One challenge associated with renewable forms of energy like wind and solar power is that power stations of these types cannot usually produce energy all the time, and may not generate it at the time when it is needed most.
It is also encouraging that battery technology is improving. A company called Corvus now makes lithium ion batteries that consist of assemblies of 6.2 kilowatt-hour modules. These can be charged in 30 minutes and discharged in 6. They could be joined together in large arrays of up to 40 megawatt-hours and may eventually be cost-effective in some energy storage and load balancing roles.