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Dairy Farm Energy Efficiency


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Dairy Farm Energy Efficiency

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Dairy Farm Energy Efficiency

  1. 1. Dairy Farm Energy Ef f iciency A Publication of ATTRA—National Sustainable Agriculture Information Service • 1-800-346-9140 • www.attra.ncat.orgBy Andy Pressman Rising energy costs and environmental concerns are causing dairy farmers to alter their managementNCAT Agriculture practices. Dairy farmers are analyzing their energy inputs and investing in cost-effective energySpecialist conservation and energy efficiency measures. This publication provides an overview of how dairy© 2010 NCAT farms can implement efficiency improvements and energy-saving technologies that can reduce energy consumption and energy-related costs.ContentsIntroduction ..................... 1Milking process ............... 2Milk cooling systems .... 3Heating water .................. 5Lighting ............................. 6Ventilation ........................ 9Farm energy audits ..... 11Financial incentives ..... 11Summary ......................... 12References ...................... 13Further resources ......... 13 Dairy farms use vast amounts of energy to harvest milk. Photo coutesy of The Lands at Hillside Farms. Introduction Energy efficiency is often an inexpensive, quick and simple way to save money. This publication focuses on dairy equipment D airy farms today face challenges upgrades, new technologies and management and opportunities fueled by rap- practices for reducing energy consumption. idly rising energy costs and con- Opportunities for cost savings and improved cerns about environmental impacts. Dairy processes include the implementation of:ATTRA—National Sustainable farms use more energy than almost anyAgriculture Information Service variable speed drives for milk vacuum pumps( is managed other agricultural operation. Energy is used and milk transfer systems, plate precoolers,by the National Center for Appro-priate Technology (NCAT) and is in the milking process, and for cooling and heat recovery systems, energy-efficient lightfunded under a grant from the storing milk, heating water, lighting and fixtures and efficient ventilation systems.United States Department ofAgriculture’s Rural Business- ventilation. Determining the best energy Information on energy audits, financial incen-Cooperative Service. Visit the efficiency and energy management opportu- tives and further resources is included. TheNCAT Web site ( for nities for dairy farms will help reduce energy opportunities presented in this publicationmore information onour sustainable agri- costs, enhance environmental quality and were developed for cow dairies but may beculture projects. increase productivity and profitability. applicable to goat and sheep dairies as well.
  2. 2. Vacuum pumps The vacuum pump operates during the milk harvest and equipment washing and can consume 20 percent to 25 percent of all electrical energy use on a dairy farm. The vacuum pump creates negative air pressure that draws milk from the cow and assists in the milk flow from the milk receiver to either the bulk tank or the receiver bowl. The airflow also sends water and cleaning agents through the milking system during the washing process. There are four main types of vacuum pumps: sliding vane rotary pumps, water- ring pumps, rotary lobe (blower) pumps and turbine pumps. Each of these operates and uses energy differently. Vacuum pumps become less efficient as the vacuum level increases (Ludington et al., 2004). Milking process Therefore, operating the vacuum pump at The milking process consists of harvesting lower vacuum levels conserves energy.Related ATTRA milk from the dairy cow and transporting thePublications Sizing the vacuum pump to meet the needs milk to a bulk tank for storage. This processFarm Energy can take place one or two or more times per of the milking and washing system canCalculators day and most dairies schedule their lactations reduce capital costs for equipment, reduceConserving Fuel on for a continuous milk supply throughout the energy operating costs during the life cyclethe Farm year. On average, milking utilizes 18 percent of the pump and ensure that the pump is of the electrical energy use on a dairy farm performing properly. The size of the vacuumRenewable Energy (Peterson, 2008). pump is dependent on all of the componentsOpportunities onthe FarmEf f icient AgriculturalBuildings:An OverviewDairy Productionon Pasture:An Introduction toGrass-Based andSeasonal Dairying The vacuum pump operates during milking and equipment washing and is often the primary electrical energy user. Photo by Andy Pressman.Page 2 ATTRA Dairy Farm Energy Ef f iciency
