This document provides an overview of pico-hydro generation systems for off-grid electrification in developing areas. Pico-hydro systems are small-scale hydroelectric generators that can be installed and maintained locally without extensive training or infrastructure. They provide enough power for limited applications using small water sources. The document describes the key components of a pico-hydro system, including the permanent magnet alternator that converts rotational energy to electricity, various water directing components like the impeller, penstock and reservoir, and optional battery charging capabilities. It explains that pico-hydro is well-suited for small, remote communities since it can be implemented with local resources and has minimal environmental impacts.

1. Figure 1: Pico-Hydro generator device engineering schematic [4]
ELECTRIFICATION OF OFF
GRID LOCATIONS USING
PICO-HYDRO GENERATION
SYSTEMS
ABSTRACT
Thisdocumentwill coverpico scale hydroelectric
devicesforimplementationinoff gridlocations. The
goal of pico-hydroconfigurationsistolimit
electrificationdiscrepanciesindevelopingnationsand
supplyeasilymaintainable powergenerationsystems
for local populations. These systemscanbe
secondarilyemployedinarange of otheractivities.
The article is designedfornewcomerstothe RET
communityaswell asthose interestedinpursuing
implementationof apico-hydrosystem.The style
guide of thispaperis IEEE conformant.
Keywords:pico,hydro,electrification,developing,
generation,RET,technical
Joshua Passmore
CMPE 185

2. 1
Table of Contents:
Introduction Pg. 2
 LimitingFactorsto EnergyDeploymentinDevelopingCountries Pg. 2
 Standalone Systems Pg. 3
 Standalone HydroandScaling Pg. 4
 IntroductiontoPico-Hydro Pg. 6
Pico-HydroTechnical ComponentOverview Pg. 7
 PermanentMagnetAlternator Pg. 7
 Impeller Pg. 9
 Headand Penstock Pg. 10
 Reservoir Pg. 11
 Trash Rack Pg. 12
 Nozzles Pg. 13
 Outflow Pg. 14
 BatteryCharging(Optional) Pg. 14
 GeneratorImplementation Pg. 16
Conclusion Pg. 17
Works Cited Pg. 19

3. 2
Introduction
For those interestedingarneringtheirownpowerfroma small scale, renewable,generation
device,atechnical overviewislikelyanecessity.While the implementationof sucha systemisnot
inherentlycomplex,startingaprojectpresentsdifficultiesforthose whohave notpreviouslycrafted
such a system.However,withatechnical backgroundof terminologyandmoderate craftsmanskills
(whichcan be providedbyathird partyif necessary) arenewable energytechnology(RET) canbe
implementedinanysuitable locationforreasonablecost.Thisdocumentwill specificallycoverpicoscale
hydroelectricdevicesforimplementationinoff gridlocations.
LimitingFactors to Energy DeploymentinDevelopingCountries
The modernworldrunson the powerof electricity.Yetasignificantportionof the world’s
population(approximately1.4billionindividuals) lacksaccesstoany formof electrification.This
discrepancyisdue toa wide range of factorsbut generallyalignswithcertainindicators.Poverty,
geographicisolation,whetherthe countryisconsideredadevelopednation,andhow rural the
community contribute tothisfundamental failure.Inordertodevelopanelectrical infrastructure in
these regions,generationmethodsasidefromtraditional biomassburning(woodandother organic
materials) needstobe considered,asbiomassproductioncannotsustainablysupportapopulation
withoutsignificantrefinementinthe process.Regionsmustconsiderwhatnatural advantagesthe
communitypossessestoassessthe appropriate generationinfrastructure needed.The currentpushin
the international generation communityisforrenewable energytechnologies(RET) that canbe crafted
and maintainedlocallywithoutthe needforextensiveexpertreview andplanning [2,7].Hydroelectric
generationwillbe focused on,while consideringthe general contextof powergenerationfor
impoverished communities.
Whena communityisconsidered,asstatedabove,the communityisgenerallyindeeppoverty,
rural/geographically isolated,andinadevelopingnation.Electrificationisoftenthe fundamental first

