HomeMy WebLinkAboutManley Alaska Geothermal Project Scoping PhaseI Final Report Millennium Energy LLC 12-2006
MMIILLLLEENNNNIIUUMM EENNEERRGGYY LLLLCC
FINAL REPORT
Manley, Alaska
Geothermal Project Scoping Assessment
Prepared for:
National Renewable Energy Laboratory
1617 Cole Blvd.
Golden, CO 80401
Subcontract #KLDJ-5-55050-05
Prepared by:
Millennium Energy LLC
PO Box 16073
Golden, CO 80403
(303) 526-2972
www.millennium-energy.net
December 2006
December 2006 ii Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
DISCLAIMER
This report was prepared as an account of work partially sponsored by an agency of the United
States Government. Neither the United States Government nor any agency thereof, nor any of
their employees, makes any warranty, express or implied, or assumes any legal liability or
responsibility for the accuracy, completeness, or usefulness of any information, apparatus,
product, or process disclosed, or represents that its use would not infringe privately owned rights.
Reference herein to any specific product, process, or service by trade name, trademark,
manufacturer, or otherwise, does not necessarily constitute or imply its endorsement,
recommendation, or favoring by the United States Government or any agency thereof. The views
and opinions of authors expressed herein do not necessarily state or reflect those of the United
States Government or any agencies thereof.
December 2006 iii Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
ACKNOWLEDGMENTS
The authors wish to thank several individuals for their assistance in the preparation of this
document. First and foremost we would like to acknowledge the efforts and leadership provided
by David Lockard of the Alaska Energy Authority. Mr. Lockard was instrumental in setting up
the site visit and scoping meeting with residents of Manley Hot Springs, as well as in pushing
this potential project forward. We would also like to thank Bob and Kathy Zeitler for leading the
GeoPowering the West team on the site visit of geothermal resources, potential locations of
geothermal facilities, and existing electrical system facilities. In addition, we also thank the Dart
family for their support of this project, and for providing a personal tour of their hot springs and
associated greenhouse/spa facilities. Lastly, we want to thank all the residents of Manley Hot
Springs for their participation in the scoping meeting and for their enthusiastic support of the
potential geothermal projects. We appreciate the time and effort these individuals spent with us.
We have made honest efforts to secure accurate and up to date information. To the extent errors
remain in the report, it is our responsibility. Please do not hesitate to contact us should you
identify mistakes in this report.
Cover photos by Millennium Energy LLC.
December 2006 iv Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
TABLE OF CONTENTS
DISCLAIMER ..................................................................................................................ii
ACKNOWLEDGEMENTS ..............................................................................................iii
1 INTRODUCTION ......................................................................................................1
2 BACKGROUND AND GEOTHERMAL RESOURCE CHARACTERIZATION .........2
2.1 LOCATION ................................................................................................................2
2.2 PREVIOUS STUDIES OF MANLEY HOT SPRINGS REGION ................................4
2.3 DISCUSSION AND RECOMMENDATIONS ..........................................................13
3 SITE VISIT AND SCOPING MEETING ..................................................................15
3.1 SITE VISIT ..................................................................................................................15
3.2 COMMUNITY SCOPING MEETING SUMMARY ................................................................19
4 CONCLUSIONS AND RECO MMENDATIONS ......................................................23
APPENDIX A: REFERENCES ......................................................................................25
December 2006 1 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
1 Introduction
Manley Hot Springs, Alaska is located about 90 miles northwest of Fairbanks, and is home to about
125 year-round residents. This remote area has a known geothermal resource, and a history of small
projects that have utilized this hot water for direct use applications (i.e., space heating, greenhouse
heating, and bathing). Recently, with the success of Chena Hot Springs in developing a similar
geothermal resource for small scale power production, and with prevailing energy rates in the area of
about 68 cents per kiloWatt-hour (kWh), the Alaska Energy Authority (AEA) applied for technical
assistance from the US Department of Energy's GeoPowering the West (GPW) Initiative and the
National Renewable Energy Laboratory (NREL) via its Task Ordering Agreement (TOA)
mechanism to conduct a feasibility study of geothermal project opportunities for Manley.
AEA was successful in its application, and Millennium Energy LLC, a Colorado-based renewable
energy consulting firm, was awarded a contract to work with AEA and Manley residents to review
and assess both direct use and power production opportunities. Under the TOA agreement (#KLDJ-
5-55050-05) with NREL, Millennium Energy was tasked to investigate the potential of geothermal
development at Manley Hot Springs, including the following applications: district heating,
greenhouse heating, lodge or resort development, swimming pool development, community cold
storage, and/or power production. The first step in this investigation was to conduct a scoping study,
or Phase I assessment, with Manley representatives to determine if a) all of the aforementioned
applications should be looked at in a cursory, qualitative manner, or b) conducting a detailed
technical and economic feasibility study on one application would be the best course of action.
Specifically, Millennium was tasked to perform the following actions:
1. Contact the appropriate state and local authorities for background information on this project and
site, starting with Alaska Energy Authority;
2. Summarize the resource information;
3. Conduct a site visit and project scoping meeting with local residents; and
4. Develop a brief scoping report delineating a statement of work developed by consensus among
AEA, Manley, Sandia National Laboratory, NREL, and Millennium. The consensus-based
statement of work would then form the basis for follow-on activities to be provided by
Millennium under Phase II of the project.
This report summarizes the task actions completed under this Phase I assessment. Specifically,
Section 2 details the geothermal resource characterization for the Manley Hot Springs area; Section
3 summarizes the site visit and community project scoping meeting conducted on August 23, 2006;
and Section 4 provides conclusions and recommendations resulting from this Phase I study,
including the recommended scope of work for Phase II activities under the NREL TOA agreement.
December 2006 2 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
2 Background and Geothermal Resource Characterization
A trading post was established at Manley Hot Springs in 1881. The trading economy transitioned
into support of mining and the site became the center of the Manley Hot Springs mining district
around the beginning of the 20th Century with the discovery of gold in the area in 1898 (Mertie,
1937). In 1906, geothermal direct-use began with the heating of a 60-room hotel and spa. In
addition, geothermal heating was applied to a dairy, hog and poultry farm. A decline in mining
activity and the burning of the hotel and spa resulted in the end of early geothermal direct-use except
for continued greenhouse heating and some small-scale space heating, which continues to this day.
The purpose of this study is to review the literature and past studies on Manley Hot Springs and
provide an up to date synthesis of the geology and geothermal potential of the hot springs. It is
anticipated that geothermal direct-use could be of substantial benefit to the current Manley Hot
Springs community and the surrounding area. Also, a preliminary analysis of the geothermal
reservoir potential for small-scale, binary cycle electrical power is presented along with
recommendations and approaches to complete a detailed assessment of the geothermal resource.
2.1 LOCATION
Manley Hot Springs is located 90 miles west northwest of Fairbanks and 50 miles east southeast of
the village of Tanana on the Yukon River (Figure 1). The Elliot Highway, Alaska Highway 2,
connects Manley Hot Springs with Fairbanks. It is a partially paved two-lane road that is often
closed for long periods of time in the winter.
The area lies within a region of discontinuous permafrost. Permanent snow elevation in the region is
about 5,000 ft (Anderson, 1970). The climate at Manley Hot Springs is similar to Fairbanks. In
Fairbanks, the annual precipitation is 10.34 inches. Fairbanks has 13,980 degree heating days with
an 18o C reference temperature (NOAA).
The area overlies the boundary of the western Yukon-Tanana Upland and northern Tanana-
Kuskowin Lowland physiographic provinces of Alaska (Wahrhaftig, 1994). Quadrangle maps
Tanana A-2 and Kantishna River D-2 cover the area. Manley Hot Springs is located at the southern
margin of the Tanana A-2 quadrangle map. The Manley Hot Springs lie at the base of the Manley
Hot Springs Dome, a local high elevation area on Bean Ridge, adjacent to the Tanana River Valley
and the Hot Springs Slough (Figure 2). The Manley Hot Springs Dome has a maximum elevation of
about 2,485 ft and the Tanana River Valley adjacent to Manley Hot Springs has an elevation of
about 275 ft.
