Holisticbluewateruseandlifecyclecostsavingsofdomesticandagriculturalrainwaterharvesting

atthewatershedscaleintheSoutheastUS

SantoshR.Ghimire1 andJohnM.Johnston21GlobalSustainabilityandLifeCycleConsultant

(GSLCConsultant)LLC2USEPA,OfficeofResearchandDevelopment

TheAnnualGeorgiaEnvironmentalConferenceAugust23-25,2017|JekyllIsland,Georgia|USA

AGENDA§ INTRODUCTION§ CONTEXT

§ Holisticimpactassessmentandcostsavingsofrainwaterharvestingatthewatershedscale

§METHODS§ RESULTS§ SUMMARY§ REFERENCES

Challengesofmanagingwaterresourcesduetoclimatechangeimpactsandpopulationgrowth

During1980-2012theweatherandclimateintheU.S.haveresultedinmorebilliondollarsdamageevents(Carteretal.2014)

§ TheSoutheastaffectedbymorebillion-dollardisastersthananyotherregion

From1970to2007mostoftheSoutheastU.S.receivedheavydownpoursinrecentautumnswhilemoderate-to-severedroughtincreasedinspringandsummer(12%and14%)(USGCRP 2012)

INTRODUCTION

OriginalFiguresource:NOAANCDC(2013)http://www.ncdc.noaa.gov/billions/events

RWHGreenInfrastructure

§ Rainwaterharvesting(RWH)practicesarereceivingrenewedinterestasgreeninfrastructureoptions

§ PotentialbenefitsofRWH:§ reducedenvironmentalandhumanhealthimpacts§ reducedstormwater runoffandcombinedsewer

overflows§ watersavingsandeconomicbenefits

§ Lackofscientificknowledgeofholisticimpacts(lifecycleenvironmental,humanhealth,andeconomicviability)ofRWHhinderstheformulationofclearpoliciesforitsuse

Energy/Material

EnvironmentalImpacts

Harvestedrainwater

Agricultural RWH

Domestic RWH

AgriculturalRWH

Ghimireetal.(2014)

1.Extraction

2.Manufac.

3.Transport

4.Use

5.ReuseRecycleRecovery

6.Disposal

LifeCycleAssessment(LCA):aholisticperspective

ISO14040CradletoGravePerspective:“Entirelifecycleofaproduct,fromrawmaterialextractionandacquisition,throughenergyandmaterialproductionandmanufacturing,touseandendoflifetreatmentandfinaldisposal.”(ISO2006)

CONTEXT

ObjectivesandScope

ComprehensivelyaddressedtheholisticimpactsofRWHatthewatershedscale§ FossilFuelDepletion§ MetalDepletion§ OzoneDepletion§ Acidification§ Smog§ Ecotoxicity-total§ Eutrophication-total§ HumanHealthCriteriaPollutants§ HumanHealthCancer§ HumanHealthNon-cancer

Onlythefirstsix(bolded)impactswillbediscussed

§ EnergyUse§ GlobalWarmingPotential§ BlueWaterUse§ GreenWaterUse§ LifeCycleWaterBalance§ LifeCycleEnergyCostSavings

METHODS

§ Watershedselection§ RWHsystemsdesignandadoptionrates§ Holisticimpactassessmentatthewatershedscale

§ Lifecycleassessment(LCA)§ Lifecyclecostassessment(LCCA)§ Holisticwaterbalance

WatershedSelection

Albemarle-Pamlico basin with 25% adoption rate for domestic RWH systems (1 dot = 100)

Watershed Totalarea(km2)

Averagefarmarea(km2)

Totalfarmarea(km2)

Numberofagricultural

RWHsystems

Urbanarea(%)

NumberofdomesticRWH

systems

BackCreek

152 0.34 11.7 34 18 5,768

Sycamore 41.5 0.42 0.91 2 49 10,296GreensMill

33.9 1.6 4.6 3 62 11,582

Watershed Characteristics

RWHSystemsDesignandAdoptionRates

Near-optimalRWHsystemdesignsminimizedinfrastructure(Ghimireetal.2014):

§ ThedomesticRWHsystems:§ apolyethylene(PE)storagetankof6.2m3

§ reducedpipelength(5m)ofchlorinatedpolyvinylchloride

§ nopumporpumpingenergy

§ TheagriculturalRWH:§ polyvinylchloridepipeof150m§ PEstoragetankof606m3

§ nopumporpumpingenergy.