4. 3
stepto improvingqualityof life inthese regions,due tofoodpreparationcapabilitiesandincome
generationpotential. Electrical gridsdonotextendbeyondurbansettingsinthesedevelopingregions
due to the assumed prohibitive costof extendingthe grid,bothininitialcostandforeseeable
maintenance/combatingvandalism[7].
Consequently,governmentsdonotinitiaterevisionsintheirinfrastructure,leavinglarge
disparitiesinaccesstoelectricity.
Electricutilitiesdeferexpandingaccesstounderservedorpoorareasbecause suchexpansionis
believedtomitigate commercial profit.Public-sectoractorscanbe stymiedbytheirinabilityto
implementorfinance projectsandare alwaysunderpressure tosatisfyotherurgentpublic
needs.National plannersmayhesitate topromote off-gridrenewable energyprojects,because
the technologymustbe importedortheymaywant to lookfor“free money”through
international donations.Governmentagencieshave prioritizedexpandingaccessforurban,
rather thanrural,areas, andtheysufferrapidturnoverinstaff,due inpart to uncompetitive pay
and unstable political climates [5].
Projectionsof the economicincentivetocommunitiesfrominfrastructure improvementare largely
theoretical,astangible numberscannotbe obtaineduntil afteranelectrificationprojecthasbeen
initiatedandobservedextensively.Inthe case of electrificationeffortsinthe Nepalese highlands,World
Bank data overa periodof 15 yearsprojected$8 of benefitforeveryinvestmentof $1.40 [6].Evenwhen
comparedagainst“worstcase scenario”criticprojectionsof $1.60 forevery$1.00 investedthere isa
cleareconomicincentiveforgovernmentstosubsidize the costof powergeneration [6].Howeversince
governmentsremaininactive inextendingservicestounderservedcommunities,non-gridpower
solutionsdevelopedbylocal communities are the reasonablealternative, inwhatare knownas
“standalone systems”[3,5].
Standalone Systems

5. 4
While standalone systemshave anumberof shortcomings,suchaspowerstorage issues, power
cap limitations(batterycapacity), necessityforlocal repair,andhigherlocal investment,theyrepresent
an opportunityforcommunitiestogainelectricity independently.The costof implementinga
standalone systemiscomparable orevencheaperthanthe cost of extendingthe grid,particularlyif the
locationisdistantfromthe nearestconnectionpoint. Standalone systemsalsoallow forunique
advantagesinlocationsthatare not onlyrural,but geographicallyisolatedsince the locationsgenerally
lack accessibility [7].Withinthese regionsdeployingastandalone systemallowsthe communityto
access whateverresourcestheyhaveinthe region(wind,solar,hydro) and deploygenerationtactics
that are scaledtotheirparticularneeds. Giventhatthe majorityof impoverished,rural communitiesare
remote villagesseparatedbysignificantmarginsfromurbancentersandone another,standalone
generationcanbe takenas a givenforthe remainderof thisdiscussion.
The keybarrierto the implementationof standalone systemsis,asexpected,the costinvolved.
Developingnationsrarelyhave the finances (orwillnotcontribute the finances) tosupportcost
mitigationtothe villagesthatneedelectricity,andmostvillagesdonothave qualifiedindividualsto
create the generationnetworkandgrid.Materialsgenerallymustbe importedfromnon-locallocations,
be that withinthe same nationorinternationally,inordertosupportanRET system [1].While thismay
seemtosuggestthat biomassalternativesorfossil fuel consumptionare betteralternatives,the long
termneedto purchase consumable fuelforpowergeneration diminishesthe viabilityof these
platforms,since local populationsrarelyhave accesstothese products locally.Thisreaffirmsthe use of
standalone RETsystemsbutnecessitatesthatanindividual(s)obtaintrainingrelevanttothe RET they
will be using.The levelof trainingisdependentonthe size and complexityof the generationmethod
beingpursued.
Standalone Hydro and Scaling

