Solar panels use photovoltaic (PV) cells to convert sunlight into electricity. They contain conductive substances like phosphorus and boron inside silicon layers. When light energy (or photons) from the sun hits the cells, electrons are released within the layers. Metal strips conduct this flow of electrons along the panels to an inverter that converts it into electricity that can be used immediately or stored in batteries for later use. Photo credit: NREL.

Renewable Energy Projects

With more than 300 days of sunshine annually, Denver is an ideal environment for sun-powered energy systems. Our wind-swept eastern Colorado plains offer a vast potential energy source, as well as opportunity to produce biofuels from home-grown grain harvests.

Through a variety of projects and partnerships, Denver is on the forefront of exploring these and other technologies to build a rich portfolio of renewable energy solutions. In addition to supporting our greenhouse gas reduction goals, they help lay the foundation for our region’s new energy economy.

Solar Array at DIA

In 2008, Denver International Airport will be home to a two-megawatt solar energy system. Currently under construction, the array will be located at the entrance to the main terminal and will consist of a series of ground-mounted tracking solar photovoltaic panels that follow the sun as it moves across the sky. The array is expected to generate 3.5 million kilowatt-hours (kWh) of clean electricity annually, helping to reduce DIA’s energy costs and avoid pumping over five million pounds of carbon emissions into the atmosphere each year.

The system, to be built by WorldWater & Solar Technologies, will be financed by MMA Renewable Ventures LLC. MMA will own and operate the system and sell power to DIA under a long-term Power Purchase Agreement (PPA). The project is part of Xcel Energy’s Solar Rewards program and will receive a rebate to offset the upfront construction costs. Xcel will also design an educational display for installation in DIA’s main terminal to explain the benefits of solar energy.

Landfill Gas-to-Energy Plant

Colorado’s only operational landfill gas-to-energy plant began operation in September 2008. Located at the Denver Arapahoe Disposal Site near Hampden Avenue and Gun Club Road in Arapahoe County, the plant produces approximetly 3.2 megawatts of electricity, enough energy for about 3,000 homes.

Landfill gas consists of approximately 50 percent methane, 50 percent carbon dioxide, and trace amounts of other gases. It is produced from the normal decomposition of organic matter. The Denver Arapahoe site, one of the largest landfills in the nation, generates approximately 1,200 cubic feet of landfill gas per minute, which is burned in four combustion engines and converted into electricity. This beneficial use of landfill gas  reduces the greenhouse gases produced at a coal-fired power plant through indirect offsets, and similarly reduce other air pollution emissions.

The City & County of Denver sells the landfill gas to Waste Management of Colorado, which constructed, owns, and operates the plant. Electricity from the plant is then sold to Xcel Energy. According to the U.S. Environmental Protection Agency, landfill gas continues to be produced for twenty years or more even after a landfill is closed. The Denver Arapahoe site could, therefore, operate for many decades to come.

• Learn more: Landfill Gas-to-Energy Fact Sheet (286K PDF)

IN-DEPTH:

• Watch a tutorial showing the inside of a solar power cell.
• Learn more about solar energy basics.