RWHadoptionratesof25%,50%,75%,and100%

Schematic of domestic RWH

Schematic of agricultural RWH

(Figs. From Ghimire et al. 2014)

HolisticImpactAssessmentattheWatershedScale

Iw = changeinwatershed-scaleimpactswithrespecttoconventionalwatersupply(Units,e.g.,TJforenergydemand)A=RWHadoptionrates:25%,50%,75%,

and100%(decimal)Nt = totalnumberofRWHsystemsQy =annualwaterdemandforahousehold

toiletflushingoracropirrigation(m3y-1)T=servicelifeofRWHsystem(50yr)∆i =icon– irwh =differenceinimpactper1m3 of

rainwaterdeliverywithrespecttoconventionalwatersupply (Units/m3)

irwh and iconaretheLCIAimpactsperm3 ofrainwaterandconventionalwatersupply,respectively

Iw =Ax Nt x Qy x Tx ∆i

Watershed-scaleLCAsystemboundary

LCA

§ Apriorstudy(Ghimireetal.2014)providedfunctionalunitLCIAimpacts(perm3 waterdelivery)of:§ domesticRWHathouseholdlevel§ agriculturalRWHatfarmlevel§ conventionalmunicipaldrinkingwaterfortoiletflushing§ wellwaterforirrigation

§ CalculationswereperformedusingOpenLCA (OpenLCA 2013)linkedtothelifecycleinventorydatabasesandtheEPA’sLCIAmethods,andTRACI(ToolfortheReductionandAssessmentofChemicalandotherenvironmentalImpacts) version2.0(USEPA2013)

§ Resultsscaledtowatershed

LCCA

Lifecyclecostassessment(LCCA)ofanagriculturalRWHsystemperformedLCCAdefinedasthesumofthepresentvaluesofaproject,product,ormeasureoverthelifetime(U.S.guidelinesforLCCA)(Register1999):

§ investmentcosts§ capitalcosts§ installationcosts§ energycosts§ operatingcosts§ maintenancecosts§ disposalcosts

IllustratedaholisticviewofeconomicviabilityofagriculturalRWHbycombiningthecumulativeenergycostsavingswithlifecyclecosts

HolisticWaterBalanceHolisticlifecyclewatersavingsestimatedbyincorporatingthelossinannualwateryieldduetowatershed-wideRWH:

BH =BUy – Wa xRy

BH =annualbluewatersavingsduetodomesticoragriculturalRWHcomparedtoconventionalwatersuppliesbyintegratingrainfall(m3/y)BUy =annualnetsavingsinlifecyclebluewateruse(m3/y)Wa =watershedareacontributingtototalwateryield(m2)Ry =thelossinannualwateryieldduetodomesticoragriculturalRWHcomparedtono-RWHannualwateryield(m/y)

Thelossinwateryieldincorporatesrainfallinfluencescombining:§ surfacerunoff§ lateralflow§ groundwatercontribution(returnflowfromshallowaquifer)§ transmissionlossesand§ pondabstractions.

LifeCycleEnergyCostSavings

Potentialtranslatedcostsavingsduetowatershed-widelifecycleenergyusewerederived:

Cs =2.78x105 xPe xEsCs =potentialcostsavings($)Es =cumulativeenergysavings(TJ)Pe =energyprice ($0.103/kWh)(USEIA2014)2.78x105 =aconversionfactor(i.e.,1TJ=2.78x105 kWh)

RESULTS

ReductioninwatershedscaleimpactsofdomesticRWHadoptionwithrespecttoconventionalmunicipaldrinkingwaterinthreewatersheds:BackCreek=BC,SycamoreCreek=SC,GreensMill=GM

LCAimpactcategory Unit

Reductioninwatershed-scaleimpactsofdomesticRWHadoptionsinthreewatersheds

Reduction(%)

100% 75% 50% 25%

BC SC GM BC SC GM BC SC GM BC SC GM

EnergyDemand

TJ 85 152 171 64 114 128 42 76 85 21 38 43 58

GlobalWarming

MgCO2 eq

4667 8331 9372 3501 6248 7029 2334 4166 4686 1167 2083 2343 52

GreenWaterUse

Mm3 -11 -19 -21 -8 -14 -16 -5 -10 -11 -3 -5 -5 --

BlueWaterUse

Mm3 13 23 26 10 17 19 6 11 13 3 6 6 100

The relative reductions in impacts ranged from 52% (Global Warming) to 100% (blue water use)

RESULTS

The relative reductions in impacts ranged from 76% (Global Warming) to 100% (blue water use)

LCAimpactcategory Unit

Reductioninwatershed-scaleimpactsofagriculturalRWHadoptionsinthreewatersheds

Reduction(%)

100% 75% 50% 25%

BC SC GM BC SC GM BC SC GM BC SC GM

EnergyDemand

TJ 838 49 74 629 37 55 419 25 37 210 12 18 78

GlobalWarming

MgCO2 eq

40369 2375 3562 30277 1781 2671 20185 1187 1781 10092 594 890 76

GreenWaterUse

Mm3 -154.5 -9 -14 -116 -7 -10 -77 -5 -7 -39 -2 -3 ---

BlueWaterUse

Mm3 154.7 9 14 116 7 10 77 5 7 39 2 3 100

ReductioninwatershedscaleimpactsofagriculturalRWHadoptionwithrespecttoconventionalpracticesinthreewatersheds:BackCreek=BC,SycamoreCreek=SC,GreensMill=GM

RESULTSWater yield loss and holistic water balance for 100% domestic RWH and agricultural RWH adoption in three watersheds

