One of the key problems with renewables is their intermittent availability. You can only generate energy from the wind when it is blowing, or from the sun when it's shining. Critics argue this is why we will never be able to rely on renewables for the majority of our electricity generation. But that criticism may soon be silenced. Researchers are developing new ways to balance supply and demand so that interruptions to the supply at a power station are unnoticeable to the consumer.