CCRI's Knight Campus is the site of an ambitious project to extract heat from the earth by means of a series of deep wells and use the heat to help warm the main building in the winter. Similarly, heat extracted from the building in the summer will be used to heat the earth and reduce cooling costs. The Geothermal Project was installed by CAM HVAC and Construction, Inc. of Smithfield, RI.
If you are wondering about the "Big Dig" down by the Knight Campus ball fields, that project is separate and distinct from the new additions to the building. It is an energy-saving project called "Geotherm". In keeping with CCRI's long term commitment to protecting the environment, CCRI has embarked on a project to extract heat from the earth to reduce its consumption of electricity and the need to burn fossil fuels. One hundred wells are being drilled. The water in the wells will be used to reduce the amount of energy required to heat and cool the Knight Campus megastructure. Narragansett Electric Company is picking up half the cost with the remaining portion being paid for by a low-interest loan. The project has an estimated 4-year payback period. A technical description of the geothermal system follows.
The existing chiller, hot, cold water system in the megastructure is a modified heat pump. The chiller has the capability of producing both chilled and hot water at the same time to take care of the varying conditions in the building. The existing system does not have a sufficient heat sink to provide enough heat or cooling for winter summer operations. To provide additional heat for winter operation a by-pass electric boiler was incorporated into the system. To remove the excess heat in the summer, cooling towers were installed on the roof. The heat pump concept was not implemented fully during original design as it was not cost effective with the low electric rates of the time.
The geothermal addition would be a closed ground loop system consisting of a series of 50 to 80 wells with polyethylene piping that would extract heat from the earth to provide a constant load to the chiller in the boiler room for heating, or add heat to the earth for cooling. The wells would be about 22 feet on centers and require about an acre of land behind the field house or adjacent to the upper soccer field. The cleared area above the wells could be used for an additional field, a track, tennis courts or parking area.
The addition of the geothermal ground loop system with appropriate piping, would allow a water circulating system to provide a constant 55 deg. F. source of water to the boiler room (i.e. below 6 ft. the ground temperature is near 55 deg. F. year around). This would provide an improved heat sink source for the heat pump system.
The heat pump system would utilize the geothermal source to cool the building via bypass piping for warmer days. With increasing temperatures, the chiller would be put into operation to provide the additional cooling. The surplus heat that is generated by the chiller would via a heat exchanger, be transported back out to the geothermal wells where it would be absorbed by the ground. On very hot days the cooling towers would be utilized to assist in the removal of heat.
The existing heat pump system would be utilized during mild weather to transfer the heat from hot areas to cool areas.
As the weather gets cooler the chiller’s heat pump capabilities would be put into operation. This would remove heat from the 55 deg. geothermal source to produce 80 deg. to 110 deg. hot water as required to heat the facility and the cold water would be transported back out to the geothermal wells where it would be absorbed by the earth. During very cold weather the existing electric boiler by-pass system would be utilized to assist in heating.
The advantage of the added geothermal unit to the heat pump system over the present resistance electric boiler is that it uses 66% less electricity for the same amount of heat generated. Instead of creating heat by electric resistance coils, the heat pump will work by transferring the heat from one source to another, which is much more efficient. Another advantage is that the circulating water from the geothermal wells will provide almost free cooling for a good percentage of the summer season. When the chiller is required, the elimination of the cooling towers will eliminate the use of about 150 hp electric motors. Also the chiller will be several percent more efficient because of the lower condenser water temperature.
By pumping underground water cooled and warmed by the earth, the Knight Campus of the Community College of Rhode Island plans to trim up to $70,000 a year off its heating and air conditioning bills.
About two acres of ledge and brush have been cleared next to the school's baseball fields for the installation of a geothermal heating and cooling system at a cost of $950,000. One hundred interconnected wells, each 300 feet deep, are being drilled in the land. An underground pump will be used to pipe water at a constant 55 degrees into the CCRI building. The water will supplement the existing climate control system in the building by giving it a head start of sorts: the system will use less energy because the water is warmer than the air in winter and cooler than the air in summer.
Half of the funding for construction of the system will come from Narragansett Electric's energy conservation program. The remainder will come from the college's budget over a period of five years. A U.S. Department of Energy grant funneled through the state Energy Office funded the design of the system, which is not included in the (new building addition) $950,000 construction estimate.
Stephen Marginson, Dean of Administration at CCRI, said when the project is complete the field will be planted with grass to add to green space at the college. No part of the geothermal apparatus will be visible above ground.
"The college doesn't have tennis courts, and this would be an ideal place to put them. We also don't have a lot of places with tables and chairs to sit outside in the summer and spring, and this could be that kind of venue," Marginson said.
CCRI hopes the project will be complete in November or December, in time for the most costly part of the heating season. The expected savings of $60,000-$70,000 from reduced electricity use means the school will recoup its costs in seven or eight years. Annual electricity costs at the Knight Campus are about $700,000 with about $250,000 of that going to heating and cooling.
"Were paying for it in five installments, so with the money we save, it's almost dollar for dollar," Marginson said.
CCRI began planning for conversion to geothermal climate control several years ago when the State Energy Office approached the college with a proposal to use federal funds to design a system for its particular needs. CCRI had the necessary land and an existing heating and cooling system that would easily adapt to a geothermal supplement.
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