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Geothermal offers cleaner, more efficient energy, engineer says
by Tyler O’Neil · News · June 27, 2007
Editor’s note: This is the second in a three-part series examining a $3.2 million school bond issue, to be held in West Branch on Sept. 11. This article describes how a proposed geothermal heating and cooling system would function at Hoover Elementary and West Branch Middle School. A previous article described the existing heating and cooling systems. Next week we’ll examine the financial impact on the school district and other schools that have invested in geothermal energy.
The passage of a $3.2 million bond issue on Sept. 11 would mean drastic changes for the inner workings of Hoover Elementary, some visible but most hidden from view several hundred feet underground.
“We first started talking informally about installing a geothermal system after the kitchen was remodeled a few years ago,” said Jim Knolls, an engineer from Shive-Hattery who has been working with the West Branch Community School District to evaluate the elementary’s geothermal potential.
Shive-Hattery has done numerous jobs with the district as to date. The company remodeled and installed new ventilators in the middle school in 2003. Shive-Hattery also revamped the district kitchen in 2005, giving it new ventilation hoods and modern air-conditioning.
So far the company has done an evaluation to give the district some different options, but says the next step is up to the West Branch community.
“If the voters endorse this improvement then a design proposal would be made for removal of the old systems with a concurrent installation of the geothermal system,” said Knolls. He says the major work schedule is dependent on the school’s preferences, but most work starts after the school’s last heating day in March or April and ends before the first day of school in August.
“Some of the work can be done while school is still in session, such as removal of non-visible infrastructure or work in maintenance rooms,” he said.
Knolls says the removal of the old system will be done very quickly but the installation of the geothermal system will take considerably longer due to the complexity of the system and the amount of installation required.
Geothermal heating and cooling systems work by harvesting heat energy stored below the surface of the earth. To do this, a large coil filled with either water or a non-toxic glycol mixture is inserted into the ground. There are two basic coil layouts: a vertical system, which penetrates the earth upward of 300 feet, and a horizontal system that doesn’t go as deep but is spread out over a significantly wider area.
“In the industry, they have seen vertical layouts as the typical first option,” said Knolls. “In Iowa, however, some homeowners have gone with horizontal systems because of costs.”
The vertical system requires deep drilling, which can be very difficult and costly depending on the geology of an area. The horizontal option doesn’t require the same type of difficult drilling, but underground utilities can make such a system difficult to arrange due to its spread out surface area.
Once the liquid is pumped into the underground coils, it takes on the same temperature as the earth at that depth, which is usually around 53 degrees Fahrenheit. From there it travels to the system’s compressor where the energy is transferred to heat pumps, which are responsible for the individual heating and cooling of individual classrooms.
To most it seems logical that 53-degree water would be capable of cooling warm classrooms, but it may seem a little cool to be heating classrooms during the winter. Knolls says that “from a physics point of view there is heat to be had” and that the geothermal system is able to extract all the warmth needed from the water to heat classrooms even in the dead of winter.
Knolls says the geothermal system will be more environmentally friendly than the district’s current system, which is comprised of 50-year-old boilers that run on fossil fuels.
“You’re taking an old, inefficient boiler out of commission and with it, the carbon dioxide it was producing,” said Knolls. As the geothermal system only requires electricity (and free heat from the earth), the system is as “green” as the electricity it consumes, whether the power comes from a coal plant or a wind farm. The system is also efficient with the energy that is does use, reducing its environmental footprint further.
Once the geothermal system is up and running, students and staff might notice a few changes within their classrooms. Overhead diffusers will replace the old radiators that reside in every classroom. The ceilings in some classrooms will be lowered to make space for heat pumps and also reduce the space that the geothermal system must heat or cool. The biggest difference that students and staff will notice will be the consistent, comfortable temperature.
“The cool thing about the heat pumps is that they are able to heat and air-condition,” said Knolls. “For instance, on March days the sun is able to warm some classrooms in the afternoon to the point where heating isn’t needed but maybe the classroom could actually use some air-conditioning. The heat pump is able to pump cool air into that sunlit room while another heat pump heats a different room on the other side of the building that is out of the sun. And all of this is automated, controlled by one computer.”
Knolls says that studies are currently being conducted to see if the improved classroom environment that geothermal heating and cooling provides can also lead to fewer sick days and improved test scores.
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