6. 5
Withinthe focusof hydroelectricgenerationthereare a numberof differingviewpoints
regardingscale.Priortothe notionof creatingsystemsthata communitycouldmaintainthemselves,
commonpractice was to suggest mini-hydrogenerationplantswhichproduce reasonablyhighamounts
of energyandcan supporta significantnumberof applicationsinthe community. Thisgeneration
methodnecessitatedthe inclusionof highlytrainedpersonnelsince the scale andcomplexityof the
generationwasrelativelylarge andmaintenancewassignificant [1].Howeverthe trendovertime has
beentowardsmaller,lesscomplex,andmore manageablesystemssince the necessityof obtaining
trainedpersonnelortrainingindividualsis lessexpensive asthe systemissimplified.
Most academicdiscussionsonthe topic of developingRETgeneration now referencetomicro-
hydrogeneratorplantsthatcan be fedbylow heads(an elevational shiftsupplyingvelocitytothe intake
water) andare designedtobe increasinglymodular,makingthe devicesmore readilyserviceable [1].A
fewcomponents canbe createdby local craftsmandue to the lowerlevel of expertise necessaryand
individualscanbe trainedwithfarquickerturnaroundthanforthe largermini-hydrogeneration
standard.The systemsare also highlycustomizabletothe locationwhere theyare beingimplemented,
makingthemideal candidatesforvaryingflow rates,waterpurity,debris concentration,penstock
(distributionpipesandwatercontrol systems) configuration, head,andenergyconsumption.However,
giventhe expenseof the systemthere isnomarginforerror or experimentation,andplanningbya
trainedprofessional isonce againnecessarytoensure optimalsystemfunctionalityismaintained [5].In
additionthe generatorandotherspecialtypartswill likelyneedtobe orderedandshippedtothe village,
unlessthere happentobe craftsmancapable of creatinglarge generatorsin house.
Thiscurrent discussionstill negatesthe price of amicro-hydrogenerationplant,whichthougha
reasonable solutionformostsituations, stillrepresentsasignificantfinancial burdenonimpoverished
communities.Once the systemisinstalledthe necessitytoregularlyservice/replace piecesof the
system,particularlythe storage batteries,representsanadditional costtothe community.Forsmall to

7. 6
mediumcommunities(50-250residents) thisisanexcellentgenerationoption,withthe assumption that
the communityisclose toa usable source of consistentlyflowingwater. However,withoutgovernment
mitigationthissolutionisnearlyimpossible toinitiatesince the initial costsof the systemoftenexceeds
the amountof moneyvillagescangather.Thiscan, and occasionallyhas [6],beenremediedthrough
international low interestloansanddonations butthese meansof financingelectrificationprojectsneed
to be initiatedfromthe national level.Villagesinneedof thisaidhave noorlimitedaccessto
communicationsinfrastructure,rebuttingthe abilitytosearchforeconomicaid.Thissuggests
generationmethodsthatcanbe enactedlocallyatlow expenseare necessaryinlocationswhere the
governmentisnottakingactive stepstowardelectrification.
Introduction to Pico-Hydro
In the case thatthe governmentisnotmitigatingthe costof an RET system, the communityis
smaller,orelectrificationneedislower(onlycertainbuildings,etc.) the use of acost affordable and
readilyportable system provestobe more ideal thana micro-hydrosetup.Particularlyin small settings
(1-3 houses) apico-hydrogenerationdevice thatcanfitin a five gallonbucketisuseful because it
providesenoughelectricityforlimitedapplications,givenenoughhead,andcanbe readilyusedwithout
a powercapture batterybank or seriesof specialtyhydroelectriccontrollers[4].Thisallowsavillage to
simplyuse electricityasitisbeingproduced,makingthe needforinfrastructure minimal,aside froman
electrical wire fromthe generationdevice tothe desiredarea, penstock, andatrash grate to prevent
debrisenteringthe penstock.The trainingisminimal andcanbe learnedquickly,while the construction
of the device canbe easilyperformedbylocal craftsmanwithoutnecessitatingthe orderof parts. All
componentscanbe createdor convertedfromhardware supplies andcar parts commonto developing
countries. Thismakesthe systemhighlymodular,exceptionallyeasytorepair, andcustomizable if
desired,since experimentationcanbe done withoutworryforthe majorityof the components.The

