‘Unlimited energy?’ shows that the Earth produces a vast amount of energy through natural radiation. Geothermal power generation can harness this energy and 40 countries in Africa, Central and South America, could generate all of their electricity in this way. In 2011, 14% of the global energy supply came from nuclear sources, but safety issues hinder its widespread use. Nuclear power generator systems and the use of uranium and plutonium are discussed. Fast reactors, small reactors, and thorium are considered acceptable solutions for the future along with nuclear fusion. This is the fusion of hydrogen nuclei to create helium, the same energy production process seen in the Sun.