Renewable energy sources capture their energy or fuel from existing flows of energy – sunshine, wind, flowing water, biological processes and geothermal heat flows. The most common definition is that renewable energy is from an energy resource that is replaced rapidly by a natural process. Capturing renewable energy by plants, animals and humans does not permanently deplete the resource. Fossil fuels, while theoretically considered renewable on a very long time-scale are used at a much greater rate than they have the ability to renew.
The Pacific Northwest relies on the hydrologic cycle for over half of its energy supply. The hydrologic or water cycle recycles the earth's valuable water supply through a process that involves evaporation, condensation and precipitation. The sun is the energy that powers this remarkable process of renewal. Water from the oceans, rivers, lakes and even puddles evaporates and warm air currents rising from the earth's surface lift the evaporated water vapor up into the atmosphere. Once these air currents reach the cooler layers of the atmosphere, the water vapor condenses around and clings on to fine particles in the air, forming clouds and eventually falls as precipitation in the form of rain, snow, sleet or hail. The water collected in rivers during this process is used by the hydropower system as "fuel" to produce electricity.
Solar thermal technologies use the sun's heat energy to heat substances (such as water or air) for applications such as space heating, pool heating and water heating for homes and businesses. Photovoltaics (PV), although often confused with solar thermal, is a technology which converts light energy directly into an electric current that can either be used immediately or stored, such as in a battery, for later use. Photovoltaics (photo=light, voltaics=electricity) is what many people refer to as "solar energy."
Many organic materials can release gases in a fermentation process referred to as biogas. Landfills actually need to release this gas to prevent dangerous explosions. Biogas can easily be produced from current waste streams, such as: paper production, sugar production, sewage, animal waste and so forth. The Coffin Butte Resource Project generates electricity from landfill gas, a natural byproduct of the decaying organic matter in the landfill.
Winds, formed as a result of the sun heating the earth unevenly, can be used to generate electricity through the use of wind turbines. Wind strengths vary and thus cannot guarantee continuous power, so some suggest incorporating wind, solar and other technologies with a system that has significant reserve capacity such as hydro to provide a reliable, stable supply of electricity.
For additional information visit the Northwest Power and Conservation Council.
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