SAVNGENERGY. On WA Dairy Farms. DAIRY Saving Energy on WA Dairy Farms 1. Western

Transcription

1 SAVNGENERGY On WA Dairy Farms This project was jointly funded through a collaboration between Dairy Australia, Western Dairy, and Department of Agriculture, Fisheries and Forestry Western DAIRY Saving Energy on WA Dairy Farms 1

2 Foreword The cost of electricity accounts for a significant proportion of a dairy farm s shed cost. Dairy farmers are under pressure from the rising cost of electricity and an increased focus on carbon emissions, with carbon legislation to be introduced in July Real opportunities exist for dairy farmers to better control their energy costs while simultaneously reducing greenhouse gas emissions. Western Dairy actively support dairy farmers in their bid to reduce the energy costs associated with milking. They recently assisted 22 dairy farms to complete a dairy energy use audit. Many of the farmers who took part in these audits are already reaping the benefits of having identified areas for improvement, and have invested in changes to their dairy. The audits found that while no two dairies were the same, milk cooling, milk harvesting and hot water production were the areas of highest energy use. The audits also revealed that while larger herds tend to have economies of scale, similar herd sizes had significant variation in energy costs at the dairy. Similar results have been found in the eastern states. Focussing on ways to reduce energy consumption for milk cooling, harvesting and hot water production provides the greatest gain for improving energy efficiency. 13% HOT WATER 43% MILK COOLING 5% SHED LIGHTS & 9% STOCKWATER 5% FEED 3% CLEANING EFFLUENT & 22% MILK HARVESTING Electricity usage from energy audits of WA dairy farms Dairy Australia has recently acquired $1 million in Federal Government funding aimed at helping dairy farmers use energy more efficiently. This funding will give 45 Western Australian dairy farmers access to complimentary energy audits. Dairy farmers are urged to contact Rob La Grange on or at rob@westerndairy.com.au to register their interest in this program. Western Dairy s aim in producing this publication is to present tips, technologies and ideas for reducing energy use in the dairy. It also provides examples of farmers who have implemented some energy optimising ideas to reduce dairy running costs. It concludes with a checklist that brings together some simple things you can check to ensure your dairy is using energy efficiently. This publication focuses on improvements that are relatively low cost, have short payback periods, and can be implemented in most dairies in WA.

3 Contents 2 Electricity at the Dairy 2 Dairy energy audits 3 Tariffs and energy supplies 4 Negotiating a price 4 Alternative energy retailers 5 Demand response programs 6 Hot Water Systems 6 Solar hot water systems 7 Thermal heat recovery 9 Heat pumps 10 Milk Cooling Systems 10 Plate coolers 11 Cooling towers 13 Improved refrigeration 14 Milk Harvesting 14 Variable speed drives 18 Big Ticket Items 18 Solar power 19 Wind power 19 Green cleaning systems 20 Dairy Energy Savings Checklist 21 References and contacts Saving Energy on WA Dairy Farms 1

4 Electricity at the Dairy Take advantage of off peak power to heat water, mill and mix grain and transfer feed and pump effluent. Finish milking before 8am during the week. Check that off peak timers are set correctly. If you spend more than $10,000 per year on electricity, consider negotiating a contract with Synergy. Consider changing your electricity provider. Dairy Energy Audit The first step to reducing the amount of power you use in the shed is understanding how much you use and what equipment uses the most. There are several on line tools that can help you calculate your dairy energy usage and identify the areas where efficiency gains and savings can be made. CowTime Dairy Energy Monitor Synergy What Wattage? You can check the wattage on motors and multiple the kilowatts (kw) by the run time to calculate the kilowatt hours (kwh) of energy usage. For anything that requires 240V you can measure the energy consumption by using an energy consumption metre. They simply plug into the power point and then you plug the equipment into the metre it turns into a real time power monitor. It tracks the power used and can display the instantaneous voltage or current being drawn as well as the peak levels that have been drawn. Costs start from $30. 2

5 Tariffs and Energy Supplies Tariff and supply arrangements vary from dairy to dairy. The table below illustrates five different supply arrangements available from Synergy, Western Australia s default electricity supplier. Review your power bill and make particular note of the units used during on peak (Mon-Fri 8am-10pm) and off peak (Mon-Fri 10pm-8am and weekends) periods. Tariff Supply Charge ($/day) Arrangement Peak (cents/unit) Off Peak (cents/unit) R1 Business Time of Use R3 Business Time of Use Fifty K1 Home Business Plan (first 20 units/day) ( units/day) L3 Business Plan Fifty First 1650 units/ day P13 Business Time of Use Types of Electricity Meters Electromechanical Dial Meter These meters have four, five or six dials. Digital Display Meter Has a six digit display similar to the odometer of a car. Electronic Meter (types may vary) - Electronic Meters have a six digit display register which scrolls through different tariff rates. Some electronic meters continuously scroll through the different channels, pausing on each channel for a period of six seconds. Other electronic meters have a fixed display that requires you to repeatedly press the reset scroll button to display all rates depending on the tariff. Time of Use or SmartPower Meter - Synergy offers time of use meters. These meters allow customers to access time based pricing. By moving usage from an expensive time period (Peak) to a less expensive time period (Off Peak) you can reduce electricity costs. The service charge for time of use is considerably higher than the normal service charge and must be taken into account when calculating the savings. Saving Energy on WA Dairy Farms 3