December 2006 3 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Figure 1. Location map of the Manley Hot Springs, Alaska area (modified from The National
Geographic Society).
December 2006 4 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Figure 2. Local digital elevation model of Manley Hot Springs (National Elevation Dataset
from US Geological Survey).
2.2 PREVIOUS STUDIES OF MANLEY HOT SPRINGS REGION
Several reconnaissance studies have been conducted on Manley Hot Springs (formerly called Baker
Hot Springs and Karshner Hot Springs). A bibliography of past studies is included as Appendix A to
this report. The earliest studies are those of Waring (1917). In the 1970’s and 1980’s several studies
covered Manley Hot Springs (ADGGS, 1983; East, 1982; Forbes and others, 1974; Gassaway and
Abramson, 1977; Miller, 1973; Miller and others, 1973 and 1975). Statewide summaries of Alaska
geothermal resources are found in ADGGS, 1983 and Miller, 1994. A bibliography of Alaska
geothermal resources is found in Liss and others (1987). East (1982) provides the onl y synthesis
specific to Manley Hot Springs. The East (1982) study discusses additional hot spring water
chemistry, a shallow temperature survey, soil mercury and helium surveys, and shallow EM
(electromagnetic) geophysical surveys.
Geologic maps for the area are found in Chapman and others (1975 and 1982), Chapman and Yeend
(1981), Patton and others (1989), Pinney (1998), Reifenstuhl and others (1998), and Wilson and
others (1998). Regional analysis of geology includes Dover (1994), Dusel-Bacon (1994), Mertie
(1937), Nokelberg and others (1994), Pewe (1975), Plafker and Berg (1994), and Silberling and
others (1994).
December 2006 5 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Regional geophysical (aeromagnetic) surveys with pertinence to Manley Hot Springs include (Burns,
1996 and 1997) and Meyer and Saltus (1995). Neotectonic analyses of the region include Gedney
and others (1972), and Plafker and others (1994).
Topical studies that are mainly concentrated on the mineral resources of the area that may have
useful information on Manley Hot Springs include Maloney (1971), McDal and others (1988),
Mertie (1932), Moxman (1964), Southworth (1982), Szumigala and others (2004), Wayland (1961),
and Yeend (1990).
GEOLOGY
Central Alaska represents a complex collage of terranes or microplates added to the North American
continent as a result of Paleozoic through Tertiary interactions and collisions of the North American
tectonic plate (mostly continental crust) with various outboard oceanic plates (such as the current
collision and subduction of the Pacific Plate) on the west, south, and southwest of Alaska (Dover,
1974; Dusel-Bakon, 1994; Nokleberg and others, 1994; and Plafker and Berg, 1994). Some of the
outboard dominantly oceanic crust plates transported continental crust fragments into tectonic plate
collision and accretion. In other cases, ripped off continental crust and island arcs of the North
American plate from other locations were pasted to the North American continent in Alaska. In
other areas, upper parts of the oceanic crust were tectonically shaved at the plate boundary and later
pasted (accreted) to the continent in Alaska. Each of the terranes is defined by packages of rocks
that internally record their unique internal depositional, structural, and tectonic history (Dover, 1974;
Dusel-Bacon, 1994; Nokleberg and others, 1994 Patton and others, 1989; Reifenstuhl and others,
1998; Silbering and others, 1994; and Wilson and others, 1998). These packages of rocks are bound
together and/or merged by complexes of high angle strike slip and reverse faults along with
relatively flat and imbricate overriding thrust faults.
A package of variously deformed, but largely unmetamorphosed clastic rocks (flysch deposits)
underlies the Manley Hot Springs region. The flysch sediments were deposited in a Cretaceous and
Jurassic submarine fan basin and comprise the Manley or Beaver Creek terrane of rocks and
structures (Silbering and others, 1994; and Dover, 1994). Older metamorphosed terranes of
Paleozoic to Mesozoic age are found to the north and are sliced by south-vergent and imbricated
thrust faults (Dusel-Bacon, 1994; Nokleberg and others, 1994; Patton and others, 1989; Reifenstuhl
and others, 1998; Silbering and others, 1994; and Wilson and others, 1998). To the south, a
metamorphic terrane of Precambrian to Mesozoic age protoliths is transported on north-vergent
thrust faults (Figure 3). All of the terranes are cut by high angle faults, many with major strike slip
components. The Kaltag and Stevens Creek faults and associated splays are among the more
important, if not larger, high angle faults in the area.
December 2006 6 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Figure 3. Geologic map of Manley Hot Springs region. Yellow represents Quaternary deposits;
green shades are Mesozoic rocks of the Manley terrane; brown and blue shades are
Precambrian and Paleozoic rocks. Red is granite of Hot Springs Dome pluton. Lines and
dotted lines with barbs are thrust faults; barbs point to the allochthon or hanging wall.
Other solid and dotted lines are high angle and strike slip faults (geology from Wilson
and others, 1998).
At Manley Hot Springs the Manley terrane consists of the Lower Cretaceous (Albian) Wilber Creek
unit (not a formal formation name) (Figure 4). The Wilber Creek unit consists of thin-bedded, and
frequently graded deposits of dark, poorly sorted, argillaceous, lithic sandstone, siltstone and shale.
Locally, the unit may also contain gray, dense, lithic quartzite (Reifenstuhl and others, 1998). The
Wilber Creek unit is intruded by the Hot Springs pluton (58 million years old) (Reifenstuhl and
others 1997). The Hot Springs pluton consists of medium- to coarse-grained biotite granite. The
Wilber Creek unit shows hornfels contact metamorphism adjacent to the Hot Springs pluton. The
north side of the pluton is in high angle fault contact with the Wilber Creek unit while contact
relationships for the southern side of the intrusion are poorly known. While hornfels metamorphism
gives information on the approximate location of the contact, the nature of the contact shape is
unknown (i.e., is the contact at high angle or low angle, etc?). Reifenstuhl and others (1998) point
out that the pluton has “extremely low magnetic susceptibility.” This could be important to
understand the southern shape of the pluton if the magnetic susceptibility of the Wilber Creek units
or the hornfels areole is substantially higher than the Hot Springs pluton.
December 2006 7 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Figure 4. Local geologic map of Manley Hot Springs and Hot Springs Dome. Green is the
Lower Cretaceous Wilbur Creek unit (stippled areas are hornfels); purple is Paleocene
Hot Spring Dome pluton (biotite granite), brown is Quaternary loess, others units are
Quaternary swamp and river deposits (geology from Reifenstuhl and others, 1998). Faults
have same symbols as Figure 3.
Bedrock is generally mantled by thin deposits of locally-derived colluvium. In scattered areas,
especially in topographic drainage, Pleistocene deposits of loess are observed mostly filling in the
depressions (Reifenstuhl and others, 1998). The Tanana Valley floor is underlain by fluvial gravel
and sand channel deposits and associated finer-grained overbank deposits (Reifenstuhl and others,
1998). Local organic-rich swamp deposits rest within and on top of the river deposits at scattered
locations.
HYDROGEOLOGY
A hot spring system requires a deep circulation path after surface recharge in order to sweep up heat
in the subsurface and concentrate that heat at or near the surface. Recharge can occur many miles
distance and over a very large area. The overall flow path may only allow seepage at low rates
through a large volume of rock. However, at the upflow or discharge end of the flow path, the flow
must be of sufficient volume and rate to transport the heat upward without loosing most of the heat
by conduction to the surrounding country rock. In other words, the process of convection or
advective heat transfer must overwhelm the process of conductive heat transfer in the upflow portion
of a hot spring system. Good vertical fracture permeability is required. Also, the vertical fracture
system must have sufficient open fracture surface area at great depth to collect or divert incoming
seepage from low permeability rock.
