Nuclear power

Types

Type	Problems if scaled up
	Fuel scarcity	Weapons proliferation	Nuclear waste
Conventional nuclear power	Yes	No	Yes
Small nuclear reactors	Yes	Yes	Yes
Uranium-238 breeder reactors	No	Yes	No
Thorium-232 breeder reactors	No	No	No
Hydrogen fusion (not viable yet)	No	No	No

So far, it seems that thorium is the only nuclear power that could really scale up enough to replace all fossil fuels.