Page 204 - Low Temperature Energy Systems with Applications of Renewable Energy

Heating with geothermal systems 191

250
Hot water usage, millions of gallons 230
240

220

210

200

Fig. 5.14 Annual hot water usage in BWSWD [14]; Pers. Comm. Del Eytchison.
3
Note: 1000 gallons ¼ 3.786 m .
thrown layers of rhyolite that are characterized by good permeability; see Fig. 5.15.
The wells are separated by about 377 m at the surface but end up in different layers
of rhyolite at different depths.
The SICM system serves the State Capitol and 10 other buildings (see Fig. 5.16).
The total gross heated floor area amounts to over 8.16 ha. The system is a double-
pipe arrangement where the produced geofluid in delivered in one pipeline and after
use is collected in a return pipeline and reinjected. When the system began operations
in 1982, only seven buildings were served. The DPW building was then a shop, but
joined the system in 1984. The Alexander House was added in 1992, but only uses
collected cooled water just prior to its being reinjected. The Parking Garage #2 was
built in 2014 (around and over the wellhead of the production well) and added to
the system; however, it uses a very small amount. The Capitol Annex (formerly the
Old Ada County Courthouse) was added in 2015 when its renovation was completed.

Fig. 5.15 Cross-section looking NNW through the SICM, BLM monitor, and CB (BGL) wells;
see Fig. 5.10, modified from [15]. See Fig. 5.12 for rock types.