8. 7
systemisalsoscalable since additional generationdevicescanbe addedasneededcomingoff the same,
or separate, penstock.
Usinga pico-hydrosetupalsosidestepsthe policydifficultiescommonindevelopingnationsthat
make obtaininglandandrightsto dam watersourcesdifficult.Since apico-hydrosystemoperatesat
much lowerwaterconcentrationsrelativetomicroor mini-hydroalternatives,asmall portionof the
watersource can be “dammed”ratherthan the entire widthof the source (poolingdoesnotneedtobe
particularlydeeporlarge).Since generationisconductedalmostexclusivelywithinthe confinesof the
generatorthere isnoneedforpumphousesor substationsoutsideof the communal land.Similarly,
regulatoryconsiderationsforsafety concerns,trainedpersonnel,etc.canbe ignoredgiventhe relative
size of the systemandlowpotential fordanger[2]. Thisgenerationmethod simultaneouslyretainsthe
general flowrate andpath of the water source,providingdistinctbenefittocommunitiesthatdepend
on the watersource for foodand livelihood. Giventhatthe majorityof these communitiesrelyonwater
sourcesfor fishingastheirprinciple foodandincome,the abilitytogenerate electricitywithout
significantlyperturbingthe watersource issignificant. Theseconsiderations,combinedwith the above
discussionmake pico-hydrogenerationanexcellentcontenderforelectrificationinimpoverished
communities.
Pico-HydroTechnical ComponentOverview
Belowfollowsthe majorcomponentsof apico-hydrogenerator. If youare already familiarwith
hydroelectriccomponentsplease skiptothe sectionheader,“GeneratorImplementation.”
Permanentmagnet alternator
The permanentmagnetalternator(PMA) isthe generationmethodbywhichrotational energyis
convertedintoelectricalenergyforconsumption. SincePMAsare brushlessandhave nobushings they
require minimal maintenance andhave alongoperational lifetimecomparedtotheirbrushed
counterparts [9].A PMA isa synchronousgenerationmethod,meaningthe magneticfieldgeneratedby

9. 8
the rotationof the magneticcore matchesthat of the rotor onwhichthe core ismounted [9].The rotor
operatesinconjunction withthe stator,whichisthe stationaryconnectiontothe electricalloadof the
device;inthiscase a wire coil.The rotationof the magneticfieldinrelationtothe woundcoilsinduces
an electrical fieldthatflowsthroughthe wire andcanbe harnessedforusage.
The relative positionof the rotorand stator elementscanbe reversed,withthe statorplacedin
the centerof the device andthe rotor situatedaroundthe stator. Thiswill affectthe electrical
conversionrate,since havingthe magnetssituatedwithinthe statorcoilsnecessitateshigherRPMto
achieve the same currentflow [9].However,the relative resistancetothe rotor islowerwhen
positionedwithinthe stator,since alowernumberof magnetsare required [4].Thistradeoff ultimately
balancesinfavorof an internal rotorforlow flow watersourcesor limitedgrade applications,since
lowerresistance istantamountatlowerwaterpressure [4]. Note thatthe rotorhas rotational
mechanical energyandconsequentlystartswithan“r,” while the statorisstationaryand startswitha
“sta.” The rotor is mountedona rotatable shaftandslidintothe stator, withthe magneticassemblyin
close proximitytothe electrical load(thewoundcoils).
The woundcoilsare situatedinthree phases,i.e.three wiresthatcorrespondtothe standard
transmissionlineformat of houses withradial separationof 120° [9]. Thisconfiguration createsasingle
syntheticmagneticdipole,ratherthana dipole foreachmagnetused,meaningthatthe current
producedhasnominal fluctuationsandcanbe usedas a stable ACcurrent.Thiscan be useddirectlyby
the useror convertedtoDC forbatterycharging usinga rectifier.(Batterychargingiscompletely
optional since itsimplyfacilitatesenergystorage duringlow demandhourssothatmore energycanbe
usedduringhighdemandhours.The ratioof cost to benefitshouldbe analyzedbythe userto
determine if abatterybankisa desiredaddition).The rotorusespermanentneodymiummagnetsto
induce currentinthe woundcoils. These magnetscurrentlyofferanexcellentcostto performance ratio
because theyare engineeredtobe highlyeffective,relative tothe magnetthickness.There isgrowing

