1
Geothermal Technologies Program
Direct Use
3
2
As charged by Secretary Abraham, the Of ce of Energy
Ef ciency and Renewable Energy provides national
leadership to revolutionize energy ef ciency and renewable
energy technologies, to leapfrog the status quo, and to
pursue dramatic environmental bene ts.
The Geothermal Technologies Program, a critical part of our
overall effort, is making great strides toward increasing the
viability and deployment of geothermal heat and power.
The peer reviewed, focused R&D and supporting outreach
activities conducted by this program will enable broad
expansion of the use of geothermal resources throughout
the western United States. Through federal leadership
and partnership with states, communities, industry, and
universities, we will ensure that geothermal energy is
established as an economically competitive contributor to
the U.S. energy supply. Our program’s success will mean
a stronger economy, a cleaner environment, and a more
secure energy future for our nation.
David K. Garman
Assistant Secretary
Energy Ef ciency and Renewable Energy
2
3
Many communities and businesses in
the western United States are showing
the way, saving large sums of energy
and money while using “direct-use”
geothermal resources.
Heat that Comes Directly from the Earth
L
ow-temperature geothermal resources exist
throughout the western U.S., and there is
tremendous potential for new direct-use applications.
A recent survey of 16 western states identied almost
12,000 thermal wells and springs, more than 1,000
low- to moderate-temperature (68° to 302°F, or 20°
to 150°C) geothermal resource areas, and hundreds
of direct-use sites.
Direct use of geothermal resources is the use of
underground hot water to heat buildings, grow plants
in greenhouses, dehydrate onions and garlic, heat
water for sh farming, pasteurize milk, and for many
other applications. Some cities pipe the hot water
under roads and sidewalks to melt snow. District
heating applications use networks of piped hot
water to heat buildings in whole communities.
Directly using geothermal energy in homes and
commercial operations is much less expensive than
using traditional fuels. Savings can be as much as
80 percent over fossil fuels. It is also very clean,
producing only a small percentage (and in many
cases none) of the air pollutants emitted by burning
fossil fuels.
Direct Use Equals
Smart Use
PIX13000 NREL, Robb Williamson
4
5
Direct-use systems are typically composed of three
components:
• A production facility – usually a well – to bring
the hot water to the surface;
• A mechanical system – piping, heat exchanger,
controls – to deliver the heat to the space or
process; and
• A disposal system – injection well, storage pond,
or river – to receive the cooled geothermal uid.
According to the Oregon Institute of Technology’s
Geo-Heat Center (DOE-funded), there are nearly
2,500 potentially productive geothermal wells located
within ve miles of towns and medium-sized cities
throughout 16 western states. If these “collocated”
resources were used only to heat buildings, the cities
have the potential to displace 18 million barrels of oil
per year!
Historically, most of the communities that were
identied have experienced some development of
their geothermal resources. However, depending
on the characteristics of the resource, the potential
The Idaho State Capitol Building (Boise) uses the city
geothermal district-heating system.
exists for increased geothermal development for
applications such as space and district heating, resort/
spa facilities, aquaculture, industrial and greenhouse
operations, and possible electrical generation in some
areas.
Use of heat pumps with low-temperature geothermal
resources can be very cost-effective, and can really
extend the usefulness of the resource. For example,
the College of Southern Idaho (CSI) uses two 36-ton
heat pumps to provide supplemental space heating
in a building that houses CSI’s Health and Human
Services Program. These two heat pumps have
performed so well that an additional sixteen 36-ton
heat pumps have been installed in another facility
to extract more useful energy from the school’s
geothermal resource.
District and Space Heating
A growing and attractive use of low-temperature
geothermal resources is in district and space heating.
District heating systems distribute hydrothermal
water from one or more geothermal wells through
a series of pipes to numerous individual houses
and buildings, or blocks of buildings. Space heating
typically uses one well per structure, but can use
more than one well. In both district and space
heating systems, the geothermal production well and
Graphical representation of a geothermal district-
heating system.
Two 36-ton heat pumps being used for space heating at
the College of Southern Idaho.
