Five Renewable Energy Sources

Five Renewable Energy Sources

by Deb Powers

While it may seem to many that "renewable energy" and the quest to harness sources of energy that are less harmful to the environment than burning coal and oil are new, the truth is that most of the renewable energy sources have been around for centuries. Biomass, solar, water and wind were used to power equipment, heat homes and cook food for centuries before we discovered ways to make burning coal and oil more reliable and started depending on coal-fired plants for electricity.

The more you know about renewable energy, the better you'll understand projects that harness renewable energy in your own neighborhood. This is important, because not all projects that are touted as "renewable energy" are necessarily green or good for your community. While I fully believe that we need to move quickly toward using alternative sources of energy, I also fully support examining proposals in your community carefully and understanding the effects that they may have on your life and the environment around you.

The truth is that there are advantages and drawbacks to most anything being proposed. The trick is in weighing the pros and cons and determining which types of projects are best for each area. Here are some quick facts about each of the five best known sources of renewable energy to help you understand projects you may hear about so that you can decide whether you support the effort or not.

Solar Power

Solar power uses heat from the sun and converts it into energy. One of the easiest ways to see how solar energy can be used for heat is with a simple solar oven, a project many kids do in Girl Scouts or Explorers. There are two main types of solar energy plants - photovoltaic and concentrated solar thermal.

Photovoltaic solar power converts solar energy directly into electricity. Solar cells are used to power many small items that most people are familiar with - calculators, watches and landscaping lights. Large solar panel arrays can be mounted on houses or other buildings to provide electricity for residential or business use. These solar panels can provide electricity even in remote areas that are far from transmission lines, but they are also often used on buildings that are connected to the power grid. In those cases, traditional electricity is available to kick in when the sun isn't shining, and if the solar panels produce more power than is used, it can be sold back to the electric company.

Concentrated solar power uses the heat from the sun to warm water or another substance, then uses the steam produced to turn turbines and create electricity. There are currently 16 solar thermal or CSP plants operating in the U.S. that each produce at least 1 MW of electricity. There may be smaller plants as well.

Hydropower

Hydropower uses the energy produced by moving water to create electricity. It is one of the oldest sources of power. Water wheels have been used for centuries to harness energy for mills and other tasks. Hydro power from dams is one of the oldest and most reliable sources of renewable energy.

Hydroelectric power is created when moving water pushes against the blades of turbines, turning a generator. There are two main types of hydroelectric systems - run of the river systems, where the energy of a free flowing river is used, and storage systems, where water is held in a reservoir created by a dam of some sort, then released to turn the turbines.

Biomass

Like both solar and hydro power, biomass is an old form of energy generation wearing a new name. There are many different methods of energy production under the label of "biomass". The best known and understood is burning wood for energy, but it's not necessary to burn fuel in order to create energy. Many of the projects being proposed as "green energy" are biomass projects. They include many waste energy systems, that create energy from the methane gasses created by rotting garbage in landfills. Other systems use human and animal waste to create methane gas which is burned to produce energy. A number of large zoos around the country are testing such waste energy systems.

Biomass energy production also includes crops grown specifically to ferment for fuel, like corn or sugar cane to make ethanol, or using waste vegetable oils or animal fats to make biodiesel fuels.

Geothermal Energy

Geothermal energy uses the heat generated inside the Earth either directly or indirectly to create power or heat. Hot springs and geysers have been used since ancient times to generate heat for homes. Using geothermal energy to generate electricity is a more recent development. The United States currently is the largest producer of geothermal electricity - but it accounts for about one half of one percent of the energy produced in the U.S. California leads the way with 34 geothermal plants, while Nevada has four. Utah, Hawaii and Montana each have one.

Wind Energy

Wind energy is the form of energy that is getting the most publicity these days. Windmills have harnessed the power of the wind for centuries, using it to turn millstones for grinding corn and grain. Modern wind turbines turn generators to produce electricity. A single wind turbine has little impact on the surrounding environment, but many communities are beginning to protest the location of large scale wind farms nearby, complaining of the effects of the noise and vibrations.

Learn More about Renewable Energy

One of the best places to get a balanced view of the pros and cons of each type of renewable energy, including how each is used and what the potential uses may be is at the Energy Kids site developed by the U.S. Energy Information Agency. Written for elementary and intermediate students, the information is accessible and easy to read for anyone.

Photo Credit: Energy Information Administration Energy Kids