Presentation on theme: "Lighting Systems and Energy Efficiency on Dairy Farms November 14, 2013 for MILK LAIT 2020, Moncton, NB, Canada John P. Chastain, Ph.D. Professor and Extension."— Presentation transcript:
Lighting Systems and Energy Efficiency on Dairy Farms November 14, 2013 for MILK LAIT 2020, Moncton, NB, Canada John P. Chastain, Ph.D. Professor and Extension Agricultural Engineer School of Agricultural, Forest, and Environmental Sciences
Electrical Energy Use on Dairy Farms Old study (1987) on 5 freestall dairies in Kentucky: 502 to 699 kWh/cow/yr. (34 to 100 cows, 63 avg) New study (2005) in New York (Ludington & Peterson): 1. 14, Tie-stall dairies: 542 to 1561 kWh/cow/yr (42 to 140 cows. 77 avg) 2. 18, Freestall dairies: 424 to 1,736 kWh/cow/yr. (65 to 860 cows, 244 avg).
So based on these data we can conclude that on the average… Old FreestallNew FreestallTie-stall 596 kWh/cow/yr811 kWh/cow/yr934 kWh/cow/yr 1. In 1987 dairy farms were more energy efficient than in 2005. 2. Tie-stall barns are at a significant disadvantage since they use more electricity per cow. 3. Energy cost are more important now than ever.
Really? What am I forgetting? Old FreestallNew FreestallTie-stall 596 kWh/cow/yr811 kWh/cow/yr934 kWh/cow/yr 1. In 1987 dairy arms were more energy efficient than in 2005. 2. Tiestall barns are at a significant disadvantage since they use more electricity per cow. 3. Energy cost are more important now than ever.
Average Electricity Use Based on Milk Production Old FreestallNew FreestallTie-stall 63 cows244 cows77 cows 14,073 lb/cow24,897 lb/cow20,582 lb/cow 63.95 hL/cow113.14 hL/cow93.53 hL/cow 596 kWh/cow/yr811 kWh/cow/yr934 kWh/cow/yr 4.24 kWh/cwt3.26 kWh/cwt4.54 kWh/cwt 9.32 kWh/hL7.17 kWh/hL9.99 kWh/hL Electrical use per amount of milk produced is a better indicator of efficiency than electrical use per cow.
Breakdown of electrical energy used has changed. 1987 Freestall 2005 Freestall 2005 Tie-stall Water Heating31.5%2.1%10.3% Milk Cooling17.8%26.0%23.2% Vacuum Pump24.3%17.1%18.0% Other26.4%54.8%48.5% Total Dairy100.0% 1. Water heating is more efficient. 2. New uses of electricity has caused the other to double.
Breakdown of electrical energy use from New York audits (Ludington and Peterson, 2005) Tie-stallFreestall Water Heating10.3%2.1% Milk Cooling23.2%26.0% Vacuum Pump18.0%17.1% Lighting16.6%26.0% Ventilation20.9%21.8% Feeding7.2%1.4% Manure Handling2.7%4.4% Miscellaneous1.0%1.2%
Water Heating – Heating Efficiency Electric is most efficient at 100%. Gas and oil is about 80%. Heat is lost in flue gases. Condensing type reclaim flue gas heat and can have heating efficiencies as high as 95% ($). Electric is more efficient, but fuel cost is important. Oil or gas may cost less. LP ($/gal) = Electric Price ($/kWh) x 21.096 10 cents/kWh = $2.21/gal LP = $0.58/L LP
Water Heating – Standby losses can be over 50% of energy use. Replacing a water heater? Buy the most efficient one possible. Tank insulation reduces standby losses. More insulation the better. Electric water heaters are easiest to insulate and have standby losses of 0.5% to 1% per hour or 12% to 24% per day. Typical gas or oil heater standby loss is 2.5%/hr or 60% per day. Insulate hot water pipes to reduce standby losses.
Water Heating – Only use what is needed. Fix water leaks. Consider having your pipeline washing system adjusted to reduce the amount of water needed to wash the milking system. Are milk lines too large? Correct sizing saves water and energy. Pre-rinse water only needs to be 100° to 110°F (38 to 43 C). Too high can cause deposition of milk solids. Use cold or tepid water for the acid rinse.
