HomeMy WebLinkAboutTok Alaska Wood Heating Biomass Project Case Study 02-2016-BIOTok, Alaska
Biomass project reduces wildfire risk and fosters community growth
Quick Facts
Project Costs
Heating System: $3.3 million (REF & match)
Design: $280,599
Construction: $3 million
Chipper: $325,000 (State)
Steam/Electrical Generation: $725,000
Equipment
Boiler Make/Output: 5.5 MMBtu/hr
Messersmith System
Chipper Make/Model: Rotochopper MC-266
Output: 200 yards/hr
Fuel Oil Offset
Estimated annual: 64,000 gallons
Actual annual: 59,000 gallons
Comprehensive savings: 180,000 gallons
(Oct. 2010-Dec. 2014)
Fuel Savings
Estimated annual: $126,562
Actual annual: $146,000
Comprehensive savings: $643,200
(Oct. 2010-Dec. 2014)
Jobs Created: 1 Full-time Operator, 4 Part-time
Tok Wood Heating Project
Project Overview
With a grant from the Alaska Energy Authority’s
Renewable Energy Grant Fund (REF), Tok School
designed and constructed a biomass wood chip
heating system in the fall of 2009. A building behind
Tok High School houses the chip-fired boiler and a
chip storage bin. In 2013, the boiler was modified to
produce steam and a steam turbine was installed to
provide electricity in addition to heat. Tok is currently
the only school in the U.S. to produce electricity using
this method.
Objectives
The objective of this project was to reduce the en-
ergy costs to the Alaska Gateway School District by
displacing fuel oil with local wood fuel. Additionally,
developing a chip industry in the Tok area would
create much needed jobs and use a fuel source that
otherwise constitutes a fire hazard.
Reason Biomass Was Chosen
200 acres were identified as a wildfire hazard by the
Tok Area Wildfire Remediation Plan. Forests sur-
rounding the school and other parts of the commu-
nity needed to be thinned to create a defensible space
in the event of a wildfire. Using this wood as a fuel
source could provide heat to the school for at least ten
years.
Economic Feasibility
The project became operational in October 2010.
Between October 2010 and December 2014, the sys-
tem provided the school with 269 megawatt hours of
electricity and 19,286 MMBtu of thermal energy, dis-
placing 180,000 gallons of fuel, and saving the school
$643,200. With proper maintenance, the boiler life is
expected to exceed 20 years. This project was one of
the first large scale demonstrations of biomass heating
in the state. Subsequent projects were completed with
lower capital costs. Tok chip storage, photo courtesy of Dan Bihn.
“This project has enabled the school to hire a full-
time counselor and restart the music program after
being put on hold for ten years.”
Community Benefits Fuel Supply & Storage
Fuel Supply & Storage
The State of Alaska funded the purchase of the Roto-
chopper wood chipper for the Tok Umbrella Corpo-
ration. The Rotochopper is leased to local sawmills
to process chips for biomass projects. The wood is
chipped and stored in a 120-ton chip bunker at the
school and in a covered shed. The school currently
pays $50/ton, but hopes to lower the cost in the next
negotiated fuel contract.
Learning Experiences & Challenges
Fuel quality is extremely important to the sucessful
generation of the biomass boiler. Silica-heavy spruce
needles, dirt, and other contaminants create clinkers in
the combusion chamber and increase maintenance and
downtime. Although a common misconception, al-
lowing dirt/contaminants to be burned with the wood
even for a short time can be detrimental to the system.
To avoid contaminants, Tok stores their wood in a dry,
covered area with a concrete foundation.
With the combined heat and power system, there is
currently about 30 percent more heat generated than is
needed by the school. When sizing a steam turbine for
an isolated system, the electrical load should be based
on the amount of needed heat. Tok School has, howev-
er, been able to add a greenhouse with the excess heat
and is pursuing additional heating opportunities.
Community Benefits
The extra heat produced by the project allowed the
school to develop a greenhouse. Students now have
fresh vegetables in their cafeteria and learn about food
preservation. They plan to make freezeable school
lunches in the future.
Because of the money that the school district is saving,
a guidance counselor was hired and the music pro-
gram was re-introduced after being put on hold for ten
years.
Students are learning about fire science and boiler op-
erations, participating in moisture content testing, and
continually visiting the boiler facility.
Tok is now a safer from the threat of wildfires. There
are defensible areas surrounding the school and other
areas of the community.
The chipper, now owned by the Alaska Gateway School
District, is leased to other entities that are developing a
regional supply of chips for biomass systems, creating
economic development and local jobs.
Project Contact Information
Parties Involved:
Scott MacManus, School Superintendent
Email: smacmanus@agsd.us
Phone: 907-883-5151, ext. 115
Jeffrey Hermanns, Division of Forestry
Email: Jeffrey.hermanns@alaska.gov
Phone: 907-883-5134
Case Study Author:
Zoe Tressel, AEA Intern
Website: Akenergyauthority.org
Tok Wood Heating Project
Tok School Greenhouse, photo courtesy of Dan Bihn.
Hurst Firebox
900-300-1,
photo courtesy
of Alaska Gate-
way School
District.
Updated February, 2016