At Manley Hot Springs, the large volume low permeability country rock may consist of the Wilber
Creek unit. Fault zones could provide the vertical permeability “window” for hot water discharge.
However, the location of the hot springs on or adjacent to the Hot Springs pluton and its hornsfel
alteration areole suggests that fracture permeability in either the contact zone or the pluton provides
the “upflow discharge window.” Regionally, there exist sufficient elevation differences to force
ground water seepage to great depth. The location of the springs adjacent the Tanana Valley floor
also points to an advective-type geothermal system with an upflow in fractured granite or hornfels.
December 2006 8 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
The association of Manley Hot Springs with a granitic pluton is a common hydrogeologic setting
with practically all of the hot spring systems in central Alaska (Miller and others, 1975 and Miller,
1994).
REGIONAL HEAT FLOW
There is a substantial lack of heat flow measurements in the interior of Alaska. In fact, there are no
measurements within a radius of several 100 km of Manley Hot Springs (Sass and others, 1981;
Blackwell others, 1991; and Blackwell and Steele, 1992; and Blackwell and others, 2004).
However, all of the above compilations and maps indicate a probable heat flow between 80 and 90
mW/m2 in the region around Manley Hot Springs. Certainly, this estimate has potential for error.
However, heat flow can be roughly characterized for “thermal” provinces using some of the criteria
discussed by Morgan and Sass (1984) and Morgan and Gosnold (1989). Age since last magmatism,
crustal heat production, crustal thickness, and tectonic style and magnitude of activity can all play
roles. On local scales, regional and local ground water flow may complicate regional assumptions.
Thermal conductivity of graywacke (flysch sediments) ranges from about 2.70 to 3.35 W/m oK
(Blackwell and Steele (1989). Therefore, conductive temperature gradients in the Manley (Beaver
Creek) tectonostragraphic terrane are likely to range between 25 and 35 oC/km with the estimated
regional heat flow of 80 to 90 mW/m2.
NEOTECTONICS
While regional heat flow and local vertical permeability are important in determining geothermal
potential, neotectonics can play a very important role. Certainly, Pleistocene magmatism, especially
that associated with large volumes of dacitic and rhyolitic eruptions, can be of major significance
(Smith and Shaw, 1978 and Wohletz and Heiken, 1992). Unfortunately, no Neogene (less than 10
million years old) rhyolitic or basaltic volcanism is known to occur within 50 km or more of the
Manley Hot Springs area (Plafker and others, 1994).
Sustaining fracture permeability and fractured reservoir volumes can be very important for
geothermal resources. Because of elevated temperatures and long flow paths, geothermal fluids
become mineralized and fractures in the outflow paths can seal with minerals such as quartz when
the fluids cool. Seismicity and active faulting can be very important to periodically break and reopen
healed fractures or create new fractures. Seismicity may also contribute to forcing very deep-seated
hot fluids toward shallow depth (Sibson, 1990).
Gedney and others (1972) and Plafker and others (1994) show that several structures in the Manley
Hot Springs region are suspected of having movement in the last million years. These include the
Kaltag, Stevens Creek, and Minook Creek fault zones. Historic earthquake epicenters (>2.0 in
magnitude) mapped in the region by Gedney and others (1972) from 1968 to 1971 show at least 3
epicenters within a couple of miles of Manley Hot Springs. On the other hand, Page and others
(1991) do not show any epicenters (>1.0 in magnitude) in the immediate Manley Hot Springs
vicinity from 1982 to 1985. One speculative hypothesis to explain the near universal occurrence of
hot springs adjacent granitic plutons in central Alaska is that the plutons focus or enhance regional
stress to allow local periodic brittle strain release (fracturing and small (<1 or 2 in magnitude)
earthquake swarms) and open favorable pathways for geothermal circulation.
December 2006 9 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
HOT SPRING CHEMISTRY AND GEOTHERMOMETRY
Water chemistry for thermal waters at Manley Hot Springs is compiled in Tables 1a and 1b from
Waring (1917), Miller and others (1975), East (1982) and the online US Geological Survey NWIS
database (http://nwis.waterdata.usgs.gov/nwis). Included in the compilation are cold water samples
from East (1982).
Table 1a. Table of Manley Hot Springs water chemistry supplemental information.
Red indicates TDS estimated from specific conductance.
# Site Date Temp pH Cond TDS Flow Reference
Manley HS oC uS/cm mg/L gpm
1 650018150375401 10/1/1954 6.5 684 391 USGS NWIS
2 650018150375401 1/14/1970 7.8 623 389 USGS NWIS
3 650018150375401 5/30/1972 57 USGS NWIS
4 650018150375401 7/9/1976 47.5 7.6 540 372 203 USGS NWIS
5 59 7.7 Miller and others (1975)
6 56 7.7 Miller and others (1975)
7 650018150375401 8/5/1915 52 110 Waring (1917)
8 A-1 59.5 8.2 850 527 East (1982
9 A-2 58.7 8.4 810 502 East (1982
10 B-1 32 7.1 650 403 East (1982
11 C-5 33.1 7.7 615 381 East (1982
12 D-1 25.4 6.6 520 322 East (1982
13 HW-1 29.1 540 334 East (1982
14 CS-1 1.5 6.4 32 20 East (1982
15 CW-4 15 East (1982
December 2006 10 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Table 1b. Table of Manley Hot Springs water chemistry.
Red indicates TDS is estimated from specific conductance.
# Temp pH EC TDS Na K Ca Mg HCO3 SO4 Cl F SiO2 B Li
oC uS/cm mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L ug/L ug/L
1 6.5 684 391 117 6.8 9.1 0 83 41 124 52
2 7.8 623 389 120 5.3 8.2 0.4 82 38 116 6.3 54
3 57 45 133
4 47.5 7.6 540 372 110 4 9.3 0.4 92 36 110 56 960 230
5 59 7.7 130 4.5 4 1 89.6 54 134 8.5 65 130 280
6 56 7.7 130 4.8 6.8 0.29 90.7 51 132 8.2 65 120 280
7 52 121 8.2 9.1 0.9 86 48 120 59
8 59.5 8.2 850 527 145 4.6 8.2 0.11 90 153 8.3 65 290
9 58.7 8.4 810 502 148 4.7 7.6 0.06 93 192 8.6 65 300
10 32 7.1 650 403 123 3.57 8.4 0.74 81 182 7.2 59 210
11 33.1 7.7 615 381 111 2.98 11.2 1.11 99 134 6.5 47 170
12 25.4 6.6 520 322 101 2.95 12.2 1.34 68 147 4.4 50 0.2
13 29.1 540 334 109 3.11 2.2 0.16 40 192 5.9 3 0.2
14 1.5 6.4 32 20 2.9 0.24 3 0.5 10 <37 0.1 20
15 15 12.6 1
The waters have low total dissolved solids (TDS), ranging from 322 to 527 mg/L. The range in TDS
suggests that mixing with shallow ground water is occurring. Figure 5 shows a plot of Na versus Cl.
A general upward to the right trend confirms that mixing is occurring. However, there is a lot of
scatter in the data, indicating that the mixing is apparently more complicated than simple mixing of
two end members. Figure 6 shows the relationship between the mole concentration ratios of Na and
Cl versus SiO2 in mg/L. Clearly, two types of thermal water may be juxtaposed at shallow depth.
One group (A) of thermal waters show mole concentration Na/Cl ratios between 0.61 and 0.67 and
the other group (B) of thermal waters show Na/Cl ratios between 0.44 and 0.54. The lower ratios
are generally associated with the cooler sampled thermal waters. Halite (rock salt) has a ratio of
0.6485. The lower ratio waters have more chloride than is required for salt balance with halite. This
may indicate that geochemical processes other than mixing may also be occurring. Anthropogenic
sources are possible considering that a hog and poultry farm once existed in the area. Analytical
error is also possible because Cl seems to be the only anomalous ion. Since there is no sulfate
analysis reported for the East (1982) data it is not possible to check the analysis for charge balance
or check TDS against specific conductance for mass balance error.