Water Heating – Use waste heat to your advantage. Milk must be cooled from 95°F (35 C) to 40°F (4 C). Most dairy refrigeration systems dump heat to the air. A refrigeration heat recovery unit (RHR) is a heat exchanger & tank that is designed to capture the waste heat from milk cooling to pre-heat water before it enters the water heater. Can save as much as 50% of the energy needed for water heating. Payback often highest for electric WH. Use water directly from the RHR tank when hot water is not needed.
Milk Cooling – Maintenance saves money. Keep area around condenser ventilated with cool air and in the shade if possible. Cooling capacity is reduced by 6°F (3 C) for every 10°F (6 C) increase in air temperature. Dirty air-cooled condensers are less efficient. Make cleaning a part of your routine. Repair refrigerant leaks – no bubbles in the sight glass.
Outdoor Condenser Better airflow than indoors. Would be better if shade was provided in summer. Easy to clean. I like a shed that can be closed in winter and opened in summer in cold climates. Can use heat for milkroom in winter.
Milk Cooling – Type of compressor makes a difference. Most compressors are of the reciprocating type Scroll compressors have less moving parts and are more energy efficient. Replacement of an old hermetically sealed reciprocating compressor with a scroll compressor can save 15% to 20% in milk cooling. Slightly more expensive.($525 CAD)
Milk Cooling – Advanced Systems ($) More efficient but may not be cost effective for small herd sizes. Shell and tube water-cooled condenser common. Two-stage instant cooling can cool milk to 38°F (3 C) before entering the tank. Photo courtesy of DeLaval
Milk Cooling – Refrigeration Heat Recovery (RHR) A RHR unit will capture waste heat to reduce water heating costs, and will improve milk cooling efficiency for an air cooled compressor. Increases the effective heat exchanger area in condenser. May not be as beneficial when used with an efficient well water pre-cooler. Less heat needs to be removed by refrigeration system.
Milk Cooling – Precoolers are often the easiest to implement. Heat exchanger that uses well water to cool the milk before it reaches the bulk tank. Can reduce milk temperature by 20°F (11C) to 40°F (22C). Can reduce milk cooling costs by 30% to 60%. Can improve milk quality. Improper matching of milk and water flow rates is greatest problem. May need a surge tank for low water flow systems.
Effect of Precooling on Energy Use System DescriptionMeasured kWh/cwt Air-cooled, reciprocating1.0 (0.8 to 1.2) Addition of well water pre- cooler 0.75 (0.6 to 0.9) Average Measured Savings =25% Source: Ludington and Peterson, 2005 Adding a VFD to the receiver pump can drop average use to 0.55 kWh/cwt and provide a savings of 45%. ($)
What to do with the water from the precooler? Dont waste it! Cows drink about 3 times as much water as they give in milk. Cows like to drink tepid water. One of the best uses of precooler water is to use it to supply waterers. Helps to keep waterers in cold barns from freezing in winter. May need an insulated storage tank in some cases.
Milking System – Proper sizing saves energy. Many older vacuum pumps were sized based on more is better. Research has shown 3 cfm per milking unit plus a 35 cfm base capacity for up to 32 units is typically adequate to prevent falloff problems. May be able to reduce pump speed or a new pump may be in order.
Saving Energy Used for Milking Maintain belt tension and condition to save energy. Check vacuum levels. If they are not at the desired level system efficiency and udder health may be compromised. Check vacuum pump motor temperature. High temperature indicates motor overload and can be an indication of motor or voltage problems.
Variable Frequency Drive (VFD) on Vacuum Pump Changes motor speed by variation of electrical frequency. Maintains efficiency at lower speeds. Reduces noise – good for cows & people. Can save 50% in electrical costs. Milk 8 hours / day? Typically a good payback. Milk 6 hours / day? Check the benefits. Payback is often too long on smaller dairies.