6 Negotiating a Price It is worth contacting your energy supplier in an effort to negotiate a better deal for your electricity requirements. For example, if you spend more than $10,000 a year on electricity you are eligible to move to a Synergy Business Plan or non-standard contract. These contracts contain different terms and conditions to a standard contract and may include variations in price, fees, charges, contract length, payment options and early termination and exit fees. Non Standard Contracts What can you save? Many dairy producers are investigating the option of moving to a non-standard contract in order to save on their electricity costs. In writing this brochure several dairy farmers were consulted on their experience in negotiating a contract for a better electricity price. In most cases the contract was for a 12 month period. An example of the new pricing arrangement in a non standard contract can be seen below. Energy Price (c/unit) Supply Charge On Peak Off Peak (c/day) Non standard Standard For one dairy farmer who had negotiated a non-standard contract, the savings on the non-standard contract compared to the standard contract, for one billing period of 68 days, was $580 dollars. Across a year this represents $3133 in savings, all for the cost of a phone call and some paperwork. Alternative Energy Retailers The majority of dairy businesses use Synergy to supply their power as they are the default electricity suppliers for WA. As a result of government policy to allow more competition in the energy industry, some customers are now able to choose their electricity retailer. The Economic Regulation Authority, who are the independent economic regulator for Western Australia, state that if you are a Western Power customer and use more than 50 MWh of electricity per year (approximately $12,600), then you can choose an alternative retailer. Current choices are Synergy, Alinta and Perth Energy. Synergy Alinta Perth Energy

7 Paying You for Power As demand for electricity continues to rise, utilities and grid operators continue to look for ways to increase the electric grid s capacity. Where once the only option was to fire up costly backup plants, power providers can now look to energy users to relieve the grid of excess demand at critical times. What is Demand Response? Demand response is simple: peaking demand triggers a dispatch across the grid. Your business responds by reducing electricity usage for a few hours. You receive a payment from EnerNOC for your participation. You also receive regular payments year-round just for being on-call during normal grid operation. They have an intuitive, web-based application, DemandSMART, which enables commercial, industrial, and institutional entities to receive payments for participating in demand response programs. EnerNOC provides demand response capacity to the South West Interconnected System in Western Australia, while helping businesses maximise payments for participating. How Does it Work? 1. When a demand response is anticipated you are notified via phone/ that the demand response event is going to begin. 2. At the start of demand response you cut or reduce your power usage according to your pre- determined energy reduction plan. 3. Before, during and after the event you have the support of EnerNOC staff to ensure that you achieve the highest level of performance, payments and satisfaction. 4. You receive quarterly payments for your participation. Payment for Power is Painless Ross Woodhouse, who farms at Scott River, is involved in the EnerNOC DemandSMART program. He commits to 24 hours across a year in which he will turn off power. The demand response usually occurs between 4-6pm during which time he uses a generator to continue milking. He is given 12 hours advanced warning to prepare and then is paid 50c/kWh plus an annual fee for the power that he is not using. Joining incentives in the first year of the program saw Ross paid $26,000. In subsequent years this had dropped to approximately $17,000 per year. The profitability of being involved in this scheme will depend on the cost of generating the power yourself and whether there is a capital expense involved. In Ross s case he did not buy the generator specifically for this program but already had it for back-up power. Photo courtesy of CSBP Saving Energy on WA Dairy Farms 5

