HomeMy WebLinkAboutCordova Heat Recovery Case Study - REF Grant 7050848 2015Cordova, Alaska
Cordova Heat Recovery Project
Quick Facts
Total Project Costs: $5,260,000
Funding: Renewable Energy Fund: $1,780,000.
Local funds: $1,990,000-$3,480,000??
Capital Costs
Engineering: $320,000
Heat Recovery Unit: $ 900,000
Installation: $560,000
Equipment
Generator Make/Model: EMD 710-20
Output: 3.6 MW
Diesel Fuel Off set:
Estimated Annual:
Actual Annual: 56,773
2012-2014: 1,192,240.59 gallons
Fuel Savings:
Estimated Annual:
Actual Annual: $283,174
2012-2014: $5,946,664.12
Estimated Payback: 10 years
Actual Payback: 18.6 years
CASE STUDY
Project Overview
With funding and technical support from the Alaska
Energy Authority, the City of Cordova developed a
heat recovery system at the Orca Power Plant, owned
by the Cordova Electric Cooperative (CEC). Th is
project captures waste heat from the Orca Power Plant
using an Organic Rankine Cycle (ORC) heat recovery
unit on a new high-effi ciency, low-emissions diesel
generator.
Objectives
Th e main objectives of this project were to reduce the
energy costs to CEC and therefore reduce costs to
community members. An added benefi t is that there
is less waste heat being emitted to the atmosphere via
radiators.
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 isn’t of any use so it is sent to
the atmosphere using radiator or cooling towers. Heat
recovery is a unique system in that it takes heat that is
lost to the jacket water and harnesses it for space heat-
ing. Th e jacket water loop is isolated from the build-
ing heating loop by a heat exchanger so that the heat
recovery system does not impact engine performance.
Relevant Information
Th e Orca Power Plant is powered predominantly by
hydroelectric facilities, one at Power Creek and one
at Humpback Creek. Power Creek is capable of gen-
erating 5.5 MW during operation and Humpback
Creek 3.5 MW. Consequently, the ORC was only used
Aerial view of Cordova, AK. Photo courtesy of city-data.com.
when hydro was not available-usually in the winter.
Th e ORC is fi tted to an EMD 710‐20 Diesel Generator
(Unit 7) to recover its waste jacket water heat. Due to
a warm winter and the absence of key electric energy
users during the 2013‐2014 winter months, electrical
systems demands were less than the operating range of
Unit 7. As a result, the ORC unit was taken offl ine.
Economic Feasibility
When the ORC is operating under ideal conditions,
fuel effi ciency has the capability to increase by almost
20% by increasing electrical production by 4-6% from
the captured heat. Th e project has a calculated benefi t/
cost ratio of 2.33 over a 20-year lifespan, meaning that
under ideal operation the benefi ts outweigh the costs
by 2.33.
Learning Experiences/Challenges
• Th ere are several challenges to operating the ORC
economically. Th e Baltimore Air Coil cooling tow-
er on the condensing side has icing problems and
has not been eff ective in providing the best possi-
ble effi ciency of the ORC.
• A changing CEC winter load profi le and warm
winters have limited the opportunity to run the
ORC.
• To date, the operational and commissioning chal-
lenges have been a strain on CEC staff resources,
and the electric use needed to keep the ORC run-
ning has exceeded the power it generates.
• It is likely that a more effi cient cooling device, per-
haps even a conventional radiator, would operate
more eff ectively in Cordova’s climate.
• Until CEC fi nds a way to incorporate the ORC
more effi ciently it will remain offl ine.
Community Benefi ts
Th ough the learning experiences and challenges of this
project have been somewhat complicated, there is a sil-
ver lining that puts the project into better perspective.
Th e fact that the Power and Humpback Creeks projects
are producing enough power for the community to
thrive on is a huge benefi t in and of itself.
Th is project not only benefi ts Cordova Electric Coop-
erative’s 1,560 customers, but
Project Contact information
Parties Involved
Clay Koplin, Cordova Electric Cooperative
Email: ckoplin@cordovaelectric.com
Case Study Author:
Zoe Tressel, AEA
Email: ztressel@aidea.org
Phone: 907-771-3000
ORC Piping, Photo courtesy of Alaska Energy Authority.
Heat recovery system, Photo courtesy of Alaska Energy Authority.
Cordova, Alaska