HomeMy WebLinkAboutMcGrath Traditional Council - Biomass Case Study - REF Grant 2195459 est 2015McGrath, Alaska
McGrath Heat Recovery Project
Quick Facts
Total Project Costs: $1,171,324.14
Capital Costs
Design: $180,024.76
Construction: $991,815
Equipment
Generator Make/Model: Caterpillar 3456
(with marine manifold)
Output: 450 kW
Diesel Fuel Offset
Estimated Annual: 60,000 gallons
Actual Annual: 27,000 gallons
2010-2014: 108,000 gallons
Fuel Savings
Estimated Annual: $250,000 at $4.25/gallon
Actual Annual: $163,250
2010-2014: $653,000
Estimated Simple Payback: 11 years
Actual Simple Payback: 7.3 years
CASE STUDY
Project Overview
Th is project completed the fi nal design, permitting,
and construction phases of a heat recovery system in
McGrath, Alaska. Th e project uses waste heat from the
McGrath Light & Power (ML&P) plant that was being
rejected to the atmosphere via radiators. ML&P sells
the recovered heat to the Iditarod Area School Dis-
trict (IASD), 3 commercial buildings, and local clinic.
IASD agreed to purchase the recovered heat for 60%
of the bulk contract price that ML&P purchases their
fuel for, and the clinic/commercial buildings purchase
heat for 60% of the current retail price of fuel.
Objectives
Th e main objectives of this project were to provide
available heat from the existing ML&P power plant
to the IASD, a clinic, and three adjacent commercial
buildings. Using recovered diesel heat that would oth-
erwise be lost to the atmosphere allows the commu-
nity to displace expensive diesel fuel, save on energy
costs, and reduce emissions.
Heat Recovery-How it Works
As a rule of thumb, engines are 30% effi cient. Th at is,
of the fuel energy input, 30% each goes to horsepower,
jacket water heat, and exhaust heat. 10% goes to radi-
ation and other losses. Jacket water cools the engine
by dissipating almost 28% of the heat it generates. Th is
heat is low grade and is sent to the atmosphere using
radiators or cooling towers. Heat recovery is a unique
system that takes heat captured in the jacket water and
harnesses it for space heating. Th e jacket water loop
is isolated from the building heating loop by a heat
exchanger so that the heat recovery system does not
impact engine performance.
Economic Feasibility
Th e system became operational in May 2010. Since McGrath HR powerhouse. Photo courtesy of AEA.
then it has provided 11,602 MMBtu of thermal energy
and displaced 108,000 gallons of diesel fuel, saving
McGrath $653,000. Th e project has a calculated ben-
efi t/cost ratio of 2.13 over a 20 year lifespan, meaning
that the benefi ts outweigh the costs by more than 2.
Allocation of Funding
Th e Renewable Energy Fund contributed $712,415 for
procurement, mobilization, and construction. Other
state funding contributed $291,765.16. Local matches
contributed $167,143.98 for equipment, supplies, and
contractual services.
Relevant Information
Th e McGrath heat recovery system is using a new
Alaskan innovation: marine jacketed diesel engines
in a stationary application. Th e original “dry” exhaust
manifold and turbocharger on the standard genera-
tor-drive type engine are removed and replaced with a
water jacketed “wet” manifold and turbocharger from
a marine series engine. Th e new system allows the
heat from the turbocharger and exhaust manifold to
be added to the jacket water, increasing the available
heat by up to 250%. Shop tests and fi eld performance
monitoring have confi rmed that the conversion does
not aff ect the fuel economy of the engine.
Learning Experiences/Challenges
Th e McGrath Heat Recovery System is one of the fi rst
heat utility models in rural Alaska, selling recovered
heat to 5 diff erent entities. Th e amount of recovered
heat sent to each building is measured with a reve-
nue grade Btu meter. Th e Btu’s are then converted
to equivalent gallons of heating fuel. Th e cost of the
recovered heat is based on the calculated heating fuel
cost. During the start-up of the project, the assump-
tions used to calculate the equivalent gallons of heating
fuel had to be verifi ed, and calculations were modifi ed
to refl ect actual Btu’s going to the buildings.
Community Benefi ts
1. Due to the heat sales agreement that was put in
place prior to construction, the IASD and clinic are
able to purchase heat at an extremely reduced price
compared to what it would cost them to heat with oil.
Heat recovery is a win-win situation for the commu-
nity and ML&P because it allows ML&P to maximize
their system’s effi ciency while making a profi t and
reducing emissions. With their increased profi t, ML&P
was able to make facility corrections and pass the ben-
efi ts onto customers.
2. Although the diff erence in waste heat emissions
might not be astronomical in comparison with the rest
of the world, it certainly aids in providing cleaner air
for the community of McGrath and sets an example for
other Alaskan communities that are seeking ways to
reduce energy costs and atmospheric emissions.
Project Contact Information
Parties Involved:
Timothy Barnum, ML&P
Email: tbarnum@mtnt.net
John Dickerson, AE&E
Phone: 907-336-8031
Steve Stassel, AE&E Project Manager
Phone: 907-349-0100
Case Study Author:
Zoe Tressel, AEA
Phone: 907-771-3000
Underground piping install. Photo courtesy of AEA.
McGrath, Alaska