The Nikkei reports that Hokkaido Electric Power Co. will invest in a 60,000 kWh vanadium redox flow battery from Sumitomo Electric Industries Ltd. to bolster its grid capacity amid rapid growth in power generation using renewable energy.
A redox battery is an electrochemical system that generates oxidation and reduction between two active materials, forming a redox system, on the surface of inactive electrodes (the electrodes themselves do not change). A redox flow (RF) battery has the electrolyte including these active materials in external containers, such as tanks, and charges and discharges electricity by supplying the electrolyte to the flow type cell by pumps or other means.
In a vanadium redox flow battery, the battery reaction principle is simply the change of valence of the vanadium ions in the electrolyte without solid phase battery reactions.
This principle gives the battery the following outstanding features: a long charge/discharge cycle service life is realized; the life of electrolyte is not susceptible to deep-dis- charge or complex charge/discharge pattern. In addition, redox flow batteries are safe by using an incombustible electrolyte. When applying storage batteries for the purpose of providing a stable supply of renewable energy, they are required to be (1) available for storing bulk energy (high output, large capacity), (2) available for state of charge (SOC) management, (3) highly responsive, and (4) available for short-term, high-output operations. Redox flow batteries meet all the above requirements.—Shibata et al. (2013)
Delivery of the battery, which has about a 20-year lifespan, is planned for 2015. Hokkaido Electric plans to install the battery at a key substation, according to the report. The project cost will total an estimated ¥20 billion (US$200 million), with financial assistance expected from the Ministry of Economy, Trade and Industry.
Renewable power sources such as solar and wind fluctuate sharply with the weather, creating concerns over the possible impact on grid voltage and frequency.
To avoid overtaxing its network, Hokkaido Electric announced in April that it would receive only up to 400,000 kW from solar power facilities with an output of 2,000 kW or more each. Other utilities could face similar issues, which in turn could hamper the growth of renewable-energy projects. By installing the new battery, Hokkaido Electric will be able to receive about 10% more electricity.
Sumitomo Electric is testing a 5,000 kWh redox flow battery at a Yokohama facility. It plans to begin mass production next fiscal year in Osaka, with an aim of generating 100 billion yen [US$1 billion] in annual sales in five to six years.—Nikkei report
Toshio Shigematsu (2011) Redox Flow Battery for Energy Storage Sumitomo Electric Technical Review, Nº 73
Toshikazu Shibata, Takahiro Kumamoto, Yoshiyuki Nagaoka, Kazunori Kawase And Keiji Yano (2013) Redox Flow Batteries for the Stable Supply of Renewable Energy. Sumitomo Electric Technical Review, Nº 76