Proposer: City and Borough of Juneau
Benefit/Cost Ratio: Applicant 1.58 AEA 1.32
The City & Borough of Juneau is proposing the design and construction of a ground source heat
pump system for Gastineau Elementary School. There was a recent sale of bond debt to renovate the school. The renovation includes renovation/replacement of the 40+ and 50+ year old heating plant and distribution system.
A preliminary analysis estimated that a $1.25-million ground source heat pump system would save the school $30,000 per year compared to the next-best alternative (oil heat), based on expected electric costs to run the system vs. savings in oil consumption. The district is proposing to fund 20% of the project with bond proceeds and the other 80% by AEA.
Applicant notes that due to the addition of the Lake Dorothy hydroelectric supply and the small increase in electric consumption required by the heat pump system, the project is not expected to increase electric rates in the area.
Contribution to Lower the Cost of Energy:
Reduction in oil consumption of about 28,000 gallons per year, at the cost of about $23,000 in electricity per year, once the capital is installed.
Applicant used 25 year project life. Replaced with AEA 20 year assumption. It appears applicant had ground source heat pump maintenance as slightly more costly than oil fired boilers, which was reversed.
The wells may be more expensive despite making appropriate adjustment for the ground conditions. Test wells will ultimately determine the conductivity, that is assumed in the application.
It is a stand-alone system for the school with no plans for expansion.
The sustainability of the resource is not in question. For any particular application, proper engineering will dictate the success of the system. The economics are largely dictated by the cost of electricity.
Potential Public Benefits:
Those who fund operations of the school are the beneficiaries, which is a combination of the state and local governments.
Lowering the cost of energy will allow the savings to be applied directly to enhanced education for students.
-- January 2, 2010