From a life cycle perspective, the water loss due to RWH can be offset by life cycle blue water savings

-1.0-0.50.00.51.01.52.02.53.0

BackCreek Sycamore GreenMills

Holisticann

ualbluewaterbalance

(Mm3)

Holisticannualwaterbalance

100%AgriculturalRWH

02468

10121416

No-RW

H

100%

DRW

H

100%

ARW

H

No-RW

H

100%

DRW

H

100%

ARW

H

No-RW

H

100%

DRW

H

100%

ARW

H

BackCreek Sycamore GreensMill

Annu

alwateryieldloss(m

m)

Annualwateryieldloss

Annualwateryieldloss

RESULTSLife cycle energy cost savings due to cumulative energy reductions by domestic RWH (DRWH) and agricultural RWH (ARWH) adoption rates in three watersheds:

Back Creek (BC)Sycamore Creek (SC)Greens Mill (GM)

24

18

12

6

0

5

10

15

20

25

30

100 75 50 25

Costsa

vings,$M

Adoptionrate,A(%)

DRWH(BC) DRWH(SC) DRWH(GM)ARWH(BC) ARWH(SC) ARWH(GM)

SUMMARY§ AholisticviewofenvironmentalandeconomicviabilityofdomesticandagriculturalRWHatthe

watershedscaleinthesoutheasternU.S.wasdiscussed§ Watershed-scaleimpactreductionsduetoagriculturalRWHwere17timeshigherforBackCreekthan

Sycamoreduetomorefarmsintheformerwatershed§ DomesticRWHimpactreductionsforSycamoreandGreensMillweretwicethoseofBackCreekdueto

morehouseholdsinthefirsttwowatersheds§ HolisticwaterbalanceanalysisrevealedgreaterannualbluewatersavingsforagriculturalRWH(at100%

adoption)forBackCreek(2.4Mm3/y)thanSycamoreCreek(0.1Mm3/y)§ Potentialmaximumlifetimeenergycostsavingswereestimatedat$5Mand$24Mcorrespondingto

domesticRWHinGreensMillandagriculturalRWHinBackCreek§ 25%DRWHandARWHadoptionledtoanumberofecologicalandhumanhealthbenefitsincluding:

§ bluewaterusereductionrangingfrom2–39Mm3

§ cumulativeenergysavingsof12–210TJ§ reducedglobalwarmingpotentialof600–10,100MgCO2eq.

§ Impactsvarywithsystemdesign,RWHregulations,wateruse,watertreatmentprocessesandpumpingenergy

§ Themethodologyisgenerallyapplicabletoregionswithcomparablewatershedcharacteristicsandwatertreatmentoptions

§ RWHsustainabilityshouldbewellstudiedacrossscales§ UpscalingagriculturalRWHimpactsattheriverbasinscale§ CouplingofRWHwithcentralizedwatersystemsaswellaswithinnovativedecentralizedwastewatermanagementoptions(e.g.,waterreuse)

SUMMARY

1. NOAA2013.BillionDollarWeather/ClimateDisasters,ListofEvents.NationalOceanicandAtmosphericAdministration,Washington,D.C.

2. Carteretal.2014.Ch.17:SoutheastandtheCaribbean.ClimatechangeimpactsintheUnitedStates.U.S.GlobalChangeResearchProgram,Washington,D.C.

3. Ghimire,S.R.,andJ.M.Johnston2017.Holisticimpactassessmentandcostsavingsofrainwaterharvestingatthewatershedscale.ElemSci Anth 5.

4. Ghimireetal.2014.LifeCycleAssessmentofDomesticandAgriculturalRainwaterHarvestingSystems.EnvironmentalScience&Technology48(7):4069-4077.

5. ISO2006.Environmentalmanagement— Lifecycleassessment— Principlesandframework.ISO14040.Switzerland:InternationalOrganizationforStandardization.

6. OpenLCA 2013.OpenLCA,ModularOpenSourceSoftwareforSustainabilityAssessment.GreenDelta.

7. Register,F.2009.ExecutiveOrder13514,FederalLeadershipinEnvironmental,EnergyandEconomicPerformance.FederalRegister.TheWhiteHouse,USA.

8. USEIA2014.Electricity.U.S.EnergyInformationAdministration,USA.

9. USEPA2013.Toolforthereductionandassessmentofchemicalandotherenvironmentalimpacts(TRACI).U.S.EnvironmentalProtectionAgency,USA.

10. USGCRP2012.RegionalClimateImpacts:Southeast,U.S.GlobalChangeResearchProgram.

REFERENCES

ThankYou!Questions/CommentsareWelcome

ContactSantoshR.Ghimire,Ph.D.sghimire02@gmail.com

§ Theopinionsexpressedorstatementsmadehereinaresolelythoseoftheauthors.Mentionoftradenamesorcommercialproductsdoesnotconstituteendorsementorrecommendationforuse.

§ WethankMikeCyterski (EPA)fortechnicalreview.

DISCLAIMER/ACKNOWLEDGMENTS