AEN-6'
ELECTRIC
ENERGYUSAGE
ONKENTUCKYDAIRIES
J. P. Cbastain, L. W. Turnu, D. G. Collhrcr,
W. E. Mutpby, I.J. Rossand G. M. Wite
ffi
^60
bt
The typical modern dairy depends heavily on electric energy for pador operations. In fact, dairy tarms
tlpically use 60% of the electricity sold to production
agriculture in Kentucky.' As a result, electric energy
usage is a sigfficant cost that concerns most dairy
farmers. Any increased efficiency of usage should increase the farm operation's profit.
Profile of Kentudry Dairies**
Daity Size and Milk Production
Table1 shows3 groupsof Kentuckydairiesby size
and the average milk production for each group.
Tablc L.-Size of Dairy Farms and.
Daily Milk Production
Avg No. Cows
Milked/Day
% Total No.
Milk Production
(lb/cout/My)
Dairy Fanrns
5to29
30 to 59
60 ro 2oo
40.7o/"
40.2%
19.1"/o
39.3
45.6
44.3
Most dairies in Kentucky (81%) milk less *ran 60
cows/day and the averagedaily milk production does
not vary greatly according to dairy size. The average
dairy milks 4O cows/day and produce s 44lb/cow/day.
The percentage ofdairies that produce grade A and
manufacturing grade milk is shown for each size class in
Figure 1. Only 28% of the dairies, according to survey
results, are manufacturing grade dairies and the majority of those (87'/") milk less than 30 cows. Over half
(60'/") of all dairies that milk less than 30 cows/day
have a manufacturing grade rating.
'Tumer et al, 1987
" Information in this publication comes from a 1986 & 87 study of
Kentucky Dairies, described on p. 5.
University
S cnoer
cnroe
$ rarurrcnrnnc
ol
o
5.0
N
U
0
a
r'"
E
o20
N
AVERAGENUMBER OF COWS MILKED PER DAY
Figure l.-Distribution of grade A and manufacturing
grade dairies according to dairy size.
Herd Make-Up
Dairy herds rangefrom 5 to 500 cattle,with the
averageherd numbering about 82 to 84. Most dairy
farmers(8I"/") raisereplacements.The herd make-up
does not vary significantly with dairy size. Figure 2
Kentucky dairy's total herd.
breaksdown the at;.erage
CALVES
14
-t=-'
.ry
cows
MILK COWS
40
Figure Z.-Average breakdown of a tlpical Kentuclry
dairy herd.
o Cooperative Extenslon
of Kentucky o College of Agrtculture
Agriculture r Home Economics , 4H . Development
Servlce
^90
-bq
70
N
5TO29
m
a
TL
50 TO 59
3ro
5ro
60 TO 200
fr+o
(L
o5o
rI20
-lo
*<o
o
STANCHION FL\T SIDE-OPENING
HERRINGBONE
OTHER
BARN
PARLOR PARLOR
PARLOR
Figure 3.-Distribution of qpes of milking facilities according to the averagenumber of cows milked per day.
Milking Facilities
The averagenumber of cows milked per day generally determines the tlpe of milking facilities that a farm
has and the level of mechanizationpossible.Stanchion
bams are the most popular tlpe of milking facility on
dairies milking lessthan 30 cows (Figure 3). On larger
dairies (60 to 200 cows milked/day) herringbone parlors are the most popular qpe of facility. About 64"Aof
Kentuclcydairies use some type of parlor. Dairies using
parlors are more likely to have qpaceheating and feeding loads.
Usesof Electricity
on Kentuclsy Dairies
Water Heating, Milking and Milk Coollng
The J largest end us€sof electricity on dairyfarms
are the water heater, the vacuum pump and the bulk
tank compressor.Ninety-four percent of Kentucky
dairies use electricity to heat water. A t'?ical dairy of
any size has only one piece of equipment for each of
these end uses.Table 2 lists equipment sizesfor these 3
usesaccording to dairy size.The maximum sizesshown
for the \racuumpump and the bulk tank compressor
motors indicate that some of the small dairies have
oversizedequipment, wtrich can increasethe dairt's
operating costs.One of the first stq)s to more efficient
electricity use is to make sure that all equipment is
properly sized.
