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7X24MAGAZINE FALL 2013
LakeandRiverCooling
Considerations forCritical Facilities
INTRODUCTION
Theuseof riversand lakesasacooling
source isnotanewconceptandhas
been inuseby the industrial sectorand
powerplants fordecades in theUnited
States.Currently riverand lakewater is
usedasaheat sink inmanybuilding
types, from industrial tocommercial to
educational facilities.
Inaddition to theelectrical energyuse
required formechanical cooling
equipment,wateruse forcoolingcan
alsobechallenging.Cooling towerscan
requiremore than 11gallonsperminute
ofmakeupwaterpermegawattof
cooling required (basedon2cyclesof
concentration).With thecost to
operatecooling towersor similarheat
rejectionequipment, chemical (or
alternative)water treatment, and
replacementaboutevery 15 to30years,
theoverall costsofheat rejection to the
atmospherecanbesubstantial. These
factorsprovidebasis forconsideration
ofalternative formsofheat rejection, in
thiscase lake/rivercooling.
Datacentersandotherhigh intensity,
missioncritical facilitiesaresomeof the
biggestusersofelectricityandhave
someof thehighestneeds forcooling.
Due to their largeenergy requirements
and increasingdemands, datacenters
aregoodcandidates toconsideran
alternatemodeofheat rejectionvia
riversand lakes tosaveenergyand
water,whilealsoultimately reducing
grid-basedelectricitydemand.By
usingamore local renewable resource
suchasa lakeora river, coolingcanbe
providedwithconsiderably lessutility
basedenergy,which reduces thecost
andnegativeenvironmental effects
associatedwithproducing thatenergy.
Given the largenumberofvariables
associatedwithclimatezones,water
body type, depth, environmental
agency regulations, temperature
stability, etc., analysis foreach
individual site isanecessity.However, a
typicalproject scopemayhavemanyor
allof thebenefitswithin these five
broadcategories:
•Electricitysavings– thecombination
ofusing riveror lakewaterwitha
centralplantpotentially reduces the
quantityand/or sizeofmechanical
equipment, therebyprovidinga
reduction inenergyuse;
•Reducing requirements formunicipal
water supplyandpotential emissions -
riveror lakewateruse results in
loweringdirectand indirectelectricity
andassociatedemissions. Indirect
energyandemissions result from the
requirement topumpwater from the
pumpingstation to the receivingsite;
• Improvedcoolingefficiencyover
traditionalmechanical cooling–by
transferring theheat rejectionmore
efficientlyviawater thanair, overall
coolingplantperformance is
improved;
•Reduction inmaintenance–with less
equipmentand fewermovingparts to
maintainand replace, a riveror lake
water systembecomeseasierand
cheaper tokeep running;
•Lessspace–byeliminating
equipment, a typical systemcould
result insignificant spacesavings.
RiverandLakeWaterCoolingSystems
Using riveror lakewaterasaheat sink
foramissioncritical facility requires
segregationof the facilitycoolingwater
from the river/lakewaterwithawater-
to-waterheatexchanger toprevent
contaminationofchilledwater loop.
Theamountofheat tobe rejectedby
the facilitydetermines thecooling
water flow rate (facilitydistribution
side). The flow rateof the river/lake
waterwould thenbederived from the
by JohnPetersonandMuntherSalim
AspartofmeetingASHRAE’sgoal forbuildings toachievenet-zero
energyuseby theyear2030, includingenergy-intensivemissioncritical
facilities,designersmustchoose themostbeneficialoptionsavailable to
them.Thisstudy reviews thebenefitsanddrawbacksofusing riversand lakes
asheatsinks for themoderndatacenterwith theneed forhigh reliability (UTITiers
IIIand IV).Forexample, in theyear2000CornellUniversity introduced their lake-
sourcecoolingsystem to replaceagingchillersand infrastructure.Toronto,Canadahas
beensupporting thecity’sdowntownbuildingswithwater fromnearbyLakeOntario.
Thewhitepaper, 2011ThermalGuidelines forLiquidCooledDataProcessingEnvironments
preparedbyTechnicalCommittee (TC)9.9MissionCriticalFacilities,TechnologySpaces, and
ElectronicEquipment,proposed five (5)classesofwatercooled ITequipment,basedonenteringcooling
water temperatures.The temperaturesof lakesand riverswillbegaugedon the liquidcooledguidelines to
determine theappropriateapplicationof lakeand rivercoolingsystemswithin the liquidcoolingclasses.