From Production Well
Geothermal Reservoir
Heat
Exchanger
To
Injection Well
Peaking
Backup
Unit
User Application
Geothermal Water
Working Fluid
Idaho Department of Water Resources
PIX13092 NREL
4
5
distribution piping replace the fossil fuel–burning
heat source of the traditional heating system.
Savings are achieved not only by eliminating the
need for conventional heating energy, but also
through elimination of the need for equipment
(e.g., boilers and gas vents) and interior space for this
equipment. Most district systems also provide chilled
water for building cooling (using conventional, but
high-efciency, modular equipment), and these
savings can be substantially greater than heating
bill savings because of the greater cost of electricity
compared to heating fuels.
Boise District Heating, Idaho
In 1892, two companies competed furiously for
Boise’s water system contract. One company,
the Boise Water Works, sweetened its proposal
by declaring the preposterous idea that it would
distribute both cold and hot water. They got the
contract, and Boise has used its geothermal resources
ever since.
Today, that system is one of four geothermal district
heating systems in Boise: the Boise Warm Springs,
Water District System (the original), the Boise City
System, the Veterans Administration Hospital System,
and the State of Idaho Capitol Mall System (all three
installed in the 1980s). Three hundred and sixty-
six buildings are heated by these four geothermal
systems. That’s 4,426,000 square feet (411,189 square
meters) – equal to about 1,770 houses. Boise has the
only state capitol building in the U.S. that is heated
by geothermal water.
In 1998, the city of Boise signed a Cooperative
Agreement with DOE that provided $870,000 for
the construction of an injection well for the city’s
geothermal heating system. The goals of the project
are to reduce discharge into the Boise river and
hydraulically replenish the geothermal aquifer
the city shares with the Boise Warm Springs Water
District, the Veterans Administration hospital, and
the state of Idaho Capital Mall buildings. Since 1999,
water levels in a nearby monitoring well have risen
signicantly, thus addressing one of the project goals.
In Klamath Falls, Oregon, a geothermal district-heating system keeps the sidewalks clear and dry at the Basin Transit
station after a snowfall.
Boise geothermal district-heating system map.
PIX08827 Geo-Heat Center
6
7
The people of Idaho also use geothermal resources for
other direct uses (see Idaho’s Buried Treasure). In 1930,
Idaho’s rst commercial greenhouse use of geothermal
energy was undertaken. The system still uses a
1,000-foot (305-meter) well drilled in 1926. At least
14 other greenhouses now operate in Idaho.
Geothermal aquaculture is also popular. Nine sh
farms raise tilapia, catsh, alligators, and other fauna.
“Using geothermal resources makes sense because
they are clean, less expensive than
other sources, and renewable,” says
Ken Neely of the Idaho Department
of Water Resources, “Geothermal
resources could become even more
important in Idaho as demands for
energy increase.”
Klamath Falls District Heating,
Oregon
The city of Klamath Falls, Oregon,
geothermal district-heating system
was constructed in 1981 to initially
serve 14 government buildings,
with planned expansion to serve
additional buildings along the
route. The original and continuing
municipal purpose of the district
heating system is to serve building
space heating requirements.
The City of Klamath Falls, with
assistance from DOE, upgraded
their district heating system in 2003
and 2004 to a thermal capacity of
36 million Btu/hr, allowing more
customers to use the system.
The district heating system was originally designed
for a thermal capacity of 20 million Btu/hr (5.9 MW
thermal). At peak heating, the original buildings
on the system utilized only about 20 percent of the
system thermal capacity, and revenue from heating
those buildings was inadequate to sustain system
operation. This led the city to begin a marketing
effort in 1992 to add more customers to the system.
Since 1992, the customer base has increased
substantially, with the district
heating system serving several
additional buildings.
Geothermally heated sidewalks and
crosswalks have been incorporated
into a downtown redevelopment
project along Main Street, starting
with the 800 block in 1995. That
same snowmelt system has been
extended to cover nine blocks
of sidewalks and crosswalks. The
heated sidewalk and crosswalk
area currently served by the city
snowmelt system is over 60,000
square feet (18,288 square meters).
