Study of Direct Use Options for Hot Springs in Adak, Akutan & Atka

Prepared for: The Alaska Energy Authority & The Aleutian Pribilof Islands Association

Prepared by: George Roe, Dick Benoit, and Chris Pike

10 February 2015

For information about this report please contact: Gwen Holdmann, Director Alaska Center for Energy and Power University of Alaska 814 Alumni Drive Fairbanks AK 99775 Tel. (907) 474-5402 [email protected]

Table of Contents Table of Contents ...... 2 List of Figures ...... 3 List of Tables ...... 4 Introduction ...... 5 Hot Spring Resource Assessment ...... 6 Adak Hot Springs Assessment ...... 7 Adak Visit Results ...... 8 Akutan Hot Springs Assessment ...... 9 Akutan Visit Results ...... 12 Atka Hot Springs Assessment ...... 15 Digital Elevation Data Resources for Geothermal Resource Studies ...... 18 Discharge of Hot Springs Water from Direct Use Applications ...... 19 Direct Use of Hot Spring Thermal Waters ...... 22 Space Heating Requirements for Residences & Community Buildings ...... 25 Domestic Hot Water Heating for Residential, Community and Commercial Buildings ...... 31 Swimming Pool & Spa Water Heating Requirements ...... 33 Greenhouse Heating Requirements ...... 36 Sidewalk & Street Snow Melting Requirements ...... 39 Environmental Data ...... 42 Aleutian Community Hot Springs Direct Use Opportunities ...... 43 Evaluating Hot Spring Temperature & Flow Rate Attributes ...... 43 Characterizing Existing Energy Costs ...... 44 Considering Hot Springs Resource Access Costs ...... 45 Conclusions ...... 49 Bibliography ...... 50 Appendix ...... 52 Sampling and Analysis of Thermal Water from the Andrew Bay Hot Springs ...... 53 Test Lab Results for Andrew Bay Hot Spring Water Sample Assay ...... 57

List of Figures

Figure 1: Location of Hot Springs on Adak Island ______8 Figure 2: Start of Trail to Andrew Bay Hot Springs______8 Figure 3: Tidewater Hot Spring at Andrew Bay ______9 Figure 4: Location of Hot Springs on Akutan Island ______11 Figure 5: Location Details for Akutan Hot Springs ______11 Figure 6: Akutan, Alaska ______12 Figure 7: Community Boardwalks and Gravel Pathways Facilitate Utilities Routing ______12 Figure 8: Hot Springs Bay Valley Views ______13 Figure 9: Views of Hot Springs Bay at NE End of Hot Springs Valley ______13 Figure 10: Hot Springs Visited Showed Consistency with Literature ______14 Figure 11: Notch between Akutan Harbor and Hot Springs Bay Valley ______15 Figure 12: Location of Hot Springs on Atka Island ______16 Figure 13: Images and Location Details for Atka Hot Springs (image from Alaska Volcano Observatory) ______17 Figure 14: Digital Elevation Modeling Example – Hillshade and Elevation Profile for Atka Island ______18 Figure 15: "Lindal Curve" guidance for direct use of hot springs thermal energy ______23 Figure 16: Climate Zones in Alaska ______28 Figure 17: Average Housing Unit Size by Census Area______28 Figure 18: Calendar Variation of Space Heating Load - Adak ______30 Figure 19: Approach for Hot Spring Heating of Domestic Hot Water ______33 Figure 20: Heating Requirement for 80 F Pool______34 Figure 21: Heating Requirement for 104 F Spa ______35 Figure 22: Heating Requirement for Free-Standing Greenhouse (60 F Interior) ______38 Figure 23: Snow Melt System at Work ______40 Figure 24: Stairway Snow Melt System Installation in Klamath Falls, OR (Boyd, 2003) ______40

List of Tables

Table 1: Summary of Results from Geothermal Literature Review ______6 Table 2: Marine Water Quality Standards for Thermal Discharges ______20 Table 3: Thermal Energy Requirements for Residential Buildings in Alaska ______26 Table 4: Thermal Energy Requirements for Non-residential Buildings in Alaska ______27 Table 5: Size and Age of Non-Residential Buildings in Alaska ______29 Table 6: Amount of Hot Spring Water for Single Use Spa Pool ______35 Table 7: Greenhouse Heating Requirement Estimation ______38 Table 8: Soil Temperatures for Seed Germination ______39 Table 9: Meteorological Data for Adak ______42 Table 10: Direct Use Application Temperature Margin Relative to Local Hot Spring Resource ______44 Table 11: Community Energy Prices in 2013 ______45 Table 12: Estimated Annual Thermal Energy Requirements for Direct Use Applications ______45 Table 13: Geothermal Power System Development Costs in Alaska______46 Table 14: Piping and Other Hot Springs Resource Development Expenses ______47 Table 15: Community Cost Burden for Hot Springs Resource Development ______47 Table 16: Estimated Pumping Power Costs ______48

Introduction

The Aleutian Pribilof Islands Association, the Alaska Center for Energy and Power, and the Alaska Energy Authority share an interest in geothermal utilization for district heating or other direct use applications to benefit communities. The purpose of this project was to assess opportunities for low-cost, non-power options for the direct use of hot spring geothermal energy, with an emphasis on district heating, to benefit the communities of Adak, Akutan and Atka.

The effort included the following task elements: • Literature review of the geothermal resources associated with the 3 target communities to develop a synopsis of characteristics associated with known surface or near-surface thermal features. • Feasibility assessment for constructing preliminary digital elevation models of the communities based on available satellite imagery data sets. • Identification of permitting implications for an open-loop district heating system with discharge to the ocean. • Background research on the development of small-scale geothermal district heating systems through contacts in Iceland, as well as a literature search of resources such as publications produced through the Geo-Heat Center at the Oregon Institute of Technology. • Collection of information for the communities related to heating requirements and sources, utilities, and general community spatial layout, as the basis for developing a district heating system strategy. • Field measurements as necessary to augment the available geothermal literature, including measurement of the natural discharge rate of thermal fluids, measuring temperatures both at the source and any discharge point to the ocean, and collecting new fluid samples for chemical analysis. • Community visits to meet with stakeholders and discuss options for direct use of geothermal energy, and to gather data required to support development of a theoretical district heating loop.

During the course of the effort, semi-monthly telephone meetings were held with representatives from the contracting agencies to review status on an ongoing basis. During these discussions, it was agreed that visits would be made to the communities of Adak (June 16-19, 2014) and Akutan (July 22-24, 2014). In-person meetings were held at AEA’s facility in Anchorage immediately following these visits to review results from the on-site data-gathering and discussions, and discuss interim results at a more detailed level. This report summarizes key results from the effort.

Hot Spring Resource Assessment

Results from review of the available geothermal literature are presented in Table 1. There are hot springs of possible interest in each of the communities, warranting engineering and economic analysis of possible direct use options.

Table 1: Summary of Results from Geothermal Literature Review

Surface Distance Road Island Site Features Elevation Temperature Flow Rate from Comments Access (F) Town This appears to be a low Cape Adak Spring 0 m 60 Unknown 8.5 miles No temperature liquid Kiguga system. Per Miller & Smith. This appears to be a Andrew Adak Spring 0 m 160 Unknown 7.5 miles Partial moderate to high Bay temperature liquid system. 75 F at 994 ft depth. Linear gradient of 3.5 Thermal deg F / 100 ft. The Mt Gradient Not Not Adak 100 m 9+ miles Yes geothermal system may Adagdak Exploration Applicable Applicable be confined to an area (TG Hole close to the Andrew Bay hot spring. 118 F at 1926 ft depth. Linear gradient of 4.2 Thermal deg F / 100 ft. The Mt. Gradient Not Not Adak 95 m 9+ miles Yes geothermal system may Adagdak Exploration Applicable Applicable be confined to an area (TG Hole 2) close to the Andrew Bay hot spring. Hot This is a confirmed high Akutan Springs Springs 8-19 m 140-212 200 l/sec 3.6 miles No temperature liquid Valley system. Thermal Hot Gradient Not Not Akutan Springs 20 m 359 at 833 ft depth. Exploration Applicable Applicable Valley (TG2) Thermal Hot 1500 ft deep hole. Gradient Not Not Akutan Springs 100 m Temperatures not Exploration Applicable Applicable Valley reported. (TG4) This is most likely a Volcano Akutan Fumaroles 400 m >212 Unknown 5.6 miles No steam cap above a Flank liquid system. This is a steam cap -the Atka Kliuchef Fumaroles 600m >212 Unknown 7.5 miles No presence of deeper liquid is uncertain. Kliuchef- This is a large volume, Atka Milky Springs High 113 >66 l/sec 7.5 miles No slightly acid spring. River This is a steam cap -the 10.5 Atka Korovin Fumaroles Low >212 Unknown No presence of deeper miles liquid is uncertain.

Adak Hot Springs Assessment

As shown in Figure 1, there are two known hot springs locations on Adak Island– Cape Kiguga and Andrew Bay. In addition, the US Navy coordinated drilling at two sites on Mount Adagdak to explore the sub-surface geothermal resource. The literature-documented temperature (59.9 F, 15.5 C), of the hot spring at Cape Kiguga was judged to be too low to warrant its consideration as a resource for the intended applications, and it is very difficult to access.

