You should do a little more reading on the subject it may help with your confusion, Nuclear and some fossil fuels are here to stay and if coal can be cleaned up in the future, that too will be reintroduced into the mix.
https://assets.publishing.service.g..._data/file/728374/UK_Energy_in_Brief_2018.pdf
The only thing with nuclear power, is that the more it's used the greater the risk of accidents and terrorism etc. I do believe we should be investigating more semi-natural ways of generating electricity such as the mountain Elidir Fawr in Wales (well it would be with that name!) inside it there are 14 kilometres of tunnels housing the Dinorwig Power Station and effectively they pump a few billion gallons of water up the top and when it runs down again through the tunnel system it hydraulically powers massive generators and they produce 1728 megawatts - enough to power 2.5 million homes. It's billed as being "low cost".
They say in this article that the locals call it "Electricity Mountain":
https://www.citymetric.com/horizons/mountain-north-wales-tried-stop-uk-s-blackout-4748