TOKYO -- Toshiba has developed a way to use hydrogen to store large quantities of electricity for extended periods of time, with a storage system deploying the technology potentially reaching the market in 2020.
The Japanese company will first provide a system capable of storing up to 40,000 kilowatt-hours of electricity -- enough to power 10,000 households for eight hours. The system will be made by assembling fuel cells, electrolysis equipment and hydrogen storage tanks on a 600-sq.-meter plot. Hydrogen obtained through electrolysis will be stored in the tanks and reacted as needed with oxygen in the air via the fuel cells to produce electricity.
Energy conversion efficiency is a measure of how much energy can be reproduced when the energy is made to change forms. Toshiba's system has an energy conversion efficiency of 80%, exceeding the 70% efficiency of pumped-storage hydroelectricity, in which water is pumped to a higher elevation and then released to generate power.
The energy storage efficiency of typical storage batteries is thought to be around 80%, but massive quantities of electrode materials are necessary to increase capacity. A 40,000kwh storage battery would cost nearly 2 billion yen ($16.8 million). Such batteries also have problems with long-term storage due to self-discharge.
If safety technology to prevent leaks can be secured, the capacity of a system using hydrogen could be increased simply by enlarging the size of the tanks. The total cost including installation and operation would reportedly be reduced by half compared with existing storage batteries.
To producers of renewable energy such as solar and wind power, the ability to store surplus electricity at low cost would help to cushion the risks from unsold output. The technology is also envisioned for use by local municipalities as an emergency power source during disasters. Toshiba plans to install a small-scale test system capable of storing 350kwh of electricity in Kawasaki this spring.