Thorium

One pound of thorium will produce as much energy as 200 pounds of uranium or 3,500,000 pounds of coal. Uranium is mostly U 238 (99.3%) which cannot be used. Only the .7% U 235 is fissile. All of thorium can be used. Burning this amount of coal would produce over 200,000 pounds of ash which contains many contaminates like heavy metals. One of those is thorium which can be separated out and used for nuclear fuel. One ton of thorium can produce one GW per year which will power a modern city of one million people for one year. Thorium can be mined without producing dangerous by products and has very little waste to dispose.