Geothermal Cooling at Wright State: A Work in Progress
Dayton, Ohio has a long history of innovation. It’s the city in which Wilbur and Orville Wright were raised and did much of their experimentation on flight. Now, the university named for them is using a unique version of geothermal technology to cool its arena.
The geothermal cooling element is a small piece of a big project at Wright State University, which is in the Dayton suburb of Fairborn. Three years ago, the school – which has 18,000 students – embarked on a series of steps with the goal of cutting energy consumption by 40 percent across two campuses. The project, which is expected to save $35.8 million during the next 15 years, features elimination of 30 piece of equipment, installation of a campus-wide Web-based control system, a lighting retrofit and other steps.
One of the steps was to use geothermal power to provide free cooling to the Nutter Center. Greg Hahn, the Vice President and Senior Branch Manager for ABM Building Solutions – the contractor on the project – said that Dayton sits atop one of the biggest aquifers in the country. (Indeed, the aquifer – which is fed by The Great Miami River, a tributary of the Ohio River — is so strong that causes flooding problems for some downtown businesses, Hahn said.)
Initially, Hahn said, the system used the a retention pond next to the building as a heat sink. In most cases multiple holes must be drilled to reach an aquifer. In this case, however, holes were drilled from a retention pond next to the Nutter Center directly into the aquifer. Heat exchangers were put right into the retention pond. In this way, energy from the aquifer has been used for the past two years to cool the building.
At that point, the project was seen as a success – to a point. “It has been I’ll say ‘somewhat of a success,’ ” Hahn said. The goal is to save $80,000 to $90,000 annually. It is impossible to determine whether that level of savings is being achieved however, because there the heating and cooling costs for the entire facility are run on the same meter. The general feeling is that the initial expectations are not quite being met.
The next step – the step necessary to take the “somewhat” qualifier out of the characterization of the project –is to extend its use. “We are just now figuring out what else can we do with the heat exchangers, how we can use them better,” Hahn said. “We are still working the kinks out.”
That step will be to extend use of the heat exchangers in the retention pond to provide cold water during spring and autumn months when no cooling tower is available. “Overnight when they turn the chillers off the water in the building gets warmer,” Hahn said. “We will use the pond every morning to pre-cool the water. We will have the advantage the pond and geothermal system to reduce the load on building. We haven’t yet put it into effect and don’t know how effective it will be.”
The geothermal system allows the arena to be more run more economically year round, Hahn said. He points out that the system is the highest profile piece of the multimillion dollar project, though it only cost about $500,000.
Not every municipality has an aquifer, of course. But those that do should give geothermal heating and cooling great consideration. “I think it’s a great opportunity,” Hahn said. “There is no downside. It’s a natural resource available to us that is free. Solar gets a bigger play but there is so much loss. With water you almost a one to one gain. You get to use [almost] every BTU you pull out of ground.”
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