8 Water Heating Minimise the volume of water used to wash the plant and vat. Wash at the lowest temperature possible without compromising hygiene. Use a thermometer to monitor hot water inputs and outputs. Install a water heater with capacity for all daily wash requirements so that all heating can occur on the off peak tariff. If a time of use tariff is in place, install a timer to ensure water is only heated during the overnight off peak period. Install a hot water pre heating device such as a heat recovery unit or solar hot water heater so that most of the heating can occur without using extra electricity. Insulate pipes to reduce heat loss. Keep storage tank out of breezeways and drafts. Use the best quality water available high levels of minerals or organic matter reduces heating performance. Solar Hot Water Systems In most cases producing hot water for the dairy using a solar hot water system is the best move financially and environmentally. There are two types of solar hot water systems, flat panel collectors and evacuated tube solar collectors. Flat plate collectors have copper pipes running through a glass covered collector, often connected to a water storage tank on the roof. The water thermo-siphons in and out of the tank, heating the water. Evacuated tubes use a glass tube with a vacuum inside and copper pipes running through the centre. The copper pipes are connected to a common manifold which is connected to a slow flow circulation pump. This pumps water to a storage tank below, heating the hot water during the day. The hot water can be used at night or the next day due to the insulation of the tank. Flat Plate Evacuated Tube Less expensive ($10,550*) More expensive ($11,039**) Operates most efficiently in the middle of the day More sensitive to frost causing damage to the collectors Heavier Can heat water to a higher temperature as they have a greater surface area exposed to the sun at any one time (40% more efficient) Can be used in sub zero and overcast conditions (can extract heat out of the air on a humid day). Risk of overheating as the water reaches its maximum temperature in the tank the pressure and temperature valve automatically activate and release some water to allow for cold water to come back in reducing the temperature build up. The number of tubes needs to be matched to the quantity of water to be heated to minimise the risk. Lighter some lightweight designs can be mounted on walls and even poles. Requires a smaller roof area. Less corrosion than flat plate systems. Are durable and broken tubes can be easily and cheaply replaced. Quotes obtained from *Solar Dynamics 3 x 300L storage tanks with no internal boost, six flat panels and three manifold kits. ** Apricus Australia - 90 evacuated tubes and heat pipes, three manifold kits. Photo courtesy of SCE Energy Solutions 6

9 Boosters In the cooler months a solar hot water system will not provide water sufficiently hot enough to clean the milking machine so an electric booster is required for both flat plate and evacuated tube systems. It is recommended that water is kept below 90 C entering the line (under vacuum) to prevent steam from damaging the vacuum pump but will still need to be hot enough to achieve an effective clean of the milking machine. Washing Regimes Is there a better way? Check the temperature of the wash water in the drum as the wash cycle commences (it should not exceed 85 C). During recirculation the drum should be around 20% full as the wash water returns. If it is more then smaller wash quantities should be considered. Investigate detergents that work effectively at lower temperatures. Use a chemical sanitiser in the final wash cycle to reduce hot water demand. Capture the final rinse for use next time. Factors to consider when installing solar hot water system at the dairy Tank sizes are limited to 315L or 440L. Costs increase dramatically when more tanks are needed (CowTime research shows that each cluster requires seven litres of water per wash. Use this to calculate the volume of hot water required). Correct installation and mounting is critical to success. The roof needs to be strong enough to hold the system. The collector should be mounted to face north or the amount of energy that can be captured is reduced. The tilt angle should be the latitude of the installation site. The higher the quality of collectors in the system the hotter the water produced. If your gas/electric hot water system has plenty of life in it, consider retro fitting collectors, pump and controller to an existing storage tank. The retrofit option can save large amounts on installation but eliminates the need to replace an existing hot water cylinder. Thermal Heat Recovery Systems A large amount of waste heat generated during milking can be harvested and used. Sources include the plate cooler, refrigeration systems and some vacuum pumps. Heat recovery systems are available that capture the heat from the milk refrigeration system and use it to heat water (to 50 C to 60 C). The system sits between the compressor on the milk vat and the air cooled condenser to extract the heat during milk cooling. The hot refrigerant gases with high pressure from the compressor are transported to the heat recovery system where the heat is released into the cycling water in the system. Most of the commercial units available have 450 L capacity. This water can then feed into the hot water system. Using water to remove heat from the refrigeration system is more efficient than using air so improves the efficiency and life of the compressor. Advantages Disadvantages Free energy from the refrigeration system Capital expense ($7000-$11,000) Can reduce milk refrigeration costs if properly designed Poorly designed systems can result in water that is too hot and reduce the overall efficiency of the refrigeration Con prolong the life of the compressor Difficult to recover heat from the large volume of warm In some cases can get water to greater than 75 C water generated from the plate cooler (without insulated storage) *information from CowTime Saving Energy on WA Dairy Farms 7

