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Geothermal Heating Part of Mainstream Thinking
Geothermal heating now part of mainstream thinking
By Jennifer Smith - Kelowna Capital News
Published: May 14, 2009 10:00 PM
Geothermal systems have become part of mainstream building vernacular, according to an expert speaking at the third Biennial International Geoexchange Conference and Trade Show.
The conference is being held on the UBCO campus this week with several speakers from out of town, including Kevin Rafferty, an engineer who counts serving as the geothermal interest group chairperson on the U.S. National Ground Water Association among his professional credits.
According to Rafferty, just a few years ago “if you knew how to spell geoexchange you were ahead of the times.”
Thursday afternoon, however, he was pitching a room full of conference attendees different ways to reduce the costs of geoexchange systems to make them even more mainstream than they’ve already become.
“Look beyond the plain vanilla approach,” he said, encouraging participants to get creative to reduce costs.
“The focus tends to be almost exclusively on the bore hole. (But) once you get a driller down to a few dollars a foot there’s really not a lot left there,” he said, noting engineers need to start using creativity with their designs to lower the expense.
One of the main ways of reducing costs is to use open-loop geothermal systems, like the one in place on the UBCO campus, he contends.
An open loop system refers to a geothermal heating system that draws energy from groundwater. Geothermal systems come in all different shapes and sizes, some using the groundwater, aquifers, or open lakes to draw heat from the water which can be run through a mechanical system to produce heat or cool a building.
Most geothermal systems are close loop systems, however, which are systems that bore deep holes in the earth to access ground with a stable temperature that can be converted using a process similar to refrigeration.
The bore hole is easy to do, in that almost any site can use it; whereas a lake system, for example, requires the land to have a lake, Rafferty pointed out.
Thinking outside the box and looking at employing things like groundwater, however, can significantly reduce the cost.
Talk geothermal and you’re automatically going to hear a few persistent old wives tales, he said. He touched on some of those persistent misconceptions.
Geothermal does not heat up the ground nor drain the water table, for example, and those open loop systems are not illegal in most states, as some might have you believe, he said.
An audience member nevertheless questioned the wisdom of using groundwater, particularly drinking water, for purposes other than drinking.
It’s not as big an issue as it appears, according to Rafferty, who said he almost never sees drinking water used in geothermal projects. Open loop systems are mainly where the industry encounters more regulatory difficulty, he acknowledged.
In general, he’s found the western U.S. tends to employ hydrologists and academics who understand the variables at play. The eastern U.S. tends to use municipal waste and water workers to control groundwater, which can lead to problems for those working on geothermal projects, he said.
He said one of the best heat sources he knows of is sewage and it’s also underutilized.
Kelowna’s sewage treatment plant is used to heat Okanagan College, a fact college president Jim Hamilton is fond of noting in his speeches—that every toilet flush in the city helps heat their buildings.
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