  3. 3. in the system that admit air during opera- pump near the end of each milking is ation. Pumps are generally sized by account- good way to detect problems with the pumping for the amount of air admitted into the or electrical load. High motor temperaturesmilking system during the milk harvest plus may indicate the need for a vacuum adjust-a 50 percent reserve to account for acciden- ment, removal of exhaust restrictions, repairtal air admittance and the wear and tear of of rotary vane oiling systems or cleaningparts (MMMC, 1993). Outdated indus- lobe blower pumps. Changes in the speedtry standards used to recommend oversized of the vacuum pump can be caused by airvacuum pumps in part because of an incor- leaks in the milking system, degraded drainrect belief that additional vacuum capacity is seals, loose pump belts, malfunctioning pul-necessary for washing. An oversized vacuum sators or a malfunctioning VSD vacuumpump may overheat as the pump ends its cycle. sensor. A 5-cubic-foot-per-minute air leak inThe current industry performance stan- the vacuum system can amount to over $100dard, ASAE Standard S518.2 Feb03, Milk-ing Machine Installations, provides current in wasted electrical costs (Peterson, 2008).sizing guidelines for dairy vacuum pumps Problems associated with vacuum pumps(Ludington et al., 2004). can be avoided by regularly checking vac- uum levels and the operation of the VSD. E nergyVariable-speed drives operatingA variable-speed drive (VSD), also referred Milk cooling systems costs of ato as an adjustable-speed drive or variable- Cooling milk accounts for most of the elec- vacuum systemfrequency drive, is an energy-efficient tech- trical energy consumption on a dairy farm. with a VSD can benology used for controlling the vacuum level Milk is harvested from a cow at around 95 reduced by up toon sliding-vane rotary pumps and rotary- to 99 degrees Fahrenheit (F). To maintainlobe pumps. Traditional vacuum systems 60 percent. high milk quality, including low bacteriarun at maximum speed only, and rely on a counts, the raw milk temperature needs tovacuum regulator to vent excess air that is be lowered quickly to around 38 degrees.not being used during milking or washing Refrigeration systems consist of a bulk tank,operations. A VSD adjusts the speed of the a motor-driven compressor unit, an evapora-pump motor to meet the vacuum demand so tor and a condenser unit. The system oper-that equal amounts of air are being removed ates by pumping a refrigeration coolant in aby the vacuum pump and entering the milk- cycle that gives off heat as it condenses. Heating system. By eliminating the amount of air exchangers cooled by well water, variable-that would be admitted through a regulator, speed drives on the milk pump, refrigerationthe motor uses less horsepower during most heat recovery units and scroll compressorsof the milking process. A VSD on a vacuum are all energy conservation technologies thatpump eliminates the need for a conven-tional regulator because less energy is deliv- can reduce the energy consumed in the cool-ered to the motor and its operating speeds ing system.are reduced. Energy operating costs of a vac- There are two types of milk coolinguum system with a VSD can be reduced by systems used on dairy farms. A direct-up to 60 percent (Ludington et al., 2004). expansion cooling system cools the milkIn addition, lowering the vacuum pump’s directly in the bulk tank by using evapora-RPMs can extend its life as there will be less tor plates that expand in the lower portionwear and maintenance costs. of the tank. Indirect, or instant, cooling systems rely on heat exchangers to precoolVacuum pump maintenance the milk before it enters the bulk tank. AFollowing the manufacturer’s maintenance precooling heat exchanger can lower milkschedule, along with routine maintenance on temperatures as much as 40 degrees, resultingall vacuum pump systems, can save energy. in refrigeration energy reductions of aboutChecking the temperature of the vacuum 60 percent (Sanford, 2003b) ATTRA Page 3
  4. 4. Heat exchangers the milk travels through multiple circuits and the coolant flows through a single pass, Heat exchangers used for precooling raw or circuit. Farms that milk for long periods milk transfer the heat from the milk to of time can use heat exchangers that are an intermediate cooling fluid, such as well designed for two coolants. The use of two water or a water-glycol solution, by having different cooling fluids, such as first precooling the milk and coolant flow in concurrent or with well water and then with chilled water counterflow configurations. In a concurrent or a glycol-water solution, can cool the milk flow configuration, the milk and coolant as it is harvested. flow in the same direction. The fluids flow in opposite directions in a counterflow pat- tern. Counterflow systems allow for lower Precooler energy savings milk temperatures. The amount of cooling Installing a properly sized precooler can reduce that takes place depends on the flow of the refrigeration energy consumption by about 60 milk in relation to the flow of the coolant, in percent (Sanford, 2003b). A properly sized addition to the heat transfer area, the num- well water heat exchanger can reduce milk ber of times the milk passes through the temperatures to within 5 to 10 degrees of the coolant and the temperature of the coolant. groundwater temperature. Higher efficiencyI nstalling a properly sized for precooling can be achieved with a 1-1 ratio Well-water heat exchangers have been imple- of coolant to milk flow and by using the larg- precooler can mented in precooling systems for more than est water lines possible in order to maximizereduce refrigeration 20 years and can reduce cooling costs by the coolant flow. Other factors that determineenergy consumption 0.2 to 0.3 kWh/cwt (hundred weight of the energy and economic savings of a precooler milk) (Ludington et al., 2004). There areby about 60 percent. include herd size, number and size of compres- two types of heat exchangers used for pre- sors, type of coolant used and the age of the cooling: shell-and-tube heat exchangers and bulk tank. An added benefit of using water plate heat exchangers. Shell-and-tube heat for precooling is that it can afterwards be used exchangers consist of a single small tube or for livestock drinking water. Cows depend multiple small tubes inside of a larger tube. on drinking water to produce milk and The milk flows through the smaller