10. 9
concernthat neodymiummagnetsmayincrease incostsince Chinaholdsalmostthe entire neodymium
supply [9].Howevertheyare still the bestoptionforPMAs.
PMAs can be constructedby skilledcraftsman,particularlywiththe use of abase car alternator.
The car alternatorcan be convertedto operate withminimal startingcurrent byrewindingthe coilswith
highergauge wire (asopposedtothe startingcurrentof 3 A inherenttomostcar alternators) [9].Thisis
supportedbyconverting fromelectro-magneticcurrentgenerationtopermanentmagnetcurrent
generation usingneodymiummagnets,ratherthanthe gasoline carengine withelectromagnets.Since
neodymiumissusceptible toatmospheric
corrosion,the magnetsneedtobe coated
witha sealantpriorto installation[9]. PMAs
can alsobe purchasedinpremade unitsfor
$350-$600, dependentonthe maximal RPM
ratingand brand of the device,thoughthisis
significantlymore expensive thanfabricating
the device yourself[4].Forlow flow
situationscheaperunitsare justaseffective,
giventhathigherRPMs will notbe obtained.
Impeller
HydroelectricimpellersoperateathighRPMand relyona cuppingactionof water.Thisis
opposedtothe large blade formatof windturbines,whichrelyonlargerbladesrotatingatlowerRPM.
By providinggreaterobstructiontothe incomingwaterstream, equivalentpowercanbe generated
withoutthe needfora larger,flatblade surface area. The impellerdrivesthe PMA shaft(and
consequentlythe rotorof the PMA) inorderto produce electrical current,andis pivotal tothe
generationefficacyof the pico-hydrogenerator.
Figure 2: PMA with three phase coils stator evident (copper wires), as
well as an eight neodymium magnet rotor with internal
implementation [8]

11. 10
Blade orientationandconfigurationare central tothe efficiencyof the impellerdesign [4].The
ideal picoscale impellerwill have alarge numberof blades(16at minimum) inordertomaximize
contact withthe waterstreamat highRPM. Withouta sufficientnumberof bladesthe impellerwill
reach a maximal rotation currentata muchlowerthreshold.Thisrelationshipis graphically asquare
root function,withthe gainsfrom anincrease in bladescontributinganincreasinglynominalamount
above blade tipproximitycloserthan 1” [4]. Blade angle shouldbe roughly45°but can be altered
dependingonthe constructionof the bladesandthe depthof the blade cuppingregion.
Impellersizingisdependentonthe necessityof the enduser.Largerimpellerscancreate higher
torque and RPMbut can onlybe utilizedbymore powerful PMAsandrequire alargercontainmentarea
to shieldthe generationdevice fromelemental corrosion.Largerimpellersalsotendtobe particularly
durable since the constructionis oftenstainlesssteel.Smallerimpellersare more readilyproducible by
craftsmanand easilyreplaceable butare limitedtolowerRPM. Theytendtobe lessdurable since
smallerimpellersare oftenconstructedfrom
PVCcomponentsbutare exceptionallycost
effective[4].Balancingsmallerimpellersto
be true/stable isessential butif done
properlycandrasticallyincrease the impeller
durability. Impellersrange from
approximately6.5”to 12” indiameter forthe
pico-hydroclass [4].
Head and Penstock
Pico-Hydrogeneratorsare drivenby watersuppliedbyapipe calledthe penstock.Waterfrom
the penstock isfedto the impeller,whichturnsthe PMA rotor.The water pressure issuppliedbythe
Figure 3: Small scale hand crafted PVC impeller design implementing
16 blades. Blade angle is approximately 45° and blade tips are
separated by roughly ¾”. [4]