December 2006 11 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Figure 5. Chloride (Cl) versus sodium (Na) for Manley Hot Springs waters.
Figure 6. Mole concentration ratios of sodium and chloride versus silica (SiO2).
December 2006 12 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Figure 7 shows a plot of Cl versus SiO2 delineating two apparent mixing trends. Geothermometry
analysis will use only the upper end member waters in the mixing trend derived from samples with
the higher Na/Cl ratio (Group A). For the purposes of this analysis the mixing is assumed to occur at
very shallow depth (<200 ft) and that the upper end member chemistry reflects largely unmixed
geothermal fluids. The lower Na/Cl ratio water will not be evaluated for geothermometry as there is
some uncertainty as to the reliability or origin of this water. However, it is possible that this water
could represent a geothermal flow with a different flow path or mixing history than the waters with
the higher Na/Cl ratio.
Figure 7. Silica versus chloride.
Chemical geothermometers comprise two basic types, silica and cation ratio geothermometers.
Silica geothermometers (especially chalcedony) are perhaps the most reliable in lower temperature
geothermal systems. With higher temperatures and reservoir rocks comprised of intermediate to
silicic volcanic and plutonic rocks, the cation geothermometers tend to give reliable subsurface
temperature estimates. Cation geothermometers which use ion ratios in the calculations may show
only small affects if shallow mixing with non-thermal water occurs. On the other hand, mixing can
modify silica geothermometers. Table 2 lists geothermometer estimates for Manley Hot Springs.
December 2006 13 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Table 2. Geothermometer estimates for subsurface reservoirs at Manley Hot Springs.
SAMPLE # (Table 1a,1b) 5 6
GEOTEMPERATURE oC oC REFERENCE
Measured at surface 59 56 Miller and others (1973)
Na/K 107.2 111.6 Arnorsson and others (1983)
Na/K/Ca (4/3) 102.5 113.6 Fournier and Truesdell (1973)
K/Mg 75.6 92.8 Giggenbach (1988)
Li/Mg 92 109.3 Kharaka and Mariner (1989)
Chalcedony 92.6 90.4 Arnorsson and others (1983)
Qrtz 114.5 114.5 Fournier and Rowe (1966)
Fournier and others (1974) discuss the assumptions for the use of geothermometers. The main
assumptions are: 1) Temperature-dependent reactions occur at depth; 2) All constituents involved in
a temperature-dependent reaction are sufficiently abundant; 3) Water-rock equilibration occurs at the
reservoir temperature; 4) Little or no re-equilibration or change in composition occurs at lower
temperatures as the water flows from the reservoir to the surface; and 5) The hot water coming from
deep in the system does not mix with cooler shallow ground water. Clearly assumption #5 is not
valid at Manley Hot Springs. However, if the mixing is at shallow depth, then the least mixed hot
water component may reliably predict deep conditions. Other more rigorous mixing models are
discussed in Fournier and Truesdell (1974); but not applied in this analysis.
The chalcedony and K/Mg geothermometers probably best characterize the reservoir in the upper
parts of the upflow zone. Temperatures between 76 and 93o C appear to be very reasonable. Quartz
and the other cation geothermometers probably reflect conditions at great depth in the Manley Hot
Springs flow path. Deep maximum temperatures in the Manley Hot Springs system probably do not
exceed 115o C.
2.3 DISCUSSION AND RECOMMENDATIONS
East (1982) reports that the composite flow for the main group of hottest springs at Manley totals
about 1,418 L/min (about 375 gpm). The total convective output is more when all the others areas
with warm seeps and wells are taken into account. Ground temperature surveying by East (1982)
shows an elongated area of elevated thermal soil about 2,500 ft by 1,250 ft that is oriented in a
northeast trend. Several very small and intense thermal anomalies are superimposed on the larger
thermal anomaly. The most intense anomalies are located along Karshner Creek. Northeast and
northwest trends are apparent. It is not known if this reflects possible bedrock fracture control on
flow or local near surface hydrology controlled by geomorphic features such as Karshner Creek. In
any case, the centers for the intense anomalies are very small (less than 50 ft to 100 ft across). It is
not recommended that drilling be done over the centers of the temperature anomalies. Because these
sites may represent spring upflow and unstable ground, well integrity may not be possible. For good
well integrity, a well must have a properly cemented and installed surface casing, especially if hot
water with positive artesian head is encountered during drilling.
December 2006 14 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Soil geochemical surveys (Hg and He) reported by East (1982) show some correlations with mapped
shallow soil temperature. However, it is not clear that the data provide adequate information to site
a well for the purpose of intersecting fractures at depth that may carry hot geothermal upflow. Also,
the soil gas technique may only be useful to survey areas without permafrost as ice may effectively
seal vertical soil gas permeability.
A shallow EM (electromagnetic) survey gives results that correlate very well with the shallow
temperature survey (East, 1982). Unfortunately, the method used does not allow evaluation of the
deeper subsurface that would be the target of dril ling.
A dipole-dipole resistivity survey or a CSAMT (Controlled Source Audio-Frequency Magneto
Tellurics) survey along roads and trails parallel to Karshner Creek is recommended to view the deep
structure prior to selecting any production or temperature gradient well sites. A surface SP (self
potential) survey may prove very useful. However, its use in permafrost areas needs to be
investigated. Also, a microearthquake survey may provide supplemental but useful information to
understand the Manley Hot Spring system. This could be accomplished by deploying three portable
seismometers at different locations on the Hot Springs Dome. Old mine workings may be available
to place the recorders and geophones. A more expensive approach would drill (core) several shallow
temperature gradient holes into bedrock to a depth no greater than 200 or 300 ft depth. A study of the
core and fractures would allow determination of reservoir characteristics. Detailed temperature logs
would allow a 3-D view of the upper part of the reservoir and aid in selecting locations for injection
and production.
Additional geochemistry should be collected to sort out whether or not one or more types of
geothermal fluids are involved or if there is error in one of the currently available data sets. Analysis
of strontium isotopes (187Sr/186Sr) in the hottest water may allow evaluation of the subsurface flow
path and reservoir host. Granitic rocks (such as the Hot Springs Dome) may have relatively high
ratios. If the sources (provenance) for the Mesozoic flysch deposits in the Manley terrane have
major fractions of arc-related volcanic clasts, the strontium ratios may be much lower. This may be
important to determine if the reservoir is in the Hot Springs Dome granite or if it is in the fractured
contact metamorphic areole (hornfels) of the Manley terrane.
The natural discharge rates of the hot springs and geothermometry indicate that important direct-use
geothermal potential exists. The geothermometry also predicts temperatures (76 to 93o C) sufficient
for small-scale power production similar to the operation at Chena Hot Springs, Alaska.
Minimal additional geophysical or geochemical work is needed. Prior to design of a production well
drilling program (and injection well), engineering design temperatures and flow rates will allow
proper and appropriate sizing and costing of a well.
December 2006 15 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
3 Site Visit and Scoping Meeting
On August 23, 2006 representatives from the US DOE's GeoPowering the West team conducted a
site visit of geothermal springs, existing and potential project sites and electrical utility infrastructure
in the Manley Hot Springs area, as well as participated in a community meeting to scope out the
geothermal project opportunities to pursue under the Phase II assessment under the NREL TOA. The
GPW team members included Joe Bourg and Kevin Rafferty of the Millennium Energy team, David
Lockard of the AEA and the Alaska Geothermal State Working Group, and Roger Hill of Sandia
National Laboratories. Section 3.1 summarizes the site visit activities conducted, and Section 3.2
details the discussion held at the community scoping meeting.