Water Heating Systems - for water heating srystems
in particular, some areasof potential imporvement in
efficiency exist in Kentucky dairies, since:
o OnIy 3.7o/oruseadd-on heat exchangersto recover
milk heat from the bulk tank;
. Only 1,6"/ousepartial in-line milk cooling (that is,
well water precoolers);
. Only I5/" of the water heatershaveadditional
insulationon the outside;
. Only 9.6"/oof the farms have insulated hot water
pipes.
A significant amount of electrical energ'ycould be
savedby adding insulation to the water heating system's
components on all dairies and by installing a precooler
or heat recoyery systemon the larger dairies.
Tablc 2.-Sizes of Water Heaters, Vacuum
Pumps and BuIk Tank Compressors on
Kentucklt Dafu'les
Arg. No. of Cows Milked/Day
EquipmentType
WAITRHEATER
Typical
Maximum
Minimum
vAcuuMPUMP
Typical
Maximum
Minimum
BULKTAI\K
COMPRESSOR
Tlpical
Maximum
Minimum
5to29
3o to 59
60 to 200
4o-5Ogal
80
20
50-80gal
120
30
50-80gd
r20
30
3hp
5hp
t0
1.5
7hp
l0
2
r5
5hp
10
r5
2
r.5
2
r5
0.5
4rrp
7lrp
Space Heating
Time-of-Day Usage
About 77"/"of the dairies in Kentucky haveheated
milking padors arrd/or milk rooms. Very few dairies
(2"/o) provide heat in calf housing. Figure 4 shows the
importance of the larious tlpes of energy used for
spaceheating on dairyfarms. Almost half of the space
heatersuse kerosene.Slightly less than one third of the
heatersare electric.
Daily pattems of electrical usageon a 48 cow
Kentucky dairy are presented for a typical winter day in
Figure 6. The two daily peaksare tJ4picalof any size
dairy. This particular dairy milks in the moming from 6
to 9 a.m.and in the evening from 5 to 8 p.m. Therefore
the moming peak (9:00) lagsthe milking period and
the eveningpeak (6:30 p.m.) occurswhile the cows are
being milked. The morning peak is generally larger
becausecows normallygive more milk in the moming.
The figure shows that the water heater and the vacuum
pump require the most electrical energy.
Grain Drying and Feed Grinding
Fansused in grain drying systemscan use a lot of
electricity during the fall. However, only 15%of the
dairies in Kentucky dry grain on the farm. On those that
do dry grain, natural air and low-temperature dryers are
the most popular. The primary heat source is LP gas.
About 69"/"of the farmers dry lessthan 9,000 bu of
corn/year. Most dairy farmers either store ear com in
cribs (54/") or buy a largeportion of the grain usedfor
feed(55'/"). This suggeststhat more dairiesuse electricity for grain handling than drying.
The majority (74/.) of the farmsthat milk 30 cows
or more grind feed on the farm. Only 15%of the feed
grinders are electric. All others are tractor PTO driven,
ELECTFIICITY
GAS 20.5%
frATt-tAL
GAS 2.6%
Seasonal Variation
of Electrtc Energy Usage
The variation of totd monthly electrical usageon a
typicd 40 cow dairy is illustrated in Figure 7. The
difference between the total usagein the winter and
srunmer is largely becausewater heating and milk
cooling energy requirements depend on the weather.
Figure 8 breaksdown energy usageon a 40 cow dairy
forJanuary andJuly. The energy required for water
heatingon a typical dairy decreasesfrom 1,043krWhto
472kVh (45'A) asthe averagemonthly temperature
increasesfrom 33' F (January)to 79" F (July). The total
amount of energy used for milk cooling more than
doublesasthe averagemonthly temperaturevariesover
the samerange.
