By Jim Van Valkenburgh
After considering installing a biomass heating system at the Stowe Middle High School in Stowe, Vermont for a number of years, the Lamoille South Supervisory Union finally acted on the idea in the summer of 2013. The $600,000 project was completed just in time for the coldest winter in many years. Facilities Director Tom Mailhoit says the system works well, the savings have been significant, and everyone in the District is happy with the results.
In past years, the school burned an average of 45,000 gallons of fuel oil each year at costs rising gradually to $3.40 per gallon in early 2013, a heavy cost in the school’s budget. With a winter as severe as the one we had, the District could have easily spent $170,000 on fuel oil at the school, but with wood pellets as fuel they expect to spend less than half of that! Tom Mailhoit said they do not have a final tally yet but he knows the savings are excellent.
Projections showed that in an average winter they would be using about 260 tons of pellets along with 4500 gallons of fuel oil. At a current cost of $225 a ton pellets would cost $58,500 and the 4500 gallons of oil would add $15,300 for an annual cost of $73,800. That is an average annual savings of $79,200.
Tom has established a great relationship with an exceptional bulk pellet supplier, Sandri Fuels from Greenfield, MA. Since The People’s Academy in Morrisville also burns pellets, the supplier has been able to deliver a full truckload about every 2 weeks. They are managing deliveries so well now that Tom no longer concerns himself with tracking fuel levels.
Dollar savings certainly made this project attractive but there are many other benefits that it provides. Wood pellets are manufactured in New England using locally sourced wood supplies, keeping over 90% of the money spent on heating fuel circulating right here in our region. This boosts employment and the local economy. On top of that, wood pellets are carbon-neutral so burning them instead of oil will reduce carbon emissions by an average of 390 tons of carbon dioxide each year.
The pellet boilers employed at Stowe Middle High School are three Froling TX-150 hot water boilers manufactured in Austria that have a net heat output of 1.5 million BTUs per hour. These highly automated boilers use sophisticated computerized controls with multiple sensors for air flow, temperature and oxygen levels to make sure the pellets are burned cleanly and efficiently at all times. They are tied into a 28-ton steel fuel silo outside the building.
Tom Mailhoit commented that even though the Froling system is state-of-the-art, operating the boilers is not difficult, especially with the training and easy-to-understand operations manuals provided.
The school’s original heating system from 1971 used oil-fired steam boilers to generate heat, which was transferred into the school’s forced hot water heat distribution system by way of large heat exchangers. The new pellet boilers inject their heat directly into the hot water distribution pipes, a much more efficient approach.
The Froling pellet boilers were sized to cover 90% of the school’s heating design load so on very cold days the oil-fired steam boilers will be needed to keep the schools fully heated. This approach held down the initial cost of the pellet system.
During initial planning there was talk of expanding the boiler room for the pellet boilers but that added too much cost so designers figured out how to get everything packed into the school’s current boiler room. Three huge water tanks of over 2000 gallons each were removed, providing enough space for the three large Froling boilers and a 500-gallon buffer tank.
The Stowe Middle High School project was undertaken by Froling Energy of Peterborough, New Hampshire, with contributions from Thomas Mechanical of South Burlington, Vermont, Black River Design in Montpelier, Vermont, and Kohler & Lewis Engineering in Keene, New Hampshire. Fröling boilers are imported and supplied by Tarm Biomass of Lyme, New Hampshire. Froling Energy specializes in installing and servicing advanced biomass heating systems. Their website is www.FrolingEnergy.com
Jim Van Valkenburgh is VP of Business Development at Froling Energy. He may be contacted at Jim@FrolingEnergy.com .