tube(s) prefer warm water to cold. The warm water while the well water flows through the larger can also be used to perform other tasks, such tube. Plate heat exchangers are made up of as washing and heating. a series of metal plates that are located side by side. Milk and well water run in oppo- site flow channels and the well water absorbs Variable-speed milk pumps the heat from the milk on the opposite side As previously stated, a vacuum is required of each plate. Plate heat exchangers are rel- to harvest milk. The milk, however, can- atively small in size and, unlike shell-and- not transfer from a pipeline that is under tube heat exchangers, additional plates can a vacuum to a bulk tank that is at normal be added to increase capacity. atmospheric pressure. To compensate for the difference in pressure, milk can flow into a Heat exchangers are designed so that the receiver bowl that triggers a milk transfer milk and coolant make single or multiple pump to push the milk from the receiver passes between the plates or tubes. In a sin- bowl either through a heat exchanger or gle-pass heat exchanger, a circuit is arranged directly into the bulk tank. Another option so that the two fluids are in contact as they that eliminates the receiver bowl and milk go through separate sets of plates or tubes transfer pump requires putting the bulk before exiting the heat exchanger. Multi- tank under a vacuum by placing rubber seals ple-pass heat exchangers route the milk and on the bulk tank covers. coolant flow through two or more circuits, putting the milk channels in contact with A variable-speed milk transfer pump the coolant channels for longer periods of can further reduce energy use by slow- time. A heat exchanger can be designed so ing the flow rate of milk through the heatPage 4 ATTRA Dairy Farm Energy Ef f iciency
  5. 5. exchanger. A lower and more continuousmilk flow rate through the heat exchangerincreases the coolant-to-milk ratio andresults in greater milk cooling. Milk can becooled by an additional 15 to 20 degreesby installing a variable-speed milk transferpump (Sanford, 2004c).Refrigeration heat recovery unitsRefrigeration heat recovery units (RHR)capture the waste refrigeration heat fromthe condenser to preheat water before it istransferred to a water heater. An RHR unitcan recover 20 to 60 percent of the energythat is required to cool milk for storage(Sanford, 2004b). Depending on the num-ber of cows being milked, the RHR storage A well water precooler (far right) cuts compressor use by using groundwater totank should be sized to provide enough hot pre-cool the milk. Photo by Andy Pressman.water for one milking. Th is includes hotwater for washing the milking system and needed to remove heat from the milk andfor washing the bulk tank. The payback for may, in fact, increase overall energy costs.purchasing an RHR unit depends on thesavings from heating water and will vary Compressorsgreatly from farm to farm. The function of a compressor is to compress the cold, low-pressure refrigerant gas fromTypes of refrigeration heat the evaporator to a high-pressure, high-tem-recovery units perature state for condensing. The threeThere are two types of RHR units: desu- types of refrigeration compressors used forperheating and fully condensing units. A milk cooling on dairy farms are the recip-desuperheating unit operates only when rocating, scroll and discus. The reciprocat-the refrigeration system operates and pro- ing compressor is the most common and canduces water temperatures around 95 to 115 be either open type, hermetic or accessibledegrees (Ludington et al., 2004). These units hermetic. The scroll and discus compressorscan be inexpensive to add, but only part of are newer and more efficient than recipro-the available heat can be transferred to the cating compressors. Research has shown thatwater. Nearly all of the available refrigeration replacing a failed reciprocating compressorheat is recovered as hot water from a fully with a new scroll compressor can reducecondensing unit, with temperatures reaching milk cooling costs by 20 percent because120 to 140 degrees (Ludington et al., 2004). of a reduction in the electrical demandThis type of RHR unit meets the require- (Ludington et al., 2004).ments of the cooling system by using a valveto control the flow of cold water through Heating waterthe heat exchanger. Once the storage tank Hot water is essential for producing high-qual-is full, excess warm water can continue to ity milk on dairy farms and is primarily usedbe used and not wasted. A fully condens- for cleaning milking systems. The amount ofing RHR unit replaces the need for a regular hot water required varies from farm to farmcondenser in the refrigeration system and is and depends on the size of the milking herdbest integrated as part of a new or replace- and the type and size of the milking system.ment refrigeration system. If nearly all of the On average, a minimum of 4 gallons of waterenergy captured by the RHR unit is used at 170 degrees are required for each milkingfor preheating water, then a precooler is not unit (Ludington et al., 2004). Hot water ATTRA Page 5