3.1 Site Visit
The first site visited was the Dart family property which contains a 120' x 30' greenhouse/bathing
facility and geothermal surface springs. Upon arriving at the property, the GPW team was met by
John Dart, who provided a tour of the greenhouse/bathing facility. Mr. Dart also briefed the team on
the history of the property and facility operations, a description of the resource on the property and
how it is utilized, as well as his support for the development of additional geothermal projects in the
Manley community. He also expressed his family's support for possibly locating geothermal
facilities, such as a small-scale power plant, on the family property and/or using the resource the
family has rights to if the community would benefit from it.
Figure 8. Greenhouse/Bathing Facility at Dart Property
After touring the Dart's facility, the team was led by Manley resident Bob Zeitler to the area of the
property containing the geothermal springs. The springs are located ~1/2 mile north of the road to
the property in a narrow, stream cut valley. There are two primary springs. Previous studies have
estimated that the larger spring flows about 300 GPM (gallons per minute) at 52oC and the smaller
one yields about 25-20 GPM at 56oC. The thermal waters from these springs are used to heat
buildings on the property as well as the greenhouse/bathing facility, flowing though 3/4 inch PVC
pipe to each site. Previous estimates indicate that only 30-40 percent of the thermal waters are being
December 2006 16 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
beneficially used by buildings and facilities located on the Dart property. It has been reported that in
the past, a 6" diameter well was drilled to a depth of ~50 feet at the site, near the smaller spring,
which yielded abundant flows of 65oF water. Additional drilling at deeper depths would be required
in the future to determine if higher temperature water existed at the site (i.e., over 75o C) with
sufficient flow rates that would support a binary power plant.
Figure 9. Larger Spring at Dart Property
Next, the GPW team traveled to the Manley Community Center for a meeting with area residents to
discuss the potential applications and priorities for geothermal development (see Section 3.2 for
meeting details). Following the community project scoping meeting, Millennium team members Joe
Bourg and Kevin Rafferty continued the site visits of potential project sites led by Bob and Kathy
Zietler. The first facility visited in the afternoon was the Gladys Dart School where measurements
were taken on boiler sizes to support any future analyses of a potential geothermal space heating
system. The Millennium team also spent an hour with the students at the school providing a tutorial
and discussion on renewable energy and potential geothermal applications in the area.
Next, the team visited the Manley Roadhouse where they examined the heating distribution system
for potential geothermal heating retrofit opportunities. The team also learned that the Roadhouse,
which is the community gathering place, would be closed for the winter for the first time in recent
history primarily due to prohibitively high electricity costs from the local utility.
December 2006 17 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Figure 10. Manley Road House
The next facility the team visited was the diesel gen set power plant run by United Utilities. The gen
set is comprised of one 90 kW and two 125 kW diesel generators. The following bullets detail the
characteristics of the power plant operations in FY 2006:
??28,000 gallons of diesel fuel used;
??$61,000 in fuel costs;
??8.6 kWh sold per gallon of fuel consumed;
??10.5 kWh generated per gallon of fuel consumed; and
??an average electrical load of 34 kW.
It was determined that this site may not be a good candidate for the location of a binary geothermal
power plant since it is believed that higher temperature geothermal resources are available on the
other side of the slough from the existing power plant. However, because a binary geothermal power
plant is a base load unit, it would likely need to be integrated with diesel generators to provide load
following capability. As an alternative, a battery storage system, load bank, or dump load could be
utilized to flatten the load curve, although a diesel generator would still be required for backup
power purposes. AEA has suggested that if a new geothermal power plant were built, that it would
likely recommend construction of a completely new power facility with new switchgear into which a
new backup diesel system could be incorporated. In addition, AEA has suggested that it would also
investigate a distribution system upgrade to include the Tribal Council building and other residences.
December 2006 18 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Figure 11. Diesel Generators at Power Plant
After the tour of the power facilities, the team traveled to the Zeitler property to examine the existing
geothermal wells owned and operated by the Zeitlers and by Thomas Hetherington on the adjacent
property. The Zeitler well is used primarily for supplying hot water to their bathing house, and the
Hetherington well feeds into a gravity fed insulated pipeline that provides hot water and heat to the
Hetherington residence approximately a 1/4 mile away. Both the Zeitlers and Mr. Hetherington
indicated an interest in additional development of their geothermal resources for community or
private benefit.
Figure 12. Well, Pump and Pipeline at Hetherington Property
December 2006 19 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Next, the GPW team visited the tribal community center for a quick tour of the facilities and layout
of the site. The tribal community has expressed an interest in geothermal space heating of the
facilities and/or greenhouse development.
The final destination of the site visit to Manley was the community water filling station, where
residents come to obtain their potable water supplies. This is a 20-acre site that is owned by the
community and was mentioned as one of the possible sites for the placement of a binary geothermal
power plant.
3.2 Community Scoping Meeting Summary
At 10 AM on August 23, the GPW team participated in a community geothermal project scoping
meeting with residents of the Manley area. Twenty-three people were in attendance at the meeting,
which was designed to garner community input into the Phase II study elements under the NREL
TOA. David Lockard kicked off the meeting with roundtable introductions of the GPW team and
resident participants. Mr. Lockard then provided some introductory remarks to the group stating that
with fuel prices changing, that there is increased interest in alternative energy in the state. He then
highlighted the recent success that Chena Hot Springs has had with the development of its 2 X 200
kW binary geothermal power plant units, noting that Chena was a turning point for Alaska, the
nation, and possibly beyond. It is the first geothermal power plant in Alaska, as well as the lowest
temperature geothermal plant in the world. He then stated that based on previous studies that the
resource at Manley is likely to be similar to that at Chena, and that we are here today to scope out
future technical assistance support and develop a focus for follow-on efforts for geothermal
development in the area. Mr. Lockard then discussed the local electric utility situation noting that a
major focus of the study could be to look at alternatives to diesel fuel generation with geothermal
power generation -- but that we are here to listen to the community to guide these future efforts. One
participant asked, "How will it change the cost of electricity with a geothermal power plant?" Mr.
Lockard responded that currently, United Utilities charges 68 cents per kWh, and that ~25 cents per
kWh is attributed to diesel costs. Therefore, a geothermal power plant would reduce the fuel cost
portion of the electricity rates significantly. However, we don't know the exact answer right now, but
that answer would be included as a part of the feasibility study. A similar question was asked
regarding the payback period of a new geothermal power plant, and members of the GPW team
agreed that it could be as low as 6-7 years, but that these numbers would be verified by the
feasibility study.
After these introductory remarks, the meeting was opened up into a Q&A type format. The questions
and answers are summarized below:
Q. Where would you drill to get to the geothermal resource?
A. While we have some ideas, based on local knowledge, this would have to be determined through
additional investigations, testing, and exploratory drilling activities.
Q. What is the downside to geothermal?
A. There are not many negatives. The main concern with geothermal is that you don't deplete the
resource by taking too much out, although with re-injection and proper design this is typically not a
major concern. Managing the resource is key.
December 2006 20 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Q. How do you get the heat out to generate electricity?
A. The short answer is with a heat exchanger. Then, the GPW team provided a detailed description
of the heat exchange process as well as a description of the binary power plant technology.
Q. What are the environmental concerns?
A. The environmental concerns are limited since the geothermal water is recycled through re-
injection, and while the old geothermal plants did have hydrogen sulfide in the emissions, this has
been eliminated with the closed loop system design. The other concern is that there is fluoride in the
water, and the design of the system needs to ensure that the equipment is tailored to avoid corrosion
from the fluoride. Also, in a binary system a working fluid is used. In the case of the Chena plant, a
benign refrigerant (R134) is used, and an MSDS (Material Safety Data Sheet) is available for it -
other low-temperature plant designs use pentane as the working fluid.
Q. Is AEA and DOE asking for permission today to proceed with the development of the project?
A. No, we are at a very preliminary stage. There is a long ways to go before we get to that point.
Today, we are here to obtain community input into the scoping of a feasibility study only, and there
is no obligation to the community to proceed any further than that. If, after the feasibility study is
complete the community decides to move forward, then we will work cooperatively with the
community in identifying local champions and proceeding in a coordinated fashion. It should also be
noted that geothermal development could change your community with the addition of a geothermal
power plant, greenhouses, and other development.
