That’s a question I’ve gotten routinely. Here’s the “official” definition from the US Government used to purchase renewable energy:

Executive Order 13323: Renewable energy is energy produced from biomass, geothermal, solar, and wind sources.

Practically speaking, renewable energy is energy whose source is not destroyed when harnessed. The principal renewable energy sources in use today are:

• Hydro: Harnesses water action (gravity, tides, etc.)
• Solar Thermal: Harnesses the Sun’s heat
• Solar Photovoltaic: Harnesses the Sun’s photons
• Wind: Harnesses wind currents
• Geothermal: Harnesses the heat of the Earth
• Biomass: Harnesses photosynthesis process

Each of these sources has a number of different technologies associated with their capture and translation to energy in our society. For instance, in the wind case, wind energy is translated to mechanical energy by physically turning a shaft. That shaft in turn is connected to a generator which translates the mechanical energy into electrical energy. Wind energy has one huge advantage over say, natural gas fired electricity generation: Wind is free. That economic benefit can’t help but assert itself as fossil fuels become more scarce and more expensive.

Besides not destroying the source of the energy, renewable energy sources often have other benefits like low levels pollutants emitted into the atmosphere. Renewable energy is also termed sustainable because of its unique properties. The renewable energy sources exist, the technologies to harness these sources exist, therefore there is little reason not to pursue renewable energy both for electricity generation and for transportation.

Ohio State’s 2006 record: 7-0 Next up: Indiana 10/21
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