  6. 6. generally produced by water heaters that use in certified organic production and process- either fuel oil, natural or propane gas, solar ing (National Organic Program) but some energy or electricity. For some dairy farms, may be permitted for use on organic dair- heating water can account for about 25 ies (USDA, 2000). Check with your organic percent of the total energy used on the farm certifier to see if they have any restrictions (Sanford, 2003a). for use of dairy acid sanitizers. Types of water heaters Electric control devices and There are several ways to reduce the amount peak demands of energy used for heating water. Whether Using a control device for electric water heat- using a direct or indirect water heater, overall ers can reduce electricity use during periods efficiency is determined by the combustion of expected increases in demand above the efficiency of the fuel source and the amount average supply level, also known as peak of heat loss from the storage tank, known demand. Time clocks provide a simple and as standby loss. A direct water heater com- cost-effective way to control water heaters. bines the water storage tank and the heat- Shifting electrical loads to off-peak or low ing element. The storage tank in an indirectO n average, demand hours and off-peak utility rates not water heater contains a heat exchanger that only ensures farmers of having hot water at lighting is connected to a separate boiler unit. Insu- a reasonable cost, but also benefits the util- represents lating the storage tank and connecting pipes ity provider by allowing direct control of the17 percent of total can reduce standby losses for both types of energy demand on their system. Many util-dairy farm electrical water heaters. The sides and top of an elec- ity companies offer incentive rates or rebatesenergy use. tric water heater and the sides of gas and oil to encourage farmers to participate in elec- water heaters can be insulated. tric water heater control programs. Not all utility companies offer off-peak utility rates, Water temperatures so it is best to check with local service pro- Proper water temperatures are essential for viders to see if off-peak rates are available. cleaning milking equipment. Using warm or cold water when possible can help reduce Lighting energy costs. A warm-water pre-rinse, about Appropriate lighting can improve productiv- 95 to 110 degrees, does not cause the milk ity and safety on a dairy farm. On average, to stick to the equipment, which is a prob- lighting represents 17 percent of total dairy lem with cold water. Additionally, a warm farm electrical energy use (Peterson, 2008). water rinse does not cause mineral and pro- Optimal lighting conditions may increase tein deposits in the pipeline, as is often the milk productivity and conserve energy con- case when using hot water. The wash cycle sumption. Factors that contribute to increased requires water temperatures between 120 milk production include the type of light, and 170 degrees. Dairy farms require the the amount of light provided per watt, the use of commercial water heaters since resi- temperature of the work area, the height of the dential electric water heaters are thermostati- ceilings and the length of the lighting period. cally controlled not to go above 140 degrees because of federal safety regulations. The Lighting requirements on a dairy farm can thermostat range for commercial water heat- be divided into three categories. The first ers is 100 to 180 degrees. A cold acid rinse category is visually intensive task lighting, will control mineral and bacterial buildup which requires the highest lighting levels in the milk lines and will help conserve hot (Ludington et al., 2004). Areas that bene- water. There are many types of dairy acid fit from this type of lighting include milk- sanitizers and each one may have differ- ing parlors; equipment washing, equipment ent rinse instructions. Most of these sani- maintenance and repair areas; offices; mater- tizers are not listed on the National List of nity and veterinary treatment areas; and Allowed and Prohibited Substances for use utility rooms. The second category includesPage 6 ATTRA Dairy Farm Energy Ef f iciency
  7. 7. lighting for holding areas, feeding areas, Fluorescent lightsanimal sorting and observation and gen- Fluorescent lights are made of a frame, ballast,eral cleanup. These areas and tasks require light socket and the lamp(s). Ballasts providehigh to moderate lighting levels. Finally, low the needed voltage, current and waveform forto moderate lighting levels are adequate for starting and operating fluorescent and high-general lighting for livestock resting areas, intensity discharge lamps. The lamps are avail-passageway lighting, general room lighting able in many different lengths and diameters,and indoor and outdoor security lighting. shapes, color temperature ratings and mini- mum operating temperature ranges. FluorescentLamp types lamps range in length from 6 to 96 inches long. The diameter of the lamp is expressed in eighthsThere are three types of lighting systems of an inch and lamps come in the followingused on dairy farms: incandescent lamps, diameters: T-5, T-6, T-8, T-9, T-10, T-12, andfluorescent lamps and high-intensity dis- T-17. A T-12 lamp is 12/8 inch, or 1.5 inches,charge lamps. in diameter, while a T-8 is 8/8 inch, or 1 inch in diameter (Sanford, 2004a).Incandescent lamps Fluorescent lamps are linear (straight),Incandescent lamps are common on many circular or U-shaped. The color temperaturedairy farms, although today they are consid- index, or CCT, refers to the color appearanceered to be an inefficient light source. Their of the light emitted by a lamp (Sanford,light output is only 10 percent, with the 2004a). It is indicated in degrees Kelvin (K).remaining 90 percent of energy given off as Lower temperature values produce a red orheat (Hiatt, 2008). orange color and refer to a warm emittedLamp Type Comparison ChartAdapted from Sanford, 2004a and U.S. Department of Energy Efficiency (Lumens/ Correlated Color Lamp Type Color Lighting Tasks Watt)* Temperature (CCT)(K) Incandescent 5-20 White 2800 General Milking parlor, milk room, holding area, Fluorescent (T-8 and 30-110 Bluish to White 2700-6500 office, equipment T-12) washing maternity/ veterinary area Compact Fluorescent 45-72 White 2700-6500 General Mercury Vapor 25-60 Bluish 3200-7000 Outdoor Milking parlor, holding area, milk room, equip- Metal Halide 41-115 Bluish 3700 ment washing, mater- nity/veterinary area, outdoor Milking parlor, hold- High Pressure Sodium 50-140 Yellow-Orange 2100 ing area, feeding area, outdoor Low Pressure Sodium 60-150 Yellow Outdoor* Efficiency defined as the ratio of light produced (lumens) to energy consumed (watts) ATTRA Page 7
