The Alaska SeaLife Center proposed a heat pump system that would “lift” latent heat from raw seawater at temperatures ranging from 37°F to 55°F, and transfer this heat energy into building heat at a temperature of 120°F.
Seawater heat pumps are water-to-water heat pumps that operate by using electric compressors in combination with the physical properties of an evaporating and condensing fluid known as a refrigerant. The specific heat pump equipment required for this process is not an “off the shelf” or conventional heat pump; it must use a wider heat range to tap into colder temperatures. While conventional heat pumps are typically lifting heat from 45-55°F water sources, seawater heat pumps are lifting heat from much lower temperatures, requiring more innovative compressor technology.
While this technology has been successfully deployed in Europe, this innovative process of removing latent heat from seawater and using it to heat buildings is an emerging technology in Alaska; and the Alaska SeaLife Center is the first installation utilizing this technology in the state.
The project included the design and installation of two seawater heat pumps, utilizing the existing seawater intake system used for exhibits, to "lift" latent heat from raw seawater in Resurrection Bay at temperatures ranging from 37°F to 55°F and transfer the energy into building heat at a temperature of 120°F. Also included in the project, was the design and installation of a public exhibit with live sensors linked to the heat pump system, a diagram showing how the system works, and a carbon and money-saving calculator, to be completed with match funding. The intent of the project was to demonstrate that seawater heat pumps can provide financial and environmental benefits to Alaskan businesses, homes, and communities.
Heat pumps are devices that transfer heat from a lower temperature reservoir, usually the ambient environment, to a higher temperature sink. The low temperature reservoir is usually the air, the ground, or a body of water, and it is essentially an unlimited source of heat. This heat, while unlimited, does not come without cost; work in the form of electricity is required to pump it to the high-temperature sink.
Heat pumps work on the same principle as refrigerators and air conditioners. They remove heat from a cold temperature source and pump it to a higher temperature sink. The difference is simply in the desired effect – cooling vs. heating.
Seawater Heat Pumps
Seawater heat pumps are water-to-water systems that operate by using electric compressors in combination with the physical properties of an evaporating and condensing fluid known as a refrigerant. The refrigerant used in the heat pumps in this project is known as R-134a. This project also used a dual high efficiency rotary screw compressors on a single water-to-water heat pump is an emerging technology; this feature is what allows the temperature lifting of heat from as low as 37°F up to the target building heat temperature of 120°F. A stainless steel and titanium coated plate-and-frame heat exchanger is also required to prevent corrosion during the process of removing heat from the raw seawater flow in advance of the heat pump.
Coefficient of Performance
The Coefficient of Performance (COP) for a heat pump is the ratio of total heat output to electricity input. For this seawater heat pump project, a minimum COP value of 3.0 can be maintained and will lead to viable economic returns. This COP is maintained because there is enough heat stored in the thermal mass of Resurrection Bay through the winter heating season to keep seawater temperatures well above freezing. This heat can be captured as renewable energy using the emerging technology heat pumps now available. The seawater heat pump process and associated COP is illustrated below:
Data and Analysis
To access more detailed analysis, quarterly reports, and the final report, please continue to the Resources, Links and Documents section of the page.
Funding and Partnerships
This project is a Denali Commission EETG Program project. The funding goal of the EETG program is to develop emerging energy technology that has the potential of widespread deployment in Alaska and has the long-term goal of reducing energy costs for Alaskans.
The Alaska SeaLife Center is Alaska’s only public aquarium, located on the shores of Resurrection Bay. Visitors to this “window on the sea” have close encounters with puffins, octopus, sea lions and other sealife while peeking over the shoulders of ocean scientists studying Alaska’s rich seas and diverse sealife. ASLC a private, non-profit corporation with approximately 105 full-time employees and dedicated staff of volunteers and interns. ASLC generates and shares scientific knowledge to promote understanding and stewardship of Alaska’s marine ecosystems.
The Alaska Center for Energy and Power (ACEP), an energy research group housed under the Institute of Northern Engineering at the University of Alaska, Fairbanks, is serving as the program manager of the EETG solicitation. As the projects deal with emerging energy technology and by nature are high risk, high reward, ACEP’s technical knowledge and objective academic management of the projects, specifically for data collection, analysis, and reporting, is a vital component to the intent of the solicitation, i.e., providing lessons learned and recommendations.
Renewable Energy Fund Grant
ASLC secured supplementary project funding through the third round of the Renewable Energy Fund Grant. The original scope of work with the EETG called for a single heat pump. This additional funding expands the project to a two heat pump system. The REF is managed by the Alaska Energy Authority.
YourCleanEnergy LLC was founded in 2006 to meet the emerging market of clean energy consulting in Alaska. Clients served by YourCleanEnergy include commercial, municipal, community, institutional and residential, with the primary service being financial evaluation and design of energy efficiency improvements and renewable energy systems. YourCleanEnergy conducted the original energy audit of the ASLC, recommending the current project, and is the primary designer of the seawater heat pump system.
City of Seward
As the owner of the Alaska SeaLife Center facility, leased and operated by the Seward Association for the Advancement of Marine Science, the City of Seward has the direct role of ensuring that the Center remains financially viable and continues to fulfill its mission to understand and maintain the integrity of the marine ecosystems of Alaska through research, rehabilitation, conservation and public education. The city has particular interest in this technology's potential city-wide application for residential and commercial district heating, as well as opportunities to extend the technology to the Seward Marine Center of the UAF School of Fisheries and Ocean Sciences, the Alutiiq Pride Shellfish Hatchery, and future headquarters building for the Kenai Fjords National Park.
Kenai Fjords National Park
The Kenai Fjords National Park is continuing in its efforts to obtain funding for a visitor center and administration building to be located in close proximity to the Alaska SeaLife Center. By adding heat pump technology to the design, the building will become more competitive in the federal process for awarding new construction by allowing the Park to reach a "Net-Zero" and LEED Platinum design.
Alutiiq Pride Shellfish Hatchery
The Alutiiq Pride Shellfish Hatchery depends on maintaining temperatures of water above ambient sources for production of larvae and algae cultures, which added $40,000 to their annual building heating requirements, or 15-20% of their annual operating overhead. The hatchery has an existing seawater intake system and is very interested in the Alaska Sea Life Center's demonstration of a seawater heat pump system for application at the hatchery.
School of Fisheries and Ocean Sciences
The Seward Marine Center, the marine operations unit of the School of Fisheries and Ocean Sciences of the University of Alaska Fairbanks, is involved in an ongoing project of the National Science Foundation to build and operate the Alaska Region Research Vessel, a 254-foot ice capable oceanographic research vessel. Seward is the intended homeport for the ship, utilizing the Seward Marine Center's facilities. Homeporting of the ARRV will necessitate an upgrading of the SMC physical plant, and the University is interested in the seawater heat pump technology demonstrated at ASLC as a heating source to take advantage of SMC's existing seawater system.
Links, Resources, and Documents
ASLC 35% Design Meeting, July 2010
ASLC Post-Construction Meeting, June 2011
Icy Heat: Part One
Icy Heat: Part Two
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