10 Cost A recent project from DPI Victoria developed a hypothetical case study dairy farm in south Gippsland to estimate the cost of energy saving technologies. The case study assessed the cost associated with a heat recovery system to heat 700 litres of water to 65 C. The preheated water entered the electric hot water service to heat to 90 C overnight. The energy saved under the system was 41kWh which equated to $2905 saved in the first year. The capital investment of the system was $7375 plus $3000 for installation. The system was a profitable investment which recouped the initial cash outlay and will cost less than business-as-usual in year five. After year five the system would be a cheaper alternative to electric hot water. At the end of year ten the system was $ better off than business-as-usual and had an internal rate of return (IRR) of 27 per cent. Factors to consider when installing thermal heat recovery systems Correct installation on the existing milk cooling system to achieve target water temperatures The volume of the water tank and volume used during and between milkings. The amount of milk to be cooled will determine how much heat can be captured. The network water temperature. Type of refrigerant gases and the configuration of the installation. Combining an evacuated tube solar hot water system with the thermal heat recovery system. This can be an option that will reduce dependency on electricity but the complexity of combining the different systems will need to be considered. Heaps of Hot Water Bob and Jacqui Biddulph realised that heating up to 1600 L of water, to wash their 44 stand rotary in Cowaramup, formed a big part of their electricity bill. Participating in Western Dairy s Energy Audit program confirmed that the decision to purchase an Energy Recovery System (ERS) was the right one. The dairy already had two 800 L Wilson hot water storage tanks which heated up cold water during off peak periods. This was complemented by the installation of two 550 L Delaval Energy recovery tanks which heat water using the waste heat generated from the vat compressors. The ERS system cost $12,500 (45 per cent was installation of electrics and plumbing) and at current electricity rates (not counting rising rate increases) the payback period will be 3 years. Bob has been very happy with the result. We recently measured surplus water from the heat recovery tank and it varies between 60 C and 73 C. This means that the electric hot water system only has to heat it another C before it is ready for washing out the milking machine Bob said. An analysis of their electricity bills estimates that the Biddulphs are using approximately 18 per cent fewer units of electricity than for the same period last year, despite milk production over that same period being up 20 per cent. Bob has been unable to quantify the savings accurately, but he feels that the milk cooling system is working more efficiently with the compressor shutting off earlier, despite this year s long hot summer. Bob and Jacqui had toyed with various ideas in the last few years for reducing costs associated with heating water but felt that the heat recovery units gave them the biggest bang for their buck. The ERS also allows for quick access to hot water through an outlet direct from the tanks. This has proved handy for washing calf buckets and general cleaning, and means that water is not sourced directly from the hot water storage tanks. 8

11 Heat Pumps A heat pump can reduce power consumption and costs by preheating large volumes of water to 60 C. A solar heat pump works like a refrigerator in reverse. The compressor on the heat pump transfers heat from the surrounding air to water held in an insulated tank. The water from the heat pump is then transferred to the hot water heater so it can be heated to the required temperature required to wash the milking machine. They are not a substitute for the hot water system. Savings of approximately 40 per cent can be made with heat pumps To heat 800 L of water to 85 C savings ranged from $700 for off peak hot water systems to $2500 where there is no off peak hot water at the dairy (Ewen Report). Facts about Heat Pumps Most have a volume of 340 L, however 400 L and 1000 L tanks are also available. Two or more tanks can be installed in manifold to supply large volumes of hot water. Tanks are made of stainless steel, copper or ceramic lined steel. Compressor motors are usually small drawing 0.7 kw to 4.2 kw depending on the model and size of the unit. Smaller units run off single phase and large models will require three phase power. Of the energy required to heat the water, two thirds comes from the heat in the air, and the remaining one third from the power used to drive the compressor. Manufacturers recommend that heat pumps should be operated during the warmer part of the day when they will work most efficiently as the ambient temperature is highest. They can operate at night as they do not require direct sunlight to work. Some heat pumps have been designed to work in ambient temperatures ranging from -10 C to +40 C. Cost The Ewen Report indicates that three tanks in manifold with a capacity to heat 800 L of water costs approximately $12,000 including installation. If there is no off peak power supply at the dairy, installing a heat pump to pre heat water can save up to $2500 each year. In this example the payback period was five years. Saving Energy on WA Dairy Farms 9

12 Milk Cooling Systems Switch to time of use metering where morning milking activities are completed by 8am. Use a plate cooler with a single pass of cool water that is not recirculated unless it is re-cooled ie with cooling tower. Ensure plate cooler is the correct size for the volume, pressure and milk flow rate. This will ensure effective cooling of milk so vat compressors are not running for extended lengths of time. Consider double bank plate coolers where the coldest source of water flows through the first plate cooler. The second plate cooler can use glycol or chilled water to cool the milk even further. It is beneficial if the chiller can be run during off peak power. Have your plate cooler regularly serviced by a technician. Cooling milk from 35 C to 4 C accounts for the biggest proportion of total dairy energy costs (43 per cent in WA audits). Designing and operating an efficient milk cooling system can reduce energy demand and operating costs. In many cases the technology, such as plate coolers, is not new but needs to be evaluated to ensure it is working efficiently and not costing you money. Plate Coolers Plate coolers are an extremely cost effective way to cool milk, but in many cases are poorly utilised. There are several factors that impact on the effectiveness of plate coolers. Flow Rates The system needs to be designed according to the peak flow rate of milk expected from the milk pump. Providing an even flow of milk from the milk pump by installing a variable speed drive will help make the plate cooler system easier to size and make efficient use of the cooling water. Using a transfer (rather than pressure) pump is a preferable way to supply the cooling fluid. Surface Area The latest plate coolers are designed to have more surface area giving them greater heat exchange capacity which improves their cooling efficiency. Different types of plate coolers require different flow rates for the cooling medium. The standard M and P series plate coolers operate on a ratio of L of water to 1 L of milk passing through the cooler. Newer industrial models work on L water to 1 L of milk. Plate Compression Plates that are too tight restrict flow so aim for 3 mm for each plate and gasket. Plate Cleanliness Contaminants of either the water or milk that adhere to the plates will affect the heat exchange capacity, flow rate and efficiency of the plate cooler. Source Water The temperature of the source water is the greatest limitation to plate coolers. In winter when water temperatures are low plate coolers operate very efficiently. In summer, when water temperatures increase, there can be very little margin between the water temperature and milk temperature. This means the vat will do the majority of the chilling which uses a lot of electricity, usually at peak tariff rates. Plumbing To maximise heat transfer the water should flow through the plate cooler in the opposite direction to the milk. Information sourced from CowTime 10

