Daily Sitka Sentinel

Alaska’s New Heat Source: Sun-Warmed Sea

By TOM HESSE
Sentinel Staff Writer
    As saltwater heat pumps become increasingly more viable, the next opportunity for coastal Alaskan communities to save money on heating their buildings may be to tap the heat in ocean water.
     Andy Baker, the owner and project manager of an Anchorage company called YourCleanEnergy LLC, stopped by the Chamber of Commerce Wednesday to discuss the potential of salt water heat pumps. Baker has already seen the installation of one such system at Seward that is saving the Seward Sea Life Center over $100,000 a year in energy costs.
    The concept has been around for decades, but recent strides have made it more and more attractive to coastal communities, Baker said.
    “The technology for these systems have advanced tremendously,” he said.
    A salt water heat pump could loosely be described as a form of solar power, although a lot happens between the moment the sun heats ocean water and when that ocean water is ready to heat a building.
    “We’re not interested in the seawater. We’re interested in the heat in the seawater,” Baker said.
    The process starts with warm water, heated by the sun near the equator. Ocean currents bring that water north to Alaska where the water sitting in the bay is oftentimes still warmer than the air temperature.
    “Even at (water temperatures of) 37 degrees the heat pumps are still efficient,” Baker said. 
    That level of heat is hard to explain but Baker puts it in terms of Alaska’s current major energy source, the Alaska pipeline.
    The Seward Sea Life Center gets its energy from a bay that is two to three miles wide and 11 miles long. That bay sees a summer temperature increase of around 15 degrees every year just from warmer water moving up from the south. Baker said to generate that same level of heat with the Trans-Alaska pipeline you would need to burn 600,000 barrels of oil a day at 85 percent efficiency for 50 days.
    “It’s an immense amount of energy, using the ocean as a solar collector,” Baker said.
    The heat pumps take all that energy and transfer it to a pipe loop filled with glycol antifreeze. The loop circulates the heated liquid around the facility or neighborhood being heated. It is the glycol, not the corrosive sea water, that delivers heat to the building.
    The water is run past glycol, which boils at a very low temperature. The glycol condenses and creates compression leading to heat which heats the buildings. The same principal is used in refrigeration.
    The Seward Sea Life Center’s unit cost over $800,000 not including the annual cost for maintaining it, but the facility is well on its way to paying that off in oil savings alone.
    “We’re still on track for an eight-and-a-half year payback on that project,” Baker said.
    On average, the heat pump was 277 percent more efficient for heating the facility than oil.
    One advantage the Sea Life Center had was that, as an aquarium, it was already pumping in sea water, which eliminated a step in the process. One place in Sitka that has that same luxury is the Sitka Sound Science Center.
    The science center is already in the process of adding a salt-water pump, and just this year finished installing a new intake.  Officials there are working on grants to fund the heat pump.
    One day, the 11,000 square-foot building may be heated by using the same plumbing that brings sea water to the exhibits, but Baker emphasized that there is the potential to heat entire communities. Seward is heading in that direction and towns in Canada and Norway are already getting their heat offshore.
    “Tap Sitka Sound. That’s your heat source brought to you all the way from the equator for free,” Baker said.