Q. The utility does not serve the tribal complex, and tribe operates its own generation. 90 kW is the
direct load at the powerhouse. The tribe did apply for service and the fee would have been $72,000.
The tribe thought it could double, and there is a political issue with the cost of companion services
so we did not proceed. Will the tribe be included in this feasibility study?
A. We would likely limit the study at this time to existing customers of the utility. We could,
however, explore opportunities for other funding sources to study the tribal complex separately.
Q. Are there risks to the resource from drilling?
A. There are always risks with drilling. For example, drilling though a fissure could allow cold water
in and cool the geothermal water, but cementing the well can mitigate this problem.
Q. What about private property rights and geothermal resource rights?
A. Every intention is to respect private property and geothermal resource rights; this must be done
legally.
Q. Manley also has good wind and hydro resources. There may be potential for a wind farm at the
top of Bean Ridge (about five miles from town) and the Tanana River is right here. Is there any way
to reshuffle some of the dollars for the geothermal assessment to look at wind and/or hydro?
A. The money from GPW can only be used for geothermal technical assistance. However, AEA has
a MET tower program, and is also involved in hydroelectric development. Therefore, AEA may be
able to assist Manley directly in wind and hydro assessments separate from the geothermal
assessment.
December 2006 21 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Q. What if United Utilities doesn't want to do anything with the geothermal project?
A. United Utilities may not be involved in the geothermal power production project, or may not want
to do it. However, Manley is on the list for powerhouse refurbishment (not soon though), and there
may be opportunities for a partnership to do the geothermal, as well as an opportunity to look at
outside partnership opportunities to own, operate, and maintain a geothermal power plant. In
addition, AEA will be looking at distribution system upgrades for Manley as part of the powerhouse
refurbishment project. We are not seeking to be hostile to local utility. The Powerhouse Operator
from United Technologies in attendance stated that they would not want to run the geothermal plant,
but that it could be transferred to AVEC or another interested party.
Comment: This project fits into Manley's informal community plan for economic development to
support keeping the school open, the roads open and paychecks coming. We are looking at tourism.
Comment: The key is economic development. Lower power costs will put more money in our
pockets, and people will develop their own businesses and economic development opportunities.
Comment: The Tribal Council is working on goals and a community plan. We want to look at
greenhouses and other economic development opportunities. David Lockard responded that state
provides help (via grants) with community plan development.
Next, the discussion focused on direct use opportunities. David Lockard posed the question, "What
would you like to look at with respect to direct use geothermal applications? The responses included:
??A community swimming pool and gym, which could be used to teach kids from other villages
how to swim, since drowning, is a leading cause of death in children in rural Alaska.
??District heating for the community. Kevin Rafferty commented that he would advise against
spending much time on district heating applications since it is typically a cost prohibitive
proposition, although there may some opportunities in the heart of the Manley community where
buildings are closer together, but that direct space heating of buildings would likely be more
applicable. However, if a geothermal powerhouse is built, there may be sufficient electric power
generated to provide electrical space heating at a different lower rate that would similar to the
cost of heating with fuel oil.
??Snow melting. Kevin Rafferty commented that again, this would be a cost prohibitive
proposition.
??Greenhouses. Growing Vegetables such as lettuce and tomatoes could also be an opportunity to
explore.
??Community Cold Storage. Cold storage could be provided with geothermal via absorption
chilling technology, such as that being used to refrigerate the Ice Museum at Chena Hot Springs.
After a discussion on the above options, it was decided that the priorities for geothermal direct use
applications were space heating of buildings, greenhouses, fish farming, and a community
swimming pool. In addition, while not a direct use, it was also mentioned that hydrogen production
could be an option to consider via an electrolysis process that uses electricity from the geothermal
power plant; since the load at the powerhouse is only 90 kW, and a 200 kW binary geothermal
power plant is currently the smallest unit available, there may be a opportunity to produce hydrogen
from the excess power. However, the sizing of a hydrogen production facility would likely need to
December 2006 22 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
wait until after the geothermal power plant is on line for awhile since it is likely that electric loads in
Manley will increase as power costs come down.
Q. What types of geothermal resource prospecting needs to be done?
A. Thermography, resistivity, and satellite imaging would be used to narrow down the sites before
exploratory drilling is done.
Q. What is the lowest temperature you can generate power at using geothermal?
A. 200oF was the lowest temperature prior to the Chena project, which is generating at 165 oF.
However, the key is the difference in the temperature (delta T) between the geothermal water and the
cooling water. Given the right conditions, temperatures as low as 140 oF could be used. David
Lockard then referred to the Alaska Renewable Energy Atlas and highlighted that the Manley
resource is probably similar to that of Chena Hot Springs.
At the conclusion of the meeting, David Lockard asked the participants for their consensus
agreement on a proposed statement of work for the Phase II study under the NREL TOA. Based on
this request, the following statement of work was developed:
??Priority I: Develop an investment-grade feasibility study to determine possible locations and the
technical and economic potential of a low-temperature geothermal binary power plant at Manley.
??Priority II: Conduct a qualitative assessment of cascaded direct use opportunities near the power
plant location including: a community swimming pool/hot tub, greenhouses, and space heating of
major buildings (school and Manley Roadhouse).
??Priority III: Conduct a qualitative assessment of distributed direct use applications beyond the
power plant site focused on greenhouses and space heating at the tribal community complex.
After consensus was achieved on the scope of work, David Lockard asked the participants if they
had any additional comments or concerns related to the proposed Phase Ii study efforts. One
participant stated that location of the power plant is critical, and that they need to know where it
would be and where the wells would be sited. Another participant questioned how the development
of geothermal projects would impact existing resources, and that he would hate to see electrical
generation from geothermal compromise the existing resource flows. The GPW team responded that
it would include a risk assessment in the write-up of the Phase II study report, as well as include
information on the ownership structure of geothermal rights (i.e., who owns the resources). Mr.
Lockard also suggested that the community should think about potential sites for power generation
and community direct use projects. One participant suggested that the community owns 20 acres that
is a publicly funded water well, and that this could be a potential site.
At the conclusion of the meeting, local contacts were designated for follow-up activities as the Phase
II project proceeds. Pam Redington was designated as the contact for Manley as she is the Secretary
of the Manley Hot Springs Community Association, Elizabeth Woods (Tribal Administrator) is the
contact for tribal related activities, and Elaine Gray of Manley Land Surveyors is the contact for
local maps.
December 2006 23 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
4 Conclusions and Recommendations
Based upon previous studies of the geothermal resource in the Manley area, as well as the resource
characterization provided in this Phase I study, it is apparent that significant opportunities exist for
geothermal project development in the community. Coupled with the fact that Manley is in a rural,
and economically depressed region of Alaska, with electricity rates of 68 cents per kilowatt-hour, we
believe that with the recent advances and lower costs of binary power plant technology that there is
an excellent opportunity to explore the potential for geothermal power generation at Manley. In fact,
Manley may be one of the better economic applications of small scale, low temperature geothermal
binary power generation technology in the State of Alaska. In addition, through the use of cascading
the geothermal resource after it is used for power generation, that economic development
opportunities also exist through direct use applications such as space heating, a community
swimming pool, space heating, greenhouses, and/or aquaculture. Distributed direct use applications
also may provide for private or tribal business ventures. Therefore, based on the site visits and the
community scoping meeting, the following consensus based statement of work is proposed for a
Phase II feasib ility study of power generation and direct use projects at Manley:
??Priority I: Develop an investment-grade feasibility study to determine possible locations and the
technical and economic potential of a low-temperature geothermal binary power plant at Manley.