  8. 8. light. Higher temperature values produce High-intensity discharge lights a blue, or cool, light source. The CCT val- High intensity discharge (HID) lamps are a ues for fluorescent lamps range from 3,000 very bright and efficient light source. HID to 5,000 degrees K, while the average CCT lamps often require a warm-up period and value of an incandescent lamp is around generate light by heating a gas mixture in the 2,800 degrees K. Minimum operating tem- lamp. HID lamps must be mounted high in peratures for fluorescent lamps are between order to spread the light and to avoid a glare. –20 and 50 degrees Fahrenheit, depending Some HID fixtures can be equipped with a on whether the ballast is electromagnetic or diff user that distributes the light horizon- the more energy-efficient electric type. tally. The four common types of HID lights The most common type of fluorescent lamp are mercury vapor, metal halide, high-pres- is the T-12. However, smaller diameter lamps sure sodium and low-pressure sodium. provide more light for a watt of power. Com- pared to a T-12 lamp and ballast, the T-8 Mercury vapor lamps fluorescent lamp provides about 15 percent Mercury vapor lamps emit a favorable blue- more light, or lumens, and the ballasts are 40 white color that mimics daylight. However, percent more efficient (Sanford, 2004a). The mercury vapor lamps are the least efficient ofA 100-watt most energy-efficient fluorescent lamp is the the HID lamps, emitting only 32 lumens for high- a watt. In addition, their disposal poses an T-5, but that lamp tends to produce too much pressure heat in an enclosed fixture. Enclosing fixtures environmental risk due to the mercury gas.sodium lamp can in agriculture lighting systems protects theprovide 2.5 times housing from corrosion and protects the lamp Metal halide lamps from dust, humidity and manure gases, all of Metal halide HID lamps provide the bestmore light than a which can shorten the life of a lamp. color of all the HID lamps and emit about 60100-watt mercury lumens a watt, making them twice as efficientvapor lamp while Compact fluorescent lamps as a mercury vapor lamp. A newer pulse-startusing significantly A compact fluorescent lamp (CFL) uses lamp technology is available for metal halideless energy. about 75 percent less energy, measured in lamps. The pulse-start system can extend watts, for the same amount of light as an lamp life by half over the standard metal incandescent bulb. CFLs are directly inter- halide lamp, provide about 8 percent more changeable with incandescent lamps, so lumens per watt and allow for faster warm- changing a 60-watt incandescent lamp to a ups and restarts (Sanford, 2004a). Pulse-start 20-watt CFL cuts energy use by one third. metal halide lamps use a different type of bal- CFLs also last six to 10 times longer than last and are not interchangeable with standard incandescent light sources (Sanford, 2004a). metal halide lamps. CFLs can be used outdoors, but should be covered to protect the lamps from all weather High- and low-pressure sodium lamps conditions. Low temperatures, both indoors Slightly more efficient than metal halide and outdoors, may reduce light levels. In lamps are high- and low-pressure sodium order to reach full output at cooler tempera- lamps. High-pressure sodium lamps tures, CFLs require a warm-up period. emit about 95 lumens a watt and give off an orange light. A 100-watt high-pres- sure sodium lamp can provide 2.5 times Factors affecting lamp life more light than a 100-watt mercury vapor Several factors can shorten the life of a lamp. These include: lamp while using significantly less energy. • Level of manure gases High-pressure sodium lamps are often • Humidity used for mixed outdoor and indoor light- • Dust ing applications. Low-pressure sodium • Frequent switching on and off lamps are the most efficient HID light source, but produce a poor color of light.Page 8 ATTRA Dairy Farm Energy Ef f iciency
  9. 9. Low-pressure sodium lamps are often used for fresh air that is cooleroutdoor security lighting. and drier into the barn, mixes and circu-Lighting ef f iciency measures lates it, and exhausts and dilutes moisture,Replacing inefficient light sources with an dust, manure gasesappropriate and higher-efficiency light can and odors, and air-result in better task lighting with energy sav- borne contaminates.ings that continue over the life of the lamp.Energy conservation opportunities involve Cows that are exposedchanging incandescent lamps to compact to fresh air are lessfluorescents, upgrading to smaller diame- likely to develop heatter and more efficient fluorescent lamps and stress, respiratory ail-upgrading to HID lighting. Since lighting ments, mastitis, repro-fixtures distribute light in different patterns, ductive problems andthe barn layout and use should be considered other diseases thatin any lighting decision. could decrease milk production. ManyEnergy savings can be achieved by using dairy producers aresimple and inexpensive technologies that realizing