Thermal springs were noted as being on Adak Island by Waring (1917). The first study of the geothermal potential on the island was made by Miller and Smith (1977) and this unpublished document is included in the work of Katzenstein and Whelan (1985). In 1981, staff from Cal Energy made a trip to Adak to examine the geothermal potential. In 1981 Morrison Knudson prepared an unpublished report for the Alaska Division of Energy and Power Development on the geothermal potential of Adak.

Miller and Smith (1977) found and sampled two thermal springs about 60 m apart on the east side of Andrew Bay which has road access nearby but the springs are located beneath a very steep bluff with no apparent access other than walking the beach cobbles at low tide. These springs are found near tide level and are much impacted by wave action. With a discharge into beach gravels, it is not possible to estimate the thermal water discharge rate. In the southern spring, a maximum temperature of 71 C was measured in a cobbled beach. In the northern spring area, temperatures of 59 – 63 C were measured. These waters have chloride contents of 12,000 to 13,500 ppm which shows they have a high component of seawater. The quartz predicted temperatures from these samples are 143 to 186 C. The Na-K-Ca geothermometer gives predicted temperatures of 182 – 187 C. Correcting for the high magnesium reduces the Na-K-Ca predicted temperatures to 121 – 154 C. Cal Energy found the springs in 1981 and measured a temperature of 68 C and performed a partial analysis of the Andrew Bay thermal springs. Cal Energy’s chemical analysis generally confirmed the earlier Miller results with one questionable exception of having far higher magnesium which reduced the Mg corrected Na-K-Ca geothermometer to values below the measured temperatures.

Cal Energy also found a 15.5 C warm spring on the beach about 1 mile south of Cape Kiguga on the far western edge of Mt. Moffett. This rugged area is quite remote from the inhabited part of the island and has no road access. These springs were sampled by both Cal Energy and the Navy with quite different results, the Navy sample being far more dilute. Even the Cal Energy sample was far more dilute than sea water.

There was an active US Department of Defense presence on Adak until 1997. In 1977, the Navy drilled two small diameter holes along then-existing roads. The first hole reached a depth of 995 ft on the SW flank of Mt. Adagdak and a single maximum reading thermometer value of 75 F was measured at the bottom of the well. The second hole was drilled less than a mile east of the Andrew Bay hot springs site to a

depth of 1925 ft with a collar elevation near 280 ft. Its temperature log shows a bottom hole temperature of 118 F, and a linear thermal gradient with no evidence of moving thermal water. Both holes have temperature gradients near 4 F/100’ which is about double the worldwide regional background.

Dick Benoit and George Roe visited the Andrew Bay site on June 16, 2014 to compare current conditions with those observed previously, assess its flow rate, obtain more accurate information as to its actual location, and evaluate the local infrastructure options available for its use.

Figure 1: Location of Hot Springs on Adak Island

Adak Visit Results

The Andrew Bay hot springs are accessed by walking approximately 1 mile along the beach on the northwest side of the island, proceeding in a southwesterly direction from Horseshoe Bay. The route is physically challenging, with ropes installed at three locations where the terrain is particularly steep. The springs are located on the weather side of the island, with significant wind and wave activity. Timing of the visit was chosen to coincide Figure 2: Start of Trail to with low tide conditions. Andrew Bay Hot Springs

GPS coordinates for the hot springs are 51 58.449 N, 176 37.744 W. The thermal waters seep through small seams and fractures in a bedrock shelf and mix with fresh water runoff from the adjacent cliff and with tidal seawater. They are typically submerged during most high tide conditions. The thermal waters accumulate and flow into the ocean via a series of small, interconnected grooves and depressions in the rock. At the time of the visit, the water in the basins was not greater than 30 cm in depth, and the volume of the basins ranged from 0.1 to 0.4 cubic meters. Slippery seaweed and active surf conditions made access to the lowest accumulations dangerous, so temperature and flow evaluations were limited to the upper regions. Moderate temperatures were found in the Figure 3: Tidewater Hot Spring at uppermost basin. Its water temperature Andrew Bay averaged at 105 F (40 C), with an estimated outflow of 2 gpm (7.6 lpm). The water temperature varied significantly with location in the second basin downslope from the cliff. The hottest temperature measured was 152 F (67 C) at one very restricted spot. Temperatures of 120 F (49 C) were more typical. Flow out of the second basin was estimated at 6 gpm (22.7 lpm). In-field pH paper measurements showed the water had a pH value of 7 (i.e., neutral). Water chemistry samples were taken from the outflow of the uppermost basin and from the bottom of the second basin. Lab evaluation and engineering analysis of the specimens are provided in the Appendix. Review of these results indicates there is an underlying geothermal system present at Andrews Bay that has temperatures as high as 350 F, based on the available geothermometry. How large or extensive this resource might be is unknown at this time. More extensive exploration, including drilling and flow testing, is required to characterize the system in more detail. The most likely location for drilling would be on the bluff above the springs.

Akutan Hot Springs Assessment

The Akutan geothermal area is one of the two best known and most extensively explored geothermal prospects in the Aleutian Islands. The Akutan hot springs are located at multiple sites in Hot Springs Bay Valley and under the beach sand in Hot Springs Bay. The general location of Hot Springs Bay Valley is shown in Figure 4. Bergfeld, et al (2014) provide details regarding the location of the hot springs locations (see Figure 5). Hot Springs Bay Valley is isolated from the city of Akutan by a steep ridge. Access is currently by helicopter, hiking (over land, no established

trail exists) or by boat to the beach at its outlet. The thermal features in Hot Springs Bay Valley have been of interest for development since the 1970’s. The most comprehensive exploration has taken place since 2009. The most recent publications on the project are from Ohren, et al. (2013) who discuss all of the exploration results and from Bergfeld et al., (2013) who discuss the most recent chemistry sampling and results. References to numerous other papers can be found in these two documents. No additional geothermal waters assays are required for the purposes of this study.

The thermal manifestations found in Hot Springs Bay Valley are among the most impressive in the Aleutian Islands and consist of all the classical geothermal features such as boiling thermal springs, fumaroles, hydrothermal alteration, etc. During the summer of 2010, two small diameter core holes were drilled in the bottom of Hot Springs Bay Valley to depths of 833 ft and 1500 ft, and documented temperatures of 359 F. These are close to the geochemically predicted subsurface temperatures. Unfortunately, the permeability of the subsurface materials in these locations was found to be too low to support high production rate extraction. Plans are in-place for drilling a vertical confirmation well (maximum depth 1500 ft) during the summer of 2015, based on the conceptual model developed for the area.

The thermal waters in Hot Springs Bay Valley are typically near neutral pH with chloride contents as high as 1,100 ppm. The natural discharge of thermal water could be as great as 3,160 gpm (200 l/sec). The 2012 chemical re-sampling of the thermal waters suggests that the total heat discharge increased from the 2.2 to 4.1 MW range in 1981 to 29 MW in 2012, and characterizes the overall average hot spring temperature in the valley to be 181 F (83 C). (Bergfield, et al, 2014).

George Roe visited Akutan on July 22-24, 2014, in order to assess possible options for direct use of the Hot Springs Bay Valley resource.

Figure 4: Location of Hot Springs on Akutan Island

Figure 5: Location Details for Akutan Hot Springs

Akutan Visit Results

Ray Mann served as the community’s representative and George’s guide during the visit.

The community of Akutan (Figure 6) is located along one shore of the harbor on the east side of the island, with pathways (in-town portion is boardwalk, extension to incinerator area is gravel – see Figure 7) providing foot and all-terrain vehicle (ATV) connectivity between all community buildings, residences, and industrial areas. Electrical power, sewage and potable water service lines are routed along the boardwalk path. Each structure is individually heated, using oil-burning furnaces of various types. All major community buildings were visited, and their GPS coordinates documented.

Figure 6: Akutan, Alaska

Figure 7: Community Boardwalks and Gravel Pathways Facilitate Utilities Routing

A local heating district may be feasible in Akutan, routing the distribution system similarly along the boardwalk, and leveraging waste heat recovered from the community power plant generators, surplus heat available from the Trident seafood processor site, and heat from the community and Trident incinerator facilities.

The Hot Springs Valley (see Figure 8 and Figure 9) visit focused on observing some of the distributed hot spring sites in Hot Springs Valley and identifying opportunities for their in situ usage as an alternative to piping the hot water to the community. Access to Hot Springs Valley was accomplished by renting “blade time” on the helicopter used to shuttle passengers and cargo from the airport on Akun Island. Ray Mann served as Akutan’s host and representative during the visit.

Figure 8: Hot Springs Bay Valley Views

Figure 9: Views of Hot Springs Bay at NE End of Hot Springs Valley Several hot spring sites identified in the geothermal literature review were visited (Figure 10). Spot measurements with a handheld digital thermometer and submersible temperature sensors indicated temperatures and flow conditions consistent with the documentation. A portable IR camera proved useful in identifying regions where springs flowed into the small stream system flowing through the valley.