Specific tasks shall include:
o Assessment of potential sites;
o Description of low-temperature binary power plant technology;
o Estimate of annual energy output;
o Assessment of economic potential, including determination of estimated project costs and
benefits and calculation of benefit-to-cost ratios, payback periods, busbar energy costs and
value of energy generation, net present value, and return on investment;
o Further exploration and geologic assessment of the geothermal energy resource; and
o Recommendations for next steps in the project development process
??Priority II: Conduct a qualitative assessment of cascaded direct use opportunities using waste
heat downstream of the binary power plant including: a community swimming pool/hot tub,
community greenhouse, and space heating of major buildings (school and Manley Roadhouse).
Specific tasks shall include:
o Estimates of unit piping costs ($/LF) for piping to the existing school building;
o Evaluation of each application to include mechanical equipment capital costs, operating
costs, and potential heating savings as appropriate (i.e., Manley Road House); and
o Conceptual designs of individual applications, as appropriate.
??Priority III: Conduct a qualitative assessment of distributed direct use applications beyond the
power plant site focused on greenhouses and space heating at the tribal community complex.
Specific tasks shall include:
o Evaluation of each application to include mechanical equipment capital costs, operating
costs, and potential heating savings as appropriate; and
o Conceptual designs of individual applications, as appropriate.
December 2006 24 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
It is recommended that NREL proceed with the development of a Phase II task order under the TOA
technical assistance mechanism to fund the consensus-based statement of work detailed above. It
should be noted, however, that the final scope of work will be dependent upon the availability of
funds, and that tasks should be funded based upon the priority order identified.
December 2006 25 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Appendix A. References
Alaska Division of Geological and Geophysical Surveys (ADGGS), 1983, Geothermal Resources of
Alaska: Alaska Division of Geological and Geophysical Surveys in conjunction with NOAA and the
U. S. DOE, 1:2,500,000 scale.
Anderson, G. S., 1970, Hydrologic reconnaissance of the Tanana basin, central Alaska: U. S.
Geological Survey Hydrological Investigation Atlas, HA-319.
Arnorsson, S, Gunnlaugsson, E., and Svavarsson, H., 1983, The chemistry of geothermal waters in
Iceland III. Chemical geothermometry in geothermal investigations: Geochemica et Cosmochima
Acta, v. 47, p. 567-577.
Blackwell, D. D., Steele, J. L., and Carter, L. S., 1991, Heat-flow patterns of the North American
continent; A discussion of the Geothermal Map of North American, in Slemmons, D. B., Engdahl, E.
R., Zobak, M. D., and Blackwell, D. D., eds, Neotectonics of North America: Geological Society of
America, Decade Map, v. 1, p. 423-436.
Blackwell, D. D., and Steel, J. L., 1989, Thermal conductivity of sedimentary rocks: Measurement
and significance, in Naeser, N. D., and McCulloh, T. H., eds., Thermal History of Sedimentary
Basins: Springer-Verlag, London, p. 13-36.
Blackwell, D. D., and Steele, J. L., 1992, Geothermal Map of North America: Geological Society of
America Map CSM-007, 1:500,000 scale.
Blackwell, D. D., Richards, M. C., Lewis, T., Majorowicz, J., Mareschal, J., and Gosnold, W. D.,
eds., 2004, Geothermal Map of North America: American Association of Petroleum Geologists,
1:6,500,000 scale.
Burns, L. E., 1996, Portfolio of aeromagnetic and resistivity maps of the Rampart-Manley Mining
Districts: Alaska Division of Geological and Geophysical Surveys Public-Data File 96-9, 14 p.
Burns, L. E., 1997, Portfolio of aeromagnetic and resistivity maps of the Rampart-Manley Mining
Districts: Alaska Division of Geological and Geophysical Surveys Public-Data File 97-23, 13 p.
Chapman, R. M., and Yeend, W. E., Brosge, W. P., and Reiser, H. N., 1975, Preliminary geologic
map of the Tanana and northeast part of the Kantishna River Quadrangles, Alaska: U. S. Geological
Survey Open file Report 75-337, 1:250,000 scale.
Chapman, R. M., and Yeend, W. E., Brosge, W. P., and Reiser, H. N., 1982, Reconnaissance
geologic map of the Tanana quadrangles, Alaska: U. S. Geological Survey Open file Report 82-734,
18 p. 1:250,000 scale.
Chapman, R. M., and Yeend, W. E., 1981, Geologic reconnaissance of east half of Kantishna River
quandrangle and adjacent areas, in Albert, N. R. D., and Hudson, T., eds., The United States
Geological Survey in Alaska: Accomplishments during 1979: U. S. Geological Survey Circular 823-
B, p. B30-B32.
December 2006 26 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Dover, J. H., 1994, Geology of part of east-central Alaska, in Plafker, G., and Berg, H. C., eds., The
Geology of Alaska, The Geology of North America: Geological Society of America, v. G-1., chapter
5, p. 153-204.
Dusel-Bacon, C., 1994, Map and table showing metamorphic rocks of Alaska, in Plafker, G., and
Berg, H. C., eds., The Geology of Alaska, The Geology of North America: Geological Society of
America, v. G-1., 1:2,500,000 scale.
East, J., 1982, Preliminary geothermal investigations at Manley Hot Springs, Alaska: University of
Alaska, Fairbanks, Technical Report prepared for the U.S. Department of Energy under DE-FC07-
79-ET-27034, 76 p.
Forbes, R. B., Leonard, L., Dinkel, D. H., Gedney, L., VanWormer, D., and Kienle, J., 1974,
Utilization of geothermal energy resources in rural Alaskan communities, a feasibility and planning
study: University of Alaska Fairbanks, Geophysical Institute Final Report submitted to the U. S.
Atomic Energy Commission under AT(45-1)-2229, Task 7, 89 p.
Fournier, R. O., and Rowe, J. J., 1966, Estimation of underground temperatures from the silica
content of water from hot springs and wet-steam wells: American Journal Science, v. 264, p. 685-
697.
Fournier, R. O., and Truesdell, A. H., 1973, An empirical Na-K-Ca geothermometer for natural
waters: Geochimica et Cosmochimica Acta, v. 37, p. 1255-1275.
Fournier, R. O., and Truesdell, A. H., 1974, Geochemical indicators of subsurface temperature – part
2, estimation of temperature and fraction of hot water mixed with cold water: U. S. Geological
Survey Journal of Research, v. 2, no. 3, p. 263-270.
Gassaway, J. S., and Abramson, B. S., 1977, Map and table showing distribution of known thermal
springs in selected igneous rocks in central Alaska: U. S. Geological Survey Open-File Report 77-
168H.
Gedney, L., Shapiro, L., and VanWormer, D., 1972, Correlation of epicenters and mapped faults,
east central Alaska, 1968-1971: U. S. Geological Survey Open-File Report 72-128, 7 p., 1:1,000,000
scale.
Giggenbach, W. F., 1988, Geothermal solute equilibria: Derivation of Na-K-Ca geoindicators:
Geochimica et Cosmochica Acta: v. 52, p. 2749-2765.
Kharaka, Y. K., and Mariner, R. H., 1989, Chemical geothermometers and their application to
formation waters from sedimentary basins, in Naeser, N. D., and McCulloh, T. H., eds., 1989,
Thermal History of Sedimentary Basins. Methods and Case Histories: Springer-Verlag, New York.,
p. 99-117,
December 2006 27 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Liss, S. A., Motyka, R. J., and Nye, C. J., 1987, Alaska geothermal bibliography: Alaska Division of
Geological and Geophysical Surveys Technical Report prepared for the U. S. Department of Energy
under DE-FG-07-84ID12524, 258 p.
Maloney, R. P., 1971, Investigations of gossans of Hot Springs Dome, near Manley Hot Springs,
Alaska: U. S. Bureau of Mines Open-File Report 29, 28 p.
