Biomass Heating for Chatham School District – Klukwan School

The Klukwan school and gym is located in the Chilkat Indian Village along the Chilkat River, just over twenty miles north of Haines, Alaska. Klukwan is one of four communities across the northern end of Southeast Alaska included in the Chatham School District and currently serves 13 K-12 students. In March 2017, Wisewood Energy was selected to conduct a biomass feasibility assessment for the Klukwan school and gym, funded by the Fairbanks Economic Development Corporation (FEDC).

The main school building is 10,500 square feet and was built in 1983. Two oil-fired boilers and baseboard heaters distribute heat via hot water to the building, which is supplemented by a hot water-coil air handler (also supplied by the boilers). The school uses approximately 9,000 gallons of heating oil per year at an average cost of $30,000. The adjacent school gym is 6,000 square feet and was built in 2007. Two oil-fired, forced air furnaces heat the two-story building, using approximately 3,600 gallons of fuel oil per year at an average cost of $12,000. Together, the school and gym consume an average of 1,817 MMBtu per year and an estimated 14,139 kWh of electricity (for heating, boiler, and controls power only, or “ancillary use”).

Converting the Klukwan school and gym is technically and spatially feasible. A 500 MBH biomass boiler would provide sufficient heat and can be containerized to minimize on-site construction and disturbance to the site. The containerized biomass system may be located west of the gym or elsewhere along the north side of the two buildings. Piping from the biomass boiler would tee into the school heating system through the mechanical room at the north side of the building and distribute heat via the existing hot water distribution system. Hydronic unit heaters would need to be installed in the gym.

Biomass boilers can be fueled by cordwood, wood pellets, or wood chips. In this case, Wisewood Energy recommends a “select” wood chip system. While cordwood is estimated to be more expensive than wood chips, lower cordwood boiler capital costs make the two systems similar in terms of economic payback. Like pellet boilers, select chip boilers have automatic ignition and can operate with minimal maintenance labor. In contrast, cordwood boilers require manual stoking, which can be challenging for personnel to consistently provide, and work best when producing low-temperature water, which would require retrofitting some of the school’s existing heat distribution infrastructure. Wood chips can be sourced now from the Yukon Territory, and from the Haines State Forest over the long-term. The Haines Borough is also currently developing a wood chip biomass system, which may lend economies of scale and shared knowledge of best practices. If the Chatham School District is confident it can provide adequate staffing, cordwood is a second option. Of the three fuel types, pellets are prohibitively expensive and must be imported from Juneau or elsewhere.

Both the proposed wood chip system and the cordwood system are estimated to pay back in 23 years, which is beyond the 20-year period typically considered in life cycle cost assessments. However, converting to a biomass heating system contributes to more stable budgeting as it is less subject to unpredictable fluctuations in fossil fuel prices, keeps more dollars in the local area, and increases energy independence. Additionally, both a wood chip and cordwood boiler become economical in a 20-year period with lower wood fuel costs ($85/ton chips or $130/ton cordwood), or if oil prices were to rise just 9.5% from today’s price to $3.55/gal. Capital cost savings also improve system economics. As such, it is Wisewood Energy’s opinion that the school is a good candidate for conversion to biomass.