the inher-go beyond lamp replacement. Some tech- ent benefits of a grass-nologies incorporate programmable logic ba sed produc t ion Circulation fansAndy improve air movment inside a barn. Photo by help Pressman.controllers and other computer-based system. Grass-basedcontrol systems and include timers, dusk- dairies utilize an ecological approach toto-dawn photo controllers, half-night health care by relying on natural immunitycontrollers and motion detectors. New and that comes with pasture access. For moremore efficient technologies are continually information on grass-based dairying, seebeing developed. the ATTRA publication Dairy Production on Pasture: An Introduction to Grass-BasedLong-day lighting and Seasonal Dairying. According to experts,Long-day lighting is a new development for heat stress in dairy cows begins when sur-dairy farms that involves increasing milk pro- rounding temperatures exceed 65 degreesduction by extending the day length with arti- and the relative humidity is 40 percent orficial light. According to researchers, dairy cows higher (Ludington et al., 2004). Maintain-are day-length sensitive and can be stimulated ing a healthy atmosphere by controllingto increase milk production by providing 16 mold, spores, dust and other irritants also helps reduce the chances of milk contamination andto 18 hours of uninterrupted lighting followed lowers health risks to the farmers. Good venti-by 6 to 8 hours of darkness (Sanford, 2004a). lation also reduces building deterioration dueBy implementing an efficient long-day lighting to excess moisture, which can cause rot, mil-system, milk production can be increased by dew and electrical problems.5 to 16 percent. Types of ventilationVentilation There are two types of ventilation: naturalProper ventilation is needed in dairy barns and mechanical. Natural ventilation usesthroughout the year to help maintain animal the least amount of energy and requireshealth and productivity, the barn’s structural the exchange of air, the ability to controlintegrity, milk quality and a comfortable ventilation rates, flexibility to provide thework environment for the laborers. The air cows a comfortable environment through-inside a barn becomes warm and humid as out the year and good barn constructioncows continuously produce heat and mois- (Wood Gay, 2002). Barns that are in theture. An efficient ventilation system brings path of prevailing winds and designed ATTRA Page 9
  10. 10. adjustable side and end walls can take advan- Circulation fans tage of breezes and thermal buoyancy and Circulation fans are mounted inside build- minimize unexpected air exchanges. ings to help improve air movement and to Mechanically ventilated barns require air reduce dead air spots. There are different inlets and exhaust fans opposite one another. types of circulation fans, all of which have Exhaust fans are powered by an electric propeller blades attached directly to a motor motor and contain hoods, protective screens or to a motor-and-belt drive system. and louvers or shutters. Each fan targets a Two common types of circulator fans used certain area to provide uniform control of in dairy housing systems are box fans and moisture and gases (Peterson, 2008). Ven- tilation fans used in livestock buildings are high-volume low-speed fans (HVLS). Box- typically axial flow fans, which are designed type fans generally operate at moderate to to let air pass straight through the fan par- high levels of efficiency, depending on the allel to the fan blade drive shaft (Arnold fan diameter, with the larger diameters being and Veenhuizen, 1994). Traditional ventila- more efficient (Sanford, 2004d). tion systems are designed with air inlets and HVLS fans are large-diameter circulation exhaust fans placed on opposite ends of a fans with diameters ranging from 8 to 24A properly building, whereas air inlets and exhaust fans feet. One 24-foot HVLS fan can move the designed in a cross-ventilation system are located on same amount of air as six 48-inch high-speed and sized opposite sides of a building. box fans and can save up to 3.3 kilowattsventilation fan in an hour of operation (Sanford, 2004d).system should Fan selection HVLS fans save energy by replacing exist- A properly designed and sized ventilation ing circulation fans that are not efficient.provide the required In addition, HVLS fans tend to be quiet, fan system should provide the requiredamounts of amounts of ventilation needed to maintain reduce moisture in buildings and reduce flyventilation needed a comfortable environment for the cows and bird populations in maintain a and the laborers during each season. Thecomfortable blade size and shape, fan speed in terms of Fan ratingsenvironment for the revolutions per minute (rpm), motor horse- The Air Movement and Control Associa- power and housing design determine how tion International (AMCA) is an indepen-cows and the laborers much air a fan can move. This is known as dent testing laboratory that rates fans onduring each season. fan capacity and is measured cubic feet per their ability to move air. Fans that meet cer- minute (cfm). The size of ventilation system tain AMCA or other reliable testing perfor- needed depends on its capacity to remove mance criteria receive a certified rating seal excess moisture during the milder and of approval. Th is rating can be helpful to colder months of the year while forcing cool select the proper fan for an intended use. For air through the building during the sum- more information on the AMCA, visit their mer to reduce animal heat stress. Exhaust Web site at The Bioenviron- fans range in size from 5 inches in diameter