Annual Electric Usage
KEROSETE
46,9%
Figure 4.-Tlpes of energy used for qpaceheating on
Kentucky dairies.
Other Uses of Electricity
Dairy farms also use electricity for lighting, water
pumping, automatic feeding, feed handling, automatic
washersand manure handling. All dairies havelighting
but only 2.6%haveelectric powered manurehandling
systems.Figure 5 shows the percentage of dairy farms
in each size classthat use electriciW for larious farm
tasks.Evidently, larger dairies use eiectricity in a more
diverseway.
The total annual electrical energy usage for a
typical40 cow dairy is estimated to be 23,640 klWh.
Table 3 shows the annual usage by load t1pe. The
largest end use of electricity on Kentucky dairies is the
water heater. The combined requirements of the water
heater, vacuum pump, and the refrigeration s:ystem
account for 86o/"of the typical Kentucky dairy's total
annual electric energy usage. Table 3 also gives annual
electric energy usagespef cow milked for each load
qpe and the whole dairy. The total energy requirements of a particular dairy can be estimated by
multiplying these values by the average number of cows
milked per day.
Tabl.e3.-Anrual UsageBy Load
Type on a Tpical Kentucklt Dairy
Usageper
Cow Milked
(kVh/cow)
Patterns of Electrical
Energy Usageon Dairies *
The amount of electricity used on a dalry farm
variesby seasonaswell asby time of day.
' The metered load studyprovided information about the annual
electrical energy usageon a qpical Kentucky dairy for the whole
dairy, water heater, bulk tank and racuum pump.
Water Heater
Vacuum Pump
Bulk Tank
Other Loads
Whole Dairy
218.7
r77.3
rt2.3
82.7
591.0 kwh/cow
Tlpical 4O
CowDairy
(kwh)
8,747(37"/')
7,092(3O%)
4,492(19"/.)
(t4"/")
3,3LO
23.640 kwh
Values calculated based on methods given by Chastain et al. 1987
-. 9 0
-bq
Eo
5TO29
(L
50 TO 59
3ro
5ro
ffiso
oU''
60 TO 200
40
E.o
Lzo
tr10
oO
AUTOMATIC
FEEDING
SILO
UNLOADER
WATER
PUMP
AUTOMATIC
WASHER
Figure 5.-Distribution of qpes of electrically powered equipment with respect to the averagenumber of cows
milked per day.
MERCERCOUNTYDAIRY
E
=
+
wHoLEO tRY
+
WA'TER
HANER
+
-+-
VACUUM
PUMP
2500
BUI.XTANK
=
I
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Lrl
zo
zzoo
a
:) 2100
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T I M E( h r )
Figure 6.-Time-of-day electrical energF usage on a.48
cow dairy for a tlpicd winter day.
1700
3P=q=33:EEeE
Figure 7.-Seasonal variation of the averagemontlly
electrical energyusageon a qpical 40 cow Kentucky
dairyin 1986.
I
uar.n-nRv
v,tt-w
zgoF
330F
WATER F€ATER
VACtl
,l PtJi/P
BLN-K TAN?<
OTI€R LOADS
o
200
4o0
600
600
'rooo
120c
MONTF.I-YENERGYUSAGEKWh)
Figure 8.-Comparison of monthly electrical energy
usageby load tJpe on a typical 40 cow dairy forJanuary
andJuly 1986.
Summary
The tlpical Kentucky dairy:
milks 40 cows/day,produces44lb/cow/day of grade
A milh raisesreplacements,has a totd herd size of
82to84 cattle and milks cows in apador;
a has one watef heater, \rracuum
pump and bulk tank;
a useselectricity for heating watef;
a usesmore electricity for water heating than any
other single use of electricity;
e could savea significant irmount of energy by insulating the water heater and hot water pipes;
. should consider adding a precooler or heat recovery
systemto further reduce the cost of water heating, if
milking 50 cows or more
Other information about increasingthe efficiencry
of energy use on dairies will be provided in the following CooperativeExtension Servicepublications
(available in the future):
o Improving Ffficiency of Dairy water Heating $stems
o Milk Heat Recoveryand Precooler S)xstems
o SelectingEnergyFfficient Electric Motors for the
Farm
o EnergyEfficient Lighting for Agricultural Buildings.