12. 11
head,whichisthe elevationalchange thatthe gradedpenstockpipe traverses tothe generator. Higher
grade resultsinhigheroperational pressure,allowingforhigherRPMto be suppliedtothe impellerfor
currentproduction. Smallerheaddistances canbe usedif the penstock lengthisincreased
proportionally [4].Thisincreasesthe material costof installingthe penstock butcanbe justas effective
at reachingoperational voltages.
The diameterof the penstock isanotherconsiderationforthe generationsystem.Larger
penstock suppliesagreateramountof waterto the systembut haslowerpressure forthe same water
velocity.Smallerpenstock operatesathigherpressureandischeapertopurchase,butis more
susceptibletoblockage andrequiressuperiorfiltration(see trashgrate). Penstock size alsolimitsthe
potential forgeneratorexpansion.Smaller penstock mayrepresentacheaperinitial investmentbutif a
largerpico-hydrosetupisdesired(eitherasasingle setupora multi-generatorsetup) the penstock may
needtobe replacedtoensure enoughwaterissuppliedtothe impeller(s). Some compromisebetween
the two configurationscanbe made bystartingwitha larger penstock (tosiphonmore waterintothe
system) andprogressively
narrowingthe penstock toa
smallerdiametertoincrease
the operational pressure [4].
Thisrequiresmore connection
piecesbutthe reductionin
cost of the system (overonly
largerpipes) mediatesthe cost
of connections.
Reservoir
Figure 4: Elevational head required to implement specific voltages through a passively
pressurized pico-hydro implementation with 2" penstock and 26 gpm flow rate [4]

13. 12
The reservoirof a hydroelectricsystemdeterminesthe capacityof waterthatis heldpriortouse
inelectricgeneration.Forpico-hydrosystemswhere the waterispassivelypressurizedoveragiven
distance of headand the waterintake isfairlyminimal,the holdingcapacityof the reservoirdoesnot
needtobe significant.Forgenerationonthe orderof 13.7 volts,the generatorneedstobe fedata rate
of 26 gallonsperminute (gpm),withincreasesinpowerproductionaccompaniedby greaterwater
volume orvelocity [4].While 26gpm soundssignificant,thisis generally obtainable fromsmall streams
and mountainwatersources.Note thatthisis the incidentwaterflow rate atthe mouth of the penstock
not the flowrate aftertraversingthe penstocklength,justbefore arrivingatthe nozzles [4].
The reservoirdepthneedstoallowthe penstock tobe submergedunderthe waterby
approximatelyeightincheswhile simultaneouslyelevatedabove the bottomof the reservoirbyeightto
twelve inches [4].Thispreventscomplicationswiththe intake of sedimentthatmayhave made it tothe
bottomof the reservoirwhilealsoensuringthatfluctuationsinwaterdepthduringsummermonths,
droughts,etc.have minimal effectonwaterintake. While these precautionslimitthe amountof
sedimentforcedintothe penstock of the system, the reservoirmustworkinconjunctionwithatrash
rack (See Trash Rack) in orderto maximallyfilterthe inboundsediment.
In the pico-hydrocase anentire watersource doesnotneedtobe dammedforreservoir
creation.Rathera smallerholdingareathatcan control waterintake tothe penstock of the systemcan
be used.Since itisthis small reservoirlocatedinaportionor to the side of the water source that
controlswaterdispersal tothe system,the environmental impactissignificantlydecreased,asitdoes
not preventmigratoryfishspawningandretainsthe natural flow of the watersource,ratherthan
completelyalteringthe flow. Forcommunitiesindevelopingnationswhorelyonfishingasamajor
source of income andsustenance,the pico-hydroreservoirofferssignificantadvantages, since itdoes
not limitthe availabilitytothe natural resources of the water.Additionally,bynotdammingthe entirety

14. 13
of the source there isno potential fordisplacementduringreservoircreation,whichisasignificantissue
duringlarge hydroelectricbuilds.
Trash Rack
The trash rack isa filtrationdevice thatprotectsthe inflow of the penstock fromtakingin
sediment.Thisisimportantfortworeasons:clogpreventionanddamage/corrosionprevention.The
obviousconsequence of sedimentbeingallowedintothe headisthatitcan create areasof impasse that
limitorpreventthe flowof waterto the nozzles.Evenif blockagesdonotoccur in the penstock,the
nozzle issignificantlysmallerdiameter(dependentonthe systembutrangingfrom¼” to 1” indiameter)
and ismore susceptible toclogging.
The secondconsequence isthatsedimenthassome granularityandroughness andwill cause
significantcorrosiontothe elementsof the generator,includingthe PMA andthe impellerwhichare the
heartof the generationsystem [4].Thiscorrosionreducesthe effectivelifetime of the generator
elements,increasingthe needformaintenance andpartreplacement.Consequently,the trashrack
needstoaddressboth siltysedimentandgranularparticlesof various sizes.
In orderto accomplishthistaska simple trashrack can be as effective asacomplex filtration
system.Bycombininganintake areawitha drop down (forsedimenttodepositin) withanoutflowthat
has a semi-permeable membrane,watercanescape the trashrack while sedimentis trappedwithinthe
device.Asanexample afive gallonbucketwithhardware clothatthe outflow andlarge escape holes
drilledinthe bottomallowssedimenttoflow outof the trash rack, back intothe watersource,while
allowingwatertoflowthroughtothe penstock [4].Note that the trash rack needstobe submergedin
the same way as the penstock.
Nozzles
The nozzlesat the endof the penstockfocusthe watersuppliedbythe penstockintoahigh
pressure jetthatcan be usedtoturn the impellerathighRPM. Nozzle placementdirectlycorrelatesto

