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K Hartman & Ralph E H SimsCentre for Energy Research, Massey University, Palmerston [email protected]@dews.co.nz
Dairy Insight Project II:On Farm Energy Savings
Why Peak Reduction?
$10,000/MWh
$10/kWh
$1/hd
3.85 million head
100w/hd
385 MW peak
The Big Question
How can I save energy?
2 sides of the “savings” coin: Conserve energy Reduce costs
Finding the Answer
Where is energy used on the farm How much am I using Where can I conserve energy How can I reduce energy costs Case studies Almost there… What if…
Further assistance
Where is Energy Used on the Farm
Proportion of energy inputs on the average farm surveyed
Barrie, 2005
y = 0.2668x + 43.991
R2 = 0.8736
0
100
200
300
400
500
600
700
0 500 1000 1500 2000 2500
number of head
kW
h/d
ay
Overall
<350
350-700
Large
Linear(Overall)
Survey Results – kWh/day vs # head
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0 500 1000 1500 2000 2500
number of head
kW
h/h
d/d
ay
Overall
<350
350-700
Large
Power(Overall)
Survey Results – kWh/hd/day vs # head
Comparison (kWh/hd/day)Massey Forest Fitz Waipawa Forest-
Head 450 550 220 800 550Type Rotary Herring Herring Herring Herring
vacuum 0.22 0.16 0.08 0.11 0.16chilling 0.16 0.13 0.12 0.19 0.13water heat 0.18 0.25 0.13 0.07 0.13Misc 0.15 0.13 0.29 0.24 0.13Total 0.71 0.66 0.62 0.61 0.54
vacuum 31% 24% 13% 18% 29%chill 23% 19% 19% 31% 23%w.h 25% 37% 21% 11% 23%Misc 21% 20% 47% 39% 24%
How much am I using
Meridian Energy Calculators Full Model
Mailed out to customers, CD based Intensive
Mini-CalculatorOn-line version (
www.meridianenergy.co.nz)Simple Model (3-5 minutes)
WWW.Meridianenergy.co.nz/yourfarm
Where can I conserve energy
Major loads Milking Machine (vacuum pump) Milk Chilling Water Heating Irrigation (not on all farms)
Miscellaneous Water and effluent pumping Lighting Other minor loads (is the kettle major or
minor?)
Vacuum Pump (non variable speed)
Constant load Fully loaded – entire milking & cleaning
Size proportionate to # of clusters More clusters - larger the load
Vacuum brakes provide reserve capacity Not doing useful work - 0% efficiency
Milk Chilling
Two parts Initial cooling of the milk Maintaining milk temperature <4 °C
(10%)
Pre-cooling Plate heat exchanger (35 – 20 °C) Dependant on cooling water
temperature Bore vs surface water
Water Heating
Electric (resistive) heating Batch or Continuous heat Initial and Maintenance heat (15%)
Centralized thermal power plant Fuel – electricity – heat Can be less than 18% efficient at point of use
3.5x the primary fuel use than if made onsite 4x more heat wasted at power plant than developed at point of use
Water Heating (B.V)
285
295
305
315
325
335
345
355
365
0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 4:00
Time of Day
Te
mp
era
ture
(K
)
HW1
T in
T out
T tank
Element
Water Heating (A.V.)
285
295
305
315
325
335
345
355
365
0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 4:00
Time of day
Te
mp
ert
ure
(K
)
HW1
T in
T out
T tank
Element
Irrigation / Pumping / Other
Individual farm dependant Age/type/condition of pump Pumping head (static vs dynamic)
Saving water saves energy
Other loads Lighting (Natural vs artificial)
Incandescent Light bulb ~2% efficient fuel to light
How can I reduce energy costs
Reduce usage Waste heat recovery – preheat water to cylinder Additional milk pre-cooling (1 °C ~ 6% cooling
load) Variable speed vacuum pump / pully size Reduce vacuum demand ? (10/20/70)
Load Shifting / Peak Reduction $/month per kW peak use charge (?) Energy Storage (Hot Water, Ice Banks)
Rate schedules Day / Night / Controlled Rates Fixed daily charges (higher daily = lower per unit)
Case Study – Almost there… Smaller farm – 220 head 20 bail herringbone Day / Night rate (night = 1/3 day rate) Timers on water heaters (batch w/pre-
heat) Ice bank
Used for morning and afternoon milking Pre-cools milk to 4 °C into the vat
Low vacuum demand (~4 kW) Short milk and vacuum runs
Enclosed milk vat, uninsulated
Cumulative Energy Use (kWh)
Cumm Energy Use (kWh)
0
2
4
6
8
10
12
0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00
Vat Htr Wash Htr Ice Bank Chiller Vac Pump Total
Case Study – What if…
