Carbon dioxide phase-change energy storage and compressed air energy storage
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I invite colleagues to discuss which of the two technical approaches – carbon dioxide phase-change energy storage or compressed air energy storage – is better.
Let me offer my perspective first: Carbon dioxide phase-change energy storage requires a small volume of liquid for storage and boasts a high energy density. However, the process involves condensation and evaporation, which affects the system’s power generation efficiency. Compressed air energy storage does not require condensation or evaporation, as it stores energy in the form of high-pressure gas; yet during energy production, the pressure of the high-pressure air keeps dropping, resulting in variable-pressure operation that impacts the efficiency of the turbines and thus the system’s overall power generation efficiency. Which technology offers better efficiency and greater prospects?
I haven’t seen the materials. It seems that this project is similar to Pang Qingnian’s concept of water-hydrogen new energy: using nano-aluminum powder to react with water to produce hydrogen, which is then used to power cars. There is theoretical feasibility to this approach, but in practice it’s completely pointless – it’s just a concept created to obtain subsidies. Mechanical energy generated by electricity is used to compress gas, and the expansion of that gas is then utilized to generate electricity. This efficiency is no match for pumping water to a high place and letting it flow back down to generate power, or for heating molten salt
The main application scenario is to level out demand peaks and valleys in order to take advantage of the price difference between peak and off-peak electricity rates; there are already many such projects in China
There are many ways to take advantage of the price difference between peak and off-peak electricity rates; common methods include pumping water and heating molten salt. The approach of compressing air and then expanding it again doesn’t seem economical