13 Is your plate cooler doing the job? The best way to check if your plate cooler is up to the task is to compare the temperature of the milk leaving the plate cooler with the incoming temperature of the cooling water. A plate cooler working properly should cool milk to within 2 C of the incoming cooling fluid ie if water coming into the plate cooler is 18 C then the temperature of the milk should be about 20 C. Step 1 Identify water inlet and milk outlet pipes. Step 2 Apply strip thermometers to water inlet and milk outlet pipes and measure the temperature of the water and milk during peak milk flow as it exits the plate cooler. Step 3 If you get more than 3 C difference there is room to improve the performance of your plate cooler. Step 4 Measure the flow rate of water leaving the plate cooler. This is done by timing how long it takes to fill a 20L bucket when the pump is operating at normal speed and flow rate. If the water is being recycled or recirculated into a tank put the bucket under the discharge pipe. For example if it takes 13 seconds to fill a 20L bucket the flow rate is = 1.5 L/sec). Step 5 Measure the time taken to fill the bucket with milk at the vat entry point while the milk pump is working at capacity (ie all cups on). If it takes 40 seconds to fill a 20 L bucket the flow rate is = 0.5 L/sec. If it is not possible to measure during milk, simulate using water at a later point. Step 6 Divide the cooling fluid flow rate by the milk flow rate to determine the ratio. Using the numbers mentioned in steps 4 and 5 the flow rate would be = 3. The water flow rate is 3 times the milk flow rate or 3:1. Information sourced from CowTime How hot is it? There are two quick and easy ways to test the temperature of either milk or water running in and out of the plate cooler. Thermometer Test Strips - temperature difference is easy to measure by applying strip thermometers to the water inlet pipe and to the milk outlet pipe. Cost $4. Digital Non-Contact Infrared Thermometer Gun can measure surface temperature of hot, hazardous or hard to reach objects. Simply point the red light at the pipe/object to be measured and pull the trigger to get a quick temperature reading. They are a great tool for around the farm. Cost start at $30. Saving Energy on WA Dairy Farms 11

14 Cutting Costs at Scott River Ross Woodhouse milks 1100 cows in a 60 stand rotary on his Scott River property. The ever increasing cost of electricity, and a desire to improve efficiency, prompted Ross to make several key changes to his dairy. After a particularly hot summer Ross realised that the vat was struggling to reduce the temperature of the milk, consistently producing the error message too slow to cool. After consulting Kim Norwell from DeLaval, it was decided that the plate cooler needed an overhaul. It was cleaned and serviced and ten more plates were added to improve its cooling efficiency. In addition, a filter was put onto the water supplying the plate cooler to ensure any contamination from leaves and sludge could not inhibit the flow through the plate cooler. With the plate cooler now taking more heat out of the milk, the vat has less work to do reducing electricity costs. Ross has also looked to make further savings by installing a VSD on his vacuum pump and negotiating a better deal on his electricity supply. He has been able to negotiate a new two year contract with Perth Energy to supply his electricity requirements at a competitive rate, with peak electricity being reduced by 5c/kW. He is also part of the EnerNOCS demand response program. Bring in the Expert Testing the efficiency of your plate cooler is an important first step that you can do yourself. If you have ascertained that there is a problem it may be a good idea to call on the services of a skilled technician. They will be able to clean the plates (a harder job than it looks) and ensure the plate cooler is reassembled properly. They will also be able to advise on resizing, extra pumping capacity, additional cooled water storage or a complete dismantle and service. The additional capital and cost of the servicing should be compared to the cost of an inefficient plate cooler. The cost of an inefficient plate cooler can run into the thousands of dollars a year depending on milk production and the difference in temperature of the water and milk entering and exiting the plate cooler. 12

