Landfills are not just an eyesore, but also produce methane as their contents decompose. Methane [CH4] is a greenhouse gas, and if not recovered, could accelerate climate change. On the other hand, recovered methane makes a great fuel, which can be used to generate electricity for the very residents and businesses contributing to the landfill.
In Texas, a city of Denton landfill recovers CH4 to generate electricity, and a recent development by two University of Texas Arlington [UTA] professors looks to increase it, possibly twofold. Sahadat Hossain and Melanie Sattler, associate professors of civil engineering at UTA, funded by a $344,414 city grant, were able to make improvements to the landfill’s gas recovery system.
The Enhanced Leachate Recirculation [ELR] system used on the Denton landfill recovers the contaminated water and gas to generate electricity. To increase gas, and therefore power, output, additional water is added to increase the rate of decomposition, but the amount of moisture needs to precisely controlled. This has made sustainable landfills somewhat difficult to achieve.
Hossain and Sattler developed a model to measure the landfill moisture content that doesn’t include drilling or sampling, which would interrupt the process, utilizing a resistivity imaging method to monitor moisture movement during ELR operation. “Resistivity imaging helps landfill managers know how quickly to recirculate the liquid and how effectively the system is working,” said Hossain.
Currently, the Denton landfill produces enough energy from ELR to power about 1,500 homes. Hossain and Sattler’s new imaging model could double that output to over 3,000 homes.