Savings Potential with VFD Vacuum Pump (Source: NATC) Without VFDWith VFD Pump Size10 hp Milking hours/day12 Average load (kW)9 kW4.5 kW Energy Use108 kWh/day54 kWh/day Annual Cost ($0.10/kWh)$3,942/yr$1,971/yr Annual Savings$1,971/yr VFD Cost$4,100 Simple payback2.08 years
Use of Fans for Ventilation and Mixing has Increased. Ventilation provides air exchange. Mixing improves air velocities past animals during hot weather and helps with heat stress. Air velocities in the range of 400 to 600 fpm (2 to 3 m/s) help.
So what do we look for in an energy efficient fan?
What we do not look for… Number of fan blades Fan diameter - exclusively Cool looking fan housing Metal versus plastic
The fan must be designed for use in agricultural buildings, and it must be a rated for air flow and efficiency at the required pressure drop.
Fan test data for a particular fan can be obtained on line from… Bioenvironmental and Structural Systems Laboratory University of Illinois Department of Agricultural and Biological Engineering 332 Agricultural Engineering Sciences Building 1304 W. Pennsylvania Avenue Urbana, Illinois 61801 Ph. 217-333-9406 Fax 217-244-0323 http://www.bess.uiuc.edu/
Need some definitions Airflow is measured in cfm – cubic feet per minute. Static pressure drop (ΔP) is a measure of how hard a fan is loaded. It is measured in inches of water using a manometer. The amount of power the fan motor requires is measured in Watts (W). Fan efficiency is determined by dividing airflow by power or cfm / W.
The high efficiency fan moves 20% more air at 0.05 and 0.10 inches of water.
The high efficiency fan is 32% to 33% more energy efficient.
Select energy efficient fans at 0.10 inches of water in most cases. Fan DiameterEfficiency range Minimum to be high efficiency @ 0.10 24 inch8.7 to 19.4 cfm/W 11.9 cfm/W 36 inch12.7 to 23.7 cfm/W 16.2 cfm/W 48 inch13.5 to 27.0 cfm/W 17.6 cfm/W Sources: ASABE EP566 and A3784-6, UW Extension
Butterfly Shutters seem to provide the least air flow restriction and maintenance problems. From Chore-Time web site.
We also need to consider how well the fan will move air if we have a strong head wind. The engineers at the BESS lab provide an air flow ratio (AFR). The AFR is the air flow at 0.20 inches of ΔP divided by the air flow at 0.05 inches of ΔP. Air flow ratio is a measure of the steepness of the fan curve. The higher the better. Minimum airflow ratio is 0.7
Select efficient fans that… Provide the required amount of air flow at 0.10 inches of water. Have a minimum air flow ratio of 0.7 to make sure adequate ventilation is provided during windy conditions. Select the highest cfm/W using these criteria.
Retrofit Ventilation System for a 103-Cow Tie-stall Barn in Minnesota Replaced old fans and improved inlets Overall ventilation efficiency was increased from 14 to 18.6 cfm/W Efficiency was increased by 33% Payback for efficient fans can range from 1.2 to 3 years.
New mechanical ventilation in 100-cow barn in Minnesota corrected air quality problems in winter. Carbon DioxideAmmonia Old System5000 ppm25 ppm TARGET3000 ppm15 ppm New System250015 ppm Outside temperature was -20°F or -28 C.
High-Volume, Low-Speed (HVLS) Fans Are More Efficient Than Basket Fans
Comparison of Mixing Fans to HVLS in Freestall Barns 315 ft (96 m) freestall barns requires 6, 24 ft (7.3 m) diameter HVLS fans @ 1.65 kW/fan Total load for HVLS = 9.9 kW Same building would need 30, 36 basket fans. @ 0.57 kW/fan (See BESS web site.) Total load for basket fans = 17.1 kW HVLS will save 42% in energy cost for same operating hours.
Fan Maintenance Is Important A study by Janni et al. (2005) has shown that the actual airflow delivered by a fan can be 20% to 50% lower than the BESS fan test data if the fan is dirty, shutters do not work properly, or the belts are loose. Janni, K.A., L.D. Jacobson, R.E. Nicolai, B. Hetchler, and V. J. Johnson. 2005. Airflow reduction of large belt-driven exhaust ventilation fans with shutters and loose belts. In Livestock Environment VII, Proc. of the 7th International Symposium, ASABE.
