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Converting trash gas into energy gold

By Daniela Chen
CNN

The process of converting landfill gas into energy is relatively simple.

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ATLANTA, Georgia (CNN) -- The trash you toss in the garbage could end up powering your lights, computer and washing machine, because in the world of alternative energy, one man's trash is another man's treasure trove of fuel.

With the growing concern for U.S. dependence on foreign oil and recognition of shrinking fossil fuel reserves, new attention is being focused on renewable sources of energy.

One such source that already is being converted to electricity is landfill gas.

According to the Environmental Protection Agency, every person in America produces an average of 4.5 pounds of garbage per day. Much of that trash goes into landfills, which are the largest human-related source of methane in the United States.

In 1994, the EPA formed the Landfill Methane Outreach Program (LMOP) under the United Nations Framework Convention on Climate Change. LMOP Team Leader Brian Guzzone said since methane is both a pollutant greenhouse gas and a source of energy, it offers a good opportunity to reduce greenhouse emissions and provide energy.

About 50 percent of all of the waste that we generate as a society today is put into municipal solid waste landfills, Guzzone said. The EPA encourages the capture of the resulting landfill gas and the energy produced from it.

The federal government has partnerships with more than 500 utilities, states, private businesses and communities. "The EPA's role is to work with communities that have landfills and help them realize the potential opportunity of their landfill," Guzzone said. That includes providing materials, technical services and community outreach.

Trash into gas

The process of converting landfill gas into energy is relatively simple. A series of wells sunk into a landfill collect the gas, which is then used to burn in engines and boilers, heat greenhouses, fuel vehicles, etc. Guzzone said landfill gas can be used just as traditional fuels such as coal and natural gas are used. "It's comparable to natural gas," he said.

In 2005, there were 396 operational landfill gas projects in the United States, Guzzone said. According to the EPA Web site, two-thirds of the current projects are being used to generate electricity, producing approximately nine billion kilowatt-hours per year.

The other third of operational projects supply gas for direct-use applications, such as fueling boilers, engines and greenhouses.

In total, the projects produce the energy equivalent of electricity for 725,000 homes or heat for 1.2 million homes.

One of LMOP's partners is textile manufacturer Interface Flooring Systems.

Located in LaGrange, Georgia, the company buys landfill gas from the city-owned landfill. The gas is sucked from the 90-acre landfill by 53 pipes, compressed and piped 10 miles to the carpet production plant where it is used as fuel.

David Gustashaw, Interface's vice president of engineering, stumbled upon the project while trying to find cost-efficient sustainable energy. "I got tired of hearing what were considered to be green renewable opportunities always costing more," he said.

After Gustashaw ruled out other alternative energy sources for practical reasons, the only option left on his list was landfill gas.

It turned out that landfill gas was the perfect fuel for his new production plant, which started operating last year.

Gustashaw's goal in approaching the project was to ensure true sustainability in its environmental, social and financial impacts.

By converting air waste into energy, Interface has reduced its dependence on natural gas by 20 percent and reduced greenhouse emissions from the landfill, Gustashaw said.

Socially, "the city is generating a revenue stream from something they were throwing away," said Gustashaw. "So now the city has more money for services for the residents."

On the financial side, the initial financial outlay for new equipment for the project was in the $2.5 to $3 million range. Gustashaw said that both Interface and the city will be able to recover the investment. The company expects to recoup its capital in two to three years, the city in four to five years, he said.

Gustashaw believes that his project pioneered the way for smaller-scale projects. On a much larger scale, Guzzone said that the fastest-growing segment interested in landfill methane is the corporate community of heavy fossil fuel users of natural gas.

But it's not a panacea for the nation's energy challenges. Both Gustashaw and Guzzone said that landfill gas projects are site-specific. Depending on the size and energy needs of the project, landfill gas may or may not be the best and most cost-effective alternative energy.

Nor is landfill gas expected to replace foreign oil. Because landfill gas is so site sensitive, Gustashaw said the best approach to offsetting our dependence on foreign fossil fuels involves a combination of alternative energy sources, including solar, wind, water, and geothermal power, as well as landfill gas, according to which resource best fits the particular situation.

One disadvantage to landfill gas is that though it's cheaper than natural gas, it has less than about half the heating capacity. However, neither Guzzone nor Gustashaw acknowledge any downsides to landfill gas energy when used in conditions that make it a good option.

"You're taking what was a liability and turning it into an asset," Guzzone said.