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News Release, Kansas Geological Survey, Oct. 18, 2004

Scientists to Study Gas from Trash

LAWRENCE--The gas that comes off of landfills is usually viewed as a smelly nuisance.

But scientists at the Kansas Geological Survey, based at the University of Kansas, are now trying to see if the gas generated from trash at the Johnson County landfill can be used to produce more natural gas from coal seams several hundred feet underground.

Deffenbaugh Industries, which operates the Johnson County landfill in northwestern Johnson County, and their business partner Kansas City LFG, currently capture the gas that is produced by the decomposition of trash. Methane is separated out of the landfill gas, cleaned, and put into a pipeline where it is then shipped and used for home heating, industry, and every place else that natural gas is used.

About 4.5 million cubic feet of landfill gas is collected through wells in the Johnson County landfill each day. About half of that landfill gas is methane.

The other half of the landfill gas is largely carbon dioxide and other waste gases.

At the Johnson County landfill, Survey scientists want to know if the non-methane gases coming off the landfill can be pumped underground and used to generate additional energy by forcing natural gas from subsurface layers of coal.

"We want to see if we can put landfill gases to work," said Survey geologist Dave Newell.

These Kansas coal beds, which underlie much of the eastern third of the state, contain methane. Drilling for this coalbed methane has boomed during the past several years because of high natural gas prices and the relatively low cost of drilling these natural gas wells in Kansas.

Now scientists want to see if the landfill gas from the Johnson County landfill might be used to push coalbed methane out of coal seams beneath the landfill.

"Many landfills in the US overlie coal beds and they may be able to use those gases instead of wasting them by flaring the gas or venting it into the atmosphere," said Newell.

Survey geologists are preparing to study the coal beds beneath the landfill and see how they might react to landfill gas. Beginning in mid-October, the Survey will drill two wells, each about 900 feet deep, at the landfill. Survey drillers will recover cores of the rock encountered during drilling, including samples of these coal beds.

Most Kansas coal beds are relatively thin (less than two feet thick), which is one reason why little coal is now mined in the state. However, several different coal seams underlie eastern Kansas, probably as many as 10 under the Johnson County landfill. Coalbed methane wells generally produce gas from several of these coal layers at the same time.

Once samples of the coal from below the landfill are collected, they will be sent to Oak Ridge National Laboratory in Tennessee, where they'll be tested by exposing them to the same kinds of gases that are produced at the landfill. During that testing, the cores will be subjected to the high pressure similar to that beneath the ground.

"We want to see how much the coal swells during this testing," said Newell. "This swelling reduces the amount of methane the coal can produce. We also want to see how much of the coalbed gas the coal will give off as it absorbs the landfill gas."

If the landfill gas is effective at pushing methane out of the coal samples, the next step may be to try a small demonstration project in which additional wells are drilled and landfill gas is pumped underground into the coal seams.

The Survey study is funded by the U.S. Department of Energy.

Story by Rex Buchanan, (785) 864-2106
For more information, contact Dave Newell, (785) 864-2183

Kansas Geological Survey, Public Outreach