The cheapest source of electricity radiation in the world is:

Nowadays, solar power, especially from solar farms, is one of the cheapest methods of producing electricity. Solar PV has emerged as the cheapest, with costs frequently dipping to $50 per megawatt-hour or less in favorable regions. In fact, in most countries of the world, the cost of electricity produced from solar photovoltaic power plants is less than that produced from coal, gas, and nuclear power. In some parts of the world, on-shore wind energy is also one of the cheapest sources of power. So, the answer to this question is: Solar energy (solar PV).