What could be slicker than using one pollutant to clean up another?

How about saving taxpayers as much as $65 million?

The Milwaukee Metropolitan Sewerage District (MMSD) accomplished both feats this fall by signing a contract to burn landfill gas to offset a significant part of the natural gas the district uses to generate the electricity needed to clean wastewater. The agreement will go into effect in 2013.

The district is building a 19-mile-long, low-pressure pipeline to carry landfill methane from Veolia Environmental Services’ Emerald Park Landfill in Muskego to the district’s Jones Island Water Reclamation Facility in Milwaukee. The $94-million construction project involves designing and building the pipeline and installation of three new gas turbines at Jones Island.
 “We’re buying the same amount of landfill gas it takes to equal one energy unit of natural gas, but at 48 percent of the cost of natural gas,” MMSD executive director Kevin Shafer explains. The savings over the 20 years of the district’s contract with Veolia are estimated at between $25 million and $65 million.

 “The price of energy is a major expense for us,” Shafer says. “Volatile natural gas costs have had a negative impact on our budget and our customers. For example, we spent $14.8 million in 2008 on natural gas.” In the contract, the district will pay 48 percent of the cost of natural gas on the New York Mercantile Exchange for landfill gas.

Veolia says its 81-acre landfill currently produces enough methane to meet approximately half of the district’s present fuel needs at Jones Island. By 2025, gas output at the landfill is expected to increase to a point it can supply all of the needs at the wastewater treatment plant.

The Veolia-MMSD contract is one of some 25 landfill gas projects in Wisconsin and more than 520 across the United States. Landfill gas emissions are controlled by federal laws, and by Wisconsin’s requirement that any large landfill have a system for collecting gas on-site. At present, the Emerald Park Landfill collects the gas and burns it off in a process known as flaring.
Controlling landfill gas is important because it is made up of about 50 percent methane and 50 percent carbon dioxide. Methane, according to the Environmental Protection Agency’s (EPA’s) Web site, is an even more potent greenhouse gas than carbon dioxide, trapping 20 times as much heat per unit of measurement. Scientists have found that methane is more abundant in the atmosphere now than at any time in the last 400,000 years and 150 percent higher than it was in 1750. Landfills are the second largest source of methane emissions, accounting for more than 22 percent of the total.

The EPA began its Landfill Methane Outreach Program in 1994 to help landfill operators find uses for the gas, and the Wisconsin Department of Natural Resources (DNR) also is helping through its Fugitive Landfill Gas Initiative.    

Landfill gas projects are making a difference for the environment. The EPA says that U.S. methane emissions have decreased 7 percent since 1990 while the gross domestic product of this country grew by 65 percent. The Wisconsin DNR calculates there was a 39 percent decrease in estimated release of fugitive landfill gas between 2004 and 2007.

Commenting on landfill methane projects, Philip O’Leary, a University of Wisconsin-Madison engineering professor and chair of the Professional Development Department, says, “The regulatory requirements are driving the increase in landfill methane projects. They [the landfill operators] have to control the landfill gas anyway, and the best way to do it is to find a use for it.” The rising cost of fuel makes it an even better economic choice.

O’Leary, who has studied landfill engineering and solid waste for 30 years, adds, “You have to hand it to the landfill operators. They’ve gone from just collecting garbage, added recycling and now projects such as these.”

By John Hill

You can contact John Hill by e-mail at jhoythill@sbcglobal.net.