Reno and Elko, Nevada
Nevada is also a hotbed of
geothermal development, with
applications growing rapidly in
this resource-rich geothermal state.
Modern geothermal energy use in
Nevada began in 1940 with the
rst residential space-heating project
in Reno. Today, almost 400 homes
Heat exchangers and circulation pumps for the geothermal
district-heating system in Klamath Falls, Oregon.
Geothermal energy is ideal for dehydration operations
(onions and garlic), as seen in Empire, Nevada.
Developing geothermal resources in the
United States translates to more jobs at
home, and a more robust economy.
PIX04133 Jeff Hulen
PIX03706 Geo-Heat Center, OR Institute of Technology
PIX03694 Geo-Heat Center, Oregon Institute of Technology
6
7
use geothermal energy for heat
or hot water in Warren Estates
and Manzanita Estates. These two
housing developments, located in
southwest Reno, Nevada, comprise
the largest residential geothermal
space-heating district in Nevada.
Production well depths range from
700 to 800 feet (213 to 244 meters)
with temperatures in excess of
200°F (98˚C). Geothermal water
is pumped at a rate of 250 to 350
gallons-per-minute (gpm) (1,137
to 1,591 liters-per-minute) from
one of two production wells to
at-plate heat exchangers at the
surface. Hot water at about 180°F
(82°C) is circulated from the heat
exchangers to the subdivisions via
underground pipes. All geothermal
water is injected back into the
reservoir through a well located on
the premises.
Elko is another Nevada community
with a long-standing history using
geothermal heating. In 1978, the
rst geothermal food-processing
plant was opened in Brady Hot
Springs. More than 25 million
pounds (11.3 million kilograms)
of dehydrated onion and garlic
are being processed annually.
Elko Heat Company has been
operating a geothermal district
heating system in Elko, Nevada,
since December 1982. The Elko
Heat Company project was funded
by DOE in the late-1970s, and
continues to operate successfully
today. This system serves 17
customers, and distributes
approximately 80 million gallons
(364 million liters) of 178°F
(81°C) geothermal water annually.
Customers are primarily using the
geothermal water for space heating
and domestic hot water heating.
Two customers are using their
return water for wintertime snow
and ice melting on walkways, and
one is using a heat pump system.
Cactus production at the Southwest
Technology Development Institute (SWTDI),
Las Cruces, New Mexico.
PIX13016 NREL, Rob Williamson
8
9
Aquaculture and Horticulture
Greenhouses and aquaculture (e.g., sh farming) are
the two primary uses of geothermal energy in the
agribusiness industry. Most greenhouse operators
estimate that using geothermal resources instead of
traditional energy sources saves about 80 percent of
fuel costs – about 5 to 8 percent of total operating
costs. The relatively rural location of most geothermal
resources also offers advantages, including clean
air, few disease problems, clean water, a skilled and
available workforce, and, often, low taxes.
New Mexico is appealing to the greenhouse industry
for several reasons, including a good climate,
inexpensive land, a skilled agricultural labor force,
and the availability of relatively inexpensive
geothermal heat. New Mexico has taken the
nation’s lead in geothermal greenhouse acreage
with more than half of the state’s acreage now
heated by geothermal resources. And there are also
many successful, thriving geothermal direct-use
greenhouses in other western states (see Geo-Heat
Center website at: geoheat.oit.edu/).
New Mexico has the nation’s two largest geothermal
greenhouses and a total of 50 acres (20.2 hectares)
of greenhouses that are heated with geothermal
energy. This represents a payroll of more than $5.6
million and sales of $20.6 million. Nearly all of
the greenhouse sales are to out-of-state buyers. In
addition, the largest geothermal greenhouse pays
royalties to the state for geothermal production, and
the smallest geothermal greenhouse pays Federal
royalties for geothermal heat.
Altogether, the projected new greenhouse acreage
and business startups by 1997 represented a capital
investment of more than $21.5 million, with sales
of nearly $26.1 million. Nearly 500 new jobs are
the result. Annual energy savings to the greenhouse
operators, using geothermal energy, approaches $1
million.
