Renewable energy comes from sources that may be continuously renewed by nature. Consequently, we will never be running out of these energy sources, that is, for as long the Sun’s nuclear fusion processes continue to provide the Earth with energy.
Here are a few examples:
Solar Power: Solar power is seen as renewable energy as expectations are that nuclear fusion processes that are powering the Sun will continue to generate sunlight for billions of years.
We are capturing the light of the Sun to:
Drive steam turbines to produce electricity (the concentration of Solar Power),
Heat homes (via so-called Passive Solar Design or via an Active Solar Heating System),
Make hot water (via an Active or Passive Solar Hot Water System),
Cook (on a Solar Oven),
Generate electricity by using solar electric (or photovoltaic) cells
Other renewable energy types:
Hydropower: We can use falling water to drive generators for the production of electricity. This method is considered renewable because of the hydrological cycle of the Earth. This system, where seas, lakes, and rivers are continuously replenished through rain, is Sun-driven so we can say that hydropower is indirectly a solar power-related.
Biomass: This is the system where heat is generated by burning trees, plants, or some other organic waste. This is renewable because photosynthesis will always create new organic matter. Biomass, as well, is an indirect solar power form.
Wind Power: Here we use the power of the wind to make propellers turn to activate turbines. Wind power is renewable because the Sun and the rotation of the Earth will always generate winds. Also, wind power is actually one more shape solar power in an indirect way. Estimated are that even if we would only develop a small portion of ‘windy’ areas in the U.S. with wind turbines, we could power the entire nations several times over. There would be no adverse social or environmental impacts. Today, wind power is the world’s fastest-growing source of energy.
Geothermal Power: This system uses the heat that’s created by the natural process of decay in radioactive elements inside the earth for heating buildings or to produce steam to drive generators for the production of electricity. Geothermal power is recognized as renewable as there are so many radioactive elements within the Earth that it will be kept warm for countless more years.
Landfill Gas: Here we use the methane gasses (CH4) that are generated in landfills as garbage gets broken down. This is actually a type of biomass energy, and though it is not really renewable in the long run, there is so much landfill gas in the U.S. that it provides a considerable source of energy. Doesn’t this tell us also something about how the volume of waste that we produce?
There are several definitions of the notation ‘renewable energy’. There are scientists and researchers claiming that nuclear power generated through earth-based uranium also needs to be classified as a renewable source of energy. They say that the sun is nuclear-powered and that there is plenty of uranium to be found on Earth.
Well, we do not subscribe to these views. Other scientists prefer the use of the word ‘inexhaustible’ rather than ‘renewable’ as it would better emphasize that this kind of energy sources never run out, at least not for mankind’s foreseeable future. One more useful term could be ‘non-extracted’, emphasizing the fact that what we call ‘renewable’ sources of energy are not require mineral extraction from the Earth’s ground.