Solar Energy

Solar Photovoltaic (PV)

Solar PV is what most consumers immediately imagine when someone mentions solar energy. PV applications provide power for devices from satellites in orbit around the earth to the flashing lights of a traffic signal.

Commonly known as solar cells, individual PV cells are electricity-producing devices made of semiconductor materials. PV cells come in many sizes and shapes, from smaller than a postage stamp to several inches across. They are often connected together to form PV modules that may be up to several feet long and a few feet wide. When light shines on a PV cell, it may be reflected, absorbed, or pass right through. But only the absorbed light generates electricity. The energy of the absorbed light is transferred to electrons in the atoms of the PV cell semiconductor material.

Photovoltaic panels can offset energy consumption at your home or business. When combined with other renewable energy devices such as on-site energy storage equipment, geothermal, or solar thermal, these locations can even be net-zero.

Solar Thermal

Direct heating of fluids by the sun can be effectively used for numerous domestic and industrial purposes. Solar thermal systems are composed of two main parts - a solar collector and a storage tank. These collector panels appear similar to photovoltaic, but there are substantial differences. Thermal panels have a pattern of small tubes which circulate water or an anti-freeze solution through the unit. The tubes are attached to a black plate, which absorbs the sunlight and heats the fluid flowing through the pipes. The fluid is usually transferred to an insulated storage tank, which can then be circulated for space heating or hot water generation.

Passive Solar Heating and Lighting

Using the power of the sun for heat and light is one of mankind's oldest technology pursuits. The Native Americans of Mesa Verde in southwestern Colorado designed their cliff dwellings so they would catch the warm rays of the sun in the winter and take advantage of the hill's cool shadows during the summer.

Today, buildings employing passive solar design take advantage of sunlight to heat and light indoor spaces through the same simple methods. Proper orientation of the building to the sun is a very important element. Solar buildings typically have large, south facing windows to allow maximum light and thermal gain. The sun heats thermal mass - floors and walls made of dense, solid materials such as concrete or tile, during the day and gradually releases the heat at night. Often, these passive solar heating features double as lighting sources, allowing natural light into interior spaces through the south facing windows, skylights and suntubes.

During the summer, passive solar design features can also keep buildings cool. West facing windows are minimized, and longer roof overhangs provide shade for windows when the sun is high in the summer, keeping thermal mass such as walls and floors darker and cooler. Open floorplans allow flow-through ventilation, reducing the need for electric fans and air conditioning.

Wind Energy

Utility Scale

Colorado has an installed nameplate capacity of nearly 1300 MW of wind power. New wind farms serving many parts of the US are being located on farm and ranch land, providing steady lease income to the landowners -- and most significantly, increased economic opportunity for depressed regions of the country. Colorado's eastern plains offer a significant resource, ripe for wind energy development. In 2009, the National Renewable Energy Laboratory published data suggesting Colorado has the potential to install 387,220 MW of wind.

Small Scale

Small scale residential and mid-sized wind facilities offer rural residents, farmers and agricultural processing facilities predictable power costs, making their business enterprises more stable and profitable. Wind turbines are often combined with photovoltaic systems to create hybrid systems, for when the sun disappears due to an approaching storm, the wind begins to blow. Wind turbines could be used to power biomass / biofuel conversion plants, creating a perpetual cycle of renewable energy generation.

Links

Wind Powering America
http://www.windpoweringamerica.gov

US DOE Wind and Hydropower Program
http://www1.eere.energy.gov/windandhydro/

NREL's National Wind Technology Center:
http://www.nrel.gov/wind

American Wind Energy Association
http://www.awea.org

Geothermal

Geothermal Overview

The earth itself offers large supplies of energy. While fossil fuels such as coal, oil, and gas are extracted from the earth and burned, geothermal energy can often be tapped with minimal environmental impact. Heat emanating from the depths of the earth can drive turbines for electricity production or used for direct building heating; and the moderate temperatures underground can supply geothermal pumps with cool water to circulate throughout buildings in the summer.

Links

Geothermal FAQ
http://www1.eere.energy.gov/geothermal/faqs.html

US DOE Geothermal Program
http://www1.eere.energy.gov/geothermal/

NREL Geothermal
http://www.nrel.gov/geothermal/

Biomass

Biomass Technology Overview

Biomass technologies use organic matter to directly generate power and heat or be processed into fuels, chemicals, and other materials.

Since many types of organic matter is constantly renewed, biomass processes offer the benefit of generating oxygen while growing, and their combustion or conversion generates much less carbon and toxins than conventional fossil fuels.

Biomass sources vary largely, including agricultural food and feed crops, crop waste and residues, wood wastes and residues, dedicated energy crops and trees, aquatic plants, animal wastes, and municipal wastes.
Key elements in making biomass technologies commercially and economically feasible involve details of collection, handling, and distribution of resources to processing plants.

Links

Biomass FAQ
http://www1.eere.energy.gov/biomass/biomass_basics_faqs.html

US DOE Biomass Program
http://www1.eere.energy.gov/biomass/

NREL Biomass
http://www.nrel.gov/learning/re_biomass.html

Water Power

Hydropower

Currently, the United States generates approximately 100 Gigawatts of electricity from hydropower. Hydropower uses the inertia of the water as it drops due to gravity to spin turbines and generate electricity.

Small Hydro, Micro Hydro & Run of River

Small hydro projects vary in size but generally projects up to ten megawatts are the upper limit of small hydro. Small hydro can be further subdivided in micro and run of river. Micro hydro is usually used in small communities, single family homes and small enterprise and is generally less than 100 kilowatts.

Hydrokinetic

Hydrokinetic technologies produce renewable electricity by harnessing the kinetic energy of a body of water, the energy that results from its motion. Unlike traditional hydropower, many hydrokinetic technologies limit their effects on riparian systems because they do not require a dam.

Links

http://www1 US DOE Wind and Hydropower Program
http://www1.eere.energy.gov/windandhydro/hydro_basics.html

National Hydropower Association:
http://www.hydro.org/

HydroWorld
http://www.hydroworld.com/index.html