15 Cooling Towers If you discover that the water entering your plate cooler is too warm, a cooling tower could be a consideration. They also allow for water from the plate cooler to be cooled so it can be recirculate without jeopardising milk cooling. Cooling towers can be very effective at cooling water in areas of low humidity. A cooling tower is a heat rejection device. A cooling tower relies on evaporation to remove heat from the water. The tower allows a small portion of the water being cooled to evaporate into a moving air stream to provide significant cooling to the rest of that water stream. The heat from the water stream transferred to the air stream raises the air s temperature and its relative humidity, and this air is discharged to the atmosphere. Water can be cooled to within 5 C of the wet bulb temperature* in a tower that is properly designed. Cooling towers are a relatively cheap technology. They do not work well on days of high relative humidity and high wet bulb temperatures. They can reduce the temperature of the water entering the plate cooler improving its efficiency and reducing the cost of milk cooling. Check the temperature of the water entering the plate cooler to see if a cooling tower could be an option. Bore and well water will have a relatively stable temperature all year round but the temperature may rise considerably in hot weather depending on how this water is stored. Positioning, burying, screening or planting shade around tanks are options to help insulate. Mechanical-draft cooling towers rely on power-driven fans to draw or force the air through the tower and are more effective than natural draft cooling towers. *Wet bulb temperature is measured using a standard mercury-in-glass thermometer, with the thermometer bulb wrapped in muslin, which is kept wet. The evaporation of water from the thermometer has a cooling effect, so the temperature indicated by the wet bulb thermometer is less than the temperature indicated by a dry-bulb (normal, unmodified) thermometer against the warming effects direct sunlight. Improved Refrigeration A new product, the Mysticool Max, is an add-on component that can help to improve the performance of milk vat refrigeration. It is a valve that changes the liquid dynamics of the refrigerant gas allowing more of it to come into contact with the copper and cooling plates. This reduces the temperature faster and more efficiently. It also enables temperatures to be held more consistently. It can be installed without altering any of the other system components. The starting cost is $ GST with return on investment between 9-36 months. Saving Energy on WA Dairy Farms 13

16 Milk Harvesting Investigate variable speed drives for vacuum pumps (best suited to blower type vacuum pumps) where there is sufficient excess vacuum being produced for the motor to be able to reduce power output. Reduce milking times where possible. Consider variable speed drives for large water pumps. In many dairies vacuum and milk pumps operate at a constant speed which is required to create a desired vacuum or flow rate. Power savings of 40-75% can be made when a variable speed drive (VSD) is fitted to the vacuum pump (Ewen Report). Further savings can be made when VSDs are fitted to the milk pump as it can improve the efficiency of heat exchange through the plate cooler. A VSD uses a sensor in the vacuum line to detect changes in pressure and then adjusts the speed of the pump motor to match the demand for vacuum or flow rate. This lowers energy consumption and emissions. There is less wear and tear on the motor and noise levels are lower during milking. One VSD can control up to three motors at one time and they can work with both three phase and single phase power supplies. VSDs can be fitted to new or existing pumps. Vane and blower vacuum pumps are the two most commonly used vacuum pumps. Blower vacuum pumps are more efficient than vane pumps but are more expensive. VSDs are better suited to blower vacuum pumps as they can operate at lower revolutions than vane pumps and still maintain sufficient vacuum. They are usually quieter and have a longer life. Some vane pumps are not suited to VSDs if the revolutions can not be lowered without wearing out the pump. They will also require additional lubricating oil which will be an added cost. VSD on VACUUM PUMPS Advantages Only uses energy needed to meet the load on the milking system The longer the milking time the better the savings Reduces noise in the dairy Reduces wear on the motor and pump prolonging their life Disadvantages Capital expense Not everyone can repair them. Requires yearly servicing. Typical pay back times range from 4-7 years depending on how many hours/day they are used for *information from CowTime VSD on MILK PUMPS Advantages Can give better milk cooling due to more constant rate of milk flow. Enables better matching of precooled water to daily milk volume which can save water Reduces the need for a choke on the milk line which may have an impact on milk quality Disadvantages Capital expense Typical pay back times for VSDs range from 2.5 to 5 years depending on daily milk volume and the expected improvement in milk cooling efficiency. Not everyone can repair them. Requires yearly servicing. *information from CowTime 14

17 Factors to consider before installing VSD on milk and/or vacuum pumps Existing pump Blower vacuum pumps are generally more efficient than a vane pump. The working condition of the pump can influence potential savings particularly on older pumps. The size of the dairy relative to the number of cows being milk influences potential savings where the greatest gains are made on longer running times. When the size of the pump is not matched to the size of the shed ie a small pump relative to the requirement of a large shed provides opportunity to save money by upgrading the pump and installing a VSD. Have the VSD correctly installed by a qualified technician. The full energy savings are often not achieved if VSD are installed without filter protections and components and not tested to ensure it is operating efficiently. Different vacuum pumps with the same motor size can have different air consumption due to the layout of the system. Leakage of air in the system as a result of incorrect installation can also reduce efficiency. Greater energy savings are possible where the pump can operate at lower RPM ie a 1400 rpm motor than can be geared down to 700 rpm will benefit from adding a VSD. If the pump can only be lowered to RPM there is relatively little benefit from installing a VSD. Motor speeds should not be lowered below the minimum operating requirement of the motor as the motor will wear out prematurely. Cost Cost will vary depending on the make, country of manufacture and whether the VSD is pre- programmed for the model and type of vacuum. The EWEN project quotes prices (ex GST) for VSD that range from $2300 for a 4 kw motor/pump to $10,500 for a 22 kw motor/pump. A recent project from DPI Victoria developed a hypothetical case study dairy farm in south Gippsland to estimate the cost of energy saving technologies. An economic analysis of installing a VSD on new and existing pumps is outlined in the table below. The most profitable option was installing a VSD kit on an existing blower vacuum pump. New blower vacuum pumps were profitable investments but new oil vane pumps would not recoup the initial costs by the end of year ten. Existing Pump New Pump VSD on vane VSD on blower VSD on new vane VSD on new blower Net present value (7% discount, 3% inflation on cash flow) Internal Rate of Return (real) Years to breakeven (before interest and tax) $10,336 $18,789 -$833 $2,102 34% 51% 6% 9% 4 years 3 years >10 years 10 years Saving Energy on WA Dairy Farms 15