McDanal, S. K., Cathrall, J. B., Mosier, E. L., Antweiler, J. C., and Tripp, R. B., 1988, Analytical
results, geochemical signatures, mineralogical data, and sample locality map of placer gold and
heavy-mineral concentrates from the Manley Hot Springs, Tofty, Eureka, and Rampart mining
districts, Tanana and Livengood quadrangles: U. S. Geological Survey Open-File Report 88-443, 54
p.
Mertie, J. B., 1932, Mineral deposits of the Rampart and Hot Springs districts: U. S. Geological
Survey Bulletin, 844-D, p. 163-246.
Mertie, J. B., 1937, The Yukon-Tanana region Alaska: U. S. Geological Survey Bulletin 872, 276 p.
Meyer, J. F., and Saltus, R. W., 1995, Merged aeromagnetic map of interior Alaska: U. S.
Geophysical Investigations Map GP 1014, 1:500,000 scale.
Miller, T. P., 1973, Distribution and chemical analyses of thermal springs in Alaska: U. S.
Geological Survey Open-File Map 570-G, 1:2,500,000 scale, 25 p.
Miller, T. P., Barnes, I., and Patton, W. W., 1973, Geologic setting and chemical characterists of hot
springs in central and western Alaska: U. S. Geological Survey Open-File Report 73-188, 25 p., 1:
250,000 scale.
Miller, T. P., Barnes, I., and Patton, W. W., 1975, Geologic setting and chemical characteristics of
hot springs in west-central Alaska: U. S. Geological Survey Journal of Research, v. 3, no. 2., p. 149-
162.
Miller, T. P., 1994, Geothermal Resources of Alaska, in Plafker, G., and Berg, H. C., eds., The
Geology of Alaska, The Geology of North America: Geological Society of America, v. G-1., chapter
32, p. 979-987.
Morgan, P., and Sass, J. H., 1984, Thermal regime of the continental lithosphere: Journal of
Geodynamics, v. 1, p. 143-166.
Morgan, P. and Gosnold, W. D., 1989, Heat flow and thermal regimes in the continental United
States, in Pakiser, C. L., and Mooney, W. D., eds., Geophysical Framework of the Continental
United States: Geological Society of America Memoir, p. 493-522.
Moxman, R. M., 1964, Reconnaissance for radioactive deposits in the Manley Hot Springs-Rampart
District, east-central Alaska, 1948: U. S. Geological Survey Circular 817, 6 p.
December 2006 28 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Nokleberg, W. J., Moll-Stalcup, E. J., Miller, T. P., Brew, D. A., Grantz, A., Reed, J. C., Plafker, G.,
Moore, T. E., Silva, S. R., and Patton, W. W. 1994, Tectonstratigraphic terrane and overlap
assemblage map of Alaska: U. S. Geological Survey Open-File Report 94-194, 53 p.
Page, R. A., Biswas, N. N., Lahr, J. C., and Pulpan, H., 1991, Seismicity of continental Alaska, in
Slemmons, D. B., Engdahl, E. R., Zobak, M. D., and Blackwell, D. D., eds, Neotectonics of North
America: Geological Society of America, Decade Map, v. 1, p. 47-68.
Patton, W. W., Box, S. E., Moll-Stalcup, E. J., and Miller, T. P., 1989, Geology of west-central
Alaska: U. S. Geological Survey Open-File Report 89-554, 56 p.
Pewe, T. L., 1975, Quaternary stratigraphy nomenclature in unglaciated central Alaska: U. S.
Geological Survey Professional Paper 862, 32 p.
Pinney, D. S., 1998, Surficial map of the Tanana A-1 and A-2 quadrangles, central Alaska: Alaska
Divison of Geological and Geophysical Surveys Public Data File 98-37C, p. 1:63,360 scale.
Plafker, G, Gilpin, L. M., and Lahr, J. C., 1994, Neotectonic map of Alaska, in Plafker, G., and Berg,
H. C., eds., The Geology of Alaska, The Geology of North America: Geological Society of America,
v. G-1., 1:250,000 scale.
Plafker, G., and Berg, H. C., 1994, Overview of the geology and tectonic evolution of Alaska, in
Plafker, G., and Berg, H. C., eds., The Geology of Alaska, The Geology of North America:
Geological Society of America, v. G-1., chapter 33, p. 989-1021.
Reifenstuhl, R. R., Dover, J. H., Newberry, R. J., Clautice, K. H., Liss, S. A., Blodgett, R. B., and
Weber, F. R., 1998, Geologic map of the Tanana A-1 and A-2, central Alaska: Alaska Divison of
Geological and Geophysical Surveys Public Data File 98-37A, 18 p. 1:63,363 scale.
Reifenstuhl, R. R., Layer, P. W., and Newberry, R. J., 1997, Geochronology (40Ar/39Ar) of 17
Rampart area rocks, Tanana and Livengood quadrangles, central Alaska: Alaska Division of
Geological and Geophysical Surveys Public-Data File, 97-29H, 22 p.
Sass, J. H., Blackwell, D. D., Chapman, D. S., Costain, J. K., Decker, E. R., Lawver, L. A., and
Swanberg, C. A., 1981, Heat flow from the crust of the United States, in Touloukian, T. S., Judd, W.
R., and Roy, R. F., eds., Physical properties of rocks and minerals: McGraw-Hill, New York,
CINDUS Data Series on Material Properties, v. H-2, p. 503-548.
Sibson, R. H., 1990, Faulting and fluid flow, in Nesbitt, B. E., ed., Short Course on Fluids in
Tectonically Active Regimes of the Continental Crust: Mineralogical
Association of Canada Handbook 18, p. 93-132.
Silberling, D. L., Jones, D. L., Monger, J. W. H., Coney, P. J., Berg, H. C., and Plafker, G., 1994,
Lithotectonic terrane map of Alaska and adjacent parts of Canada, in Plafker, G., and Berg, H. C.,
eds., The Geology of Alaska, The Geology of North America: Geological Society of America, v. G-
1., 1:250,000 scale.
December 2006 29 Manley Hot Springs, Alaska
Millennium Energy LLC Geothermal Project Scoping Assessment
Smith, R. L., and Shaw, H. R., 1979, Igneous-related geothermal systems, in Muffler, L. J. P., ed.,
Assessment of Geothermal Resources of the United States – 1978: U. S. Geological Survey Circular
790, p. 12-17.
Southworth, D. D., 1982, Cobalt investigation of the Manley Hot Springs Dome area: U. S. Bureau
of Mines Field Report, 19 p.
Szumigala, D. J., Graham, G. E., and Athey, J. E., 2004, Alaska resource data file, Tanana
quandrangle, Alaska: U. S. Geological Survey Open-File Report 2004-1386, 309 p.
Wahrhaftig, C., 1994, Maps of physiographic divisions of Alaska, in Plafker, G., and Berg, H. C.,
eds., The Geology of Alaska, The Geology of North America: Geological Society of America, v. G-
1., 1:2,500,000 scale.
Wayland, R. G., 1961, Tofty tin belt Manley Hot Springs District, Alaska: U. S. Geological Survey
Bulletin 1058-I, 363-414 p.
Waring, G. A., 1917, Mineral springs of Alaska: U. S. Geological Survey Water-Supply Paper 418,
114 p.
Wilson, F. H., Dover, J. H., Bradley, D. C., Weber, F. R., Bundtzen, T. K., and Haeussler, P. J.,
1998, Geologic map of central (interior) Alaska: U. S. Geological Survey Open File Report 98-133,
64 p. 1:250,000 scale.
Wohletz, K., and Heiken, G., 1992, Volcanology and Geothermal Energy: University of Cal ifornia
Press Los Alamos Series in Basic and Applied Sciences 12, 432 p.
Yeend, W. 1990, Gold placers, geomorphology, and paleo-drainage of Eureka Creek and Tofty
areas, Alaska, in Dover, J. H. and Galloway, J. P. eds., Geologic Studies in Alaska by the U. S.
Geological Survey, 1989: U. S. Geological Survey Bulletin 1946, p. 107-109.