Former Derry man helps an Alaskan aquarium tap seawater's warmth for energy savings
Heating a four-story, 120,000-square-foot building through Alaska's seven-month winter is no small task.
The Seward-based Alaska SeaLife Center used to consume up to 500 gallons of oil each day to keep conditions comfortable for visitors and staffers who come to see, study or care for the puffins, sea lions and other creatures on view at the nonprofit aquarium and ocean wildlife rescue center.
That changed in December, when the center switched to obtaining most of the warmth it needs from an innovative heat pump system designed by a team led by former Derry area resident Andy Baker.
Beginning in 2006, Baker's consulting firm, YourCleanEnergy in Anchorage, developed a variety of renewable energy systems in Alaska, including solar-powered systems that help heat water for residential buildings in the state's largest city.
A few years later, Baker drew upon his experience with those projects and his degree in civil engineering as he headed a team that put together a system for warming the SeaLife Center with heat obtained from the seawater in adjacent Resurrection Bay.
In 2008, with the price of oil spiking at $5 per gallon, “they were in trouble as far as their energy budget,” Baker said of the center's staff. “They asked me if I wanted to do an evaluation for them, as far as heating their building.”
In addition to researching seawater heat pumps in use in Norway, Baker took a 10-day trip to Vancouver to see how Canadian engineers were harnessing the heating potential of their coastal waters.
“The evaluation showed it was very favorable — about a 10-year payback on the system without any grant money,” Baker noted.
But the Seward project did get state and federal funding, covering most of the $830,000 cost. According to Darryl Schaefermeyer, operations manager at the SeaLife Center, it may take as few as six years to recoup the cost, with an expected reduction in the heating bill of about $15,000 per month.
Baker noted the two heat pumps at the SeaLife Center so far are exceeding that estimate, generating a savings of $18,000 in January and $17,000 in February.
‘A real showpiece'
The center's heating system, funded as a demonstration project, is breaking ground in several areas, Baker said.
“I wanted to design a system that was an improvement, that would be a real showpiece and put us on the map against Canada and Norway, put us in the lead at least a little way,” he added.
Among seawater-driven heat pumps, the Seward project has staked out a place as the most northern such system in North America.
In addition, Baker said, “we've added multiple heat loads, more than what any other projects have done.”
He explained the heat pumps at the SeaLife Center simultaneously provide warmth for air handlers that keep the building interior comfortable through outdoor winter temperatures that can plummet to just above zero; a 600-gallon tank that provides hot water for human needs; and a system that melts snow and ice on paved slabs surrounding exterior wildlife habitat tanks.
Baker and his team also designed a web-based monitoring system so he can use his laptop to help Schaefermeyer adjust operations.
During a visit home to the Latrobe area over the Christmas holiday, Baker took time to check in on the system while catching up on emails in a Route 30 cafe.
“I have done the same thing in the past year while in Washington, D.C., Nova Scotia and Hawaii,” Baker said. “I can see it from anywhere on the Internet.”
Among the data Baker can monitor is the system's coefficient of performance. The COP is the ratio of the heating provided over the electrical energy needed to run the heat pumps and related parts of the system. The greater the COP, the better.
The pumps' efficiency increases in direct relation to the level of heating demanded from them.
“Our record we hit this winter was a COP of 4.06. That was the heat pump by itself,” Baker said.
The number drops when other parts of the system are factored in.
Schaefermeyer noted the total system COP has been averaging 2.64. “For every unit of energy we're spending, we're getting back 2.64 units in heat energy,” he said.
According to Schaefermeyer, the center's heat pump system works on the same principle as a refrigerator, but in reverse mode — providing a warming rather than a cooling effect.
He explained seawater is pumped from the bay to a heat exchanger that features a titanium plate. Several degrees of heat are transferred from the seawater on one side of the plate to a mixture of fresh water and glycol on the other side.
Baker said the glycol mixture is warmed from about 30 degrees to 38 degrees. It is then brought into contact with a refrigerant that boils at a very low temperature, turning into a gas. The gas is compressed to raise its temperature further before it is used to warm water that is then piped to provide heat to various building systems.
‘A solar bathtub'
Despite the often frigid winter air temperatures in Seward, Baker explained it's possible to extract usable heat from the local seawater because of the geography of Resurrection Bay.
One thousand feet deep and 11 miles long, from north to south, the bay is like “a solar bathtub,” Baker said. “It's a huge amount of water with a relatively small surface area. There are no currents from the ocean rushing through it. It's not getting flushed out on a regular basis, so it holds the heat.”
The water in Resurrection Bay warms up to about 52 degrees during the summer months and doesn't drop below about 37 degrees during the winter.
“You would have to burn the same amount of oil that flows through the trans-Alaska pipeline in 50 days (at about 600,000 barrels per day) to heat by 15 degrees what the sun does naturally for free,” Baker asserted. “This is what we're tapping into. It's extremely powerful, it's reliable and it's renewable.”
Another element that made the heat pump system a good option for the SeaLife Center was the fact that the facility was pumping 5,000 gallons of seawater per minute from the bay on a constant basis to maintain a healthy environment for the sea creatures it harbors. According to Baker, his team had to tap only about one-eighth of that flow to drive the heat pumps, a goal it was able to achieve through retrofitting of the 1998 building.
To allow the heat pumps to run with few interruptions, Baker noted, the center installed a strainer system last summer to automatically clean sediments and marine growth from the water intake pipe.
Further steps are being planned to make the center's heat pump system even more efficient, Baker said. He's hoping the center will be able this summer to install an additional heat recovery system.
Heat that now escapes through exhaust fans would be tapped to raise the temperature of the glycol/water mixture by an extra 2 to 4 degrees, he explained.
Additional waste heat could be captured that is generated in electrical and data technology rooms at the center, Baker said.
According to Baker, installing the heat pumps at a high-profile location such as the SeaLife Center, which welcomes 160,000 visitors per year, has had the desired effect of spreading interest among similar facilities with access to seawater.
An aquarium in Seattle is among those considering the technology, he said. He's also been involved in planning the addition of a heat pump at a smaller aquarium in Sitka, Alaska.
Baker and Schaefermeyer agree there are environmental as well as economic benefits to replacing oil-burning boilers with a seawater heat pump system.
Schaefermeyer said that shift in heating strategies should allow the SeaLife Center to reduce the carbon emissions it releases into the atmosphere by 1.3 million pounds per year.
“The energy savings part is critical to us, and the avoidance of CO2 emissions,” he said. “We put a lot of effort into operating as green as we can.”
Baker also suggested that transferring heat from seawater to the center's heat pump before releasing the water back into the bay may help counteract factors such as urban runoff that have been increasing the temperature of the water, causing a potential problem for the salmon spawning cycle.
“We're actually solving two problems at once,” he said.
Jeff Himler is an editor for Trib Total Media. He can be reached at 724-459-6100, ext. 2910, or firstname.lastname@example.org.