Until 1984 the Croton Landfill was the dumping site of much of Westchester’s garbage and solid waste. But beginning in 1996, what might once have been considered science fiction will become reality. A county program, now in the design stage, will convert the methane gas produced at the landfill into a source of revenue.
The program will use existing technology to capture the methane, a gas that is produced by the decomposition of vegetable matter, purify it and convert it to electricity and compressed natural gas. Methane at the landfill is now burned off and must be eliminated to prevent the possibility of fire. The county is also studying the possibility of taking another landfill gas, carbon dioxide, and capturing it for commercial sale.
The electricity generated by the program will be used at the 125-acre Croton Point Park, which is next to the landfill. The county spends $250,000 a year for electricity to light the park and heat buildings. Any excess electricity produced will be sold to Con Edison, which under state law must purchase it. The compressed natural gas will be used in the county’s natural-gas-powered vehicles, with any surplus being sold to pipeline operators.
The gas-conversion system, including machinery and a building to house it, will cost the county $6.9 million. This will come from savings in the budget for capping the landfill. Once closed, a landfill must be capped, or covered and ventilated, to prevent buried waste and gases from leaking into the environment. That part of the job will be completed this fall. Other Sites in Operation
But even after capping, the landfill will continue to produce methane gas until the year 2031, according to preliminary estimates prepared by the county. Once in operation, the gas-conversion plant will pay back its capital costs in 4.3 years. During the 35-year life of the program, the county estimates electricity savings at the park and net earnings of $19.2 million.
“This program will work for everyone,” said Anthony P. Trelewicz, Commissioner of the county’s Department of Environmental Facilities based here. “The first benefit is to the environment. By creating electricity, methane gas is not released or burned into the atmosphere. The second benefit is to the taxpayers of Westchester. The money saved on electricity will reduce the park budget. The electricity and natural gas sold will be a revenue.” In large concentrations, methane is regarded as an environmental pollutant.
Mr. Trelewicz said methane is being converted to electricity at landfills in Macedon and Oceanside, both in New York State, and in New Milford. Methane is being turned into natural gas in Wisconsin Rapids, Wisc., and Cleveland bottles and sells carbon dioxide from its landfill.
“The gas-extraction system already exists underground at the Croton Landfill,” the Commissioner added. “The pipes and wells underground are usable and were put there as part of the capping of the landfill. When you cap a landfill, you must put in that underground system to vent the gases or there could be an explosion and fire.”
Methane is now burned off at the Railroad 1 Landfill in Croton, an adjacent 20-acre municipal site, which was capped in 1986 and will be included in the gas-extraction program. While burning methane is considered safe for the environment, county officials feel that this program is a better way to eliminate the gas and provide income.
Within the next few months, the county will award a consulting contract for a design study, a job that Mr. Trelewicz estimates will take six to nine months. In addition to providing construction specifications, the study will determine how much methane the landfill can produce and how long it will last. When the study is completed, bids will be sought for the project.
As proposed, the gas-collection system will capture 1.5 million cubic feet of gas a day. One-third of the gas will be used to power a 740-kilowatt generator in a sound-deadening building, which will produce power for the park. The remaining gas will be used to create the natural gas equivalent of 700 gallons of gasoline a day. The building will be large enough, though, to allow a switch to total-electric production if desired.
“The compressed-natural-gas conversion is a pilot program that will last for one year,” Mr. Trelewicz said. “During this time, we will study the market for compressed natural gas in the county. If we want to sell it, we have to make sure there are customers out there besides us. One possible customer would be the municipalities. But if we can’t sell it, there is no use producing it. In that case, we can convert the plant to total generation of electricity.”
The county is now operating five natural-gas-powered vehicles in a pilot program to test the economic and environmental benefits. The vehicles travel 150 to 200 miles on two cylinders of natural gas, approximately the equivalent of 16 gallons of gasoline. The county purchases fuel for these cars under a contract with Con Edison, which has a fueling station in Rye.
Mr. Trelewicz expects the gas-conversion plant to be operating by 1996. “This is an exciting project,” he said. “We build waste-treatment plants, but this is different. We are using the byproducts of what was once waste to make fuel and energy.”
Source: The New York Times and WIH Resource Group
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