The largest geothermal greenhouse in the nation is
the Burgett Geothermal Greenhouse near Animas in
southwestern New Mexico. This 32-acre (13-hectare)
facility produces high-quality cut roses that are
marketed widely, contributing substantially to county
tax receipts, and creating local jobs.
This is an example of a geothermal “direct-use”
application in horticulture in Idaho (Mountain
States Plants, Flint Greenhouses).
PIX13097 NREL
8
9
AmeriCulture Fish Farm
AmeriCulture Inc., located in Animas in southwest
New Mexico, is among the largest domestic suppliers
of tilapia ngerlings and is able to produce between
four and seven million ngerlings annually.
AmeriCulture markets and sells a disease-free tilapia
fry to growers and researchers nationwide for grow-
out to full size. Tilapia is a sh that is growing in
popularity for its taste. AmeriCulture ships male
tilapia ngerlings by UPS throughout the country. In
recent years, local Red Lobster™ seafood restaurants
have added tilapia from AmeriCulture to the menu.
Geothermal offers several advantages for sh
culture. For example, AmeriCulture facilities
are heated at much lower costs, compared to
fossil fuels like propane, with a downhole heat
exchanger installed in a 400-foot (122-meter)
depth well. Many species have accelerated
growth rates in warm water, adding to energy-
saving advantages.
Masson Radium Springs Farm
The Masson Radium Springs Farm geothermal
greenhouses are located on private land in
southern New Mexico 15 miles (24 kilometers)
north of Las Cruces. The operation started in
1987 with four acres of geothermally heated
greenhouses. Masson selected New Mexico and
the Radium Springs area to take advantage of the
sunshine, ease of climate control because of the
dry desert air, a willing and trainable work force,
and geothermal heat. Today, the greenhouses
employ 110 people, and cover 16 acres (6.5
hectares) in two major modules, each with
shipping and warehousing buildings attached.
The Masson Radium Springs Farm geothermal
greenhouses produce more than 30 groups
of potted plant products, including seasonal
products such as poinsettias and carnations.
Tilapia is growing in popularity for its mild taste.
PIX13027 NREL, Rob Williamson
NREL, Rob Williamson
10
11
Masson Radium Springs Farm greenhouse in New Mexico. NREL, Rob Williamson
The greenhouse space is heated by geothermal energy
from three wells that are located on private land.
Two are shallow wells less than 350-foot (107-meter)
depth, and produce 165°F (74°C) water. The third well
was drilled about two years ago to 800-foot
(244-meter) depth, and produces water at 199°F
(93°C). The water is stored in a newly constructed
167,000-gallon (760,000-liter) storage tank used
mainly for nighttime heating. After use, the
geothermal water is injected back into three shallow
(less than 250-foot/76-meter depth) injection wells.
Mountain States Plants
Flint Greenhouses, owned and operated by
Mountain States Plants, and located in the Hagerman
Valley of south
ern Idaho, uses geothermal uid
ranging in temperature from 98° to 110°F (37° to
43°C) for greenhouse heating. The two-acre (0.8-
hectare) greenhouse facility achieves an estimated
annual savings of about $100,000 over propane gas,
representing a signicant competitive advantage on
operating costs. Compared to Mountain States Plant’s
other two greenhouse operations (not geothermally
heated), the Flint Greenhouses delivers the best cost-
per-square-foot operating performance. About 20
permanent employees and 10 to 15 seasonal employees
work at the Flint Greenhouses raising potted plants.
DOE Support and Assistance
Through its support of the Geo-Heat Center (website
at geoheat.oit.edu/) at the Oregon Institute
of Technology in Klamath Falls, Oregon, DOE
conducts research, provides technical assistance,
and distributes general information on a wide range
of geothermal direct-use applications. The center is
the primary source of data and information about
all types of direct-use operations. Those interested
are encouraged to contact this organization by the
Internet or by phone (541-885-1750) for technical
assistance and consumer information.
■
10
11
Idaho’s Buried
Treasure –
Geothermal
Energy
Homegrown, abundant, secure
energy right beneath the ground.
