Digging into energy from the earth

Posted on 29. Aug, 2012 by in Academic Departments, Annual Report, Civil and Environmental Engineering, Energy Independence, Engineering Professional Development, Environment and Sustainability, Interdisciplinary Degree Programs, Issues, Research, Students

Drilling group

From left: Industry partner Bruce Walker, Geology Professor David Hart, Associate Professor Dante Fratta and Assistant Professor James Tinjum on the DISH drilling rig.

Drawing on data gathered from a heavily instrumented Adams County, Wisconsin, home, Engineering Professional Development and Civil and Environmental Engineering Assistant Professor James Tinjum is seeking to provide scientific support for a deep insulated single-hole (DISH) geothermal heat pump system, a novel heating and cooling method that capitalizes on heat stored in geological structures deep underground.

In Wisconsin—a state that imports most of its energy resources, including natural gas, coal and oil—local contractors can install geothermal heat pumps, which boosts local economies and reduces our reliance on outside energy resources.

By circulating a liquid through a series of buried pipes, geothermal heat pump systems extract heat from the ground for heating in winter and transfer heat back into the ground for cooling in summer. Vertical wells for such systems take advantage of the geothermal gradient—the rate temperature increases with depth in the earth—and typically range from 100 to 500 feet deep.

However, the Adams County DISH system employs a single, 1,400-foot-deep well, installed with funding from the UW-Madison Innovation & Economic Development Research Program. There, Tinjum, Civil and Environmental Engineering and Geological Engineering Associate Professor Dante Fratta, Geology Professor David Hart and their industry partners are studying whether higher temperatures at that depth will make the entire system more efficient, and in the long run, more cost-effective and environmentally friendly. Because even “green” technologies use materials and non-renewable energy resources to manufacture and install—and in some cases, operate—the researchers also are conducting a life-cycle assessment. “This will be one of the first instrumented deep-well projects that will supply life-cycle science to the practice,” says Tinjum.

In addition, to further inform the science underlying geothermal heat pump system choices and to fill the Wisconsin-sized hole in national geothermal gradient maps, the team has drilled and instrumented six 1,000-foot-deep wells in strategic locations around Wisconsin.

Nine students—funded through a three-year National Science Foundation research experience for undergraduates grant in energy geotechnics—are actively participating in all aspects of the research, from field analyses to the life-cycle assessment. Tinjum, who shares his appointment with the Department of
Engineering Professional Development, also will incorporate the research results into short courses for professional engineers.

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