Republic Services’ Hickory Ridge solar landfill cap in Atlanta is the largest of its kind.
SWEET SOLAR SANITATION: One of the highlights of the opening ceremony for the Hickory Ridge solar landfill installation was the remarkably accurate cake made in its image.
In early October, the ribbon was cut on a solar farm on Republic Services’ Hickory Ridge Landfill on the south side of Atlanta. The innovative facility is the largest solar plant in Georgia and the largest solar landfill cap in the world according to Andy Keith, an environmental specialist for Republic who’s closely involved with the project.
Permitting of the Hickory Ridge project began three years ago after Republic successfully installed a smaller solar cap atop the Tessman Road Landfill in San Antonio as a proof of concept. Construction on Hickory Ridge, a 48-acre site that opened in 1993 and closed in 2008, began in earnest in September 2010. Keith says the site was chosen due to its unique combination of attributes: the timing of its closure, its proximity to a major metropolitan area, and its large south and west facing slopes (preferable for optimal collection of the sun’s rays).
Keith says the solar cap is made possible through the use of several technologies. The 6,974 individual photovoltaic laminates are remarkably thin and flexible, enabling them to flex and settle with the landfill without compromising function. Each generates 144 watts.
The cap also relies on thermoplastic polyolefin, a membrane material produced by Carlisle SynTec. “Though it is new to the landfill world, it has been in use in green roofs for years,” says Keith. The membrane covers the entire cap and also is used to encapsulate the million feet of wiring that runs over the surface of the hill, connecting the panels to four large inverters at the base. There the electricity is converted from DC to AC and passed to the Georgia Power grid.
The project received additional funding from the Georgia Environmental Finance Authority, which effectively doubled the number of solar panels that could be installed. The facility generates just over one megawatt (1,000 kilowatts), enough to power 224 homes.
The solar facility had its official unveiling on Oct. 4. A range of public and industry officials were on hand to praise the forward-thinking project, including Georgia Lieutenant Governor Casey Cagle. The event featured a sheet cake crafted in the likeness of the Hickory Ridge facility. Such was the fidelity of this post-closure pastry that its interior featured varying strata, fondant gas collection piping and a gray frosting sanitary liner near the bottom.
A landfill-gas-to-energy project is also planned for Hickory Ridge, and Republic is looking for other sites where solar caps may be viable.