What is all the buzz about our need to cut down on using oil? Even though the earth continues to produce fossil fuel, technology and power use has increased so much that people are using fossil fuels at a higher rate than the Earth can produce. Because most of the energy the U.S. uses comes from fossil fuel, and because this fuel will eventually run out, scientists and researchers are looking for alternative energy sources.
Alternative energy sources can be either non-renewable (once they are used they don’t come back) or renewable (they can never be exhausted). Non-renewable sources are the fossil fuels we currently use: coal, natural gas, crude oil, etc. There are many types of renewable energy, harnessing power from things like the sun, water, wind and biomass.
Renewable sources can be used over and over again, and can often harness enough power to meet a significant amount of demand. Currently, renewable energy accounts for 25% of the human energy use around the world.
We can use the water that naturally flows in rivers and streams to make power. Rivers are dammed to create a reservoir of water. The water from the reservoir is released, and as it flows it spins turbines that run electric generators. Hydropower is the most widely used renewable energy source. It made up 3% of the U.S. energy usage in 2009.
While hydropower does not produce any air pollution, damming rivers means changing the natural habitats of the region in a big way. Fish and plants that usually live in or along the river could die because of changes in water temperature or water level.
Wind power is harnessed through wind turbines which are large windmills that are designed to capture air and convert it to electricity. The wind turbines are connected to generators that then produce electricity. This electricity then goes into power lines that bring it right into people’s homes.
However, in order to gather the most electricity, the wind has to be constantly blowing. This doesn’t happen very often, so wind power does not always generate enough electricity. An upside is that wind, unlike the sun, is available day and night.
Biomass can be trees, plants, corn, plant waste—basically any plant matter that can be burned for heat/electricity or turned into fuel, which can be liquid (ethanol/methanol) or gaseous.
Fuel made from biomass has great potential for being the next big source of energy for transportation. Biodiesel can replace typical diesel fuel to run cars.
Biomass might not be a renewable energy source if we use it faster than it can be made. Also, when creating this fuel, there will be pollutants released when biomass is burned.
The sunshine that warms you on a chilly day also contains energy that can be collected as electricity to keep our lights running and our kitchen appliances humming. Many homes are now being designed to better harness the energy from the sun. You can also use solar power to heat up water in your house.
Energy from the sun produces electricity. This is done in two main ways: the photovoltaic process and solar thermal electric process. The photovoltaic process uses special cells that take sun’s rays and make them into electricity. It’s useful for places that can’t otherwise get near an electric grid. Solar thermal electricity uses the sun’s heat to boil water. The boiling water makes steam which moves a turbine that causes a generator to make electricity.
Solar power has some problems too—the sun isn’t always up so its heat isn’t available 24/7. But, solar power is a renewable, environment-friendly source.
Geothermal energy is gathered from heat inside of the earth. Deep wells are drilled into the surface of the earth to penetrate hot water that has been heated by magma and to be used as a source of energy. This heated water, like in solar thermal electricity, can then move a turbine that runs an electricity generator. Geysers are usually the best places to access this kind of energy.
However, geothermal energy might not be a renewable energy source if we use it faster than it can be remade by the earth.
Even trash can be used for power! Solid waste can be burned in plants to produce electricity and a gas called methane can be harvested from landfills as solid waste decays.
A Renewable Future?
The United States and other countries around the world are investing in research around renewable energy. How can these sources be used more effectively? What technology needs to be implemented to get the most energy out of things like the wind? Scientists and researchers are working towards answers to these questions. Maybe one day the world will run on renewable sources!
U.S. Department of Energy: Energy Efficiency and Renewable Energy
Energy Information Administration: Hydropowder