I
daho holds enormous reserves – among the largest
in the United States – of this clean, reliable form
of energy that to date have barely been tapped.
According to U.S. Geological Survey estimates, Idaho
ranks seventh among the 50 states in geothermal
energy potential. These resources could provide
up to 20 percent of Idaho’s heat and power needs.
Idaho’s history of geothermal use begins with
Native Americans who congregated at hot springs,
as indicated by artifacts and petroglyphs on nearby
rocks. Settlers, miners, and trappers also used hot
springs by the mid 1800s. In 1892, the nation’s rst
district heating system was birthed in Boise (see
Direct Use Equals Smart Use). Geothermal water was
put to use along Warm Springs Road to heat over
200 buildings including homes, businesses, and the
Boise Natatorium, a 65 by 125-foot (20 by 38-meter)
swimming pool.
The district heating system is still in operation and
has been joined by three more district heating systems
in the Boise area. The current city system is used to
heat about 2.7 million square feet (250,838 square
meters) including the City Hall, the new Ada County
Courthouse, and over 40 businesses. The water is
extracted from several wells that range in depth
from 880 to 1,900 feet (268 to 580 meters). Water
production temperature is about 175°F (80°C). Most
of the used geothermal water is re-injected about a
mile to the southwest of the welleld.
In 1930, Edward’s Greenhouses became the rst
commercial greenhouse operation in the United
States to use geothermal water for a heat source to
grow plants. The facility still exists and prospers
today. Several other greenhouse businesses were
developed throughout southern Idaho in the next
half-decade to take advantage of the natural hot
water available in many places.
In 1979, the College of Southern Idaho (CSI) drilled
the rst geothermal well on its campus in Twin Falls.
During the 1980s, district heating operations were
put in place in Twin Falls and Ada counties.
Geothermal resource map of Idaho, showing areas in
pink with potential for direct-use applications (mostly
lower half of State).
The Natatorium was a landmark in Boise.
Idaho State Historical Society (73-2.52)
12
13
CSI drilled a second geothermal well in 1981.
Throughout the 1980s, CSI converted their existing
heating system into a geothermal heating system
by laying the underground supply and return lines,
retrotting the existing buildings, and installing
heating systems in the new buildings. The heating
system serves 12 buildings and 4 greenhouses, with
over 440,000 square feet (40,877 square meters) of
facilities kept warm by geothermal energy. About
35,000 square feet (3,252 square meters) of this area
is conditioned with two 36-ton heat pumps using
geothermal uid. Water temperature from the two
production wells is about 101°F (38°C). The system
currently produces about 209 million gallons (950
million liters) per year. The spent water is discharged
over the south rim of the Snake River Canyon.
In the early 1980s, the State of Idaho drilled two
wells in the vicinity of the Capitol Building. By 1982,
the State of Idaho geothermal system was supplying
heat to nine buildings in the Capitol Mall complex,
including the State Capitol. Currently, the system
is used to heat about 4,426,000 square feet (411,189
square meters).
The Ada County Courthouse in Boise, Idaho, uses the city
geothermal district-heating system. PIX13078 NREL
The Capitol Mall geothermal district-heating system, Boise, Idaho.
The Idaho State Capitol Building in Boise is heated by the
city geothermal district-heating system. PIX13100 NREL
12
13
Geothermal interest has grown in Idaho since the
early 1990s. In the mid 1990s, a computer modeling
study was conducted for the Boise geothermal system
in an effort to predict how different production
scenarios might affect water levels and temperatures.
In 1999, the City of Boise began re-injecting its used
geothermal water into the aquifer through a newly
completed (cost-shared with DOE) injection well.
Since 1999, water levels in a nearby monitoring well
have risen signicantly and in a manner similar to
modeling predictions.
These resources could provide up
to 20 percent of Idaho’s heat and
power needs!
Although there has been a great deal of development
of geothermal energy in Idaho, considering its small
population and large land mass, the potential for
further use of this resource is great. Development
of geothermal energy resources for various
applications has proven to be a positive economic
impact for Idaho.
