How Dairy Farms Use Energy

How Dairy Farms Use Energy

A Summary of Electrical End Uses

Major Energy use Functions on a Dairy Farm

• Milk Harvest*

• Milk Cooling*

• Lighting*

• Air Circulation* and Ventilation

• Washing and Water Heating*

• Feed Handling

• Manure Handling

• Water Pumping

• Compressed Air*Indicates uses where significant

energy savings is possible

WHERE IS ELECTRICITY USED ON DAIRY FARMS?

Summary of electric energy use on a typical dairy farm

Manure handling5%

Feeding equipment3%

Lighting17%

Ventilation24%

Electric water heating5%

Miscellaneous2%

Milk cooling26%

Milking18%

Source: NATC, Ithaca, NY

Freestall vs. Tie Stall Operations

• Freestall operations • Tie stall operations

Manure Handling

4%Feeding Equipment

1%

Ventilation22%

Lighting26%

Misc.1%

Vacuum Pumps17%

Milk Cooling27%

Electrical Water Heating

2%

Milk Cooling23%

Electrical Water Heating

10%Lighting

17%

Ventilation21%

Misc.1%

Vacuum Pumps

18%

Feeding Equipment

7%

Manure Handling

3%

What are EUIs?

• Energy Utilization Indices refer to the amount of energy used to accomplish a certain activity or process.

• EUIs for dairy farms are stated in one of two ways:

• kWh/cow/year• kWh/cwt. milk shipped

Average EUIs for Dairy Farms

• Summary of EUIs from DLtech audits

Tiestall Freestall Total Barn Barn All Farms

Farm - kWh/cow-yr. 934 811 865 Range (542 - 1561) (424 - 1736)

Vacuum Pump - 72 54 62 kWh/cow-yr-milking Range (33 - 116) (12 - 149)

Milk cooling - kWh/CWT 0.92 0.75 0.824 Range (0.435 - 1.8) (0.40 - 1.4)

What are ECMs?

• Energy Conservation Measures refer to equipment or operational measures that will increase efficiency and save energy

Most Common ECMs for Dairy Farms

• Variable speed drive vacuum pump

• Plate milk precooler

• Energy efficient lighting

• Refrigeration heat recovery

Dairy Hot Water Needs

Rule of thumb: 2 – 2.5 gal hot water per cow per day

“Hot” water means temperatures from 160 to 170° F.

High temperatures are required for proper sanitation and equipment wash

How is Water heated?

• Smaller dairies (75 cows and under) often have electric water heaters

• Propane water heaters are common

• Larger dairies often have oil-fired water heaters or boilers to produce high volumes of hot water quickly

Reducing Energy Use for Water Heating

It takes about 872 BTUs to heat a gallon of water from 55°F to 160°F

• That yields four gallons of hot water per kWh of input energy

• Repair dripping hot water faucets– One drop per second adds up to gallons of

lost hot water every day

Refrigeration Heat Recovery

On average, a heat recovery system will save from $200 to $1,100 per year depending on the level of milk production and daily hot water requirements

If you have an existing heat recovery system, isit still functioning properly?They wear out, too!

Typical EUIs for Milk Cooling Systems

Milk cooling system EUI, kWh/cwt cooled

Conventional 1.2 – 0.8

Well water precooler 0.9 – 0.6

Well water precooler with VFD on receiver pump 0.7 – 0.4

Low Cost Refrigeration Maintenance

• Keep your condenser well ventilated with cool air

• Keep air-cooled condensers clean

• Repair all refrigerant leaks

• For every 10-degree rise in ambient air temperature, cooling capacity is reduced 6%

• Dirt on condenser reduces air flow volume and decreases heat transfer

• Check refrigerant sight glass often. There should be no bubbles

Pre-cool your milk Before it Reaches the Bulk Tank

• Can reduce the milk temperature by as much as 20 degrees

• Can reduce cooling costs by as much as 30% or 0.3 kWh/cwt.

• Adding a VSD to the milk pump will enhance pre-cooler savings

• Pre-cooling can improve milk quality

Well Water Pre-cooler

• Example of a well water pre-cooler

Product O ut

S in g le P a ssWater O ut

Product In

Water In

Remote Outdoor Condensers

Scroll Compressors Use Less energy

• Replacing an old, worn hermetically seal reciprocating compressor with a new scroll compressor can reduce milk cooling costs by 20%

Fix Air Leaks in Compressed Air Systems

• Air leaks in compressed air systems waste a lot of energy.

• Poor system maintenance can reduce air compressor system efficiency by 20% to 30%

• Annual cost of compressed air leaks

(Source: Compressed Air Challenge – Fact Sheet #7, April 1998)

Let’s Take a Break!!

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10 minutes

Save Energy withHigh Efficiency Lighting

• Lighting represents 17% of dairy farm electric energy use, on average

• Incandescent lights are still used extensively on many dairy farms.

