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City turns trash into treasure

The idea of generating usable gas from garbage may sound like an idea you would hear from a guy trying to sell you a bridge, but this process is no joke.

In fact, Denton captures enough methane from the city landfill to power about 1,600 homes.

All the city has to do is add water, which it has been doing in a process used since 2008, and researchers at the University of Texas at Arlington are helping to double that power-generating capacity.

The project, which sounds like an excellent idea to us, is the first of its kind in Texas, according to UTA’s lead researcher, Sahadat Hossain.

Hossain, an associate professor of civil engineering and internationally renowned expert on landfill management, told us that landfills typically are kept covered and dry in order to limit methane emissions. When a landfill is kept dry, natural decay occurs much more slowly, Hossain said.

However, with the right amount of moisture and the right system to capture the methane, decaying organic matter can create enough gas to run a power plant.

A power plant? You read that correctly. Several such plants are running in Florida and other states, Hossain said.

Through April 2012, Hossain and his students studied an imaging system that allowed them to measure moisture in the Denton landfill without having to drill monitoring wells, which can let methane escape. The Denton study allowed UTA researchers to create a new model that helps crews know when, where and how to water the pile in order to make the most gas.

The city paid the UTA researchers about $182,000 for the work. This year, the city agreed to another three-year grant, this one for $344,414, to pay for Hossain and Melanie Sattler, also a civil engineering professor at UTA, to study fugitive emissions at the landfill.

Methane is a powerful greenhouse gas that contributes to climate change, Sattler said, and municipal landfills are a significant source of methane emissions.

The first year of the study, the group will be taking measurements where gas is escaping, Sattler said, and in the second and third years, they hope to field-test some strategies to reduce escaping gas. The strategies should not only help lessen the impact on the atmosphere but also help the city capture more gas for the power plant, Sattler said.

Vance Kemler, director of the city’s solid waste division, said the power plant is operated by DTE Biomass Energy. The plan is small and currently generating about a third of the capacity it is designed to generate. Long term, Kemler said he sees the power plant as one of many strategies that could help extend the life of the landfill.

Sattler said the project also could encourage other cities to consider a similar project. Some officials are reluctant to look at the concept, in spite of research backing it up, because it’s different and nontraditional, he added.

Kudos to the city of Denton for developing this project. It’s a great idea and one that we believe will eventually be a standard in cities across the nation.

Trash to treasure? It seems to be working here in Denton.