Geothermal Test for New Convention Hall Produces Good Results

CAPE MAY — A test boring to determine if it is possible to heat and cool a new Convention Hall here with geothermal energy produced positive results.
City Manager Bruce MacLeod told the Herald the city received a 20-page report Tue. Nov. 30 from Geothermal Services Inc. which drilled a test well three weeks ago on Beach Avenue in front of the old Convention Hall.
The city was working from a base number of 1.0 for thermal conductivity and the test boring yielded better results with 1.4, he said.
“We were hoping for 1.1 to 1.2,” he said.
Engineers will determine how many bore wells would be needed for a geothermal system, said MacLeod.
The test boring went to a depth of 450-feet. He said he believes geothermal wells for Convention Hall would be installed to that depth.
The data from the test boring will be forwarded to the mechanical, electrical and plumbing engineers for the Convention Hall project for analysis.
According to a paper entitled “Development of Correlation for Soil Thermal Conductivity from Becker, Misra, and Fricke from the Mechanical and Aerospace Engineering Department of the University of Missouri-Truman Campus, “Factors affecting soil thermal conductivity include moisture content, dry density, mineral composition and temperature. Moisture content, by far, has the greatest impact upon soil thermal conductivity. As moisture is added to a soil, a thin water film develops which bridges the gaps between the soil particles. This ‘bridging’ increases the effective contact area between the soil particles, which increases the heat flow and results in higher thermal conductivity.”
It also notes: “soil thermal conductivity also increases with the dry density of the soil. With an increase in soil dry density, more soil particles are packed into a unit volume and the number of contact points between the particles increases. This increase in contact points provides a larger heat flow path and, thus, increases the soil thermal conductivity.”
Mineral composition in soil also affects thermal conductivity, according to the paper.
“For example, sands with a high quartz content generally have a greater thermal conductivity than sands with high contents of plagioclase feldspar and pyroxene.”
While the city is committed to a geothermal system for the new Convention Hall, in question is whether it will heat and cool the entire building or exclude the auditorium and climate control the retail and lobby spaces.
MacLeod said the design for a larger Convention Hall the city was unable to build due to its cost exceeding estimates by almost $2 million, called for geothermal for all spaces except the main hall. He said it remains to be seen if that premise will continue for the scaled back facility or whether the city is in a position to consider using geothermal for the entire building.