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By Dan Rudy 

Saltwater heating pumps harness power of the sea

 


Around two dozen Wrangellites—residents, business managers, shop owners, as well as city and borough officials and curious others—came out to the Nolan Center Monday evening to learn more about making use of saltwater heating pump technology in the community.

Wrangell Municipal Light and Power electrical superintendent Clay Hammer invited Andy Baker to deliver the presentation. Baker is the owner and project manager of YourCleanEnergy LLC, an Anchorage-based firm he founded in 2006 which provides clean energy consulting, financial evaluation and project design.

YourCleanEnergy recently completed a million-dollar project designing and installing a pair of industrial-scale saltwater heating pumps at the Alaska SeaLife Center in Seward.

“That’s kind of the showcase, premier project of the state right now,” said Hammer. A similar system has been used at the Auke Bay Laboratory in Juneau, and the city of Seward is considering having a district loop system installed for wider use.

The idea behind the system is relatively simple: “We’re borrowing heat from the ocean and moving it into the building at a higher temperature,” Baker explained. “The attraction of the ocean is that the amount of heat is almost infinite for what we’re looking for.”

The seawater found off southeastern Alaska’s coasts has been warmed by Pacific currents and solar energy. He said the water ranges from 37 to 52 degrees, rising to its warmest just when air temperatures begin to drop to their coldest in November.

“Anything over 45 degrees is a great source temperature for a heat pump,” Baker said. “The fact is you have the same Alaska current flowing through the Inside Passage.”

Seawater is drawn into the heat pump system through a filtered intake with a wet-well and strainer points. The system at SeaLife also uses an automatic backflush, further protecting it from detritus material and all but the heaviest storm disturbance.

“Having a good intake is important,” said Baker.

Water is drawn into a titanium-plated heat exchanger that is resistant to corrosion from the salt water. The heat is transferred there from the seawater to a glycol mixture, which is then piped to the heat pump system. The slightly chilled seawater is meanwhile returned to the ocean.

In the heat pump the refrigerant vaporizes and then is compressed before heating the building loop. These pipes then provide hot water and heat for the building—in SeaLife’s case, some 120,000 square feet worth, plus its exterior pavement.

Water has substantially better capacity to maintain heat than does air, which requires backup resistance heating, making this system highly efficient. For every unit of electrical energy put in, three units are gotten back out.

Baker pointed out that Alaska already has some of the lowest electricity rates in the country, so the transition from oil-based heat generation to these seawater pumps offer a substantial savings in cost.

In 2008, he said that heating oil hit $5 per gallon. At that time, SeaLife Center was using about 500 gallons of oil per day at its peak times, and its annual utilities budget was quickly becoming untenable as an average 6- to 10-percent rise in oil prices could be expected each year.

“It’s only going to escalate,” Baker warned.

With the money the center began saving from its monthly oil costs, he calculated the system will have paid back its initial investment within 8.5 years and now offsets 1.3 million pounds of carbon dioxide emitted each year. Though such emissions are not currently a tax liability, they may become such in future.

Hammer pointed out that winter heating can be a huge expense, sometimes costing as much as people’s mortgages might in a year.

“Any time you can do that in a more cost effective manner, the savings get passed along to the community,” he said.

Not only would budgets be affected positively, but less pressure would be put on the utility network, freeing up capacity for other uses. Among these, Hammer mentioned possible industrial purposes and new business opportunities.

“It’s not something that would necessarily happen overnight,” he said.

“Heat pumps require planning,” Baker explained. “How you’re going to use them, how you’re going to fund them.” Just for the preliminary preparation, planners in Seward would be looking at a five-year plan to set up its underground pipeline based around its street repaving schedule.

On his visit, Baker was shown around the Nolan Center and its current utility system. Using it as an example, he pointed out the building uses overhead, air-based, electric heat and lacks a recovery system. In 2013 its electric boiler costs were $22,940.

Were it to utilize a pump system, Baker would recommend adding radiant floor heating and baseboards instead of the overhead ventilation, focusing on heating from the ground up. For something like the Nolan Center, he estimates its pump’s intake would only need to accommodate a 100 gallon-per-minute flow on the coldest day.

Initial investments are high, however.

“Once you build a seawater intake ... you might as well heat as many buildings as you can with that,” he said. If such a system turned out to be practical for Wrangell, Baker advised setting up a loop servicing the largest buildings first in order to ensure its fiscal vitality, and then possibly expanding the network to individual residences. But costs to partake in the system would have to be both substantially lower than the cost of an oil- or purely electrical-heating system, yet enough to also cover the costs of running the system.

The process would likely be a long one in the making, but in the end he felt the benefits would prove the investment worthwhile. Baker foresees long-term job opportunities to maintain such a system, as well as the money saved from lower costs of business during winter.

Lastly, he said it would “put Wrangell on the map” for clean energy. “It’s really something to see,” he said.

“Eventually, the most powerful motivator is the savings,” Baker concluded. “You have to be patient with these systems.”

Or as Hammer pointed out: “If we can use the power we’ve got in a more sensible way, then everybody benefits.”

 

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