15. 14
generationefficiency,since the nozzlesare the onlyadjustableelementinthe generator.Byalteringthe
positionof the nozzles,greaterwaterpressure canbe placedincidenttothe impellerblades, giving
variedamountsof currentproduction.Formaximal currentgenerationthe nozzle shouldhitthe impeller
blade at roughlythe centerof the blade end(i.e.centeredvertically,off centerhorizontally) [4].Thiscan
be illustratedusingaleverexample.If youare givenalongleverthe conversionrate of yourworkto
liftingsomethingismuchhigherthanif youwere toattemptto move the objectwitha shorterlever.
Similarlyhavingwaterpressure incidentatthe endof the bladesismore effective atgeneratingcurrent
because the workof the waterismore effectivelyconvertedusingthe lengthof the impeller,whichis
actingas a leverforcentripetal motion.
Outflow
The outflowof the pico-hydrogeneratorallowsthe watertoreturnto the watersource or into a
holdingtank/animaltroughs/irrigationlinesafterthe potentialhasbeenexhausted.Thisallowsthe
waterto eitherbe recycledtothe watersource or put to use as a methodof automation. Employing
methodsof automationallowsdevelopingcommunities,whomayotherwiseneedtotraverse difficult
terrainto obtainwater,toaccess waterdirectly. Asmentionedabove,thiswatercanbe usedfor a
multitude of activities,thoughit
doesrequire anadditional
investmentinpenstockto
transportthe waterto the desired
locations. Bynotsimplylettingthe
waterseepintothe groundat the
outflow,apico-hydrosystem
minimizesthe environmental
impactof siphoningoff water.Figure 5: Return of exhausted potential water to water source through outlets at
bottom of pico-hydro containment unit [4]

16. 15
Battery Charging(Optional)
Batterychargingis, as discussedunderthe PMA header,asignificantfinancialinvestment.The
cost of implementingbatterystorage isresultantfromthe necessityof batteries, arectifier, ashuntload
regulator,anda powerinverter.Before beginningtoimplementbatterychargingthe userwill have to
determine the numberof batteriesthatare neededtosatisfy powerdemands. Batteriesthatare
employedinchargingimplementationsare generallylarge capacitydeepcycle storage batteriesthatrely
on a leadacidcompositionforenergystorage.Since deepcycle batteriescansurvive temperature
fluctuationsandlongperiodsof discharge theyare distinctfromcar batteries,thoughtheyare similarin
constructionandoperation.The costof these batteriesdependsonamultitude of constraintsbutrange
fromapproximately$85to $350 each. It islikelythatbetween 4and8 batterieswill be employedif the
loadto the systemwill be significant,suchasrunningconventional appliancesora multitude of small
devices.
Once the batterybank size hasbeendetermined,the currentbeingproducedbythe PMA needs
to be directedintothe batterybank.Since PMAsare ACproducingsystemsarectifierwill needtobe
usedto create stable DCpowerfor batterystorage.Most pre-fabricatedPMAscome withanincluded
rectifierwiththe assumptionthatthe userwill be pairingthe PMA witha batterybank [1].However,if
the PMA doesnot have a rectifierone willneedtobe includedexternal tothe PMA (Thiscan be created
by anyone familiarwithcircuitsbutmayrepresentatechnical challengefordevelopingcommunities,
particularlywithobtainingcircuitelements).
To preventthe batteriesfromoverchargingandbeingdestroyedashuntloadregulator needsto
be employedbythe system.A shuntloadregulator sitsinparallel withaload(inthiscase charging
batteries) andacts as a variable resistor[4].Thisallowsthe systemtohave aconnectiondirectlyto
groundonce the batteriesare filledinordertodumpthe excesspowerproduced.Thiswastesany

