Electricity supply has to exactly match electricity demand at all times, which is why (in my opinion) 100% renewable energy doesn't make sense. There has to be /some/ source of electricity that a country can turn to if the wind stops blowing, the sun goes behind a cloud, or - indeed - demand for electricity suddenly spikes.
The only way you could do this with renewable energy is if you had a way of 'storing' electricity, which could be used to meet demand if there was a shortfall in supply -- and this becomes incredibly expensive very quickly.
The most efficient approach to the electricty supply is to have a base-load of electricity being supplied by something which is 'always on', e.g. fossil fuels or nuclear energy, and then having renewables top up the rest.
[All this is just my opinion, by the way, but didn't want to litter the whole post with "in my opinion..."! You get the idea!]
The only way you could do this with renewable energy is if you had a way of 'storing' electricity, which could be used to meet demand if there was a shortfall in supply -- and this becomes incredibly expensive very quickly.
The most efficient approach to the electricty supply is to have a base-load of electricity being supplied by something which is 'always on', e.g. fossil fuels or nuclear energy, and then having renewables top up the rest.
[All this is just my opinion, by the way, but didn't want to litter the whole post with "in my opinion..."! You get the idea!]