In a new development, the UK is to test its first battery system to provide grid-frequency following the recent establishment of a partnership between energy utility firm National Grid and UK-based Renewable Energy Systems (RES). The 20MW battery storage system is equivalent to the batteries of up to 1000 pure electric cars, and will provide a dynamic frequency response service that can detect a second of deviation higher or lower than 50Hz, the company claims. It appears that the call to replace diesel gensets (which have a global base of at least 600GW) is also spurring the use of large lithium-ion battery packs in grid and microgrid applications.