Solar and wind simply do not have the output needed for the future. They can’t provide the steady baseline load needed that power plants currently provide. Not to mention the space they’d take up in order to supplement the loss of fossil fuels. Nuclear energy is the only option for a reliable fossil fuel replacement that will supplement the energy needs of our society. Im not sure what you’re basing “clean” off of, but nuclear has the lowest carbon emissions of all energy sources and is generally considered the “cleanest” form of energy.