MAY 2009

Republic caps landfill with flexible solar cover

Republic Services, Inc. has embarked on an initiative to greatly increase renewable energy output at its landfills. The company combined a first-of-its-kind solar technology with an existing biogas-to-energy system to turn its Tessman Road Landfill in San Antonio, Texas into a sustainable energy park.

Republic’s latest green energy venture will cover portions of soon to be closed areas of active landfills with flexible, laminate-type photovoltaic (PV) solar collection strips developed by United Solar. The flexible solar laminates, which capture the sun’s rays for conversion into electricity, are adhered directly to a Firestone manufactured synthetic green-colored geomembrane used to cover and close a landfill as it reaches capacity. Unlike the more traditional rigid solar panels, which are bulky and frequently cost-prohibitive to install, Republic’s system uses flexible nonreflective collection strips less than 1/4 inch thick.

The flexible solar strips can be configured to maximize the hours of sunlight exposure throughout the year, depending upon a landfill’s design and site contours. For its demonstration project at the Tessman Road facility, Republic will partner with CPS Energy, Greater San Antonio’s electric and natural gas provider, to deploy 5.6 acres of the 680-acre landfill with the solar energy cover, attaching over 1,000 Uni-Solar flexible solar strips to the landfill’s south facing side slope. Republic and CPS Energy will study and document the results of this solar demonstration project for use in the deployment of solar energy covers on owned landfills throughout the region. Construction on the project, approved by the Texas Commission on Environmental Quality (TCEQ), began in December, 2008 and became fully operational in March, 2009.

The new solar cover will complement the landfill’s existing biogas-to-energy system, in operation since 2002. The system collects and processes biogas, which is naturally produced at the landfill through the decomposition of waste. The solar strips, which have flexible photovoltaic silicon cells that convert sunlight directly into electricity, will complement the amount of renewable energy provided by the landfill.

With over 300 days of sunlight in San Antonio per year, Republic estimates that the energy produced by the two fully-operational systems, will continuously create about nine megawatts of power – enough to power 5,500 area homes.

“The solar energy cover is easier to inspect, maintain and repair than a traditional clay cap, and is technically superior in terms of odor control and storm water management,” said Tony Walker, project manager for Republic. “Geomembrane covers are already in use across the country, but Republic is the first to integrate flexible solar cell technology to create an energy-producing cover system. We look forward to working with state regulators across the country to capitalize on the opportunities provided by landfills and, specifically, our efforts to further the country’s energy independence movement through new sources of solar power.”

Republic has 213 operating landfills in 40 states across the country. The company’s research suggests that as much as 2,350 acres could be covered with solar energy covers, depending on regulatory approvals. That translates into enough solar energy to power up to 47,000 homes per year. Combine that with existing biogas-to-energy technology, and Republic has the potential to generate enough green electricity to power 300,000 homes across the country.