17. 16
overage incurrentproductionbutprevents
the batteriesfromdrastically reducingtheir
lifetimes [1][4].Aswiththe rectifier,the
shuntloadcontrollercanbe createdby
anyone familiarwithcircuitsbutisfar more
complex thanthe rectifierandrequiresa
substantial numberof discrete components
that may notbe available indeveloping
communities.
Once the above componentshave been
constructed,a powerinverterwill be
necessary toconvertthe storedDC back into
AC.The powerinverteralsoamplifiesthe ACsignal tohigherfrequencies,makingthe ACcurrentmore
readilyusable ata standard120 V (US) [10].The invertercanbe createdfrom discrete circuit
components,just asthe previouselementsof the batterychargingconfiguration,andrequiresasimilar
level of expertise.Since nearlyall modernelectronicstake inAC currentdue to ACfidelityoverdistance,
the powerinverterisacritical portionof the device [10].Asa side note,if the distance betweenthe
batterybankand the area of usage issignificant,astepupand stepdowntransformersetwill needto
be constructed to limitline losses.Thesecanbe constructed bythe individual butrequire asignificant
time commitmentinordertofabricate andwindthe transformers,aswell asan understandingof
transformerapplicationsandwindingratios.
GeneratorImplementation
A reasonable guidetobuildingapico-hydrogenerationsystemcanbe found fromreference [4].
Thisdesignishighlymodularanddeployablefordevelopingworldapplications,aswell asremote
Figure 6: Shunt load regulator circuit from discrete electrical
components. This particular configuration is being implemented for a
solar array control but the function is identical and the design is
interchangeable. [4]

18. 17
scientificequipmentchargingandsimpleoff-gridpowerconfigurations.Giventhe above overview on
technical componentsthe buildmanual shouldbe approachable,if skillheavy.
Conclusion
As discussedinthe pre technical portionof thisdocument,the needforpico-hydro
implementationindevelopingnationsisevidentandpersistent.Thisneedsnofurtheroverview.
However,the benefitpico-hydroprovidestoscientificendeavorswarrantsfurtherexplanation.For
animal observationprojects,remotemeteorological stations,conservationmeasurements, etc.aswell
as temporarybase powergeneration,pico-hydrosystemscanbe employedtoconsiderableeffect.Since
the systemismodular,readilymovable,andminimal inenvironmentalimpact,small researchteamscan
construct anddeploysystemsfortheirvariousprojectswithoutthe needforconstantin-person
monitoring. Thisallowsshorterfieldtimesforresearchersandforcommunicationequipmenttobe left
at the researchsite.Communicationinfrastructureallowsprojectionof videofeeds,datasets,remote
commandusage,and variousotheractivities,due tothe pico-hydropowergeneration.
Individual usersindevelopednationscanalsouse pico-hydrogenerationtomove theirown
residence off-grid.Thisisoftenastrictchoice by the propertyowner,ratherthana solutiontoa lackof
powerinfrastructure.Systemconstructionischeapenoughtobe viable forindividuals,makingpico-
hydroaccessible tomotivatedparties.Whilethe focusof thisdocumentwasonelectrificationfor
impoverishedlocationsandthe role of pico-hydroincombattingthatdiscrepancy, individual usage is
valuable andencouraged.
Regardlessof the application,componentconstructionandinteractionare central tothe success
of pico-hydrosystems.Aswithanyhandcrafteddevice,there will be variabilityinthe final productand
optimizationof eachsystemwill needtotake place.The numberof unique factorsarisingfromlocation,
need,buildprecision,andall otherspecificelementsof the buildcontribute tothe unique nature of
each generationsystem.There will be problemsthe firsttime creatinganyRET system. Donot be

19. 18
discouraged. Simplyrememberthatproblemscanbe remedied,partscanbe fixed,informationcanbe
obtained,andeverythingisbeingenactedonacost effective energyplatformsoinefficiencies canbe
accountedfor.

20. 19
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