Figure 10: Hot Springs Visited Showed Consistency with Literature The local hot spring temperatures and volumes appear to be consistent with the space heating and hot water requirements for a small eco-tourism site in the valley with a supporting greenhouse, should this be of interest to the community.1 Services offered to visitors could include low-impact hiking, vista enjoyment, flower and animal watching, beachcombing, hot water soaking, and place-based learning (ecology, energy, geology, anthropology, etc.). Alternatively, or perhaps in addition to the eco-tourism application, a commercial greenhouse facility and on-site support center could be considered, with space heating provided by the hot springs and fresh water from the non-geothermal streams in the valley.

If the geothermal resource is successfully developed for power generation by the AEA and DOE contract activities under-way, it could provide the electrical power needed for lighting, ventilation, water pumping and other housekeeping functions at the eco-tourism and/or commercial greenhouse site(s), and it may be possible to integrate its outflow as part of their thermal water supply. Otherwise, electrical power would need to be generated on-site, or routed via new transmission lines from the town. Discharge of the spent thermal waters would be to Hot Springs Bay.

Access by the current town site to the geothermal resources would require implementing some type of water collection system, pumping the hot water over or around the ridge between the town site and Hot Springs Valley, and then either discharging the spent fluids into the harbor or piping them back to Hot Springs Valley for pressurized sub-surface injection or release into Hot Springs Bay. The harbor area has existing liquid waste outfalls from the Trident plant. Routing of the

1 Per private communication with a community representative, this is likely to be pursued in the next 5-10 years.

pipe would most probably be through the notch located at the end of the harbor (Figure 11), or perhaps to a storage tank located near the community water reservoir located on the hillside above the town. There is no established road or trail access to the valley from the town, and the new harbor facility is not currently connected via road to the town. There is a dirt road from the town to the water reservoir area.

Approach to Notch from Akutan Harbor Flying Through Notch

Figure 11: Notch between Akutan Harbor and Hot Springs Bay Valley

Atka Hot Springs Assessment

Atka is a long island with a large recent volcanic field at its northeastern end with the Kliuchef and Korovin stratovolcanos being dominant. Near this volcanic field several substantial thermal manifestations are present. The two most prominent thermal areas are 12 km (7.4 miles) and 17 km (10.6 miles) north of the village of Atka (see Figure 12). These thermal areas are partially accessible via an ATV trail from the village (overland hiking of approximately 1.5 miles from the trail end).

The primary geothermal literature available for the area is based on site visits in the 1980’s (Motyka, et al, 1981 and 1993). The thermal areas are characterized by abundant steam features, and the collected water samples were all notably acidic and low in chloride suggesting that they represent steam condensate from a vapor dominated system. The Alaska Volcano Observatory image database indicates that the most recent visit to the thermal areas was in 2004 (see Figure 13). Water discharges were estimated as 263 gpm at the Kliuchef site (temperature not indicated) and 1,053-1,316 gpm of 113 F (45 C) water from the Milky River thermal area. There is no record of the thermal features at Atka having ever been visited by a geologist with geothermal industry experience.

Access to the hot springs on Atka can most easily be accomplished via helicopter, but the available funding was not sufficient for that level of expense during the current effort. In addition, during the summer of 2014, the community was heavily

engaged in a range of activities, resulting in challenges with respect to availability of ground transportation, local guides and lodging. Therefore, priority was placed on evaluation of possible hot springs energy utilization opportunities using information available via the technical literature and communication with community representatives.

Figure 12: Location of Hot Springs on Atka Island

Figure 13: Images and Location Details for Atka Hot Springs (image from Alaska Volcano Observatory2)

2 Map and images from http://www.avo.alaska.edu/images/image.php?id=12511, courtesy of Alaska Volcano Observatory / U.S. Geological Survey, photographer / composer: Game McGimsey. .

Digital Elevation Data Resources for Geothermal Resource Studies

Digital elevation data is available for most areas of Alaska from a variety of sources. Areas south of 60 degrees latitude are available as part of the shuttle radar topography mission (SRTM). This data has approximately 30 meter resolution. This is the primary data that will be useful for examining geothermal areas in the Aleutians. Other areas of the state are available as part of other mapping projects and could have higher resolutions. Aerial imagery is also available for nearly the entire state with imagery over many villages approaching 2.5 meters or better. The most convenient place to obtain these types of digital elevation model (DEM) data for Alaska is from the Geographic Information Network of Alaska (GINA) website. ArcGIS can be used to add data directly from the GINA servers, making for a convenient and fast process. Once organized, the data can be used to quickly obtain elevation profiles for any area of interest. Maps are also easily made by converting DEM files to hillshade formats in ArcGIS. An example is shown in Figure 14 for the village of Atka. Statewide shape files representing hydrology, villages, hot springs etc. are also available from the Alaska Geo-Spatial Data Clearinghouse website, and can be overlaid on maps in ArcGIS.

Figure 14: Digital Elevation Modeling Example – Hillshade and Elevation Profile for Atka Island

Discharge of Hot Springs Water from Direct Use Applications

Direct use geothermal waters, cooled from their original elevated temperatures by heat transfer to facilities and systems, can be discharged to the environment via pressurized injection into the ground, gravity-driven re-entry into the groundwater resource by spraying over fields or collection in intermediary ponds, or low pressure / low velocity diffusers to proximal bodies of water (stream, freshwater lake, marsh, estuary, ocean).

For an open-loop district heating system discharging to the ocean, consideration must be given to three primary questions – whether the geothermal waters are being introduced into new ecosystem areas, whether the geothermal waters are free from contamination (metals, disinfectants, corrosion inhibitors, human or animal waste, deodorants, perfumes, etc.) and whether unacceptable warming will occur in the water body receiving the geothermal waters.

Materials naturally present in geothermal waters (e.g., calcium, manganese, sodium, potassium, iron, magnesium, silica, chloride, fluoride, lithium, hydrogen sulfide, arsenic) can have significant effects on the flora and fauna in a water system, at both microscopic and macroscopic levels.

Human-related contamination risks can be reduced by appropriate selection of piping and components in the geothermal water transport system, by using heat exchangers and intermediary loops where possible to isolate the geothermal fluids, and by establishing operational controls to protect the water from exposure to pollutants.

Heating effects of water in the discharge area will be determined by the temperature, volumetric flow and discharge location of the geothermal water system relative to the temperature, volume, water change rate, and heat transfer to the local environmental. Coastal water temperature measurements are available from the National Oceanographic Data Center3 for many stations shown located in Alaska, primarily in the South-Central and Aleutians region, at a range of time intervals. It indicates that the two-week average temperatures at the Adak and Unalaska sites vary from 39 to 46 F and 38 F to 48 F, respectively.

Multiple other types of impact (e.g., historic sites, flood plains) are also included in the permitting process. The overarching objective is to maintain and protect existing water quality via the control of human-originated pollution point sources. Water quality standards (WQS) are identified in Sec 303(c) of the Clean Water Act (1972) and are included in the contaminant-specific criteria set forth by the Water Quality Standards and the Alaska Water Quality Criteria Manual for Toxic and Other Deleterious Organic and Inorganic Substances managed by the Alaska Department of

3 See http://www.nodc.noaa.gov/dsdt/cwtg/.

Environmental Conservation (DEC).4 WQS requirements pertaining to thermal discharge effects are presented in Table 2 for marine water locations.

The level of effort related to compliance with permitting criteria may be minimized by not moving the geothermal discharge location away from its naturally occurring area of impact, minimizing opportunities for water contamination by using intermediary fluid loops wherever practicable, extracting as much heat as possible from the hot springs water before releasing it, and locating the outflow in an area with large volumes of sea water and active tidal / current mixing. Table 2: Marine Water Quality Standards for Thermal Discharges

Marine Water Usage Category Water Quality Standard (22) A. Marine Water Supply i. Aquaculture May not cause the weekly average temperature to increase more than 1.8 F (1 C). The maximum rate of change may not exceed 0.9 F (0.5 C) per hour. Normal daily temperature cycles may not be altered in amplitude or frequency. ii. Seafood Processing May not exceed 59 F (15 C). iii. Industrial May not exceed 77 F (25 C). (22) B. Water Recreation i. Contact Recreation Not applicable. ii. Non-contact Recreation Not applicable. (22) C. Growth and Propagation of Fish, Shellfish, Same as (22)(A)(i). Other Aquatic Life, and Wildlife (22) D. Harvesting for Consumption of Raw Same as (22)(A)(i). Mollusks or Other Raw Aquatic Life

In Alaska, discharge permit applications are reviewed and issued by the DEC.5 Permitting will require availability of field-based chemical, thermal, ecological and anthropological assessments (before project implication, and a plan for ongoing assessment), as well as geothermal system design details and performance analysis. In all of the communities considered, due to the distance of their hot springs from the existing community buildings and residences, direct use of the hot springs water in a one-way system (i.e., without return flow to the point of origin) would result in discharging the water in areas where it does not naturally flow. Detailed chemical, thermal, ecological and engineering assessments would be required to determine

4 Available online at https://dec.alaska.gov/water/wqsar/wqs/index.htm. 5 Source for water-related permit applications for Alaska-controlled waters: http://dec.alaska.gov/water/wwdp/online_permitting/permitentry.htm.

whether the required permits could be obtained, and to estimate the cost of any required mitigation provisions.