■
Geothermal production well at the College of Southern Idaho, Twin Falls. This district-heating system now heats nearly
half a million square feet (46,450 square meters), with more area reached by this winter with 16 heat-pump units.
PIX13108 NREL
14
15
Fish Breeders
of Idaho
In 1973, Leo Ray became the rst person to use
geothermal water to raise catsh in the Hagerman
Valley near Buhl, located in the Snake River Valley
in southern Idaho. In fact, Mr. Ray may have
been the rst person in Idaho to put geothermal
resources to work for sh farming, raising tilapia,
sturgeon, blue-channel catsh, and rainbow trout.
Mr. Ray’s site has hot artesian wells that produce
abundant quantities of 95°F (35°C) water. Mixing
this hot water with crystal-clear cold springwater
produces the ideal temperature for growing these
sh. The climate is too cold and the growing
season too short to grow these aquatic species
without hot water. Geothermal water changes
a non-commercial area into a 365-day optimum
growing season.
After processing onsite, the sh are shipped daily
to supermarkets and restaurants throughout the
United States and Canada. Mr. Ray also raises
alligators with geothermal water – 2000 alligators!
Some of the alligator hides are even sold to
Gucci™ for women’s purses. (For more details, see
GATORS IN THE SAGE, geoheat.oit.edu/bullletin/
bull23-2/art2.pdf, Geo-Heat Center Quarterly
Bulletin, Vol. 23 #2.)
Tilapia ngerlings being raised in Idaho with the
aid of geothermal energy.
Mature alligators at Fish Breeders of Idaho – without geothermal heat, they could not survive in Idaho.
Leo Ray in front of geothermally heated cascading sh
raceways. Geothermally heated water accelerates sh growth.
14
14
15
Energy ef ciency and clean, renewable energy will mean a stron-
ger economy, a cleaner environment, and greater energy inde-
pendence for America. By investing in technology breakthroughs
today, our nation can look forward to a more resilient economy
and secure future.
Far-reaching technology changes will be essential to America’s
energy future. Working with a wide array of state, community,
industry, and university partners, the U.S. Department of Energy’s
Of ce of Energy Ef ciency and Renewable Energy invests in a
portfolio of energy technologies that will:
* Conserve energy in the residential, commercial,
industrial, government, and transportation sectors
* Increase and diversify energy supply, with a focus on
renewable domestic sources
* Upgrade our national energy infrastructure
* Facilitate the emergence of hydrogen technologies
as vital new “energy carriers.”
Biomass Program
Using domestic, plant-derived resources to meet our fuel,
power, and chemical needs
Building Technologies Program
Homes, schools, and businesses that use less energy, cost less to
operate, and ultimately, generate as much power as they use
Distributed Energy & Electric Reliability Program
A more reliable energy infrastructure and reduced need
for new power plants
Federal Energy Management Program
Leading by example, saving energy and taxpayer dollars
in federal facilities
FreedomCAR & Vehicle Technologies Program
Less dependence on foreign oil, and eventual transition
to an emissions-free, petroleum-free vehicle
Geothermal Technologies Program
Tapping the Earth’s energy to meet our heat and power needs
Hydrogen, Fuel Cells & Infrastructure Technologies Program
Paving the way toward a hydrogen economy and net-zero carbon
energy future
Industrial Technologies Program
Boosting the productivity and competitiveness of U.S.
industry through improvements in energy and environmental
performance
Solar Energy Technology Program
Utilizing the sun’s natural energy to generate electricity
and provide water and space heating
Weatherization & Intergovernmental Program
Accelerating the use of today’s best energy-ef cient and renewable
technologies in homes, communities, and businesses
Wind & Hydropower Technologies Program
Harnessing America’s abundant natural resources for clean
power generation
To learn more, visit www.eere.energy.gov
16
Produced for the
1000 Independence Avenue, SW, Washington, DC 20585
By the National Renewable Energy Laboratory,
a DOE National laboratory
DOE/GO-102004-1957
August 2004
Printed with renewable-source ink on paper containing at least
50% wastepaper, including 20% postconsumer waste
