There is a good chance the stuff will return -- morphed into methane in the bowels of a regional landfill, cleaned up, pressurized, injected into the rivers of natural gas flowing through utility pipelines -- and eventually back into your house.
It took nature millions of years to build the vast reservoirs of natural gas trapped thousands of feet underground. These days, it takes a landfill owner only a few months to begin generating a similar mixture of gases in pockets just a few hundred feet down.
Landfill gas is not as naturally potent as so-called natural gas, because it contains 40 percent to 50 percent carbon dioxide, along with chemical impurities. But it can be cleaned up.
And, unless it is used as a fuel, it must by federal law be immediately flared (burned) on site because the U.S. Environmental Protection Agency has identified it as a greenhouse gas at least 20 times more potent than carbon dioxide. Of the nation's 1,000 or so large landfills, more than 400 in 43 states are today producing commercial gas instead of flaring, said the U.S. Environmental Protection Agency.
The gas is used in boilers, ovens, manufacturing processes, space heating, electricity generation and as a truck and bus fuel.
There are 11 Ohio landfills participating in the EPA's gas-to-energy program. And more will be added soon.
The publicly owned facility near Columbus is fueling a car and a truck with pure methane that it began to produce on-site in September from just 8 percent of its landfill gas. It plans to power its garbage transfer trucks with the gas and run a turbine to generate electricity for on-site use.
Small as it is, SWACO's purification system can generate the methane equivalent of 250,000 gasoline gallons per year, said spokesman John Remy. The authority is talking with school districts and transit systems about converting their buses to run on methane.
Landfill gas is definitely big business.
Houston-based Waste Management, the nation's largest investor-owned trash hauler, is producing fuel from landfill gas at more than 100 landfills, including four in Ohio -- Solon, Dayton, Toledo and Waynesburg, near Canton..
"It's resource recovery," said Paul Pabor, Waste Management's vice president for renewable energy. "The gas flow at a landfill will increase as long as it keeps receiving waste."
The company's new business focus is to use the gas to generate electricity with small gas-fired generators producing 3 to 6 megawatts, and shipping the power to local utilities. There is a federal tax credit for power produced with "biogas" - 1 cent credit for every kilowatt-hour generated.
"We directly own 43 power plants," said Pabor, "generating about 220 megawatts."
Add that to the power produced by outside companies at some of Waste Management's other landfills and you have enough electricity to power nearly one million homes, according to the company's Web site.
The company added six new gas production plants this year and hopes to add another nine next year, Pabor said.
Waste Management is looking to generate electricity at two additional Ohio sites in the future.
Waynesburg landfill supplies Dominion
Currently, its largest Ohio project is the American Landfill in Waynesburg, which has about 15 million tons of waste already buried and 3,000 tons to 4,000 tons of new trash arriving daily from all over Northeast Ohio. The 234-acre landfill ships 4 million cubic feet of gas every day to Dominion East Ohio Gas Co.'s underground storage reservoirs about nine miles away.
"We have 155 wells, which we tune on a pretty consistent basis," he said.
"We have to make sure the methane gas is of the right quality," Brady said. "It varies based on the depth of the well, how much organic there is and how old the trash is."
Brady especially likes household garbage and trash.
"The higher your residential percentage, the higher the organics," he said. "Probably 95 percent of what you throw away is going to break down - old clothes, left over pizza boxes, anything like that."
The trash typically has to be buried 18 to 24 months before it gets cooking. Then the wells, unless they were installed as the garbage was put in, have to be drilled.
Conventional rotary drilling rigs are used to bore into each self-contained landfill section, called a cell. But that's about all these wells have in common with a traditional natural gas well.
Landfill wells stop at about 150 feet, are interconnected near the surface and operate at negative pressure.
In other words, they are a kind of sprawling vacuum system, gently sucking the gas from the deeply buried, decomposing garbage and piping it to a pump station.
There is it either immediately burned -- or analyzed, cleaned up, pressurized and sent to a customer. The landfill at Waynesburg sends the gas to Dominion East Ohio gas company.
Filtering plant cleans up the gas
Getting the gas safely out of the ground is where Waste Management's role stops. The cleaning is done by Toro Energy of Ohio, a subsidiary of National Fuel Gas Co. of Williamsville, N.Y.
Toro's automated filtering plant at the landfill is interfaced electronically with Dominion's pipeline and reservoir control center. And a Dominion employee watches over the system.
Because Toro's clean-up plant removes only the chemical contaminants -- not the carbon dioxide -- the gas cannot be mixed one-for-one with the utility's pipeline gas because its energy value is only about half that of pipeline-quality gas.
Instead, it is piped into Dominion's underground storage nine miles away, to await careful mixing with gas flowing in a nearby major Dominion pipeline.
"It's about a 20 percent blending rate," said Darrin Wiechman, Operations Manager with National Fuel Gas. In other words, the blend is one part landfill gas, five parts pipeline gas.
At that percentage, the lower-BTU landfill gas does not dilute the pipeline gas energy levels below the industry standard --one million BTUs per 1,000 cubic feet.
"It's all automatically controlled within the system" said Wiechman. "If the gas flow rate of Dominion's pipeline reduces, the system will automatically back down our flow rate. The gas is continuously monitored downstream of the blending."
Dominion spokesman Neil Durbin said the big transmission pipeline carries 80 million cubic feet of gas per day -- 20 times the 4 million cubic feet coming from the landfill.
He said the energy density of the gas is measured after the blending to make sure it meets industry specs.
And just for the record, Durbin said, Dominion does not actually own the gas -- but only stores it and ships it on behalf of gas marketers, who asked not to be identified for competitive reasons.
Integrys Energy, an independent gas supplier that now markets "biogas," does not buy from Waste Management, a spokeswoman. said
Other independents are evidently considering the move to "green," however. Durbin said Dominion is talking to a number of landfill operators about accepting landfill gas -- which if shed of its carbon dioxide has the same energy value as natural gas.