HomeMy WebLinkAboutAlaska Gateway School District - Tok Wood Heating Case Study - Sept 2015 - REF Grant 2195417Tok, 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 Messer-
smith System
Chipper Make/Model: Rotochopper MC-266
Output: 200 yards/hr
Diesel Fuel 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)
Tok Wood Heating Project
Project Overview
With a grant from the Alaska Energy Authority’s
Renewable Energy 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 boilers 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 energy
costs to the Alaska Gateway School District by dis-
placing diesel fuel 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 creates a fire hazard.
Reason Biomass Was Chosen
200 acres were identified as a fire hazard by the Tok
Area Wildfire Remediation Plan. Forest surrounding
the school and other parts of the community 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 10 years.
Economic Feasibility
The project became operational in October 2010.
Between October of 2010 and December of 2014, the
system provided the community with 269 mega-watt
hours of electricity and 19,286 MMBtu of thermal
energy, displacing 180,000 gallons of fuel and saving
the community $643,200. With proper maintenance,
the boiler life is expected to exceed 20 years. This proj-
ect was one of the first large scale demonstrations of
biomass heating in the state. Subsequent projects were
completed with lower capital costs.
Fuel Supply & Storage
Rotochopper MC-266, photo courtesy of ADNR.
“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
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
1. Fuel quality is extremely important to the sucessful
generation of the biomass boiler. Silica-heavy pine
needles, dirt, and other contaminants create clinkers
(glass chunks) in the combusion chamber and increase
maintenance and downtime. It is a common miscon-
ception that allowing dirt/contaminants to be burned
with the wood isn’t harmful, but doing so even for a
short time proves detrimental to the system. To avoid
contaminants, Tok stores their wood in a dry, covered
area with a concrete foundation.
2. With the combined heat and power system, there is
currently about 30% more heat generated than is need-
ed 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, however,
been able to add a greenhouse with the excess heat and
is pursuing additional opportunities.
Community Benefits
1. 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.
2. Because of the money that the school district is
saving, a guidance counselor was hired and the music
program was re-introduced after being put on hold for
ten years.
3. Students are learning about fire science and boiler
operations, participating in moisture content testing,
and continually visiting the boiler facility.
4. Tok is now a safer from the threat of wildfures.
There are defensible areas surrounding the school and
other areas of the community.
5. The chipper, owned by Tok Umbrella Corporation,
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.
Published August, 2015