18 VSD Gets Thumbs Up at Benger After shifting their dairy operation from the Ferguson Valley to Benger in 2006, Michael and Sophia Giumelli, who milk 380 cows in a 20 unit double up herringbone, began looking at ways to reduce electricity costs in the dairy. Installing a variable speed drive on the milk pump appeared to be one of the areas where big savings could be achieved. In December 2011 a variable speed drive was fitted to the existing DeLaval LVP4500 blower type vacuum pump at a cost of $5000. While the direct savings of installing the VSD have not been able to be monitored directly, Michael and Sophia have noticed savings in their power consumption compared to the same time last year. When you compare last month s power bill with the same time last year we are using about 4000 units less of electricity. Our power bill has come down, even though the price of power has gone up so we are pretty happy, Michael said. The Efficient Water Energy and Nutrients (EWEN) project involved monitoring the energy consumption following the installation of a VSD on the same vacuum pump found that without the VSD the motor would be running at full load and drawing a 37 kwh/ day. This adds up to 13,500 kwh each year at a cost of $2650. Installing the VSD reduced energy costs by 65%. 16

19 One of the significant advantages of installing the VSD has been a reduction in the noise in the dairy at milking time. Since we have installed the VSD it is very quiet in the dairy. The only time you hear the motor is when a set of cups is kicked off and vacuum pump has to speed up to alter the vacuum. We can t quantify the effect of reduced noise but we know it is definitely a big plus, Michael said. Michael has also envisaged that there will be less wear and tear on the pump reducing maintenance costs in the future. Michael and Sophia are investigating other energy savings including a heat recovery system to complement the existing electric hot water system. In the short term, Michael and Sophia have negotiated better rates for their power by entering into a non-standard contract with Synergy. Saving Energy on WA Dairy Farms 17

20 Big Ticket Items Solar Power Solar photovoltaic panels convert energy from the sun into electricity which reduces reliance on energy sourced from the grid and reduces carbon emissions. The savings that can be achieved by converting to a solar system will depend on the size of the solar panel (kw), the feed in tariff, when you supply excess electricity, and current electricity tariffs on individual farms. A solar power system consists of photovoltaic panels made up of a connected group of photovoltaic cells to form a usable size and output. Typically sunlight produces 1 kw per square metre. A 1m 2 efficient panel can convert as much as per cent of this 1 kw to electricity. The panels are connected to an inverter which makes the generated electricity suitable for dairy use. Factors to consider Any system larger than 4.5kW will need energy distributor approval and the farm needs to have three phase power. The size of the transformer at the farm will determine the allowable size of the solar panel system. Electricity is only fed back into the grid if there is an excess produced. The proportion fed back into the grid is highly variable between days and between farms. The quality, orientation and tilt of the panel will determine the maximum electricity generated from the system. Some farmers may be disadvantaged through losing their off peak entitlements or by having increased base tariffs. The expected energy savings will depend on the electricity price particularly on the standard feed in tariff on systems larger than 5kW as savings are based on your current tariff. The quality of the solar panel will influence the effectiveness of converting sunlight into electricity particularly under limited sunlight. A recent project from DPI Victoria developed a hypothetical case study dairy farm in south Gippsland to estimate the cost of energy saving technologies. They compared a 5kW and a 30kW system on a dairy farm using kWh of electricity in the last financial year. Based on off peak and peak prices the cost of electricity for the whole farm was $14,960. Cost For the case study farm the cost of a quality 5 kw solar panel was $13,100 exc. GST and 30 kw was $75,000 exc. GST. These prices included installation and reductions through the solar credit scheme. Most systems will require new metering costs associated with installing the solar panel system to the grid and an independent electrical inspector fee ($400). Do they Pay? An economic analysis of the solar panels on the case study farm found that they were both profitable as they were better than the business-as-usual option at the end of year ten. The 30kW system was more profitable than the 5kW system despite the larger capital outlay. This is due to the larger annual savings and a greater increase in the tariff between years in line with a ten per cent increase in market value of electricity. Net present value (7% discount, 3% inflation on cash flow) 5 kw solar system 30 kw solar system $6,805 $41,159 Internal rate of return (real) 14% 14% Years to breakeven 10 Years 9 years (before interest and tax) 18

