Transcript Summer Internship Progects

Summer 2014 Internship Projects
John Venables
Alaska Center for Energy and Power
1
• Case Study of Solar Power in the Northwest Arctic
Borough
• Lessons Learned Paper from Organic Rankine Cycle
Machine Used by Cordova Electric Cooperative.
Solar Power in NAB
• 11 Rural Communities
• ~7,500 Residents
• 39,000 square miles – Second largest borough in Alaska
• Small plane access year round
• Seasonal boat access until rivers freeze
• No road system – Some ATV/Snowmobile Access during
winter
Deering, Alaska
• Kotzebue is the central hub of the region with an airport
that can support jets. Ships must harbor offshore since
the waters aren’t deep enough.
• Average cost of gasoline ~$8.5/gal
• Average cost of diesel for power generation ~$4/gal
• Average Pre-PCE cost of Electricity is $0.63/kWh
Pilot Solar Array in Ambler
• Water and Sewer Treatment Plants add big costs to
communities
• Solar arrays designed to offset the base power load of
these facilities with average rated capacity - 10 kW
• Grant Funded by Coastal Impact Assistance Program
• Cost ~$75,000
• $7.5 per watt
• First array was installed March 2013, 8.4 kW array in
Ambler
Year Solar Production in Ambler
1,395
1,330
1200
1,036
1,011
1000
863
781
800
759
738
695
694
603
600
406
322
400
200
103
37 1 37
2013
2014
Month and Year
Jul
Jun
May
Apr
Mar
Feb
Jan
Dec
Nov
Oct
Sep
Aug
Jul
Jun
May
Apr
0
Mar
Solar Power Produced (kWh)
1400
• Annual Production from Ambler: ~6.981 MWh
• Fuel savings: ~500 gallons = $2,105
• Electric Savings @ $0.62 / kWh: $4,330
• Pounds of CO2 offset: 28,406.3 = 3 acres of trees
• Lifetime Electric Savings (25 year lifespan) = ~$108,205
• ~13 year payback
• Excess power sold back to utility (~$0.14/kW)
Circular Array in Kobuk
Multiple Angle Array in Noatak
• Currently 6 communities have these arrays
• 5 new arrays being installed Summer/Fall 2014
Organic Rankine Cycle Machine
• Lessons Learned from failed ORC project in Cordova
• First cold climate use of ORC coupled with diesel
generator
• Goal was to take waste heat from the generator to
produce extra electrical power
• Rankine Cycle is basis for steam engines used today
• ORC uses an organic working fluid with phase change at
much lower temperatures than water
ORC Cycle Diagram
• Pratt & Whitney Power Systems, Inc
• PureCycle Model 280 coupled to Electro-Motive Division
3.7 MW diesel generator
• Uses R245fa, pentafluoropropane, as the working fluid
• Also used as foam-blowing agent in insulation industry
• No flash point, also no chlorine so won’t deplete ozone
P&W ORC Model 280
EMD 3.7 MW Generator
• Hot liquid resource from the generator between 195F-300F
(90C-149C)
• Cooling < 85F (30C)
• Greater temperature difference, more power generated
• For full output power, flow rate of hot resource between 1801100 gallons per minute
• Gross output of 280 kW, net output of 260 kW (parasitic
load from working fluid pump)
• Shutdown if power less than 80 kW
• Hasn’t been operated since May 5th, 2013
• More power used than being produced by the ORC
• Cooling issues: cooling tower freezing/tearing,
thermostats on the generator shutting, not able to get
temperature difference far enough apart
• Well designed, but issues dealing with the manufacturer,
expensive shipping of parts to Alaska
• Good concept but technology isn’t at a point to be
sustainable
Cooling Tower Used by CEC
Thank You ACEP!
Special Acknowledgments:
Mentor: Daisy Huang
Cordova Electric
Cooperative:
Danny Ackmann
Northwest Arctic Borough:
Ingemar Mathiasson
Robert Bensin