials in these regions is limited. The current cost of lithium-ion batteries ranges from Rs 13,600 per kWh to Rs 20,000 per kWh, while the cost of vanadium flow batteries ranges from Rs 24,000 to Rs 32,000 per kWh. However, projections by organizations such as Bloomberg New Energy Finance (BNEF) and the National Institute for Transforming India (NITI Aayog) indicate that the cost of lithium-ion batteries could drop to around Rs 5,500 per kWh by 2030. In addition, according to projections in a report by the International Renewable Energy Agency (IRENA), the cost of vanadium flow batteries is expected to drop to around Rs 8,700 per kWh by 2030.

Reference website: https://www.huntkeyenergystorage.com/