• High efficiency lighting systems can help dairy farmers save energy dollars

• Compact fluorescent• Fluorescent• High Intensity Discharge (Metal Halide, High

Pressure Sodium)

Take a Serious Look at Your Lighting

• Are you still using incandescent lamps in the barn?

• Consider an economical switch to compact fluorescent and save up to 70%

Installation Incandescent

Lights Compact

Fluorescent Flourescent

Fixture 100 Watt 30 Watt 4' - 2 tube, T-8 # of lamps 30 30 20 Total Lighting Load 3kW 0.9 kW 1.44 kW Hours per day 8 8 8 kWh/day 24 7.2 11.52 kWh/yr 8,760 2,628 4,205 Energy Cost/yr $1,051 $315 $505 Bulb Replacement Cost/yr $144 $204 $70 cost/yr Total Annual Operating Cost $1,195 $519 $575 Annual Savings ---- $676 $620 Installed Cost existing $240 $1,900 Simple Payback ---- 0.36 yrs 3.1 yrs Good Investment? no yes yes

Lighting Savings Potential

What About Livestock Fountains?

• Heated livestock fountains are nearly a necessity in northern climates

How Can You Save Energy?

• Try to locate fountains in a sheltered area out of the wind

• Carefully size fountains to the number of cattle using them– It is difficult to keep water above freezing if

cattle seldom drink– When cattle drink from a fountain, the

replacement water is usually warmer than the thermostat setting

Understanding Water Fountain Heat Loss

• Most heat is lost from the water surface

Water Fountain Energy Savings

• Consider covered water bowls to conserve heat in the fountain

• Consider energy free water fountains– Highly insulated– Water bowl covers– Must be sized to number– of animals drinking

Always Check Temp. Setting• Keep thermostat setting no higher than 40 to 45

degrees F.

• You don’t want to be constantly heating the groundwater (500 F.)

Milk Harvest

• The centerpiece of the milk harvest operation is the vacuum pump.

• The vacuum pump or pumps can consume up to 26% or the total electric energy used on a dairy farm

• Vacuum pumps not controlled by a variable speed drive (VSD) represent an excellent energy savings opportunity

Sliding Vane Rotary Vacuum Pump

Water Ring Vacuum Pump

Rotary Lobe (Blower) Vacuum Pump

Turbine Vacuum Pump

Saving Energy Used for Milking

• First the easy stuff• Check vacuum levels often – vacuum levels that

have changed from the desired value cause system performance changes, efficiency changes, and herd health problems

• Check vacuum pump temperature near the end of milking – a significantly higher temperature than normal indicates that service is required including vacuum adjustment, removal of exhaust restrictions, repair of rotary vane oiling systems, or cleaning lobe blower pumps

More Easy Stuff

• Check vacuum pump motor temperature – high vacuum pump motor temperatures indicate a high motor load perhaps caused by a vacuum pump problem or a problem with the supply voltage to the motor

• Check variable speed drive operation – if vacuum pump motor is running too fast, too slow or erratically, check for problems with the variable speed drive system or the milking system such as

» Air leaks in milking system» Loose pump belts» Malfunctioning pulsators» Variable speed drive vacuum sensor fouled

Check Air Leaks in Vacuum System

• A 5 cfm air leak in your milking system could cost you $150 per year in reduced milking system efficiency!

Adjustable Speed Drives on Vacuum Pump

Adjustable speed drives on vacuum pumps can save 50% or more of the energy used for milking.

• If you milk more than 4 hours per day, an adjustable Speed Drive might be a good investment

• ASDs also reduce wear on the vacuum pump and reduce pump noise for better operator comfort

Saving Energy with Adjustable Speed Drives on Vacuum Pumps

• Typical energy use for operating vacuum pumps on dairy farms (without ASDs) range from 70 – 100 kWh/cow-year

• An Adjustable Speed Drive on the vacuum pump can reduce the energy use by as much as 60%, resulting in use as low as 25 to 50 kWh/cow-yr

Savings Potential with VSD Vacuum Pump

• System   Without VSD With VSD•      

• Pump Size 10 hp 10 hp• Hours/day 12 hrs 12 hrs• Average load (kW) 9 kW 4.5 kW• Energy/Day 108 kWh 54 kWh• Annual Energy Cost $4,730 $2,365 • (@ 12¢/kWh)      • Annual Savings ----  $2,365 • Cost of VSD ----    $4,100 • Simple payback ----    1.75 yr• Source: NATC

ASD on a Sliding Vane Rotary Vacuum Pump

What if you adopt all these ECMs on your Dairy Farm?

• You could save as much as $3600.00 per year in electric energy costs.

• Energy conservation pays!

Now Richard will TalkAbout Ventilation