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What is Sustainable Energy?
There are three basic demands an energy source must meet to be characterized as “sustainable:"
- The long-term availability of the energy source that guarantees to meet any present or future consumption needs.
- The energy source must be replenishable without human intervention.
- The amount of energy consumed to exploit the available resources should not exceed the amount of energy these resources produce (ie, the energy efficiency of the source).
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Sustainable vs Renewable Energy – Are They the Same?
Many use the terms “sustainable" and “renewable" energy without any distinction. Contrary to the common belief, there is a difference between them. Although renewable energy sources share all the sustainable energy characteristics described above, they are clean sources that do not pollute the environment during consumption and have minimum impact on human health and the ecosystems. Therefore, the term "sustainable" is wider and includes all types of renewable energy.
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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.
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Types of Sustainable Energy Sources
Nuclear power, municipal waste, etc. are not renewable sources of energy since they are responsible for polluting the environment. However, they are sustainable:
Nuclear Fission-Fusion: Nuclear fission energy is the energy derived from the splitting of Uranium atoms within the reactor of an atomic power plant. The chain reaction releases vast amounts of energy from a very small fuel quantity and therefore this source can be regarded as sustainable. However, the power generation process releases radioactive wastes, a very dangerous byproduct that causes irreversible damage to all living organisms. Nuclear fusion energy, on the other hand, relies on the energy released by the joining of two or more nuclei to form a heavier and more stable nucleus. The burning fuel here is hydrogen. The controlled use of this process for energy production would provide us with a cheap renewable source of energy.
Municipal Waste: This is a new sustainable energy source that has become available during the last decades. Household garbage is used as burning fuel to produce electricity and this process also helps to keep the landfills clean.
Oil, natural gas, coal and other forms of fossil fuel cannot be considered as sustainable sources of energy. This is due to the environmental damage they cause and the limited supplies left. The future generations will have to focus on the renewable energy sources and find innovative ways to increase their efficiency.