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Aquarium lifts heat from ocean's stored energy

Published on NewsOK Modified: December 16, 2012 at 6:48 pm •  Published: December 16, 2012

Federal and state agencies reviewed Baker's findings and offered $713,000 in demonstration project grants.

In principal, the heat pump technology is no more complicated than a refrigerator, he said. However, instead of discarding heat like the kitchen appliance does, the system discards the cold and uses the heat.

It's hard to think of 42-degree seawater as a hot medium but steam rising from the surface on a cold day is a clue to the warmth below the surface of Resurrection Bay. From Baker's perspective, any seawater that stays above 35 degrees is a potential heating source.

The system works like this: seawater from the bay is piped to a titanium heat exchanger, where it warms a mixture of glycol and water.

The cooled seawater returns to the ocean. The glycol mixture moves by pipe to a heat pump, where it comes into contact with refrigerant. The warmed glycol mixture causes the liquid refrigerant to boil, turning it into gas. The gas is run into an electric-powered compressor. Compressing the gas raises the temperature.

The compressed gas raises the temperature of another loop of water from 100 to 120 degrees. That water is pumped throughout the building to warm ventilation air, preheat the hot water system and warm concrete slabs to keep ice from forming on pavement around animal enclosures and walkways.

The project only pays off if heat energy produced by the seawater system exceeds the electrical power used by the heat pumps. The system has been consistently producing three units of heat for every one unit of electricity.

Schaefermeyer sees possibilities for heating commercial buildings and homes in Seward. Alaska's Panhandle and communities such as Cordova and Homer are also candidates, Baker said. The water off Alaska's largest city, Anchorage, may not be suitable. Cook Inlet is silty, Baker said, and the water temperatures drop to 30 degrees and stay there.

"It's really a bit too cold," he said.

Low-cost electricity, preferably clean hydro, is needed to power the heat exchange system, Baker said. The SeaLife Center has a favorable industrial rate and also had the advantage of a seawater intake system for its aquariums.

There's a fairly large capital cost and technical experience is required to design and run systems, Baker said. That may not be appropriate for small communities currently struggling to operate less complicated equipment.

"You're probably not doing them a service by giving them one of these systems," he said.

Jones is happy with the results so far at her four-story aquarium.

"It's winter and we've turned off our fuel boilers," she said.