The remote and exposed locations of the hot springs in Adak and Atka introduce construction and access challenges for development of any new facilities that could use the thermal waters locally and discharge them into their existing drainage area. Similar, but potentially less severe, challenges would exist for establishing facilities that would directly use hot spring waters in Akutan’s Hot Springs Bay Valley.

Direct Use of Hot Spring Thermal Waters

Options for using hot spring thermal energy directly (i.e., rather than as a means of generating electrical power) include: space heating, water heating (or pre-heating), greenhouses, and pools / hot tubs. Multiple factors must be taken into account when evaluating these opportunities for a specific location. From a geothermal resource perspective, the temperature of the water, its flow rate, and its chemistry are among the more critical focus areas. Distance and type of terrain between the hot spring and the intended energy usage site, and local meteorological conditions figure significantly in the piping system design and economics. Key economic criteria include local on-dock equipment prices, installation costs, operation / maintenance costs, local price of fuel, and the energy efficiency of the end user system(s).

The “Lindal curve”6, a version of which7 is shown in Figure 15, provides a helpful first approximation for matching water temperature with possible direct use application areas. As a rule of thumb to allow for temperature losses in distribution and application, the temperature of the hot spring resource should be at least 5 F higher than that associated with the desired application. Otherwise, some other source of thermal energy (e.g., boiler, generator heat recovery, heat pump) must be incorporated into the overall solution, either as a supplement to the hot spring resource or perhaps as a more affordable alternative.

6 Lindal, B. Industrial and other applications of geothermal energy (except power production and district heating), in Geothermal Energy: Review of Research and Development (Earth Sciences, 12), UNESCO, 1973, p. 135-148. 7 From Geothermal Education Office (http://geothermal.marin.org), used with permission.

Figure 15: "Lindal Curve" guidance for direct use of hot springs thermal energy Allowance must be made for heat lost to the surrounding environment in the piping system, and for temperature gradients required to drive heat transfer in any intermediary heat exchangers. Thermal losses in the piping are determined by the velocity of the water flow, the type and temperature of the environment surrounding the pipe, and any insulation between the pipe wall and the environment. General practice is to move the thermal waters through the piping at the maximum velocity that is consistent with the available pumping power and piping material properties, in order to minimize temperature loss in transit. Experience with geothermal systems in Iceland and Oregon, and with district heating systems in Alaska, indicate that thermal losses can be held to 1 F per mile with a properly designed system. This requires an appropriate balance of pipe diameter, insulation (pipe and connections), and support system. Lower temperature losses (i.e., the water will not cool as much) can be expected for pipe that is properly installed (depth, insulation) in below-grade trenches or within utilidors (above or below grade), relative to above-grade installations. Piping system design guidelines and online calculators are readily available from multiple sources. 8

8 For example, see the various ASHRAE handbooks, and the manuals published as part of the United States Department of Defense Utilities: Arctic and Subarctic Construction series.

For the communities considered by this study, there is no permafrost along any of the potential piping routes between the hot springs and potential locations for direct use of the hot spring water. Above ground installation avoids uncertainties associated with the variable soil depth common in the Aleutian islands, but does introduce greater vulnerability to damage from vehicles, large animals (e.g., feral cattle on Akutan), and vandalism. Above grade PEX arctic pipe with 2 inch thick polyurethane foam insulation and a protective HDPE outer jacket should provide sufficient thermal protection of the pipe hot springs fluid to limit heat loss to no more than 1 F / mile.

If the chemistry of the hot springs water is not compatible with the materials used in the plumbing system elements it contacts, then it will be necessary to incorporate protective provisions, revise the materials employed, or introduce an intermediary loop to isolate the hot springs water. Hydrogen sulfide is frequently found in hot spring water, and can have adverse effects on the available service life of components containing copper (e.g., fittings, valves, heat exchangers, pumps). For example, the Geo-Heat Center at the Oregon Institute of Technology (OIT) reported that failures were found to occur in brazed plate-fin heat exchangers after 12 years of exposure to fluids containing 1 ppm hydrogen sulfide, and after only 7 years at concentrations of 5 ppm.9 Silica and other materials dissolved or suspended in the thermal water can clog passages and foul heat exchanger surfaces. There may be scenarios where the odor of the thermal water is objectionable for the intended use. In some cases, these considerations can require the incorporation of settling tanks and/or filters, chemical additives, or use of an intermediary loop. These countermeasures can be expected to increase the overall system cost and introduce constraints on usability of the hot spring resource.

In many case, one or more attributes of the hot spring water require the use of an intermediary loop to transfer energy into the system being heated. OIT has established rules of thumb that can be used to conduct preliminary sizing studies without resulting in excessively high power requirements for pumps and fans or highly customized heat exchanger designs.10 For liquid-to-liquid heat transfer, a 10 F temperature difference is recommended between the warmer and cooler fluid. For liquid-to-air heat transfer, the recommended temperature difference is 15 F. In those cases where heated air is used for space heating, OIT suggests warming the supply air to 25 F above the design air temperature level, and notes that air introduced into human-occupied areas should be maintained above 95 F in order to avoid perceptions of a “drafty” condition. 70-72 F are typical design air temperatures for residential and office settings.11

9 Rafferty, Kevin (2001, September). Domestic Hot Water Heating. Geo-Heat Center Bulletin, 18-21. 10 Rafferty, Kevin (2004, June). Direct-Use Temperature Requirements: A Few Rules of Thumb. Geo-Heat Center Bulletin, 1-3. 11 For example, see Manual J or IECC 2012.

Space Heating Requirements for Residences & Community Buildings

Space heating of occupied structures using hot springs energy can be accomplished using either forced air or hydronic (baseboard, radiator floor, ceiling, wall panel) systems.

The size, usage, design and construction of the building structure will determine the thermal energy required to address the space’s heating requirements, thereby maintaining the desired interior temperature. It is important to consider both the short term heating rate (e.g., hourly) and the longer term (e.g., multiple days) integrated heat load. Heating rate defines the flow rate of the hot water provided to the structure; integrated heat load establishes the total amount of hot water required over a given period of time.

For an existing structure, the integrated heat requirement can be estimated from the associated historical energy costs, assuming its physical condition, equipment operated within it, ventilation practices, and occupancy conditions are reasonably stable and consistent with the anticipated future use. This can be a useful resource for approximating integrated heat requirements for new systems in a similar setting.

Heating requirements can be determined using software tools such as AKWARM12, but these require more detailed information than is available for this effort. Engineering and architectural consulting firms determine the heating requirements as part of their overall design process. And, individuals within organizations such as the Alaska Energy Authority, the Alaska Housing Finance Corporation (AHFC), the Cold Climate Housing Research Center (CCHRC), and the Rural Alaska Community Action Program (RurAl CAP) can sometimes provide data from other projects that can be scaled to estimate the heating requirement for a particular scenario. Additionally, the Alaska Village Energy Model (AVEM) can be used to develop representative heating requirements for communities in Alaska. 13

The Alaska Energy End Use Study14 includes typical annual thermal energy requirements for a variety of structure types at representative locations across Alaska, as shown in Table 3 (residential buildings) and Table 4 (non-residential buildings). These encompass urban and rural settings, and both large and small

12 AKWARM is available at no fee from the Alaska Housing Finance Corporation website (http://www.ahfc.us/efficiency/research-information-center/akwarm- energy-rating-software/). 13 AVEM is available at no fee from the Institute of Social and Economic Research website, and includes estimates for space heating, water heating, electrical loads, and transportation fuel requirements. An example of its use is provided in the Economic Analysis of an Integrated Wind-Hydrogen Energy System for a Small Alaska Community. 14 WH Pacific, 2012, Alaska Energy End Use Study: 2012.

communities. Climate Zones are used as a means of comparing areas with similar heating (or cooling) requirements. Figure 16, adapted from the Alaska Building Energy Efficiency Standard15, can be used to identify the Climate Zone for a particular community. Typical housing sizes in Alaska are shown in Figure 17.16 Information pertaining to the size and age of community buildings in Alaska are provided in Table 5.17

Table 3: Thermal Energy Requirements for Residential Buildings in Alaska

Domestic Hot Space Heating Region Climate Zone Residence Type Water kBTU/ft2/yr kBTU/ft2/yr Southeast 6 Mobile Home 112.30 19.36 Single Family 103.40 13.13 Multi Family 79.20 13.95 Railbelt Mobile Home 155.40 29.13 7 Single Family 119.70 16.99 Multi Family 115.40 22.71 Mobile Home 213.80 17.20 8 Single Family 117.60 13.28 Multi Family 105.20 16.49 Rural Single Family 79.70 21.68 8 Multi Family 71.80 23.27

15 See http://www.ahfc.us/efficiency/research-information-center/bees/. 16 Alaska Housing Finance Corporation, 1 April 2014, 2014 Alaska Housing Assessment. Contents available at http://www.ahfc.us/efficiency/research- information-center/housing-assessment/. See Figure 2 in Appendix E. 17 Alaska Housing Finance Corporation, 7 November 2012, White Paper on Energy Use in Alaska’s Public Facilities.

