Modernized SSWI Composting Facility Nearing Completion
It is nearly complete, and the world is watching.
Sevier County’s new state-of-the-art solid waste disposal facility will soon be online, and if future opportunities come to fruition, additional trash-to-energy conversion technology could result in the generation of electricity and practically no landfill material.
“This technology would definitely place us on the cutting edge of solid waste disposal,” said City Manager Cindy Cameron Ogle. “It would generate power to operate the compost plant and open a new frontier which could be huge for Gatlinburg and the entire County.”
Sevier Solid Waste, Inc. (SSWI) was formed in 1989 to service the rapidly expanding solid waste disposal needs of Sevier County, including Gatlinburg. The original SSWI Composting Plant was considered among the most efficient (65 to 75 percent of waste diverted from landfill) in the world when it burned on Memorial Day weekend, 2007.
Since 1992, waste from the areas of Gatlinburg, Pigeon Forge, Sevierville, Pittman Center and Sevier County has been delivered to the composting facility and broken down by a composting technology developed by Bedminster, an Irish BioEnergy Technology Company which specializes in recovering high-quality, carbon-rich waste material normally disposed of in landfills.
The waste is dumped onto the tipping floor where large items are removed and placed in a trailer and disposed of at the county’s demolition landfill. A front end loader then pushes the garbage into one of five loading hoppers and a compactor pushes the material into one of five rotary composting digesters. Each digester can hold 75 tons of solid waste. Biodegradable material (paper, food waste and bio-solids) in the material is then broken down over a three-day period and turned into compost, which is then sold.
After the three-day retention period, the remaining digester material is discharged and sent through a screen. Screened materials are moved by front end loader to the aeration floor where the material is periodically turned and dried and continues composting for an additional four weeks.
The new four-building operation is scheduled to open in January 2009 with its capacity expanded and streamlined, including two aeration buildings encompassing 140,000 square feet of area plus tipping floor and discharge buildings. The result will be a 65 percent reduction in landfill material, but that number could be increased to 95 percent or even better if a new process is pursued. SSWI leaders are strongly considering a BioEnergy Conversion Technology also developed by Bedminster, which is on the leading edge of waste disposal technology resulting in renewable energy.
The new technology, which could be added at the SSWI site with a price tag ranging around $30 million financed by Bedminster, would use all unfinished compost material (BioMass) for the creation of electricity. Bedminster has set up a small prototype of its trash-to-energy system in which solid waste is “cooked” through gasification, a process called “pyrolysis” which converts the material into renewable energy with extremely
low emissions and a negative carbon footprint. The initial retention period the waste would spend in the digesters would be cut to two days, further streamlining the process and increasing the capacity of the plant from 375 to 575 tons of garbage per day.
Three pyrolysis units are being considered for SSWI, two for compost material and a third for residual inorganic fractions including plastic, gas, aluminum and metal. The heated product gives off a gas (hydrogen in the case of organic material) which is stored and then used by generators to produce power. The process produces eight megawatts of electricity for every one megawatt used, resulting in “green” electricity which can be sold, resulting in “carbon credits.”
If SSWI officials should decide to move forward with the Bedminster system, the carbon emissions savings could be equal to removing 135,000 cars from the road each year, Bedminster Chief Scientific Officer Ian Hargraves has said. In the short period the prototype pyrolysis system has been operating at SSWI, it has attracted attention nationwide and from worldwide government bodies and other organizations, who have sent officials to the area to get a look at the facility.
“If this all works out, we would generate electricity to run the entire facility and we would not have to haul much of anything away,” said Tom Leonard, manager of SSWI. “This will be one of the premier composting facilities in North America and an example of how the world can take advantage of waste-to-energy technology, something the people of Sevier County should be really proud of.”
