2016 ASME Power and Energy Conference

Economic Study of a Novel Geothermal ThermoElectric Generation-plus-Membrane

(G-TEG-M) System

June 26-June 30, 2016, Charlotte Session 1-7-8 Advanced Technologies for CHP Systems 2

Kevin McCabe

Southern Research

Abstract•  SouthernResearchIns1tute(SRI)andNovusEnergyTechnologies

(Novus)aredevelopinganovelGeothermalThermoElectricGenera1on(G-TEG)systemwithintegratedtemperaturedrivenmembranemineralconcentra1ontechnologyforusewithlowtemperaturegeothermalbrines.ThisGeothermalThermoElectricGenera1on-plus-Membrane(G-TEG-M)concentra1ontechnologyallowsforelectricpowergenera1on,cleanwaterreclama1on,andbrineconcentra1on(withtemperaturedrivenmembranedis1lla1on)toefficientlyrecovervaluablemineralsfromlowtemperature(<150°C)geothermalsources.Thispaperwillstudythelimi1ngeconomicfactorsforthisnoveltechnologyatacommercialscale.Variablessuchasgeothermalbrinethroughput,mineralconcentra1onthresholds,capitalcostvariance,andothercri1calitemshavebeenstudiedtofindtheminimumsellingpriceoftherecoveredmineralsinaplantproducinga10%IRR.

ProjectTeam

Workperformedwithsupportfrom:

USDOEEEREAwardDE-EE0006746

Background

Source:h\p://www.carbonneutral.com/carbon-offsets/geothermal-energy

Background(cont.)•  Waterispumpedundergroundandcollectedassteamorhotwater.

•  Theproducedsteam/hotwaterisusedtogenerateelectricity.

•  Wellswithhighertemperature(180-350°C)wouldusemoreefficienttechnologiesandachieve>10-12%efficiency(highestreported21%)

•  Thecollectedwaterfromthetargetinjec1onwellsisrichinmineralsandis~100-150°C

•  Couldbeusedonslipstreamoflargerplanthighertemperatureplant.

ProjectGoals•  Developandvalidateathermoelectricbasedpowergenera1onsystemthatcanachievedisrup1velyhighconversionefficienciesfromlow-temperatureresources(η>5.50%@∆T=100C),toeconomicallyproducebaseloadrenewableelectricity

•  Extractlithiumfromthefilteredandconcentratedbrinetoprovideaddi1onalsystemrevenueandtoincreasesupplyforthiscri1calmineral

ProcessFlowDiagram

BlockFlowDiagram

WaterResearchCenterInfrastructure

•  Pilotcoagula+on,floccula+on,sedimenta+on–  6gpmIntuitech

•  DiscFilter–  AmiadSpinKlinArkal

technology•  MembraneFiltra+on

–  VibratoryShearEnhancedProcessing(VSEP)

–  ReverseOsmosis•  EvaporatorandCrystallizer

–  Enconevaporator-submergedelectricheatexchanger

–  Sen1nelcrystallizer–atmosphericorvacuum

WRCTreatabilityTes1ngInfrastructure(con1nued)

•  Bioreactorpilot–  Intuitech,4filtercolumnswith

associatedfeedequipment,8gpm•  Adsorp+ontes+ng

–  usingbioreactorcolumns•  Filterpress

–  PacPressplateandframe,100psi–  Spaceandu1li1estobringin

technologiesforevalua1on•  Pilotcoolingtower•  Abilitytousepowerplant

infrastructure–  Fluegasforevapora1on–  Variouswaterstreams

TEGtechnology64couplemodulefabricatedwithNovushotpressedp-andn-typeBi2Te3materials

Developmentof10x10cmunitwhichis2.5xlargerthanstandardunits,producing>5.5%efficiencyforΔT>100°C,atacostof$0.40/wa\

Simulated Feed Geothermal Brines

Component Low Strength Brine

(mg/L) High Strength Brine

(mg/L) Ca 22 400 - 460

Cl 1,800 7,000 - 14,000

Li 1 20 - 22

Mg 13 60 - 230

Na 900 3,400 - 7,000

Si 2 0 - 12

SO4 63 380 - 400

Pro-formaModel•  Includesconstruc1onofplant•  FixedandVariableopera1ngcosts

–  Chemicals,U1li1es,O&M,G&A•  DebtService(10years)

–  Equitycontribu1on=25%–  Interestrate=8%

•  IRRtarget=10%•  Currentlithiumsellingprice=$6600/ton•  Forpurposesofthisanalysis,itisassumedthataddi1onal

surveying/inspec1oncostsareincurredtobasegeothermalplantandnotthismineralrecoveryplant.

TechnicalBaseline/Assump1ons•  Plantsize=500gpm•  Inletlithiumconcentra1oninbrine=28mg/L•  Inletbrinetemperature=150°C•  SilicaRemoval=>80%•  TEGefficiency=>5.5%

AnalysisofPlantSize

AnalysisofBrineConcentra1on

AnalysisofCapitalConstruc1onCost

WorldLithiumProduc1on&Reserves

2013 2014UnitedStates 870 W 38,000Argentina 2,500 2,900 850,000Australia 12,700 13,000 1,500,000Brazil 400 400 48,000Chile 11,200 12,900 7,500,000China 4,700 5,000 3,500,000Portugal 570 570 60,000Zimbabwe 1,000 1,000 23,000WorldTotal(rounded) 34,000 636,000 13,500,000

W=Withheldproprietaryinformation

Production Reserves

(1000’softonsperyear)

BaselinePlant(500gpm–28mg/L)=~80tons/yearlithiumcarbonateproduc1on

Source:USGSMineralCommoditySheet-Lithium

Applica1onPoten1al•  AccordingtoUSGSproducedwatersdatabase306wellsintheUShavesufficientLiconcentra1ons(>28mg/L)fora500gpmplant–  135geothermal–  167conven1onalhydrocarbon–  4other

•  Theproducedwaterdatabaseshows10stateshaveLiconcentra1onsgreaterthan28mg/Lwith4statesrepresentedbygeothermalwellavailability–  Geothermal:California,Idaho,NewMexico&Texas–  All:Ohio,Wyoming,NewMexico,Oklahoma,Texas,Alabama,Utah,California,Idaho,&Pennsylvania

NextSteps

•  Integrateen1resystemfordemonstra1on•  Developmentofselec1verareearthelementrecovery

•  Developbe\erphysicsbasedpredic1vemodelsofindividualprocesscomponents(analyzeeffectofbrinetemperature,effectofbrineconcentra1ononmembranelife1me,etc.)

Conclusions

•  Sufficientlithiumrecoveryiscri1calforplantviability(higherbrineLiconcentra1ons,higherrecoveryneeded,etc)

•  Produc1onwouldnotsaturatemarket(pricestability)

•  Amplepoten1alexistsfordeploymentoftechnology

Acknowledgments

•  Co-Authors–  JayRenew,SRWaterResearchCenter– AndyMuto,SREnergyandEnvironment– TimHansen,SREnergyandEnvironment

•  DepartmentofEnergyEERE

ThankYou!

Ques1ons?