Making it work: Geothermal on campus

from Wildlife Promise

Geothermal small
In case you haven’t heard, geothermal and ground-source heat mining are pretty hot right now — though someone needs to come up with a catchier title for the latter, we think.

In short, geothermal electricity comes from using scalding groundwater to power turbines and generate electricity, and ground-source heat pumps use the temperature of the earth to heat buildings in the winter and cool them in the summer (although electricity from another source is necessary to power these pumps, they are often more efficient than traditional HVAC systems).

Location really determines the potential for using these technologies. Oregon Institute of Technology, geologically-blessed as it is, has identified enough geothermal energy to power its entire campus off superhot groundwater, and is already in the process of doing so. Other colleges, lacking that resource, are experimenting with ground-source heat-pumps, both open- and closed-loop.

We covered both types last fall, with a three-part series on geothermal and ground-source heat. The first piece describes electricity-generating geothermal installations (like the one at OIT), the second explains ground-source heating/cooling, and the final story
breaks down some of the most interesting campus examples of
ground-source heating, with figures on cost, energy savings, and
drawbacks. 

As we were researching these stories, we found that these systems
are not only complicated, but also very sensitive to the geology of
their region, making a universal, fool-proof process, particularly for ground-source heating, hard to implement.

Bill
Johnson notes in an article for Facilities Manager that “the state-of-practice shows high geothermal system failure rates, particularly in large-scale applications. This is especially true for open or standing column well designs, which require specialized geologic and hydrogeologic expertise.”

Since a university definitely qualifies as a “large-scale application,” what can be done to reduce the failure rate? These installations are hardly cheap.

Johnson recommends a phased approach, in which geothermal engineering experts are brought in for preliminary studies where information on everything from the site footprint, HVAC loads and GHG emissions targets to hydrogeologic data and permitting issues is collected. Then, after the installation of a test well and detailed reports of the well field, construction can move forward, monitored all the while by trained geotechnical engineering experts. Everything from soil structure to aquifer sustainability must be taken into account to ensure the wells continue to function.

When applied correctly, Johnson says, these systems are invaluable. “Proper application of ground source geothermal technology can dramatically impact the efficiency and financial performance of energy utilization (30%+) in a building or on a campus. At the same time, this alternative energy resource can significantly contribute to the institution’s carbon reduction goals. Geothermal applications also offer the possibility of aesthetic and noise abatement benefits (eliminating cooling towers and dry coolers in sensitive locations or on historic structures) and, when combined with “green” or lower cost, on-site electrical power, the benefits are many.”