Energy Savings on Farm: Where Will You Get the Biggest Bang for Your Buck?10 November 2014
If you are serious about saving money and being more efficient, then you really must consider measuring how much, where and when you are using energy, according to E.J. McGahan, B.R. Warren, R.J. Davis, F. Phillips and T. Naylor in a paper presented at PIX 2014 and published in 'Drumstick' from the New South Wales Department of Primary Industries.
Saving money by making smart decisions about where to invest your dollars in energy efficiency Making an investment in energy efficiency is an obvious way to reduce your farms operating costs. But before rushing out to buy new lighting equipment, solar panels, wind turbines or any other equipment it makes sense to first understand where you will get the most value from your investment. To do this, you need to figure out where your biggest energy costs are and where to make smart investment choices to give you the best possible bang for your buck.
FSA Consulting in Queensland together with Wollongong University have recently worked on a project to answer some of these questions. Their research was funded by the Rural Industries Research and Development Corporation (RIRDC) chicken meat programme.
“If you aren’t measuring it, you aren’t managing it” goes an old saying. This is what the project team set out to do — to figure out where growers are using the most energy and where the opportunities are to make savings. They also provided some useful tips that are relatively cheap to implement and will potentially lead to significant savings in energy use.
What Did They Do?
They monitored energy use at four sheds on three tunnel-ventilated grow-out farms in southern Queensland during 2011−2012. Electricity, gas, diesel and petrol use were all monitored. For each farm, electricity use was measured separately for each component of the shed. This meant that they could figure how much electricity was being used by:
- mini vents
- heating and cooling pumps
- feeding augers
- other minor equipment.
Gas, diesel and petrol usage was not metered individually for sheds and was apportioned to the studied sheds based on bird production. They also measured fan efficiency, in other words, how much electricity was used by individual fans to move air and maintain varying levels of static pressure. Measurements were converted to energy use per tonne of liveweight production so that comparisons could be made between farms and sheds with different stocking rates. What did they find? They found large variations in both electrical and total energy use between farms and even between sheds on the same farm.
This tells us that there is an opportunity for improvement and cost savings if we can figure where the energy is going and if it is being used effectively, or being wasted. Fans are by far the biggest energy user on a tunnel ventilated farm. Measurements showed that fans use between 68 per cent and 88 per cent of the total electrical energy used to run a shed.
This means that improving fan performance represents the greatest opportunity for potential electrical savings. Lighting represents the next highest electrical energy use but was still less than 10 per cent of the total electrical energy use for three of the farms. Annual energy use by each of the shed components on one of the farms is shown in Figure 1.
Fan monitoring in one of the sheds showed that the air flow decreases with higher static pressure inside the shed. A higher static pressure makes the fans ‘work’ harder to achieve air flow. There was large variation between the efficiency of each fan in the tunnel ventilation system. For low static pressure (<5 Pa), the air flow ranged between 26,000 and 21,500 m/hour. Under high static
pressure (>40 Pa) the air flow varied between 20,500 and 16,000 m/hour.
These results highlight the importance of controlling the shed’s static pressure and selecting high performing fans. The variation in fans performance is due to accumulated dirt and corrosion, differences in flow resistance from the shutters, and differences in motor and bearing wear over time. The inconsistent performance between the individual fans shows that improvements to performance are possible. General maintenance of the fans (motors, pulleys, belts, shutters etc.) will improve fan performance resulting in efficient cooling.
Figure 2 shows us that electricity and gas usage are the two biggest costs in terms of total energy consumption. This isn’t news to most growers. However, what is useful to conclude from this graph is that there is quite a large variation in energy usage between farms, as well as between sheds on the same farm. This means that these farmers may have an opportunity to make some changes that will save them money in the long run. What could these farmers do to be more energy efficient and save money?
Fans impact upon energy use in two ways, they require energy to operate, and the management of the fans impacts the efficiency of the heating energy used within the building. Select quality and correctly designed fans that suit a specific shed. All manufactured fans should be rated by an independent lab to show air flow and efficiency as a function of static pressure. Fans should not be chosen on diameter alone. It iss never wise to assume that two fans of equal size will have the same performance, as different motors, blade curvature and other attributes greatly affect performance.
Fans should be selected based on air flow and efficiency ratings. Choose fans which are in the upper 25 per cent of rated fan efficiencies. University of Illinois BESS Laboratory 'Agricultural Ventilation Fans Performance and Efficiencies' test booklet is one of the leading sources for agricultural fan performance information. An electronic version of the test booklet can be found at Installing discharge cones can increase fan efficiency by more than 15 per cent. Ensuring there is no back pressure created from fans discharging air into blocked or tight spaces will also help improve performance.
