Since the day that man first made fire, humans have sought out the resources of the earth to power their needs. Whether it's fuel for cooking, heating or powering, that resource is in high demand. Fortunately, the world provides a vast variety of energy sources for our consumption, though some are better for us and our surroundings than others.
Perhaps one of the oldest forms of fuel known to civilization, biomass fuels are any kind of biological matter that people can burn in order to produce heat or energy. In the beginning, biomass consisted of woods, leaves, and grasses, but today, we rely on many more sources. For example, ethanol, an alcohol derived from plants like corn, sugar, hemp, and soy crops, is now blended with gasoline, or used to replace it in some vehicles. While considered more environmentally friendly than some alternatives, biomass still emits particulate pollution when burned.
Fossil fuels are the most commonly used type of fuel in developed nations today. Examples include oil, natural gas, and coal, which are used to power cars, trucks, trains and the majority of power plants around the world. The popularity of fossil fuels initially stemmed from their low prices, but as demand continues to rise, supplies are dwindling and prices have skyrocketed. In addition, fossil fuels are responsible for the majority of particulate emissions today.
While solar energy does not technically come from the earth, but the sun, it is still considered one of the earth's most plentiful source of energy. Silicon compounds help to absorb the energy rich rays of the sun and the radiative heat it provides, making possible its use as functional energy for our vehicles, homes, and transportation infrastructure. This is one of the cleanest forms of energy on the planet, but low reserves of silicon, and the price of solar panel production, have rendered it an underused utility.
Hydroelectric energy, also known as hydropower, relies on the movement of freshwater bodies of water to move propellers and generate energy. This is typically achieved by building dams at strategic points on rivers. While this provides consistent, clean energy, hydropower is often criticized, as the dams destroy marine habitats and interrupt the mating patterns of key species of fish. A variation of this renewable energy source uses the surface waves of the ocean to generate energy in a similar fashion.
Wind energy uses giant turbines to harness the natural power of the wind to turn propellers and generate energy for general use. While people can build individual turbines and attach them to homes, this type of energy is more commonly used in flat, plain areas, with the construction of fleets of turbines that are hooked up to a generator that provides for the community. Ruled the cleanest, most environmentally friendly form of energy production, the only complaints against wind energy are that they negatively impact small populations of bats and birds and are accused of causing headaches in humans.
This type of energy is generated by heat from the earth's core heating water into steam, which turns turbines in order to generate electricity. Typically limited to borders of tectonic plates, new discoveries are, for the first time, allowing scientists to explore the idea of using geothermal power in other areas of the world. The energy is totally clean, although some people have concerns about the safety and reliability of building plants over fault lines.
Ocean Thermal Energy Conversion (OTEC) relies on the difference in temperature between the different layers of ocean to churn a generator and produce electricity. The result of this pushes warm water to deep levels of the ocean, pushing colder water to the top. Some claim that this results in larger amounts of vegetation and healthy marine environments, whereas others argue that this creates an unnatural setting that throws off the food chain in an area.