APPEI\IDD(
In 1986 and,1987 the Agricultural Engineering
Department conducted a study of electrical energy
usageon Kentucky dairies in confunction vrith East
Kentucky Power Cooperative.The study had 2 pertst a
metered load study of severaldairies and a comprehensivemail survey.
The mail surveywas conducted in the qpring of
1987. Its purpose was to get information about:
. dairy size and production levels,
. types of milking facilities,
o size and distribution of major electrical equipment,
r distribution of smaller end usesof electricity.
A total of 194 dairy farmers pafticipated in the survey.
Theserespondentsrqrresented 4.2",6of the dairy
farmers in Kentucky that had a license to sell either
grade A or manufacturing grade milk as of December
1986.
The metered load study involved installing equipment to monitor electrical energy usagepattems on
severalKentucky dairy farms. The monitoring equipment was placed on these farms beginning inJanuary of
1986 and removedafter December 1986.The whole
dairy (or parlor) energy usagepattems were monitored
on 5 dairies ranging from 34 to 100 cows milked per
day. On one of these farms (a 48 cow dairy) the water
heater, bulk tank and rracuumpump were also monitored sqrarately. Other water heaters,bulk tanks and
vacuumpumps were monitored on 2 additional dairies.
None of the measurementsincluded the house or any
other farm electrical loads.
The results of this study are being used asa basis
for additional publications and researchprojects concemed with increasingdairyfarming profits through
the efficient use of electricity.
Acknowledgements
'$(re
are grateful to the EastKentucky Power
Cooperativeand its member coop€rativesfor their
rraluableassistancein obtaining and analyzingthe data
for the metered load study, and the more than 200
Kentucky dairyfarmers who participated in the meter
study or the mail srryey.
This project was iointly funded by EastlGntucky
Power Cooperativeand the University of Kentucky.
References
Chastain,J.P.,
Turner, LV., Enoch,H., Murphy,lV.E.,
Colliver, D.G. 1987.Arulysh of Electrical Energt
Usageand Loads on Kmtucky Dairies. 1SAJ,
Technical paper no. 87-3519,American Societyof
Agricultural Engineers,St.Joseph,MI 49085-9659.
Turner, L.W.,Chastain,J.P.,
Colliver,D.G.,Murphy, \trfl.E.,
Ross,IJ., and $7hite,G.M. 1987.Load Managunmt
andLoad Building Opportunities on KentuckJ,
Fanns. Agricultural EngineeringDqrartment,
University of Kentuclry, I€xington, l{Y 40546-0075.
ThecoiegeofAg|icultureisanEqUalopportunityoranizationwithrespecttoeducationdndemploymentandauthoizationtoprovldersearch,aducationalin
sericesonlytoindividuatsandinstitutionsthatfunctionwithoUtregardtonce,coloLnationalofigin,sex,religion,ageandhandicap.tnquiriesrega
TitlevllofthecivilRightsActof1w'TitlelxoftheEducationalAmendmentg,section501ofthaR6habilitationActandotherr6latedmattershouldbedircte
Offi@, Coltege of Agriculture, Unive8ity of Kentucky, Room S-105, Agricultural Science Building-North, Lexington, Kentucky 40546.
|ssuedinfurtheranceolcoopera1iveExten3ionwork,Actso'May8andJune30,1914,incooperationwiththeU.s.DepartmentofAgricu|ture,c.oranLi|o,D
Extension Service, University of Kentucky College of Agriculture, Lexington, and Kentucky Slate University, Frankfort.
Issued 5{9,5M