Theory:

Geothermal energy:
 
Molten rocks formed in the earth's crust's deeper hot regions are pushed upward and trapped in certain regions known as "hot spots" due to geological changes. Steam is produced when underground water comes into contact with the hot spot. Hot water from that area occasionally finds its way to the surface. Hot springs are the name for these types of outlets. The steam trapped in the rocks is piped to a turbine, where it is used to generate electricity. Although the cost of production would be low, there are only a few commercially viable locations where such energy can be used. In New Zealand and the United States of America, a number of geothermal energy-based power plants are operational.
 
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Geothermal energy
 
Nuclear energy:
 
How is nuclear energy generated?
 
When bombarded with low-energy neutrons, the nucleus of a heavy atom (such as uranium, plutonium, or thorium) can be split apart into lighter nuclei, a process known as nuclear fission. If the mass of the original nucleus is just a little more than the sum of the masses of the individual products, a tremendous amount of energy is released. For example, the fission of a uranium atom produces \(10\) million times the energy produced by the combustion of a carbon atom from coal. Such nuclear 'fuel' can be part of a self-sustaining fission chain reaction that releases energy at a controlled rate in a nuclear reactor designed for electric power generation. The released energy can be used to generate electricity.
 
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Nuclear power plant
Reference:
https://pixabay.com/photos/nuclear-central-energy-radiation-4168906/