How blowing hot air propelled Chinese scientists to energy storage breakthrough
- Recent test using compressed air at energy storage site achieved record efficiency
- Achievement comes as China moves to take global lead in advanced energy storage systems
The project is being led by the same team that designed the world’s first 1.5MW and 10MW national CAES demonstration systems.
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Typical energy storage systems have included mainstream pumped hydroelectric energy storage (PHES), which use water, and the popular battery energy storage (BESS) system, which rely on various types of batteries. The CAES system uses compressed air as a working medium.
Pump storage has a relatively long lifespan and a conversion efficiency rate of 75 per cent, but it has highly specific site requirements and necessitates long construction periods. Battery storage boasts a higher conversion efficiency rate of 90 per cent, but the life cycle of the systems is limited and battery costs remain high.
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CAES works by storing compressed air in hard rock formations underground. High performance electric centrifugal pumps compress the air to 140 atmospheres. When the high pressure air is released, it pushes generator blades to make electricity.
The core component of the system is a heat collection device. It collects the heat generated in the compression process and then stores it. The device later uses that heat to raise the temperature of the compressed air during its release to increase the output power.
The efficiency of the device is directly related to the overall conversion efficiency of the system.
Scientists from IET designed their own heat collection device. According to their statement, “test results show that the heat storage efficiency remains 98.95 per cent after eight hours and 98.73 per cent after 16 hours, which is the highest record of current CAES heat storage devices”.
A 100MW energy storage system based on vanadium flow batteries is under construction in Dalian, Liaoning province. Lithium-ion battery energy storage, flywheel energy storage and other energy storage projects are also under way in Inner Mongolia, Ningxia and elsewhere.
“Although China’s installed capacity of energy storage ranks first in the world, the ratio of energy storage to new energy (wind and photovoltaic) installed capacity is less than 7 per cent,” the People’s Daily report said.
According to a development plan released in March, China intends to take the global lead in advanced energy storage systems and start mass construction by 2025.