mental and Structural System (BESS) Labo- to 72 inches. Exhaust fan motors may be as ratory provides research, product testing and small as 1/20 horsepower and may exceed education on agricultural fans. Performance more than 50 horsepower (NFEC). test results are available on their Web site at Static pressure is the difference in pressure between inside and outside of a building, ventilation fan or air inlet (Ludington et Ventilation control systems al., 2004). It is measured in inches of water The use of thermostats to control ventila- or inches of mercury. The static pressure tion systems reduces energy consumption by of an efficient exhaust fan should be having the fans operate only when needed. between 0.05 and .125 inches of water and Properly located thermostats should accu- is measured with a manometer. rately reflect the average temperature insidePage 10 ATTRA Dairy Farm Energy Ef f iciency
  11. 11. the building. Mounting a thermostat at least10 feet from a fan and at least 1 foot belowthe ceiling reduces the thermostat’s exposureto adverse factors, such as sunlight and airintake drafts, that can alter the thermo-stat’s temperature reading (Wells, 1990). Allcontrol systems should be located so theycannot be bumped by the livestock.Timer controls and moisture sensors can alsobe used to control ventilation rates. How-ever, the use of these control devices may notsave energy. Timer controls cycle motors onand off to meet set ventilation rates and mayuse more energy to start the motors from theoff mode. Timer controls also create largertemperature swings. Furthermore, moisturesensors have been reported not to workadequately in barns (Wells, 1990). NCAT Energy Engineer Dave Ryan performs a farm energy audit. Photo by Andy Pressman.Ventilation system maintenanceDairy ventilation systems require routine Farm energy auditsmaintenance to keep fans operating at high A farm energy audit is a tool to help agri-performance levels. Poorly maintained fans cultural producers conserve energy and saveand obstruction to air inlets and fan outlets money by implementing energy efficientcan reduce fan efficiency by as much as 40 equipment. The audit collects and analyzesto 50 percent. Cleaning fan parts, lubricating information on farm energy consumptionbearings and other moving parts, checking and its associated costs, and then makesbelt tension and alignment and removing recommendations on ways to reduce them.any obstructions will keep fans performing Farm energy audits also explore ways toat peak efficiency and reduce energy costs. capture renewable energy resources thatLong-term efficiency can be improved by are available on a farm. Dairy operationsrepairing or replacing bent, damaged or are often good candidates for farm energymisaligned fan blades, shutters, guards audits as there are significant opportunitiesand other fan parts. An air velocity meter for dairies to save energy and money throughcan be used to detect reductions in the conservation and efficiency measures.performance of the ventilation system. Farm energy audits can be conducted by aControl systems should be cleaned regularly professional or through do-it-yourself energyand thermostats should be checked yearly efficiency calculators. For more informationfor accuracy by comparing their readings on energy audits and farm energy calculators,against a mercury thermometer. see the ATTRA publication Farm Energy Calculators:Tools for Saving Money on the Farm. Factors that affect the ef f iciency of a livestock ventilation system Financial incentives 1. Ventilation system design There are several federal, state and nonprofit 2. Fan blade type and design grant and incentive programs for imple- 3. Ef f iciency of electric motors to power fans menting energy efficiency and renewable energy systems on dairy farms. For informa- 4. Use of fan control system tion on state and federal incentives, see the 5. Routine maintenance and cleaning Database of State Incentives for Renewables and Efficiency (DSIRE) at ATTRA Page 11
  12. 12. Saving energy at The Lands at Hillside Farms The Lands at Hillside Farms is a historic dairy farm and nonprofit sustainable agriculture edu- cation center located in Shavertown, Penn. The farm’s grass-based milking herd of around 60 cows is made up of Jerseys, Holsteins and Jersey- Holstein crosses. After the cows are milked in a tie-stall barn, the raw milk is collected and pro- cessed on the farm. In 2007, the National Center for Appropriate Technology (NCAT) conducted a farm energy audit at The Lands at Hillside Farms. The study found that most of the energy on the farm is used for pasteurizing and homogenizing raw milk, making dairy products and refrigeration. NCAT also identified several energy conservation opportunities for harvesting milk in the dairy barn. Recommended energy conservation measures with a short payback period included replacing incan- descent lamps with compact fluorescent lamps, insulating the water heater with a blanket, insu- lating hot water piping with foam insulation and using water from the precooler as drinking water for the cows. These energy conservation measures would save about $300 a year in energy costs. Install- ing a variable-speed drive to control the vacuum pump and milk flow through the plate cooler was not recommended because of the high implemen- The Lands at Hillside Farms, Shavertown, Penn. Photo by Andy Pressman. tation costs in relation to the size of the herd. For information on grant and loan guaran- harvesting, milk cooling and storing, ven- tees to assist agriculture producers with pur- tilation and lighting. An energy audit can chasing renewable