Three former Coast Guard biomass boilers on way to Alaska
From Biomass Magazine
By Katie Fletcher
Three biomass boilers are being shipped to Haines, Alaska, with the potential to heat a variety of buildings throughout town. The boilers are expected to arrive next month and utilize either wood pellets or locally produced wood chips as a feedstock.
Upon arrival in Haines, the boilers manufactured by Unilux will remain in storage for the next year or so. Twelve to 24 months later they are expected to be up and running, displacing around 80,000 gallons of heating oil. “We are either going to be installing biomass heat in eight or nine municipal buildings, or creating a district heating system,” said Darsie Culbeck, contractor for the borough to help facilitate the biomass project. “In either case, the Coast Guard boilers will be useful.”
The boilers could be used to heat the school, the pool and Chilkat Performing Art Center. Culbeck said hopefully the district heating system will heat the wastewater treatment plant (WWTP), the school, the pool, the vocational technology building, the library, the administration building, the public safety building and maybe the city shop.
Culbeck said the feedstock could be pellets from British Columbia or Seattle, but that they are looking at locally produced wood chips as well. The boiler specifications are 1.5 MMBtu, 1.7 MMBtu and 500,000 Btu.
Haines borough officials recently approved the $60,000 purchase of the used boilers. The purchase includes the three boilers, 60-ton storage silos and an accumulator tank. Funding for the installation is provided through the $1.2-million Haines Borough Municipal Buildings Biomass Project grant. A resolution was voted upon at a recent borough assembly meeting, allowing borough manager, Dave Sosa, to make the purchase—five of six voted in favor. “The $60,000 was over the manager’s spending authority so it had to go to the assembly for approval,” Culbeck said.
Overall, the system was originally valued at over $450,000. The boilers were previously used in Sitka for heat by the U.S. Coast Guard, but a mishap occurred and the project was abandoned. “The combustion chamber of one of the two new pellet boilers in the AIRSTA Hanger suffered an explosion due to the buildup of the explosive gases hydrogen and carbon monoxide during testing by the installation contractor,” Culbeck said. “The building’s HVAC control system also played a role in this. This system was designed in-house by an engineer unfamiliar with biomass boiler systems.”
According to Culbeck, the result of the explosion caused some blowout plugs on the boiler to pop (as designed), some deformation of exterior non-structural panels and the chamber door to forcefully blow open (as designed) to avoid a much more catastrophic pressure buildup. The water pressure vessel side of the boiler remained undamaged.
He added that the boiler design itself was not without some blame. “The control system should have had more checks in it to detect that combustion was not happening,” Culbeck said. “The components were in place, but the boiler control logic did not take advantage of them. These have since been addressed by Unilux.”
These boilers joins five other biomass systems in town, one in a municipal building. “The success of these boilers caused me to write the original grant and pursue biomass funding,” Culbeck said.
Cost savings, a lower carbon footprint and the chance to become more energy independent top the list of potential benefits of the biomass system, according to Culbeck. “If we can source local wood chips, we are less impacted by global events and interruptions in the supply chain,” he said. “Currently, the municipality spends about $300,000 annually on heating oil. Most of this money leaves town immediately. The same amount spent on local biomass could have a multiplier of four to six times. This creates jobs and stimulates the local economy.”
Unilux will train the locals hired to operate the system. “I’m excited to be moving this forward,” Culbeck said. “Even with all the challenges and risks, I believe it is the right thing to do for our community. It’s good for the environment, it’s good for the economy and it shows the kids that it’s worth taking a chance to move a good idea forward.”
Read the original here.