2007_1015_Packet - Laserfiche WebLink

Home

Roseville Skatina Center and Citv Hall Feasibility Study September 23, 2007 The cost of electricity used in the Speed Skating Oval is high because of the high demand charges. The average cost of electricity (not including the high cost per ktil�lh at the Oval) is approximately 43% higher than the cost of natural gas per E�CWh. Geothermal heat pumps can be expected to operate at an average COP of 4.5 if they are connected to an integrated system operating at 50° to 75°�" because of the large amount of thermal energy stored in the GHX. This means that the cost per k� of thermal energy, taking into account the efficiency of a heat pump operating at a COP of 4.5 is approximately $0.016 per kWh. Therefore a heat pump providing heating in this type of system can be expected to operate at a cost approximately 60% lower than the current system using natural gas as the primary fuel. The following table shows the energy cost that can be expected if the system integration is implementedfor each of the campus buildings. Ice Arena 1 Banquet Hall City Hall 1 Public Safety MaintenanceGarage Fire Hall sp�d sF�atfx�t� ��raa ��tal � �4v�r�s�a Current Gas Heating Cost $31.117 $6,811 �,�1 � 5i ��,��3 Integrated System Heating Cost 612,513 $2,724 �.�� A completely integrated system can be expected to provide energy cost savings, based on current gas and electricity costs, of approximately $69,116 annually. A geothermal system is usually designed to provide air conditioning as well as heating and producing hot water. A large GHX is typically designed to operate at temperatures lower than $0° to 9(}°� to the heat pump equipment. The efficiency of air cooled equipment, especially air cooled condensing units, is significantly lower than water cooled geothermal heat pump equipment. Typically, water cooled equipment is approximately 35% to 45% more efficient than comparable air cooled equipment. The City Hall / Public Safety Building and the Ece Arena ! Banquet Hall facilities both have significant cooling loads. There is approximately 84 tons of installed cooling capacity in roof mounted cooling units for the offices, meeting rooms and banquet rooms in the Banquet facility, a 50-ton air cooled unit for the City Hall, and a 60-ton air cooled unit for the Public Safety Building. Energy consumption data for the City Hall / Public Safety Building provided by the City of Roseville and Xcel Energy shows energy consumption increases significantlyfrom April to September. The increased consumption can be linked to the power draw of the cooling units for this building. Figure 21 shows the increased electrical consumption. Geo-Xergy Systems Page 20 of 33