Table 4: Thermal Energy Requirements for Non-residential Buildings in Alaska

Figure 16: Climate Zones in Alaska

Figure 17: Average Housing Unit Size by Census Area

Table 5: Size and Age of Non-Residential Buildings in Alaska

Space heating loads can be estimated as follows: • Obtain Heating Degree Day (HDD) information for the community from online (e.g., http://www.degreedays.net) or other (e.g., design handbooks) resources. Ideally, the information will be available on a daily or at least monthly basis, in order to account for seasonal changes in space heating requirements. • Estimate the daily space heating energy use intensity by multiplying the annual space heating energy use intensity (Residential: Table 3, Non- Residential: Table 4) by the ratio of the daily HDD to the annual HDD. • Determine the daily space heating load for a specific structure using its footprint area.

Following this procedure, the daily distribution of the annual space heating load using heating degree day data for Adak is as shown in Figure 18. This information can be used to size plumbing system elements to handle peak requirements.

Figure 18: Calendar Variation of Space Heating Load - Adak For preliminary estimating purposes, the average hot spring flow rate required for space heating can be approximated from the annual heating requirements, using the equation:

Required Flow Rate = (q/A)annual*Aspace*(1/ service)* Cgpm (q/A)annual = Annual Space Heating Requirement, kBTU/sq ft Aspace = Size of Building, sq ft ΔT service = Temperature drop of geothermal fluid at structure Cgpm = a conversion constant related to the density (8.2 lbm/gal) and specificΔT heat (1.0 BTU/lbm/deg F) of water, for kBTU energy levels Cgpm = 1000/8.2/1.0/365/24/60 = 2.32x10-4 gpm

Adak and Atka are in the “Aleutians West” census area, while Akutan is part of “Aleutians East”. All three communities are in Climate Zone 7. Using the data in Table 3, the “Aleutians East” data in Figure 17, and assuming a typical temperature drop of 20 F in the geothermal fluid providing heat to a structure, the hot spring flow rate required to serve an individual home in Akutan would be:

Required Flow Rate = (q/A)annual*Aspace*(1/ service)* 2.32x10-4 gpm (q/A)annual = 79.7 kBTU/sq ft, per Table 3 Aspace = 1,300 sq ft, per Figure 17 ΔT service = 20 F Required Flow Rate = 79.7*1300*(1/20)*2.32x10-4 gpm RequiredΔT Flow Rate = 1.2 gpm / residence

Space heating requirements for non-residential structures in a given location will vary with the building’s size, age, level of weatherization, occupancy, internal equipment, and usage. Using the “3 Villages” data in Table 4 to represent Adak, Akutan and Atka, the average space-heating energy use intensity is 166.1 BTU/hr/sq ft, and can range from 73.9 to 427.3 BTU/hr/sq ft depending on the type of building. Per the information in Table 5, average non-residential building size

ranges from 1,200 to 361,698 sq ft, with an average of 41,864 sq ft. The average non-residential hot spring flow rate required for space heating can be estimated as:

Required Flow Rate = (q/A)annual*Aspace*(1/ service)* 2.32x10-4 gpm (q/A)annual = 166.1 kBTU/sq ft, per Table 4 Aspace = 41,864 sq ft, per Table 5 ΔT service = 20 F Required Flow Rate = 166.1*41,864*(1/20)*2.32x10-4 gpm RequiredΔT Flow Rate = 80.7 gpm / non-residential building

Many Alaska homes and public buildings already have hydronic heating systems installed, with boilers (typically fueled with oil or biomass) as the source of hot water. Room heat can be delivered via radiant panels (floor, ceiling, wall or some combination thereof), baseboard heaters or radiators. Legacy systems are typically designed for inlet temperatures of 160-200 F. Recent trends in hydronic heating design practice use lower inlet temperatures (typically 120 F, sometimes lower) to allow better utilization of thermal energy storage systems, and with greater numbers of distribution circuits than in older systems. Hot spring water can sometimes be used directly in hydronic heating systems, if all of the materials in the heating circuits are compatible with the chemicals and minerals in the hot spring water. However, intermediary fluid loops (water or a water /propylene glycol mixture) are typically used to isolate the hot spring water, with heat transferred to the space heating system via a liquid-liquid heat exchanger. Performance of the space heating system can vary significantly as a function of the supply temperature, and manufacturer data should be reviewed to assess the impact of proposed liquid temperatures outside of the equipment design point.

Domestic Hot Water Heating for Residential, Community and Commercial Buildings

“Domestic” hot water is used here to refer to any requirement for heating of potable water (e.g., hand washing, showers, laundry, dish washing). The amount of hot water and the rate at which it is required will depend on the type of building and its usage within the community. For example, residential domestic hot water usage is typically greatest in the morning and evening. And, in hot-water-intensive commercial buildings such as washeterias, the demand for heated water is during working hours. Conventional hot water heaters (e.g., oil, natural gas, propane, electric) for domestic use are typically set to a maximum temperature of 120 F, or 130 F if the residence has an automatic dishwasher without an internal temperature booster.18 Temperature settings for hot water tanks in commercial laundries (low risk of scalding) can be on the order of 160 F for some fabrics and to ensure disease control, although lower temperature water can be used with appropriate detergents.19

18 From http://www.seattle.gov/light/conserve/resident/cv5_faq.htm#Answer3. 19 From http://www.cdc.gov/HAI/prevent/laundry.html.

Typical annual hot water requirements in Alaska are shown in Table 3 and Table 4. Daily requirements can be approximated as 0.27% (i.e., 1/365) of the annual requirement. In general, it is advisable to avoid circulating hot spring water directly through building plumbing, unless provisions can be made to protect all copper elements within the system from hydrogen sulfide dissolved in the water. Figure 19 illustrates a design concept developed by the Geo Heat Center allowing isolation of the hot spring water from the hot water system plumbing.20

Estimates were developed for the hot spring water flow rates required for water heating, assuming an approach similar to that shown in Figure 19, the 10 F temperature differential rule of thumb guidelines recommended by the Geo Heat Center (Rafferty, June 2004) for liquid-to-liquid heat exchangers, and a 10 F temperature decrease in the hot spring water flowing across its interface with the hot water system. The hot spring flow rate required for hot water heating can be estimated using the equation

Required Flow Rate = (q/A)annual*Aspace*(1/ service)* 2.32x10-4 gpm (q/A)annual = Annual Space Heating Requirement, kBTU/sq ft Aspace = Size of Building, sq ft ΔT service = Temperature drop of geothermal fluid at heat exchanger

ResidentialΔT Hot Water: (q/A)annual = 21.68 kBTU/sq ft, per Table 3 Aspace = 1,300 sq ft, per Figure 17 service = 10 F Hot spring flow = 0.65 gpm for average residence ΔT Non-residential Hot Water: (q/A)annual = 8.47 kBTU/sq ft, per Table 4 Aspace = 41,864 sq ft, per Table 5 service = 10 F Hot spring flow = 8.2 gpm for average building ΔT

20 Rafferty, Kevin (2001, September). Domestic Hot Water Heating. Geo-Heat Center Bulletin, 18-21.

Figure 19: Approach for Hot Spring Heating of Domestic Hot Water

Swimming Pool & Spa Water Heating Requirements

Hot water requirements for swimming pools and soaking tub spas are determined by the heat loss (evaporation, convection, and radiation) from the water surface, and by sanitation requirements for water recirculation / replacement. Evaporation from the water surface is the most significant means by which heat is lost from a pool. Floating pool covers are an effective means of reducing evaporation and convection / radiation heat losses from the pool when it is not in use. Enclosures or windbreaks can be used to reduce pool heat loss at all times. For cases where the pool or spa is enclosed, care must be taken to manage the relative humidity (ASHRAE recommendation: 50%-60% recommended) and temperature of the air (ASHRAE recommendation: 2-4 F above pool temperature, but not greater than 86 F) in the building.21

To conserve water and energy, swimming pool water is typically re-circulated, using filters, chlorination and heaters to condition the water before it is returned to the pool. In some cases, heating is accomplished via heating elements (e.g., hot water

21 Guidelines for pool temperatures, recirculation, and heat loss rate were drawn from (American Society of Heating, 2007, p. 4.6-4.8 and 49.22-49.23) and (Lund, 2000). Additional information is available in these resources to support more detailed heat loss calculations, ventilation requirements definition, etc.

tubes) embedded in the walls of the pool. The circulation rate is chosen to completely change the water every 6 (public pool) to 8 (residential pool) hours. Comfort and safety considerations determine the water temperature: 80 F is frequently used as the design point for swimming pool water; hot tubs / soaking pools are typically maintained in the 101-104 F range. In those cases where hot springs water is used directly in a soaking tub, care should be taken to keep the maximum temperature below the scalding point (120 F, (Lévesque, Lavoie, & Joly, 2004)). If hot spring water is stored in a tank to allow rapid refill of a single-use tub, maintaining the tank at or above 140 F is desirable to mitigate the risks from disease-inducing bacteria (Lévesque, Lavoie, & Joly, 2004).

