Over the past several years, the solid waste industry has worked to re-brand itself as environmentally conscious by promoting its increased recycling efforts, landfill gas-to-energy projects, and the Leadership in Energy and Environmental Design (LEED) certification of new or expanded facilities. Nearly two years ago, the National Solid Wastes Management Association (NSWMA) adopted a new motto for the industry: "Environmentalists. Every Day."

Now, an increasing number of landfill operators are giving the industry another environmental initiative to tout. These operators are making better use of closed facilities or closed sections of working landfills by installing covers that capture energy from the sun to power their operations, nearby neighborhoods or entire towns.

"A closed landfill can't be used for anything else," says Vince Guthrie, utility programs manager at Fort Carson, Colo., where a closed landfill has been capturing solar power since 2007. "It's just used-up land. Using the space to capture solar energy is the most sustainable way to continue to use the resource. Utilizing landfills to help address our nation's energy challenges makes sense."

While industry leaders hesitate to call the practice a trend, they agree that it could grow. "There definitely is a potential in the waste industry for an expanded use of solar technology," says Bruce Parker, president and CEO of NSWMA.

San Antonio and Atlanta

Phoenix-based Republic Services has garnered kudos and awards for its Tessman Road landfill in San Antonio, which features a cover with solar panels placed over a closed section. The firm is installing a similar cover on a closed portion of its Hickory Ridge landfill, located just outside Atlanta in DeKalb County, Ga.

The engineered cover system used by Republic features laminate-like, solar-energy collection strips that adhere to a synthetic, geomembrane cover, says Tony Walker, an engineering manager for Republic Services. "The solar panels convert the sun's rays to produce renewable energy, while the geomembrane substrate provides an environmentally safe and economical method for capping closed landfills," he says.

At the Tessman Road facility, the solar-energy system produces approximately 185,000 kilowatt hours of electricity per year. The Hickory Ridge project will produce approximately 1.4 million kilowatt hours of energy per year. As at the Tessman Road facility, the electricity produced by the Hickory Ridge site will be fed into the local grid and used to help power the surrounding areas.

"When it comes to the environment, we wanted to show our neighbors and customers that we are committed to being part of the solution by creating better, cleaner processes and programs through fresh thinking and innovative solutions," Walker says.

Fort Carson

At the Fort Carson Army Base in Fort Carson, Colo., sustainability goals call for the base's power supply to be "100 percent renewable" by 2027, according to Guthrie, who oversees Fort Carson's utilities and electric bills. In 2007, when base leaders were looking at ways to better use the site's resources, they realized the landfill that had been closed for years could be used to collect solar power and reduce the base's dependence on fossil fuels.

Working with the Department of Energy's Western Area Power Administration (WAPA) and other public and private organizations, Fort Carson engineers developed a plan for converting the landfill into a solar-energy site. Fort Carson leased the land to a group of utility investors who built the system, which consists of a 12-acre array of solar panels mounted directly into the ground. Under its power marketing authority, WAPA wrote two contracts to allow Fort Carson to buy power from the array for a low fixed cost for 20 years. The installation actually purchases the power from Colorado Springs Utilities, provider of all of Fort Carson's electricity. The lead contractor on the project, meanwhile, then sells the resulting renewable energy credits to Denver's utility company, Xcel Energy, under Xcel's Solar Rewards program. Xcel then applies the credits to its compliance with the state's renewable energy portfolio standard.

Since 2007, the solar array at Fort Carson has produced 3,200 megawatt hours of power each year, which is about enough to power 500 base homes for a year. "Reducing Fort Carson's reliance on fossil fuels helps us build a sustainable energy future that is good for our bottom line, the environment and national security," said Guthrie.

Haywood County, N.C.

At Evergreen Packaging's closed landfill in Haywood County, N.C., a solar photovoltaic array was installed earlier this year and began generating electricity in March. The facility, renamed Evergreen Solar Farm, is now owned and operated by FLS Energy and all electricity produced there is purchased by Progress Energy Carolinas, which distributes the power to its local customers.

Because of landfill site regulations, the support structure for the solar energy system cannot penetrate the ground, says Joanna Malcolm of FLS Energy, Inc. To abide by those regulations, FLS Energy designed 195 ballasted units, each supporting 12 panels that can stand up to high winds and are able to withstand the settling of the landfill. Currently, the system is producing an estimated annual 800,000 kilowatt hours of electricity, Malcolm says.

"The solar array is a great use of land that might otherwise be non-productive," says Mike Cohen, a spokesman for Evergreen Packaging. "When we had an opportunity to use the landfill for a solar array in a way that wouldn't disturb the land beneath it, we were more than happy to participate. A closed landfill is a big, open space with great exposure to the sun and limited other uses, so a solar array is a great choice."

As these projects demonstrate, using closed landfills to capture solar energy can provide environmental and financial benefits, but they can represent significant financial outlays. "With solar technology, the cost of panels, installation, monitoring and regulatory compliance are expensive," NSWMA's Parker says. "For this reason, to a large extent, renewable energy projects are dependent on continued federal subsidies, such as the Production Tax Credit and the Investment Tax Credit, which encourage capital investment in renewable energy projects. Not only are landfill owners looking at producing and selling solar energy to utilities, but financial investors are too."

According to the U.S. Environmental Protection Agency, there are about 100,000 closed landfills in the United States, which could potentially represent hundreds of thousands of acres of property that could be used for solar energy development. "A lot of these closed landfills are close to urban areas and have infrastructure in place to deliver solar energy economically," Republic Services' Walker says. "Currently, there is a lot of interest from developers wanting to use landfill property to construct solar parks. Also, the current administration is encouraging the reuse of old landfill property."

"As long as the government maintains their push for a renewable energy society and the cost of solar keeps coming down to compete with fossil fuel energy sources, then the trend should continue for solar developers wanting landfill property," Walker adds.

While the movement to go solar at closed landfills is not yet widespread, it "is an important step for the industry," Parker says. "Using solar technology at landfills is another important 'green message' to support our commitment [to the environment] and build credibility."

Nancy Mann Jackson is a Huntsville, Ala.-based writer.

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