Can Ground Source Heat Pumps Perform Well in Alaska?

Garber-Slaght, Robbin; Peterson, Rorik

doi:10.22488/okstate.17.000525

Cited by 6 publications

(5 citation statements)

References 5 publications

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“…As of 2020 the worldwide installed capacity of geothermal heat pumps (GHPs) accounted for 77,547 MWt * power around the world, with China, the United States, and Europe leading in installed capacity (Lund and Toth 2021). Installed GHP systems exist across climates, including at a number of DoD installations (OSD 2007), cold regions like Scandinavia (Gehlin 2019), and even limited deployment in Alaska (Meyer et al 2011;Garber-Slaght and Stevens 2014). As of 2020 worldwide installed capacity of geothermal space heating was 12,768 MWt, of which about 91 percent is believed to be incorporated into district heating systems (Lund and Toth 2021).…”

Section: Shallow Geothermal and Cold Regions Opportunitymentioning

confidence: 99%

Shallow geothermal technology, opportunities in cold regions, and related data for deployment at Fort Wainwright

Zody¹,

Gisladottir²

2023

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The DoD considers improving Arctic capabilities critical (DoD 2019; HQDA 2021). Deployment of shallow geothermal energy systems at cold regions installations provides opportunity to increase thermal energy resilience by lessening dependence on fuel supply and supporting installations’ NetZero transitions. Deployment can be leveraged across facilities, for ex-ample using Fort Wainwright metrics for implementation of geothermal in cold region bases. Fort Wainwright is an extreme case of heating dominant loads owing to harsh conditions in Alaska, making it ideal for proving feasibility in most heating dominant installations. Proven feasibility and potential mass deployment will help reduce emissions and increase resilience across the DoD cold region network. This report introduces the shallow geothermal energy and storage technology combination that would best fit demonstration in Alaska. Focus is on leveraging shallow, low-temperature geothermal for the development of a larger geothermal district heating and cooling (GDHC) system with underground thermal energy storage (UTES) and geothermal heat exchangers (GHX). Such systems are proven in cooling dominant climates, and individual components are proven in heating dominant climates, but deployment of a larger system in a heating dominant climate is not well established. Deployment at Fort Wainwright would represent an improvement in the technology.

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Section: Shallow Geothermal and Cold Regions Opportunitymentioning

confidence: 99%

Shallow geothermal technology, opportunities in cold regions, and related data for deployment at Fort Wainwright

Zody¹,

Gisladottir²

2023

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“…Garber-Slaght and Peterson [58] describe a ground-source heat pump system utilizing horizontal ground heat exchangers in a sub-Arctic climate with permafrost present. The permafrost layer at the site was 3 to 7.3 m deep in 2006 and the slinky heat exchangers are installed at a depth of 2.7 m. The GSHP serves a 446 m 2 office space.…”

Section: Of 34mentioning

confidence: 99%

Measured Performance of a Mixed-Use Commercial-Building Ground Source Heat Pump System in Sweden

Spitler

Gehlin²

2019

Energies

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When the new student center at Stockholm University in Sweden was completed in the fall of 2013 it was thoroughly instrumented. The 6300 m2 four-story building with offices, a restaurant, study lounges, and meeting rooms was designed to be energy efficient with a planned total energy use of 25 kWh/m2/year. Space heating and hot water are provided by a ground source heat pump (GSHP) system consisting of five 40 kW off-the-shelf water-to-water heat pumps connected to 20 boreholes in hard rock, drilled to a depth of 200 m. Space cooling is provided by direct cooling from the boreholes. This paper uses measured performance data from Studenthuset to calculate the actual thermal performance of the GSHP system during one of its early years of operation. Monthly system coefficients-of-performance and coefficients-of-performance for both heating and cooling operation are presented. In the first months of operation, several problems were corrected, leading to improved performance. This paper provides long-term measured system performance data from a recently installed GSHP system, shows how the various system components affect the performance, presents an uncertainty analysis, and describes how some unanticipated consequences of the design may be ameliorated. Seasonal performance factors (SPF) are evaluated based on the SEPEMO (“SEasonal PErformance factor and MOnitoring for heat pump systems”) boundary schema. For heating (“H”), SPFs of 3.7 ± 0.2 and 2.7 ± 0.13 were obtained for boundaries H2 and H3, respectively. For cooling (“C”), a C2 SPF of 27 ± 5 was obtained. Results are compared to measured performance data from 55 GSHP systems serving commercial buildings that are reported in the literature.

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“…The results of this GSHP project have been presented by Garber-Slaght et al [2]. in American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) journal, Garber-Slaght and Peterson [3] in International Ground Source Heat Pump Association (IGSHPA) conference proceedings and Garber-Slaght and Spitler [4] in Cold Climate Heating Ventilating and Air Conditioning (HVAC) conference proceedings.…”

Section: A Ground Source Heat Pumps In Cold Regionsmentioning

confidence: 99%

Experimental and Numerical Results on the Performance of a Heat Pump

Garber-Slaght*,

Mishra,

Das

2019

IJEAT

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A 21 kW ground source heat pump (GSHP) operating since 2013 in Alaska is described in this paper. Six years of successful operation in an extreme climate and measured performance data from 2013 to 2017 prove the viability of heat pumps for extreme cold regions. Summary of performance evaluation data such as monthly electric energy use and cost, savings of the heat pump system compared to the cost of heating oil, energy extracted from the ground, heat delivered to building are tabulated by months. The coefficient of performance (COP) of the heat pump is calculated from the experimental data, which show the COP to vary from a maximum value of 4.15 to a minimum value of 2.34 depending on the heating load of the month and the ground temperature. Cost comparison shows savings by heat pump over regular heating oil boilers of 80% efficiency. In cold regions it is of concern that GSHP can create frozen ground or permafrost around the ground heat exchanger coil by extracting too much heat from the ground. A finite element heat conduction simulation performed over the ground heat exchanger coil spanning over a 30-year period shows that small volumes of frozen ground form around the coil each season, but they melt away during the summer by the recharge of heat from the solar heat gain. The mechanical system of the heat pump, sensors for measurements and cost of the system components are presented, which would be valuable to designers implementing heat pumps in various locations of the world.

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Can Ground Source Heat Pumps Perform Well in Alaska?

Cited by 6 publications

References 5 publications

Shallow geothermal technology, opportunities in cold regions, and related data for deployment at Fort Wainwright

Shallow geothermal technology, opportunities in cold regions, and related data for deployment at Fort Wainwright

Measured Performance of a Mixed-Use Commercial-Building Ground Source Heat Pump System in Sweden

Experimental and Numerical Results on the Performance of a Heat Pump

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