Heating rates for swimming pools and spas can be estimated from Figure 20 and Figure 21, respectively. For soaking pools where the water is emptied between uses, Table 6 provides a guideline for estimating the amount of hot spring water required to achieve a soaking pool temperature of 104 F.

Figure 20: Heating Requirement for 80 F Pool

3500

3000

2500

2000 10 mph Wind

Still Air 1500

1000 Heat Loss (BTU/hr/sqft) 500

0 -100 -50 0 50 100 Ambient Air Temperature (F) Figure 21: Heating Requirement for 104 F Spa

Table 6: Amount of Hot Spring Water for Single Use Spa Pool

Spa Temperature (F): 104 Hot Spring Water Cool Water Temperature (F) Temperature (F) 40 50 60 110 91% 90% 88% 115 85% 83% 80% 120 80% 77% 73% 125 75% 72% 68% 130 71% 68% 63% 135 67% 64% 59% 140 64% 60% 55% 145 61% 57% 52% 150 58% 54% 49% 155 56% 51% 46% 160 53% 49% 44% 165 51% 47% 42% 170 49% 45% 40% 175 47% 43% 38% 180 46% 42% 37% 185 44% 40% 35% 190 43% 39% 34% 195 41% 37% 33% 200 40% 36% 31% 205 39% 35% 30% 210 38% 34% 29%

It can be reasonably assumed that a public pool in the study area would be located inside a conditioned building to maximize its availability for community use, and to better manage heating loads. For a pool water temperature of 80 F, with the conditioned space maintained at 83 F and 50% relative humidity, hot spring thermal energy requirements for maintaining the pool temperature would be approximately 50 BTU/hr/sq ft, per Figure 20 for still air conditions. Assuming a 15 F reduction in the geothermal water temperature after heating the pool, the hot spring water flow requirement would be on the order of 6.78x10-3 gpm / sq ft. Community pools range in size, depending on the purpose(s) served and the number of clients. In Adak, the community pool has a surface area of approximately 3,300 sq ft. It would require 22.4 gpm of hot spring water to heat.

An open air hot tub in a region with an average ambient temperature of 40 F would require 500 BTU/hr/sq ft for a site sheltered from the wind, and 1,300 BTU/hr/sq ft in an exposed location. A soaking tub eight feet in diameter and a water depth of four feet contains 1,500 gallons of water, with a top surface area of 50 sq ft. Hot spring flow rates required to safely maintain the tub at a design temperature of 104 F can be estimated using the following equation:

Required Flow Rate (gpm) = (q/A)heat_loss*Asurface*(1/(Tscald-Tdesign)* 2.03x10-3 (q/A)heat_loss = Heating requirement per Figure 21, BTU/sqft/hr Asurface = Area of water surface exposed to air, sqft scald = Maximum temperature of water to prevent scalding, (120 F) design = Design temperature of spa water, (104 F) ΔT ShelteredΔT site: Hot spring flow = 500*50/(120-104)*2.03x10-3 = 3.2 gpm

Exposed site: Hot spring flow = 1,300*50/(120-104)*2.03x10-3 = 8.3 gpm

Greenhouse Heating Requirements

There is a rich supply of information related to greenhouse and soil-warming applications associated with direct use of hot spring thermal waters.22 Key parameters for consideration in the overall design and operation of a greenhouse include the size (area exposed for heat loss by convection and radiation, system and contents mass effects on ability to retain heat), design (heat loss through walls and roof, solar heating through transparent surfaces), ventilation (fresh air requirements for plants and human occupants, moisture control), climate (air and ground temperature, solar energy, wind, snowfall), internal lighting (heat added by lights), crop(s) to be raised (temperature, moisture, atmospheric composition,

22 Examples include (Bartok, 2000), (Jahns, 2009)(Bartok, 2000), (Oregon Institute of Technology Geo-Heat Center, http://geoheat.oit.edu)

lighting requirements) and operating season (time of year, seasonal versus year- round).

Table 7 allows the heating requirements for several common types of greenhouses to be estimated on the basis of the floor surface area for a range of outdoor temperature conditions, and an indoor air temperature of 60 F. Figure 22 presents the data for a free-standing greenhouse in graphical format, and includes a curve-fit that can be used to extrapolate to a specific outside air temperature. Hot springs heat can be provided by passing the thermal fluid through a heat exchanger warming the air in the greenhouse, by circulating the fluid through tubes in the floor, by circulating the fluid through the growing beds, or by some combination of these techniques. In the study area, the average ambient temperature is 41.1 F, corresponding to a heating requirement of 45 BTU/hr/sqft. A greenhouse with a land footprint area of 10 ft x 30 ft (300 sq ft), and a heater-fan for maintaining the internal air temperature at 60 F, would require 1.4 gpm of hot spring water, with a 20 F temperature change between inlet and outlet.

For cases where soil warming is accomplished using fluid in distributed tubes, a temperature change of no less than 15 F should be assumed between the inlet and outlet, in order to maintain reasonable distribution system attributes.23 In general, since the temperature of the root zone has a more significant impact on plant growth than the temperature of the leaves, energy savings can often be achieved by providing heat directly to the soil bed. If the soil is maintained at the optimum temperature, air temperatures can be 5-15 F cooler than would otherwise be the case. Approximately 8 watts of thermal energy is required per square foot of soil bed (i.e., not the overall greenhouse footprint area) which is equivalent to 2.77x10-3 gpm/sqft water flow, with a 20 F temperature change between inlet and outlet.24 Six planting beds, each 4 ft x 8 ft in size, could be accommodated in a 10 ft x 30 ft space, and would require a total hot spring flow rate of 0.5 gpm for their warming. For seed germination, the preferred soil temperature varies with plant species. Table 8 provides soil temperature guidelines for many common vegetable types.25

23 Rafferty, Kevin (2004, June). Direct-Use Temperature Requirements: A Few Rules of Thumb. Geo-Heat Center Bulletin, 1-3. 24 Root zone heating guidelines were drawn from (Bartok, 2000) – see pages 85-87. 25 From http://www.ianrpubs.unl.edu/pages/publicationD.jsp?publicationId=1457.

Table 7: Greenhouse Heating Requirement Estimation

Heating Requirement (BTU/hr/sqft, for 60 F interior) 26 Minimum Outside Air Temperature (F) Greenhouse Style -40 -30 -20 -10 0 15 30 Lean-to - Single glazing 370 330 290 250 210 175 140 - Double glazing 250 220 190 160 130 100 70 Free-standing - Single glazing 400 360 320 280 240 180 120 - Double glazing 250 225 200 175 150 110 85

450

400 Free-Standing / Single Glaze y = -4x + 240 350 R² = 1 300 250 200 150

Heting Rate (BTU/hr/sqft) Rate Heting 100 Free-Standing / Double Glaze y = -2.5361x + 149.07 50 R² = 0.9998 0 -60 -40 -20 0 20 40 60 Exterior Air Temperature (F)

Figure 22: Heating Requirement for Free-Standing Greenhouse (60 F Interior)

26 Heating rate data from (Jahns & Smeenk, 2009), illustrations from (Jahns T. R., 2013).

Table 8: Soil Temperatures for Seed Germination

Minimum Soil Temperature Plant Type at Planting (F) Cabbage 45 Carrot 46 Cucumber 58 Lettuce 41 Onion 41 Pea 42 Pepper 57 Potato 45 Pumpkin 60 Radish 40 Snap Beans 57 Spinach 38 Sweet Corn 55 Tomato 57

Sidewalk & Street Snow Melting Requirements

Geothermal energy has been used successfully at multiple locations world-wide to melt snow and mitigate icing-related challenges on sidewalks, streets and bridge decks. Figure 23 illustrates a system operating27 in Klamath Falls, OR – note the contrast between the areas with and without the snow melting system.

27 Illustration downloaded from National Renewable Energy Laboratory photograph archives, http://images.nrel.gov/viewphoto.php?imageId=6315676.

Figure 23: Snow Melt System at Work Key elements affecting the amount of hot springs energy required to provide snow melting for walking (sidewalks, boardwalks, docks) and transportation surfaces (roads, bridges, parking lots) include the local climatic conditions (air and ground temperatures, type and amount of precipitation, wind), and design of the surface to be kept snow-free (surface material type and thickness, on-grade versus elevated surface with free air beneath). In all cases, it is essential to provide adequate drainage to ensure removal of any liquid water. System operation can be accomplished simply opening / closing valves, or via automated systems using temperature, and sometimes snow accumulation, sensors.

An intermediary glycol-water fluid mixture is typically circulated via flexible plastic tubing beneath the surface (e.g., see Figure 24) to accomplish the snow-melting, in order to protect against fluid freezing in the tubing and to reduce the likelihood of corrosion and scaling that can result from direct exposure to geothermal fluids. As a rule of thumb, sufficient thermal fluid energy is required to Figure 24: Stairway Snow Melt System support a heat flux of 200-300 Installation in Klamath Falls, OR (Boyd, 2003)

BTU/hr/sqft over the surface to be protected from icing.28 In order to minimize the possibility of violating tubing material property limits and to avoid thermal shock to the load-bearing surfaces, ASHRAE29 recommends limiting the maximum temperature of the glycol-water mixture to no greater than 140 F and the maximum temperature change between inlet and outlet to no greater than 20 F.

