Summer Internship Progects

Summer 2014 Internship ProjectsJohn VenablesAlaska Center for Energy and Power1

1Case Study of Solar Power in the Northwest Arctic BoroughLessons Learned Paper from Organic Rankine Cycle Machine Used by Cordova Electric Cooperative.

Solar Power in NAB

11 Rural Communities~7,500 Residents39,000 square miles Second largest borough in AlaskaSmall plane access year roundSeasonal boat access until rivers freezeNo road system Some ATV/Snowmobile Access during winter

Deering, AlaskaKotzebue is the central hub of the region with an airport that can support jets. Ships must harbor offshore since the waters arent deep enough.Average cost of gasoline ~$8.5/galAverage cost of diesel for power generation ~$4/galAverage Pre-PCE cost of Electricity is $0.63/kWh

Pilot Solar Array in AmblerWater and Sewer Treatment Plants add big costs to communitiesSolar arrays designed to offset the base power load of these facilities with average rated capacity - 10 kWGrant Funded by Coastal Impact Assistance ProgramCost ~$75,000 $7.5 per wattFirst array was installed March 2013, 8.4 kW array in Ambler

Year Solar Production in Ambler

Annual Production from Ambler: ~6.981 MWhFuel savings: ~500 gallons = $2,105Electric Savings @ $0.62 / kWh: $4,330Pounds of CO2 offset: 28,406.3 = 3 acres of treesLifetime Electric Savings (25 year lifespan) = ~$108,205~13 year payback Excess power sold back to utility (~$0.14/kW)

Currently 6 communities have these arrays5 new arrays being installed Summer/Fall 2014

Circular Array in KobukMultiple Angle Array in Noatak

Organic Rankine Cycle MachineLessons Learned from failed ORC project in CordovaFirst cold climate use of ORC coupled with diesel generatorGoal was to take waste heat from the generator to produce extra electrical powerRankine Cycle is basis for steam engines used todayORC 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 generatorUses R245fa, pentafluoropropane, as the working fluidAlso used as foam-blowing agent in insulation industryNo flash point, also no chlorine so wont deplete ozone

P&W ORC Model 280EMD 3.7 MW GeneratorHot liquid resource from the generator between 195F-300F (90C-149C)Cooling < 85F (30C)Greater temperature difference, more power generatedFor full output power, flow rate of hot resource between 180-1100 gallons per minuteGross output of 280 kW, net output of 260 kW (parasitic load from working fluid pump)Shutdown if power less than 80 kW

Hasnt been operated since May 5th, 2013More power used than being produced by the ORCCooling issues: cooling tower freezing/tearing, thermostats on the generator shutting, not able to get temperature difference far enough apartWell designed, but issues dealing with the manufacturer, expensive shipping of parts to AlaskaGood concept but technology isnt at a point to be sustainable

Cooling Tower Used by CEC

Thank You ACEP!

Special Acknowledgments:Mentor: Daisy HuangNorthwest Arctic Borough:

Ingemar Mathiasson

Robert BensinCordova Electric Cooperative:

Danny Ackmann