There should be sufficient distances between sheds to allow for unobstructed airflow. General maintenance of fans will also ensure efficient performance and reduce fan operating costs. Methods for improving fan performance include:
- General maintenance of pulleys and belts. Loose belts cause inefficient fan performance while over-tight belts will cause excess wearing upon bearings.
- Regularly cleaning fan blades, motors and shutters.
- Replace burnt-out motors with energy efficient motors
- Investment in more capital (e.g. energy efficient fans and cowlings). This decision should be based on potential pay-back.
- Ensuring shed ventilation (fan performance) is meeting manufacturer requirements.
- When constructing sheds, select energy efficient fans, pay attention to the fan’s energy efficient rating (cfm/watt) and air flow ratio. Go to www.bess.uiuc.edu for more information.
- Reducing the fan speed with a variable frequency drive (VFD) unit reduces airflow rate and the energy consumption of the fan; operate in accordance with ventilation requirements.
- Data from the US shows for every 2 CFM/watt increase, power usage is reduced by approximately 10 per cent.
The value of good insulation should never be underestimated. Quality shed insulation is important for cooling and heating as it will prevent heat and cold air loss. During summer insulation reduces external heat load entering the shed, while in winter heat is maintained inside the shed. Poor insulation, either low quality (poor thermal retention) or damage (leakage) will cause undesirable air loss. Both walls and ceiling should be insulated with high quality materials with suitable U values (heat transfer coefficient).
The insulation efficiency or minimum thermal resistance (R value) of insulation materials decreases when moist. Vapour barriers can be used to avoid humidity build-up. The condition of existing insulation should be checked for any signs of wear and tear. For sheds with side-curtained walls, the curtains should be secured to prevent air loss when the shed is running under tunnel ventilation. Poultry sheds with insulated side walls are more energy efficient than open sides with curtains.
pads Proper management of the cooling pads can also improve the ventilation systems energy efficiency. This involves regularly cleaning the cooling pads to ensure air flow is not restricted, minimising the load on the fans. During use, the cooling pumps should be running continuously to keep the pads wet and as clean as possible. Auburn University have a great website with plenty of helpful information on maintaining your cooling pads to ensure maximum efficiency. Go to www.aces.edu/poultryventilation and click on the Equipment link on the left of the page.
Electronic devices are installed to control the ventilation system in poultry sheds. Timers, sensors and thermostats lose accuracy over time and because of dust and humidity. Sensors and controllers should be cleaned, tested and recalibrated regularly to ensure the shed maintains the conditions programmemed into the system during the entire day. This allows the system to operate efficiently, saving energy.
There is great potential for energy savings from lighting due to the rapid development of technology. New lighting technology should be investigated as a viable option for replacing poor energy efficient, aging lighting infrastructure. Traditional incandescent bulbs are inefficient as they only convert 5 per cent of energy into light; the remaining energy is given off as heat. Energy efficient options exist, such as compact fluorescent bulbs, and fluorescent tubes, cold cathode, high pressure sodium (HPS) or LED. These lighting types use far less energy and have a much longer lifetime. For some excellent information on the different lighting options available, as well as calculations on energy saving and cost benefit, go to www.aces.edu/poultryventilation and click on the Equipment link on the left of the page.
Fuel and Gas
With high costs of gas and fuel (petrol and diesel) chicken farms can reduce costs by using these energy sources more efficiently. For chicken farms that use gas for heating purposes, usage can be minimised by ensuring sheds are well sealed and insulated. Fuel and diesel use should be recorded routinely so the farm is aware of consumption.
Fuel and diesel use can be reduced by good management practices and by maintaining and using suitable equipment. Good management involves running pumps and motors when required and switching off once done. Regular servicing of equipment will ensure fuel use is maintained at manufacturer’s specifications. When selecting the type of motors for a particular job, the motor capacity should be chosen based on the specific requirement. Fuel will be wasted choosing a large, powerful motor for a job that requires less energy.
Peak Energy Loads – Get a Better Deal
Peak electricity use periods can be monitored by installing electrical power meters on the power supply to each shed to monitor energy used per day or per batch. Another option in reducing electrical energy costs is to negotiate with the supplier for a reduced tariff if reliance on grid electricity can be reduced by running back-up generators several days a year during peak energy demand on the grid.
The work by FSA and the University of Wollongong has shown that large variations in energy use between farms, and even between sheds on the same farm means that there may be huge cost savings by improving the efficiency of energy use.
Fans are the big ticket item when it comes to electricity use and making improvements to fan efficiency is likely to give pay offs if you have inefficient fans.
If you are serious about saving money and being more efficient, then you really must consider measuring how much, where and when you are using energy.
The investment in good quality measuring equipment is likely to pay for itself pretty quickly because it will help you make smart decisions about where you are likely to get the best bang for your buck.