Following these guidelines, an intermediary system using a 50-50 mixture of propylene glycol-water fluid mixture would need to provide 12-18 lbm/hr/sqft (1.4-2.1 gal/hr/sqft) of the fluid at 140 F fluid to the surface requiring anti-icing protection. This would require on the order of 2.03x10-2 – 3.05x10-2 gpm/sqft of hot spring water at a supply temperature of 150 F and a return temperature of 130 F. If hot spring water were to be used directly, the same flow rate (2.03x10-2 – 3.05x10-2 gpm/sqft) would be required, but the hot spring water temperature requirements would be reduced to 140 F at the supply point and 120 F at the return. In the direct use case, system provisions would need to be included to protect against freezing of the water (e.g., continuous flow, off-season system drain).

28 (ASHRAE, 2007, p. 50.12). 29 (ASHRAE, 2007, p. 50.13).

Environmental Data

Ambient temperature information is required to estimate heat loss from piping, and heat loss from exposed water surfaces. “Heating Degree Day” (HDD)30 provide insight as to variations in space heating requirements within a calendar year.

Adak, Akutan and Atka are all in Climate Zone 7. Due to their proximal geographic location and similar climatic conditions, meteorological data available for Adak were also be used for Akutan and Atka. Historical air temperature and heating degree day data are provided in Table 9 for Adak. Engineering design guidelines include margin to accommodate potential extreme condition events. The low temperature recommended for system design in the Manual J Residential Load Condition Outdoor Design Conditions handbook is 23 F for Adak.31

Table 9: Meteorological Data for Adak

Parameter Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Low Temperature (F) 28.0 29.0 30.6 33.1 37.0 41.2 45.3 46.9 43.9 39.0 33.4 29.6 36.5 Average Temperature (F) 32.7 33.5 35.0 37.6 41.4 45.5 50.0 52.0 48.5 43.7 38.1 34.3 41.1 High Temperature (F) 37.3 38.0 39.4 42.0 45.8 49.8 54.6 57.2 53.1 48.5 42.8 38.9 45.7 HDD (65 F base) 1003 882 930 823 732 585 467 402 495 659 807 953 8737 From http://climate.gi.alaska.edu/climate/normals, 1981-2010. Data as reported by weather station at Adak.

30 “Heating Degree Day” values indicate the number of days and amount by which the ambient air temperature is cooler than a specified temperature level for a heated space. While a variety of temperature settings can be used for these calculations, 65 F is widely used. See ASHRAE’s Handbook of Fundamentals, and similar publications in the heating, ventilating and air conditioning literature for in- depth discussion of the metric. 31 Air Conditioning Contractors of America, 2011 (8th edition, version 2). Manual J Residential Load Condition Outdoor Design Conditions.

Aleutian Community Hot Springs Direct Use Opportunities

Evaluating Hot Spring Temperature & Flow Rate Attributes

The initial step in identifying possible direct use opportunities for hot spring water is to compare the temperature and flow rate attributes of the resource with those required by the possible application. Flow rate and development / utilization costs must also be considered before committing to in-depth analyses of possible hot spring resource usage.

With consideration given to the previously described temperature requirements for the various direct use applications (Figure 15), and assuming a minimum 5 F temperature loss in the hot spring water processing and distribution system, Table 10 indicates possible application options for the three communities under study. Greenhouses are the only application that is potentially viable in all of the communities addressed by this study. Adak and Akutan have multiple space heating and bathing (both swimming pool and spa) scenarios that are compatible with their hot spring resource temperatures. Akutan is the only community with an apparent opportunity for domestic water heating via hot spring water, although in all of the communities fuel usage could be offset by using the hot springs resource to pre-heat the water and oil to provide any required supplemental heating. None of the communities have hot spring resources that are hot enough to be considered for commercial hot water applications without supplement heating using other energy sources. Based on the available resource data, Atka’s only apparent direct use application for their hot spring resource is for greenhouse heating.

Hot spring flow rate requirements for direct use applications are included in Table 12. Ideally, these flow rates would be naturally occurring in the existing ground- level-accessible springs. However, drilling and pumping is typically required (if possible, depending on the specifics of the underlying geothermal resource) to provide the required flows. Drilling and pumping would be required in Adak, given its low natural flow rate (2-6 gpm) at the Andrew Bay site. The overall thermal water flow rate estimated for Akutan’s Hot Springs Bay Valley (3,160 gpm) are well- aligned with the flow rates required to support multiple application opportunities in that area. High flow rates appear to be available at Atka (263 gpm at Kliuchef site and 1,053-1,316 gpm at Milky River site) per the geothermal literature, although at temperatures suitable primarily for greenhouse applications.

Table 10: Direct Use Application Temperature Margin Relative to Local Hot Spring Resource

Characterizing Existing Energy Costs

The second step for assessing hot springs direct use viability is to estimate the cost for the energy that would be either replaced, or possibly added (e.g., if new greenhouses were considered). Space heating and hot water heating in the Aleutian communities studied is typically accomplished using furnaces (central with hydronic distribution systems, or free-standing local heaters) burning fuel oil. The average energy content of fuel oil is 134,000 BTU/gal.32 Oil-fired heaters can be

32 University of Alaska Fairbanks Cooperative Extension Service, October 2011, EEM-04253, Building in Alaska: Heating Value of Fuels.

assumed to have an energy utilization efficiency on the order of 78%.33 Energy prices for the communities in 201334 were as shown in Table 11.

Table 11: Community Energy Prices in 2013

Electricity Expense Utility Fuel Price Residential Heating Oil Community ($/kWh) * ($/gallon) ** Price ($/gallon) ** Adak 0.77 $4.88 $6.28 Akutan 0.76 $4.06 $5.46 Atka 0.44 $5.21 $6.61 * Total expense per kWh sold ** Price includes all applicable taxes

Estimated oil-based space heating and hot water costs for the communities are provided in Table 12, assuming the thermal energy requirements of Table 3 and Table 4, the building attributes in Table 5 and Figure 17, and the fuel prices shown in Table 11. These can be used as a basis for assessing the financial costs and benefits for direct use of the local hot spring resources.

Table 12: Estimated Annual Thermal Energy Requirements for Direct Use Applications

Considering Hot Springs Resource Access Costs

The cost for developing and accessing the hot spring resource can then be compared with the cost of using conventional energy resources to perform the functions of interest.

Up-front costs will be incurred to develop the hot springs resource. The magnitude will depend on multiple parameters, including items related to land ownership,

33 See www.eia.gov/tools/faqs/heatcalc.xls. 34 Utility fuel prices are per Alaska Energy Authority, February 2014, Power Cost Equalization Program: Statistical Data by Community. An add-on adjustment of 1.40 $/gal (2013 dollars) is used to estimate home heating fuel prices, per Institute of Social and Economic Research, 30 July 2014, Alaska Fuel Price Projections 2014- 2040, when local community data were not available.

permitting, and development of the required infrastructure and support facilities, in addition to the cost of establishing the geothermal water extraction. Guidelines for estimating geothermal power site development extracted from the Alaska Geothermal Development: A Plan35 publication are shown in Table 13. This information can be used as the initial basis for estimating development costs for a hot springs direct use project, keeping in mind that the costs are in 2007 $, as illustrated in Table 14. Using 2010 census data, Table 15 pro-rates the hot spring development project costs on a per-residence basis. Payback time periods can be determined by comparing operating and maintenance costs, new / refurbishment costs for community capital assets, life times, and avoided fuel costs, when this information is available.

Table 13: Geothermal Power System Development Costs in Alaska

35 See (Kolker, 2007)

Table 14: Piping and Other Hot Springs Resource Development Expenses

Distance Distribution to Exploration Development Infrastructure Location Piping 3-4,7-9, 11 9-11 5-6 Total Spring 1,2 (mile) Adak 7.5 $1,366,200 $3,340,000 $1,170,000 $1,805,000 $7,681,200 Akutan 3.6 $655,776 $5,340,000 $1,170,000 $1,025,000 $8,190,776 Atka 7.5 $1,366,200 $9,240,000 $1,170,000 $1,805,000 $13,581,200 Notes: 1: Piping Cost ($/ft, FOB outside Alaska), straight line distance $30 2: Piping Shipping Markup 15% 3: Road costs (assume twice distance of straight line), no new roads post-exploration), $500,000 $/mile 4: Assume only two miles of new road in Adak 5: Power lines, follow piping route, $/mile $200,000 6: Physical plant (10 ft x 10 ft & 10 ft x 20 ft structure at 350 $/sq ft) & equipment $305,000 ($200,000) 7: Shallow exploration wells drilled - quantity 2 8: Shallow exploration well costs, $/hole $800,000 9: Well testing, $/hole $70,000 10: Production well - one hole assumed, $/hole $500,000 11: Equipment rental & mobilization $600,000

Table 15: Community Cost Burden for Hot Springs Resource Development

Population Hot Spring Cost / Residence Occupied Location In In Group Total Residences Piping Only Total Households Quarters Adak 326 109 217 44 $31,050 $174,573 Akutan 1027 90 937 40 $16,394 $204,769 Atka 61 61 0 24 $56,925 $565,883

PEX arctic pipe with 2 inch thick polyurethane foam insulation and a protective HDPE outer jacket was assumed as the baseline for transporting hot springs water. This type of insulated pipe was estimated by an Anchorage-based building supplier at 28.98 $/ft (FOB, Dallas, TX) for 2.0 inch ID material when procured in large (10 mile) quantities. Bare (i.e., non-insulated) 2-inch ID PEX was estimated at 7.75 $/ft (FOB, Dallas, TX).