Mid-sized farm – 550 head 2x 20 bail herringbone pits Anytime / Controlled rate 15 kW vacuum demand 2 hot washes per day Uncovered, insulated milk vat 15 psi artesian bore 27 kW for effluent stir / pumping
Total energy use (before)
0
5
10
15
20
25
30
35
40
45
5023
:00
1:00
3:00
5:00
7:00
9:00
11:0
0
13:0
0
15:0
0
17:0
0
19:0
0
21:0
0
23:0
0
VacuumChillerHWMiscVacuumChillerHWTotalTotal
25% 75%
Hot Water (before)
0
2
4
6
8
10
12
14
1623
:00
1:00
3:00
5:00
7:00
9:00
11:0
0
13:0
0
15:0
0
17:0
0
19:0
0
21:0
0
23:0
0
VacuumChillerHWMiscVacuumChillerHW
System Wash
Vat Wash
Hot Water (after)
0
2
4
6
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10
12
14
1623
:00
1:00
3:00
5:00
7:00
9:00
11:0
0
13:0
0
15:0
0
17:0
0
19:0
0
21:0
0
23:0
0
VacuumChillerHWMiscVacuumChillerHW
Milk Chiller (before)
0
2
4
6
8
10
12
14
1623
:00
1:00
3:00
5:00
7:00
9:00
11:0
0
13:0
0
15:0
0
17:0
0
19:0
0
21:0
0
23:0
0
VacuumChillerHWMiscVacuumChillerHW
Milk Chilling (after)
0
2
4
6
8
10
12
14
1623
:00
1:00
3:00
5:00
7:00
9:00
11:0
0
13:0
0
15:0
0
17:0
0
19:0
0
21:0
0
23:0
0
VacuumChillerHWMiscVacuumChillerHW
Vacuum Pump (before)
0
2
4
6
8
10
12
14
1623
:00
1:00
3:00
5:00
7:00
9:00
11:0
0
13:0
0
15:0
0
17:0
0
19:0
0
21:0
0
23:0
0
VacuumChillerHWMiscVacuumChillerHW
Vacuum Pump (after)
0
2
4
6
8
10
12
14
1623
:00
1:00
3:00
5:00
7:00
9:00
11:0
0
13:0
0
15:0
0
17:0
0
19:0
0
21:0
0
23:0
0
VacuumChillerHWMiscVacuumChillerHW
Total System (after)
0
5
10
15
20
25
30
3523
:00
1:00
3:00
5:00
7:00
9:00
11:0
0
13:0
0
15:0
0
17:0
0
19:0
0
21:0
0
23:0
0
VacuumChillerHWMiscTotal
55% 45%30% 70%Overall 33% energy savings Overall 50% cost savings
Further Assistance
Dairy Insight Phase II Identify energy saving techniques and
technologies Demonstrate on-farm examples Getting the word out
Process-specific information sheets Water Heating Milk Cooling Milking Machine Tractor Fuel Use (revisiting Tractor Facts from
80’s) Lighting / Other
VERSION: 1
DATE: March 2006
ENERGY SAVINGS IN DAIRY SHEDS THE HOT WATER TANK
(40% OF TOTAL DAIRY SHED ELECTRICITY USE)
CCAASSEE SSTTUUDDYY
566 cows, 2 hot washes of 367 litres water per day, uninsulated hot water tank, heating to 85.4 oC, air temperature: 10 oC, total electricity consumption: 91,078 kWh/yr, electricity price: 12.01 c/kWh.
Annual Cost of Electricity for Hot Water Tank: $ 4,375
SSOOUURRCCEE:: 22000044 SSUURRVVEEYY OOFF 6644 FFAARRMMSS
BBEESSTT PPRRAACCTTIICCEE DDEETTAAIILLSS IINNFFOORRMMAATTIIOONN
Insulation Material: Thermowrap, service life: 10 years
Cost: $ 169 for a 400 litre tank
Additional costs: None
Annual Cost of Electricity for Heating Water: Without insulation: $ 4,375 With insulation: $ 2,511
INSULATE THE HOT WATER
TANK
Annual savings from using insulation: $ 1,695
(Payback time on insulation: less than 2 months)
Supplied by: DTS
Phone: 0800-500-387
Address: National
Website: www.dts.co.nz
Installation: DIY (easy)
COST SAVING: 39% of hot water electricity cost
Hager 24 hour timer, service life: 10 years
Cost of timer: $ 170 (excluding installation)
Annual Cost of Electricity for Heating Water: Without timer (24 hours): $ 2,511
With one wash and heater on for 7 hours: $ 1,212
Additional Information
Use a hot wash after the morning milking and a cold wash after the evening milking. There is no change in the amount of detergent used in the wash, whether it is a hot wash or a cold wash.
The same timer with a contactor costs about $ 250 with additional costs if an electrician does the installation.
USE ONE HOT WASH PER DAY WITH A TIMER
TO HEAT FROM 1.00 a.m. TO 8.00
a.m.
Annual savings from using timer: $ 1,129
(Payback on timer: 2 months)
Supplied by: Julian’s Electrical
Phone: 0800-102-464
Address: National
Website: www.julians.co.nz
Installation: DIY (if familiar with electrical circuit) or use an electrician.
COST SAVING: 26% of hot water electricity cost
Review
Big ticket items – in the shed Water Heating Milk Cooling Milking Machine (vacuum pump)
Fast payback Batch hot water vs constant feed Day / Night rates Timers – Lighting / Hot Water Minimize water use
Future TechnologiesOn-site co-generation (biofueled?)
Wind/Hydro/PV/solar thermal
Waste-to-energy (AD) systems
Enhanced thermal storage
The Matrix
