1. Fossil fuel
Fossil fuels are carbon based chemicals derived from decomposed remains of plants and animals. These fossil fuels are burned to create electricity and propel vehicles. Most of these fuels were formed millions of years ago over time due to natural decomposition processes. Although they may have been very useful at the time, many people now believe that their use has caused tremendous damage to the environment.
2. Nuclear power
Nuclear power uses nuclear fission to generate electrical power. In order to do this, huge amounts of uranium are processed into smaller pieces called atoms. These atoms are placed inside metal cylinders known as reactors where they are bombarded by neutrons. When enough nuclei split from their parent atom, they release energy and cause a chain reaction. Uranium is mined underground and then enriched before it is put into a reactor. Due to its dangerous nature, nuclear power generation requires very tight control and safety measures.
3. Hydroelectricity
Hydroelectricity is produced when water flows across turbines that generate electric current. A dam creates a reservoir behind it and diverts the flow of water onto a turbine located on the side of a river or stream. The force generated by the falling water turns the turbine, which then rotates a shaft connected to an electric generator. Many consider hydroelectricity to be environmentally friendly, since the flowing water does not disturb the surrounding land. However, critics argue that the construction of dams and diversion of streams destroys ecosystems and habitats.
4. Biomass
Biomass is any chemical substance that comes from living organisms, including crops grown on farms. This includes both biomass created naturally and those created using industrial means. Wood is often cited as an example of a type of biomass, although biomasses exist outside of woody materials. This term often refers directly to combustion byproducts and indirectly to sewage sludge. Critics of industrial agriculture claim that the practice contributes to global warming and soil depletion in addition to causing mass deforestation. Supporters maintain that modern farming methods allow for greater production of food than ever before in human history while still preserving natural resources.
5. Water Pollution
Water pollution occurs when raw sewage, industrial wastes, and agricultural run-off contaminate surface waters. The effects of this kind of contamination may vary greatly depending on the amount and type of pollutant present, and whether aquatic species are harmed or humans consume contaminated drinking water. There are several types of pollutants commonly found in water supplies, including heavy metals (e.g., mercury, lead), noxious compounds (e.g., nitrates, pesticides), radioactive elements (e.g., cesium-137), and pathogenic germs (e.g., Giardia).
6. Air Pollution
Air pollution consists of toxic substances released into the air from industry and automobiles. Toxic substances include ozone, sulfur dioxide, particulate matter, lead, arsenic, benzene, formaldehyde, and asbestos. Ozone is an oxygen molecule composed of three oxygen atoms bonded together. Because it is extremely reactive, ozone forms harmful clouds above urban centers and near heavily industrialized regions. Sulfur dioxide reacts with moisture in the atmosphere to produce acid rain. Acid rain damages
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