The world's first carbon dioxide+flywheel energy storage demonstration project was completed on Aug 25.
It represents a leapfrog development in engineering application of a new type of energy storage technology in China.
One of the demonstration application scenarios at the 2022 World Conference of Clean Energy Equipment, the project was jointly constructed by Dongfang Turbine Co., Ltd., a subsidiary of Dongfang Electric Corporation (DEC), and several other enterprises and universities.
Covering an area of 1,800 square meters, about 2.5 times as large as a football pitch, the project has an energy storage scale of 10 megawatt/20 megawatt-hours and can store 20,000 kWh of power within two hours, making it the carbon dioxide energy storage project with the world's largest single-machine capacity and energy storage capacity. It is also the world's first carbon dioxide-flywheel integrated energy storage station.
Carbon dioxide energy storage is a kind of compressed gas energy storage that uses carbon dioxide as a cycle fluid for charging and discharging.
A view of the site of the carbon dioxide+flywheel energy storage demonstration project [Photo/sasac.gov.cn]
During low energy consumption periods, 250,000 cubic meters of carbon dioxide can be compressed into a liquid in a huge flexible gas module in two hours, with a volume of only 1/300 of the original. In peak energy consumption periods, the liquid is made to convert back into gas, the process of which pushes the turbines to generate 20,000 kWh of power within two hours. The power is enough to support more than 60 households for a month.
The flywheel energy storage is a kind of energy storage method that realizes two-way conversion of electric and kinetic energies through a highly-efficient electricity-generating two-way integrated motor and the flywheel in the vacuum. The method can achieve a millisecond response time.
Combining the advantages of long duration and large scale of carbon dioxide energy storage and the fast response capacity of the flywheel energy system, the project is expected to effectively smooth out power grid volatility, eliminate problems of intermittency and realize safe and environmentally friendly grid operation.
It's worth noting that during the entire process, no fossil fuel is used and neither solid waste nor carbon dioxide is released.
Compared with pumped storage and compressed air power generation, the carbon dioxide energy storage system can be built anywhere, normally in less than two years.
Different from electrochemical energy storage, the carbon dioxide energy storage system does not use rare or precious metals, and offers stability and a cycle efficiency that is expected to be maintained at more than 60 percent during its 30-year service.
What's more, carbon dioxide is non-toxic and non-flammable, and is easy to obtain. It can be liquefied at normal temperature and can be easily stored as a liquid with low storage costs.
The carbon dioxide energy storage system has outstanding economic benefits through large-capacity and long-term energy storage, especially for 10-MW, 100-MW and 1,000-MW systems.
It can also support new energy-based power stations, reducing unstable and unsustainable power supply, and can also work together with a thermal power station to help improve peak-load regulation capacities and comprehensive energy utilization efficiency.
Once operational, the project is expected to accelerate construction of China's new-type power system and give the country the global lead in new energy storage technology.
It is expected to play a role in realization of China's "dual carbon" goals of peaking carbon emissions by 2030 and achieving carbon neutrality by 2060.
A bird's-eye view of the carbon dioxide+flywheel energy storage demonstration project [Photo/sasac.gov.cn]
(Executive editor: Wang Ruoting)
