<P> A typical coal plant generates billions of kilowatt hours per year . </P> <P> Nuclear power is the use of nuclear fission to generate useful heat and electricity . Fission of uranium produces nearly all economically significant nuclear power . Radioisotope thermoelectric generators form a very small component of energy generation, mostly in specialized applications such as deep space vehicles . </P> <P> Nuclear power plants, excluding naval reactors, provided about 5.7% of the world's energy and 13% of the world's electricity in 2012 . </P> <P> In 2013, the IAEA report that there are 437 operational nuclear power reactors, in 31 countries, although not every reactor is producing electricity . In addition, there are approximately 140 naval vessels using nuclear propulsion in operation, powered by some 180 reactors . As of 2013, attaining a net energy gain from sustained nuclear fusion reactions, excluding natural fusion power sources such as the Sun, remains an ongoing area of international physics and engineering research . More than 60 years after the first attempts, commercial fusion power production remains unlikely before 2050 . </P>

1. what types of energy resources provide most of the world’s power why do you think this is