21 Wind Power Wind turbines convert kinetic energy from the wind into mechanical energy to produce electricity. The turbines generate electricity suited to conversion to single phase 240 V AC (between 400W and 10kW output). The wind power market is still developing in Australia and turbines suitable for dairy farm requirements will become more prevalent. For more information Green Cleaning Systems TM Green Cleaning systems are milking machine wash systems that operate at low temperatures, re use the cleaning solutions and are energy efficient. They comprise of an automated cleaning unit that is capable of capturing, storing and re-using the wash solutions. They use chemicals that are specifically designed for re-use and to work at lower temperatures (less than 50 C). Heating of the wash solutions utilises energy from renewable sources such as solar & heat recovery. The storage tanks are well insulated to minimise any heat losses. The same wash program can be used at every washing and the control unit monitors the concentration of the cleaning solution and doses as required. Capital outlay for a Green Cleaning system range from $ $ depending on dairy size and the existing system. They have been demonstrated to be more profitable than conventional cleaning systems, particularly on large and new dairies. For more information Saving Energy on WA Dairy Farms 19

22 Cow Time Dairy Energy SavingsChecklist Hot Water Systems YES NO Is the off-peak time clock meter set correctly at the power box (weekdays 10:00pm-8:00am and all weekend)? Is the hot water system protected from the weather and kept dry? Does the capacity of the hot water system match the daily requirement for milking (without using the daytime booster)? Are the sacrificial anodes in the hot water service checked regularly? Is the hot water unit free of hot spots? Is the hot water system flushed regularly to remove sludge or mineral build up? Are the metal pipe connections into the hot water service well insulated? Have you reviewed you washing regime with your chemical reseller to look for opportunities to reduce costs (ie reduce hot water volumes required)? Does the hot water system deliver hot water into the CIP barrel at 75 to 85 C? Check by comparing the morning hot wash temperature with the thermostat setting and adjust. Do you commence morning wash up after 8am? If cold water enters the hot unit before 8am it will be heated up unnecessarily Have you eliminated hot water leaks and wastage? Do you conserve heat by only filling the CIP barrel immediately prior to cleaning the machine? Does the hot water system boil at night? Milk Cooling Pre Cooling Has the plate cooler been correctly sized for the job? Are you using the coldest water available? Do you have an even flow of milk through the plate cooler? Does the water and milk flow in opposite directions through the plate cooler? Does the water flow rate exceed the maximum milk flow rate by at least 3:1 for m type plate exchangers (2:1 for industrial types)? Refrigeration Plant Is the refrigeration unit protected from rain and direct sunlight? Is the condenser located to take advantage of prevailing winds/allow unrestricted airflow around the unit? Is the vacuum pump exhaust positioned far enough away to prevent oil build up on condenser fins? Are condenser cooling fins clean and undamaged? Is the compressor and refrigeration motor clean and free of oil leaks? Does a qualified refrigeration mechanic undertake annual maintenance? Dairy Equipment Are annual tests carried out by a technician to check vacuum regulation, airflow, leaks, drive belts etc? Is the vacuum pump motor clean and well ventilated? Do you clean your light tubes and fittings annually? Have you replaced incandescent lights with energy efficient fluorescent bulbs and/or metal halide lights? 20

23 Need More Information? Western Australia Dairy Energy Audit Project Summary A summary report which presents the outcomes, observations, results and recommendations as determined by the Western Dairy Energy Audits. Copies available by contacting Western Dairy on (08) CowTime A national dairy industry project aimed at making milking easier. It encompasses milk harvesting research and extension from when the cows leave the paddock for milking right through to cleaning up the milking shed. Victorian Department of Primary Industries Report Economic Analysis of Technologies to Reduce Dairy Energy Consumption The Ewen Project Efficient Water Energy and Nutrients Project, Nick Bullock and Associates - Fact sheets and case studies on energy use in dairies on the Mid North Coast of NSW Dairying for Tommorow Dairy Self Assessment Tool To help you identify areas for improvement in all areas of dairying Dairying for Tommorow - RRR Reduce Reuse and Recycle at the Dairy Shed 2007 Series of factsheets on improving energy use at the dairy Useful Contacts Western Dairy Rob La Grange Dairy Industry Development Specialist Tel: Mob: rob@westerndairy.com.au Esther Price PO Box 341 Mundijong, Western Australia 6123 Tel: Mob: + 61 (0) esther@westerndairy.com.au Dairy Australia Level 5, IBM Centre, 60 City Road Southbank, Victoria 3006 POSTAL ADDRESS: Locked Bag 104, Flinders Lane, Victoria 8009 Tel: Fax: Memberline: Consumerline: Saving Energy on WA Dairy Farms 21

24 This project was jointly funded through a collaboration between Dairy Australia, Western Dairy, and Department of Agriculture, Fisheries and Forestry Western DAIRY