CCAT - Renewable Energy

Renewable Energy
Currently, most of our energy demands are met by non-renewable and polluting sources. Fossil fuels are running out and can’t be replaced for millions of years. They also create air pollution and greenhouse gasses. Nuclear energy creates radioactive waste that cannot be safely disposed of and persists for countless generations. Hydroelectricity from dams impairs fisheries and disturbs natural ecosystems.

Renewable energy is energy obtained from a source that is infinite, or able to be easily replenished by natural means. Renewable energy is sometimes referred to as "clean energy" because it creates far less pollution than conventional sources. Renewable energy includes solar electricity, wind power, micro-hydro energy, solar/hydrogen fuel cell technologies, and digester gas. Geothermal energy, biomass co-generation and bio-fuels are sometimes considered renewable as well. CCAT demonstrates a utility-intertied solar electric system that feeds excess energy to the grid and decreases our dependence on fossil fuels.

Grid Intertie
CCAT's Grid Intertied PV System
Home Power Article by Jim Zoellick and Andrew Posner © 2002

Solar Electricity
This is obtained using a photovoltaic cell, which releases electricity as sunlight hits it. Photovoltaic cells are made from the world's most abundant mineral, silica. Solar cells are expensive and polluting to make, but provide clean energy for 40 to 70 years or more.

Wind Power: Wind energy spins turbines, which create electricity via an electric motor. It is cleaner to produce and less expensive than photovoltaic cells, but only functions in consistently windy areas.

Solar L.E.D.'s Lighting System [PDF 84.8KB]
HSU Student Article and Handout by Idyath Yassemi (Fall 2004)

Micro-hydro Energy
Flowing water spins turbines, which create electricity via an electric motor. Unlike dams, micro-hydro turbines don't block the natural flow of waterways because they are much smaller. Micro-hydro turbines can work in small streams as long as there is sufficient water that flows fairly rapidly. Systems range in size from 200 watts to 10 kilowatts.

Solar/Hydrogen Fuel Cell
Solar electricity can be used to split water into hydrogen and oxygen gasses. Hydrogen can be passed through a fuel cell, which generates electricity as the hydrogen recombines into water. Fuel cell technology can eliminate the need for battery storage of electricity by storing hydrogen instead. Hydrogen fuel cells can be used to run electric cars or home systems. They are a renewable technology only when the hydrogen is derived from a renewable electricity source. Currently, fuel cell technologies are cost prohibitive.

Digester Gas
This is a natural gas (methane) that is most commonly obtained from animal or human manures, which are decomposed in a sealed container without oxygen. It is usually used for heating or cooking, but is likely to give off a foul odor during use. The by-product from methane production is compostable organic matter.

Geothermal Energy
There are two types of geothermal energy: passive and active.

Passive geothermal [energy] uses the ambient ground temperatures 100-200 feet below ground to moderate the temperatures in the home. At this depth, the earth is a constant temperature of approximately 503⁄4F. In the winter, when air is cold, passive geothermal will warm the house. In the summer, it will keep it cool.

Active geothermal [energy] uses the high temperatures from deep earth vents to generate steam that turns electricity-producing turbines. This type of geothermal may not be renewable because generating steam could cool the vents, making them unusable.

Biomass
This is the burning of agricultural or mill wastes to heat water, which makes steam that turns an electricity-producing turbine. While this is often considered a renewable energy source, it may not be sustainable because it adds CO2 to the air and depletes soil of nutrients and organic matter.

Biofuel
This includes bio-diesel, ethanol, and methanol, which are all liquid fuels made from organic materials that can fuel automobiles, or generate electricity.

Bio-diesel is diesel fuel made from waste vegetable oil. See the Bio-diesel section for more detailed information.

Ethanol is an alcohol usually made from the fermentation of corn stalks. Methanol is an alcohol made from the fermentation of wood. While these fuels provide energy without petroleum, producing them is an energy inefficient process that adds CO2 to the air and depletes soil of nutrients and organic matter.