A new generation of technologies that use air and gravity to store renewable energy such as solar and wind energy is getting closer to practicality. A British start-up backed by Japan's Sumitomo Heavy Industries, Ltd. is set to open its first energy storage facility in 2024, which will use renewable energy to turn air into a liquid state and then turn it back into a gaseous state to power turbines when generating electricity. The equipment has a long service life, and the cost can be reduced by up to 60% compared with the battery. With the increase in energy storage options, it may promote the realization of a decarbonized society.
Renewable energy sources are mostly vulnerable to weather and natural conditions. For large-scale introduction of renewable energy, supply and demand must be balanced, and to achieve this, energy storage technology is indispensable. At present, batteries such as lithium-ion batteries are mainly used for energy storage, but their lifespan is only 10 years, and the cost is relatively high in the long run.
In the energy storage space, a company in the spotlight is Highview Enterprises, a UK start-up that Sumitomo Heavy Machinery invested $46 million in 2020. The company's technology is to use the surplus electricity generated by renewable energy to compress air to 20 atmospheres, cool it to below minus 160 degrees Celsius, make it liquid, and then heat the liquid air to expand it when generating electricity. This drives the turbine to work.
The company will build commercial facilities in the UK in 2024. The scale of energy storage reaches 300,000 kWh, which is equivalent to the annual electricity consumption of 70 households in Japan. The construction cost is about 15 billion yen. Although it is higher than the lithium battery equipment of the same scale, the service life is 40 years, which is 30 years longer than that of the lithium battery. In the long run, the cost is cheaper. It is estimated that the cost of electricity storage per kilowatt-hour is about 110 euros, which the company says is "60% cheaper than lithium batteries".
The report pointed out that after the air becomes liquid, the volume is only 1/300 of the gaseous state, so it is also convenient for use in urban areas with limited land area. It is said that the conversion efficiency of electric energy to electric energy is 55% to 60%, although it is inferior to the 70% to 80% of the battery, but there is still room for improvement in the utilization of waste heat.
Highview Enterprises also plans to build such a facility in Spain. Each facility has a capacity of more than 300,000 kWh, and the total capacity in Spain is expected to reach more than 2.1 million kWh. In Japan, the joint construction of a test facility with Sumitomo Heavy Machinery will begin in 2022, with the earliest opening in 2024.
Start-up Hydrostor is vigorously developing compressed air energy storage technology. The company will build a facility in Australia with a maximum energy storage capacity of 1.6 million kWh in 2025 and a facility with a maximum storage capacity of 4 million kWh in 2026. Compressed air requires more space than liquid air, and Hydrostor envisages using underground caves, etc., as energy storage sites.
Some companies are also promoting another initiative, similar to pumped storage power generation using nighttime electricity, but instead of using water, the "blocks" are raised to a high place in advance, and then put down when electricity is needed generate electricity.
Leading the charge in this regard is Energy Vault, a Swiss start-up backed by SoftBank Group Corp and Saudi Aramco, according to the report.
