“There are signs that a range of new technologies is getting closer to cracking [challenges]. Some, such as flow batteries may, in the future, be able to store liquid chemical energy in large quantities analogous to the storage of coal and gas.
“Various solid battery options are also competing to store electricity in sufficiently energy-dense and cheaply available materials. Newly invented graphene supercapacitors offer the possibility of extremely rapid charging and discharging over many tens of thousands of cycles. Other options use kinetic potential energy such as large flywheels or the underground storage of compressed air.”