Types of Sustainable and Renewable Energy Sources
Sources such as the sun, the wind, and the earth's heat can be characterized as both sustainable and renewable energy sources, since they have minimum impact on the environment:
Solar Energy: The sun provides us with a completely clean and environmentally friendly source of energy. Technology is currently focused on manufacturing high efficiency solar modules to exploit this energy.
Wind: This is another clean energy source with high efficiency. However, the wind turbines will have to be placed in windy locations in order to be effective. Denmark and Germany are the world leaders in this field.
Biomass: Plants, trees, switchgrass, corn, and other biofuels are converted into ethanol which in turn, is burned to generate power. Switchgrass is thought to have higher energy efficiency than corn. Hydrogen can also be made from biomass, although this is not a very efficient way to exploit biomass just yet. Many suggest the use of buffalo urine as a biofuel. In this case, huge quantities of urine would have to be produced, which is almost impossible. Anyway, any kind of urine could be used to produce hydrogen, which is a better fuel.
Geothermal Energy: Geothermal plants take advantage of the earth's internal heat to produce electricity. The usual process involves the heating of water until it becomes steam and then the conversion of the steam's kinetic energy to produce electricity with the aid of electric generators. No pollution is produced through this process; however this kind of energy is only available in certain countries across the world such as Iceland.
Wave and Sea Power: Waves, sea current power, and tidal forces could be used to provide a clean sustainable/renewable source of energy. The technology for exploiting this energy, however, requires strong equipment and resistant materials to endure the mechanical stress and fierce conditions in case a hurricane or a storm strikes.
Hydrogen: Hydrogen can be used as an energy source, although it has to be produced through another source of energy such as fossil fuels, biomass, solar, or wind energy. Depending on the source and the efficiency produced, it could be characterized as a sustainable energy source. However the production of hydrogen through water electrolysis can only guarantee a clean renewable energy source.