Expense will also be incurred for operating and maintaining the hot springs distribution system. Pumping-related electrical power requirements can be used to estimate the minimum annual operating expense costs. Pump power is a function of the flow rate, pipe internal diameter, pipe material, distance, and pump efficiency. Assuming 2-inch ID PEX, with an internal velocity of 6 ft/s, electricity costs per Table 11, and one-way piping distances per Table 14, an estimate of the annual cost for pumping water from the hot spring source to the community is provided in Table 16. There is not a clear economic advantage for direct use applications of the

hot spring resources, if the thermal waters must be pumped long distances from the springs to the existing community building and residence locations. In some cases, however, it may only be necessary to pump the hot spring water over a short distance, if a storage tank can be located near the spring and at an elevation sufficiently high36 above the community application area. In these situations, gravity-driven flow can be used to move the water over the remaining terrain.

Table 16: Estimated Pumping Power Costs

Distance Pwr Cost Elec Pwr Elec Cost Location (miles) ($/kWh) (kW/gpm) ($/gpm/year) Adak 7.5 $0.77 0.86 $5,797 Akutan 3.6 $0.76 0.41 $2,746 Atka 7.5 $0.44 0.86 $3,313

36 Typically on the order of several hundred feet, or more. Required elevation is a function of distance, pipe diameter, pipe material, and pipe routing.

Conclusions

Given the relatively low temperature (120 F) and flow rate (6 gpm) of the existing surface spring in Adak, challenges associated with its physical location, and its distance from the main location of the Adak community, it not an economically viable resource in its current state. Exploration drilling would be required to determine whether the resource could be expanded to better meet the community’s needs. Currently available information does not indicate that a commercially-viable community-level heating project would result. Weatherization, power plant waste heat utilization, and wind-to-heat systems integration warrant higher prioritization for the near term.

The hot springs in Akutan are a significant direct use resource, with the potential to address a large fraction of the community’s heating requirements and potentially support development of community and/or commercial greenhouses. Results from the 2015 geothermal power exploration drilling program and the ongoing water quality surveys in Hot Springs Bay Valley should be consulted to refine characterization of the hot springs resource and to investigate possible synergies related to shared infrastructure costs and possible use of spent thermal water from a geothermal power plant.

Unless future exploration significantly changes our understanding of the Atka hot spring resource, its consideration for direct use applications does not appear warranted.

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Appendix

• Sampling and Analysis of Thermal Water from the Andrew Bay Hot Springs • Test Lab Results for Andrew Bay Hot Spring Water Sample Assay

Sampling and Analysis of Thermal Water from the Andrew Bay Hot Springs By Dick Benoit July 10, 2014

On June 15 George Roe and I flew from Anchorage to Adak, Alaska in part to observe and collect water samples from the Hot Springs on the shore of Andrew Bay, near the northern end of Adak Island.

The thermal springs are located on the beach as described by Miller and Smith (1977). The majority of the shore on the northwest side of Adak Island (outside of a couple of small bays) is narrow, covered by large highly rounded volcanic cobbles up to a few feet in diameter, and bounded by very steep slopes or cliffs. Our “guide”, Justin took us to the most obvious of the thermal springs which occur on a flat wave cut bedrock bench of andesitic lave bedrock. At this location the thermal orifices are clearly visible and are easier, but still challenging, to document and sample than where spring flow is through the large cobbles 60m further south as reported by Miller and Smith (1977).

Figure 1. View to the WSW of the main or central thermal pool which is outlined in yellow and trending directly away from the photographer. The northern side of Mt. Moffitt is in the background. There is a smaller and cooler thermal discharge upper pool closer to the camera (also outlined in yellow) that discharges about 1 gpm into the central pool. Water flow direction

is away from the camera into a cooler lower pool. The picture was taken at low tide. During high tide all the pools must be regularly beneath the sea.

Figure 2. View ENE of the lower and central pools and the cliff located directly above the pools. The prominent gully in the cliff may be defining a small fracture zone. There are no visible areas of intense hydrothermal alteration visible on the nearby cliffs.

Within the main pool there is one distinct seam or joint which is producing a small volume of continuous bubbles from a few pinholes. The hot water is coming from very restricted locations within this seam. The thermocouple showed maximum temperatures of 151.9 F in a very restricted part of the main pool. Moving the thermocouple even a fraction of an inch from the hottest spot resulted in significantly lower temperatures. There are also a few other seams producing small volumes of warm water outside of the main pool. The outflow from the main pool was visually estimated at 2-3 gpm. The GPS coordinates for the main pool are 51 58.449 N and 176 37.744 W.

A sample of water from the main pool was collected from near the bottom of the pool in its hottest spot to try to minimize contamination of the 0.5 -1 gpm of warm fluid flowing into the upper end of the main pool. This sample was pumped up through a short length of tygon tubing. A sample was also collected from the outflow of the upper pool to potentially determine how much it might be diluting or contaminating the main pool. The visually estimated flow out of the main pool was 2-3 gpm.

Name Andrews Bay Andrews Bay Andrews Bay Andrews Bay Andrews Bay Sea Water (Miller+Smith) (Miller+Smith) (Cal Energy) ACEP ACEP (76AMm220) (76AMm221) (main pool) (upper pool) Year 1976 1976 1981 2014 2014 Temp C 63 71 66.6 40 pH 7.4 7.5 6.51 (lab) 7 (field) Na 6800 6100 5800 6300 6900 10800 K 460 380 460 540 580 392 Ca 1500 1300 1300 1400 1200 411 Mg 70 110 460 110 180 1290 Li 6.8 6.8 .17 B 87 70 88 81 4.45

SiO2 218 110, (210 no 192 212 (diluted) 200 (undiluted) 2.9 dilution)

HCO3 420 430 340 130

SO4 120 330 350 190 2700 Cl 13500 12000 14000 14000 14000 19400 F .49 .55 .6 n.d. 13 geothermometry

SiO2 (quartz) C 186 175, 143 177 184 180 4 Na-K-1/3Ca C 187 182 195 200 202 173 Na-K-1/3Ca Mg corr C 154 121 32 136 88 -84 Na-K-4/3Ca C 212 204 215 224 237 272 Na-K-4/3Ca Mg corr C 179 143 52 160 123 14

Miller and Smith (1977) described the Andrews Bay thermal springs as being essentially brines. For this reason sea water chemistry is included in the above table. This comparison suggests that the thermal waters are 63 – 72 % seawater on the basis of sodium and chloride contents. What is not clear is whether the sea water represents a component that may have been added to the geothermal water shortly before the sample was collected or if the sea water component is an integral part of the geothermal fluid. The silica, boron, and lithium contents of the thermal water are far greater than found in sea water. These elements unquestionably show that there is truly a geothermal system present with hot water circulating deeply through bedrock. This

geothermal system has a large dilute water component that must have ultimately originated as rainfall on Adak. The fluoride present in sea water must have precipitated as fluorite to get the hot spring fluoride contents down to about half a part per million.

The appropriate geothermometers in the table are highlighted in yellow. The silica geothermometry is not complicated, with the exception of the 1976 sample 76AMm221, and due to the near neutral nature of the waters no pH correction is necessary. The only significant question regards the Miller and Smith sample 76AMm221 which reported 210 ppm SiO2 in an undiluted sample and 110 ppm in a diluted sample. This makes a 32 C difference in the quartz geothermometer and the low value appears to be the outlier data point. No such difference in silica contents was present in the two samples collected by ACEP in 2014. The obvious conclusion of the silica geothermometry is that the thermal water recently equilibrated at a temperature between 175 and 186 C.

The Na-K-1/3Ca gives values of 182 to 202 C but these values are most likely excessively high due to the very high magnesium contents in the thermal waters. Normally, high temperature thermal waters contain less than 1 ppm of magnesium. Making the magnesium correction reduces the predicted subsurface temperatures of 88 to 154 C, which is lower than the silica geothermometer.

The Na-K-4/3Ca geothermometer with the magnesium correction gives a reasonable value for sea water. The Na-K-4/3Ca geothermometer is calibrated to apply to waters with temperatures less than about 100 C.

The five available analyses of the Andrews Bay thermal water show some significant variation in terms of salinity. This is a relatively common occurrence in high salinity thermal waters. Whether this represents analytical variability or errors, or some natural variation in the thermal water chemistry is unknown with this limited amount of data. Much more extensive sampling and analysis would be required to more precisely know the true chemistry or chemical variation of the available thermal waters at Andrews Bay.

In conclusion, there is a geothermal system present at Andrews Bay which has temperatures as high as 175-186 C based on the available geothermometry. How large or extensive this resource might be is unknown at this time.

Test Lab Results for Andrew Bay Hot Spring Water Sample Assay