Summer 2014 Internship Projects John Venables Alaska Center

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/k. Wh 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 k. W • Grant Funded by Coastal Impact Assistance Program • Cost ~$75, 000 • $7. 5 per watt • First array was installed March 2013, 8. 4 k. W array in Ambler

Year Solar Production in Ambler 1, 330 1, 200 1, 011 1, 000 863 1, 036 759 781 738 695 800 600 406 103 200 694 603 322 400 37 1 37 Jul Jun May Mar Apr 20 14 Month and Year Feb Jan Dec Nov Oct Sep Aug Jul 20 13 Jun May Apr 0 Mar Solar Power Produced (k. Wh) 1, 400 1, 395

• Annual Production from Ambler: ~6. 981 MWh • Fuel savings: ~500 gallons = $2, 105 • Electric Savings @ $0. 62 / k. Wh: $4, 330 • Pounds of CO 2 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/k. W)

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 • Pure. Cycle Model 280 coupled to Electro-Motive Division 3. 7 MW diesel generator • Uses R 245 fa, 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 195 F-300 F (90 C-149 C) • Cooling < 85 F (30 C) • Greater temperature difference, more power generated • For full output power, flow rate of hot resource between 1801100 gallons per minute • Gross output of 280 k. W, net output of 260 k. W (parasitic load from working fluid pump) • Shutdown if power less than 80 k. W

• Hasn’t been operated since May 5 th, 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