energy technologies and be a valuable tool to a dairy farmer who energy efficiency improvements, see the is trying to understand how energy is U. S. Department of Agriculture’s Rural currently being used on the farm and Development Business and Cooperative identify cost-saving opportunities. Programs Web site at rbs/farmbill. Acknowledgments Summary Special thanks to Joseph Schultz, with Focus on There are many opportunities for dairy Energy and GDS Associates, Inc., and John Frey, farms to reduce their electrical energy executive director of the Center for Dairy Excel- consumption. Dairy farms can become lence, for providing technical review of this publi- more energy efficient by upgrading older cation. Thanks also to Margo Hale and Dave Ryan equipment, installing new technologies and of NCAT for providing input for the equipment changing management practices for milk and water heating sections of this publication.Page 12 ATTRA Dairy Farm Energy Ef f iciency
  13. 13. ReferencesArnold, Glen and Michael Veenhuizen. 1994. Livestock Publication (A3784-7). Madison, Wisconsin:Housing Ventilation Fan Selection. Ohio State Cooper- University of Wisconsin.ative Extension Factsheet. Columbus, Ohio: The Ohio Sanford, Scott. 2004d. Ventilation and CoolingState University. Systems for Animal Housing. University of Wisconsin -Hiatt, Richard. 2008. Agricultural Lighting. Cooperative Extension Publication (A3784-6).Presentation at the Farm Energy Audit Training for Madison, WI: University of Wisconsin.Field Advisors workshop. Augusta, ME. January. U.S. Department of Agriculture. 2000. 7CFR Part 205Ludington, David, Eric Johnson, James Kowalski, of the National Organic Program. Washington, D.C.:Anne Magem and Richard Peterson. 2004. Dairy Farm USDA Agriculture Marketing Service.Energy Efficiency Guide. Ithaca, NY: DLTech, Inc. U.S. Department of Energy. 2009. “Energy Savers:Milking Machine Manufactures Council (MMMC). Lighting.” Washington, D.C.: Energy Efficiency &1993. Maximizing the Milk Harvest. Chicago, IL: Renewable Energy. Manufactures Institute. Wells, Grant. 1990. Dairy Barn Ventilation: ExhaustNational Food and Energy Council (NFEC). Date Fan Systems. University of Vermont Extension Publication (BR-869). Burlington, VT: University ofUnknown. Controlled Livestock Ventilation. Ag Vermont Extension.technical Brief. Columbia, MO: National Food andEnergy Council. Wood Gay, Susan. 2002. Natural Ventilation for Freestall Dairy Barns. Virginia Cooperative ExtensionNational Organic Program. National List of Allowed Publication. Blacksburg, VA: Virginia Tech.and Prohibited Substances. Sections Further resourcesPeterson, Richard. 2008. Energy Managementfor Dairy Farms. Presentation at the Farm Energy Web sitesAudit Training for Field Advisors workshop. Center for Ecological TechnologyAugusta, ME. January. Organization provides publications and links on energySanford, Scott. 2003a. Heating Water on Dairy Farms. efficient and renewable energy technologies.University of Wisconsin – Cooperative ExtensionPublication (A3784-2). Madison, Wisconsin: Pennsylvania Center for Dairy ExcellenceUniversity of Wisconsin. Organization dedicated to improving the profitability ofSanford, Scott. 2003b. Well Water Precoolers. the dairy industry. Web site provides resources and toolsUniversity of Wisconsin - Cooperative Extension for improving profitability through energy efficiency.Publication (A3784-3). Madison, Wisconsin:University of Wisconsin. DLTech, Inc. Dairy Farm Energy www.dairyfarmenergy.comSanford, Scott. 2004a. Energy Conservation in Information about dairy mechanical systems, theirAgriculture: Energy Efficiency Agricultural Lighting. functions and efficiencies.University of Wisconsin - Cooperative ExtensionPublication (A3784-14). Madison, Wisconsin: EnSaveUniversity of Wisconsin. This commercial site offers technical papers on vari-Sanford, Scott. 2004b. Refrigeration Systems. able speed drives for dairies, efficient fans and lightingUniversity of Wisconsin - Cooperative Extension and other farm energy topics.Publication (A3784-4). Madison, Wisconsin: Milking Machine Manufactures CouncilUniversity of Wisconsin., Scott. 2004c. Variable Speed Milk Pumps. harvest.htmUniversity of Wisconsin - Cooperative Extension Part of the Equipment Manufactures Institute ATTRA Page 13
  14. 14. association that provides resources, research funding Wisconsin’s Focus on Energy information and educational materials that benefit dairy farmers. Link is to Maximizing the Milk Harvest – Wisconsin-based program providing information, A Guide for Milking Systems & Procedures. resources and financial incentives to help implementRural Electricity Resource Council energy efficient and renewable energy projects. tural & Rural Business Programs provides information National clearinghouse and technical support on energy efficiency for agricultural producers. provider on energy efficiency with an emphasis Innovation Center for U.S. Dairy on rural applications. www.USDairy.comThe Dairy Practices Council Industry-wide consortium working to address and opportunities in the dairy industry by promoting Nonprofit organization that publishes approved sustainable business practices. Web site contains infor- educational guidelines for the dairy industry. mation on energy savings opportunities for dairy farms.NotesPage 14 ATTRA Dairy Farm Energy Ef f iciency
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  16. 16. Dairy Farm Energy Ef f iciency By Andy Pressman NCAT Agriculture Specialist © 2010 NCAT Holly Michels, Editor Amy Smith, Production This publication is available on the Web at: or IP355 Slot 354 Version 011410Page 16 ATTRA