Lawmakers in California have just introduced a new bill that would require electric utilities to provide grid-scale energy storage in their operations. The bill would call for a capacity of 2.25% of daytime peak demand by 2014 and 5% of peak demand by 2020.

A number of different technologies could be included to provide grid energy storage, including pumped storage hydro, compressed air storage, utility-scale batteries, and flywheel storage systems.

The hopes are that this will encourage utilities companies to promote efficiency measures and to encourage load shifting, in order to lower the amount of storage that would be required.