Lighting Proper lighting is needed for worker and animal safety Can increase worker productivity 8 to 13% (office work) Can improve quality of work (20% reduction in defects) Photoperiod control can improve milk production by about 5 lb/cow-day or 2.2 L/cow-day
Need the right amount and quality of light based on tasks Parlor pit – 50 fc (540 lux = lumen/m 2 ) Parlor stalls & return lanes – 20 fc (216 lux) Holding area – 10 fc (108 lux) General lighting in barn – 20 fc (216 lux) Minimum amount needed for photoperiod control – 10 fc (108 lux) Need CRI of 80+ in places like the parlor and office. Uniformity also important in parlor and animal handling areas (spacing/mounting height, 0.87 – 2.0).
Compact Fluorescent Vs. Incandescent Energy savings is about 70%. Lamp use = 8 hr/day: payback period is about 0.36 yr. Lamp use = 2 hr/day: payback period is about 1.5 yr. Problem with CFLs is they tend to burn out early if turned off and on. CFLs contain mercury, a hazardous waste.
T8 Tube Fluorescent Vs. Incandescent Energy savings is about 52%. Ballast increases use. Lamp use = 8 hr/day: payback period is about 3.1 yr. Lamp use = 2 hr/day: payback period is about 12 yr. More reliable lamp life than CFL. Burned out lamps also a hazardous waste.
T8 Fluorescent Lamps Reduce Energy Use Compared to T12 by 29% to 35%.
Recommendations for low-bay & office applications Eliminate incandescent lamps Use CFLs for simple lamp swaps. Use T8 tube fluorescents if a complete system retrofit is needed.(T5s dont seem to last.) LED lighting will overtake CFLs in the near future similar efficiency, longer life, non-hazardous waste, dimmable, good cold temperature starting. Price of 40W to 60W replacement LEDs have decreased to $10 - $12. Lamps appear to meet typical life of 25,000 hr
Energy Efficient Options for High-Bay Applications – Freestall Barns, Parlors High Pressure Sodium Metal Halide Best lighting uniformity provided using bulbs in the range of 150W to 250W. 400W may work at mounting heights of 20 ft (6 m) or more.
Low-bay HPS is in the range of 10 to 12 ft. (3.05 to 3.66 m) Fixtures are available Need to use 100W to 150W lamps. Promotes better uniformity. If designed correctly energy use is the same.
LED High Bay VS. 250W HPS 250W HPSLED High Bay Fixture + Lamp $280$290 Rated Life24,000 hrs100,000 hr ? Lumens25,200 avg.11,200 Lumens/W10077 1. 2.25 LED fixtures will be needed to equal one HPS. 2. So the longer life of LED cost twice as much and is 30% less efficient.
Winter Day Length is not Optimal for Dairy Cows in Northern Latitudes. Can you get some free quota with this in the fall?
Supplemental Lighting Needed to Provide 16 hours/day if Natural Light Can be Used.
Tie-Stall Barn: Provided 10 fc with 32W T8 Fluorescent Lamps Spaced 12 ft (3.66m). Controlled with timer to provide 16 hr/day.
Supplemental Lighting in Tie-Stall Barns Yields a 6% to 8% increase in Milk Production Increase in milk production paid for lighting over mangers, control timer, and additional feed cost in 4 months assuming with an 8% increase in milk (6% increase in DM). If milk production increased by only 4% the payback was still 267 days. Tie-stall dairies can implement this relatively easily. Does not include cost of additional quota.
Supplemental Lighting in Freestall Barns Using HPS – can use MH or LED in future. Control lights with timer and photocell. Open ridge provides natural light during the day. 8% increase in milk provided a payback in 2 months. 4% increase in milk provided a payback in 124 days No quota cost included.
Conclusions Efficient water heating is common. Many are using precoolers. Use the water. Opportunities to save energy in milking and cooling. Use efficient ventilation Use efficient mixing fans to reduce heat stress. Efficient lighting is needed and photoperiod control could provide an opportunity ($). Reduce the cost of making purchased quota.