system was built in 1983, at a time when natural
gas pricing for commercial use peaked at $6 per
thousand cubic feet. It pumps about 190 mil-
lion gallons of water a year from the ground at
about 170°F (82°C) and distributes it through
13 miles ( 20 km) of pipe to about 58 commercial
customers around the downtown district, heat-
ing nearly 4 million square feet (370,000 square
meters) of building space. After going through
heat exchangers at the buildings, the water enters
return lines and is injected back into the ground
at a city-owned site about 3,000 feet (1 km) from
the production well.
Now, the Boise Public Works Department
through about 12,500 feet ( 3. 8 km) of fiberglass
pipe, which is insulated with polyurethane foam,
and comes back at 140°F (60°C). En route, it
heats 24 city-owned and commercial buildings
(including process heat for the Klamath Basin
Brewing Co.), plus four greenhouses and a fish
farm. Along the way, it melts snow from 150,000
square feet ( 14,000 square meters) of sidewalk.
Next door, the Oregon Institute of Tech-
nology (OIT) drilled its first geothermal well
in 1961, and today pumps water at
iStocKPhoto.co M/haRRiSon deSign
192°F (82°C) to heat a dozen build-
ings on campus and
l
sary. Dozens of residents sank their own wells to
provide bathing water. The discharge water is not
reinjected, but finds its way into the river.
In 1982, when the town built its own Geo-
thermal Heating District (funded largely by the
DOE), it used a similar drill-and-discharge sys-
tem. The well, just 375 feet (114 meters) deep,
sends water into the heat exchanger, under arte-
sian pressure, at 146°F (63°C). It exits at about
125°F ( 52°C), and flows through a 200-foot pipe
to the river. This is, for water-rights
purposes, a “consumptive use.” Local
residents were concerned that
the municipal system would
LLy WRch-WiKiMedia
couRteSy oF idaho touRiSM
the SPRingS ReSoRt
Klamath Falls, Ore.
Boise, Idaho
Pagosa Springs, Colo.
Copyright © 2011 by the American Solar Energy Society Inc. All rights reserved.
has undertaken a $5.5 million expansion to send
water across the Boise River to heat six buildings
on the Boise State University (BSU) campus.
Eventually, the system will heat eight university
buildings totaling 1 million square feet and save
the campus about $80,000 a year (depending on
the price of natural gas, of course). About half
of the project’s cost is underwritten by the U.S.
Department of Energy (DOE), the rest by the
U.S. Department of Housing and Urban Devel-
opment, the city of Boise and BSU.
Klamath Falls, Ore.,
has been piping hot-
springs water into homes for space heating since
1900, and a commercial greenhouse used the
resource beginning in 1926. Today, the town has
about 600 privately owned wells, most of them a
few hundred feet deep and equipped with down-
hole heat exchangers (a closed loop to take city
water down and back up). Water typically comes
out of the wells at just about boiling — 100°C
(212°F).
The town started building its own Geother-
mal District Heating System in 1981, but it
didn’t see full operation until failed pipes were
repaired in 1991. Pumps pull 750 gallons per
minute ( 47 liters per second) from two wells.
After going through a heat exchanger, the water
is reinjected half a mile (750 meters) away. The
distribution water goes out at 180°F (82°C), runs
For more information
on municipal geothermal districts
Boise: cityofboise.org/Departments/Public_
Works/Services/Geothermal/ index.aspx
Klamath Falls: ci.klamath-falls.or.us/
departments/works/water/geothermal
Oregon Institute of Technology: geoheat.
oit.edu and pangea.stanford.edu/ERE/pdf/
IGAstandard/SGW/2009/lund.pdf
Pagosa Springs: tinyurl.com/pagosa
melt snow from sidewalks, saving about $1
million annually. Last April, OIT dedicated a
280-kilowatt electric generating plant, tapping
heat from the existing three wells to provide
about 20 percent of campus electric needs. In
2009, OI T drilled a mile-deep (1.3-km) hot well
that will drive a 1-M W electric plant by the close
of 2012.
In Southwest Colorado, Pagosa Springs
is an old ranching and resort town on the San
Juan River.
Pagosa
is a Ute Indian word that may
mean “healing water” or “sulfur-stink water,”
depending on who’s telling the story. The water,
heavy in salts and sulfates, heats in a very deep
underground reservoir and comes to the surface
under artesian pressure — no pumping neces-
draw down the aquifer and attenuate their own
supply, so while the system was designed to use
1,000 gallons ( 3,800 liters) per minute, the town
was granted rights to only 450 gallons (1,700
liters) per minute.
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