Study pushes trash-to-gas process

Researchers say convert garbage to ‘syngas’ rather than shipping to landfill

By Dameon Pesanti, Columbian staff writer

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While studying abroad as a Washington State University Vancouver student in Monterrey, Mexico, Philip Behrend was taken aback by the volume of garbage choking the streets.

He returned home with a whole new appreciation for how well the United States processes its trash — but that appreciation didn’t last very long.

“I learned we produce more waste in the U.S. per capita, but we’re just really good at hiding it,” he said. “I started thinking about what we could do with the waste, because there’s a lot of energy in it.”

Behrend, who was an applied mathematics student at the time, partnered with his professor Bala Krishnamoorthy. The two determined that over a 10-year period it would be more environmentally and economically beneficial to send some of Western Washington’s trash to a gasification facility in Seattle where it could be converted to a synthetic gas, so-called syngas, to produce electricity.

The results of their study were recently published in a paper titled “Considerations for waste gasification as an alternative to landfilling in Washington state using decision analysis and optimization.”

Steam gasification is a process that heats organic materials to very high temperatures without combustion and breaks them into their primary elemental components. The process is considered to be a sustainable way to reduce waste while simultaneously producing energy and useful by-products, but it is an expensive technology to employ.

As a result, gasification is found in only a few places in the U.S., but it’s often used in Japan and Scandinavian countries where land comes at a premium.

“I think that’s the issue in the western U.S.; there’s enough open land to dump it. We’re not thinking long term,” Krishnamoorthy said.

The United States is among the world’s top waste producing nations, but unlike most of the developed world, we typically bury it somewhere out of town rather than putting it to good use. Washington, which prides itself on being environmentally conscious doesn’t buck the trend.

Roosevelt Landfill

The state is home to the Roosevelt Regional Landfill, one of the largest in the country. Tucked into the eastern edge of the Columbia River Gorge, it receives some type of solid waste from 28 of 39 Washington counties, according to the Department of Ecology’s 2014 annual status report on solid waste in Washington. It also accepts garbage from parts of British Columbia and Southeast Alaska.

By Behrend’s and Krishnamoorthy’s calculations, nearly a fifth of the trash that would be shipped to the Roosevelt landfill and buried, could instead go to one steam gasification facility in Seattle. There it would be used to produce syngas, which can be used in a variety of applications including plastic and electricity production, and fly ash, that can be used to make cement and other products.

“If you look at it for one year, you think it’s a big expense and it’s too costly now, so let’s just dump (the trash) in a landfill,” Krishnamoorthy said.

Although gasification facilities are initially very expensive, their research showed that over a 10-year period it would be more economically and environmentally beneficial to capture trash from Washington’s five largest trash-producing counties than shipping it to Roosevelt as they currently do.

“Considering the economics of the high-value by-products, in addition to the environmental costs savings, it’s a positive business model,” Behrend said.

In fact, as gasification technology continues to improve and become cheaper, they expect it to become an important option for future waste management.

“Landfills spend significant resources on toxic emissions sequestration and waste containment,” they wrote in their paper. “By choosing alternative options, these funds may be diverted toward investment in superior processing technologies such as gasification, leading to a reliable source of alternative energy while eliminating many negative consequences associated with traditional techniques.”