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Saving Energy for Fruit Production

Posted: July 22, 2011

Energy-efficient practices on the farm bring to mind fancy new equipment like solar panels, wind turbines, and biofuels. But you don’t have to jump head-first into buying the latest technology. With just a few simple changes to your operation, you can start to see real savings at the pump and on your electricity bill.
Storing your irrigation pump and filtration system in a protected area translates to smart energy savings.

Storing your irrigation pump and filtration system in a protected area translates to smart energy savings.

Dr. Katie Ellis, Penn State Specialty Crops Extension Educator

Saving Fuel

The biggest energy drain on in-field tree fruit operations is fuel use for tractors, trucks and other farm equipment.  Mowing, spraying, checking traps and moving bins and harvest crews around orchards can consume a lot of fuel.  More precise pest management methods can help reduce fuel use, as can a move to higher density plantings.  But how can you save fuel even more?  Alex Leslie, a graduate of Penn State’s Agricultural and Biological Engineering program, developed a fuel use calculator for tree fruit orchard blocks. 

To calculate estimated fuel use for specific blocks, you enter several variables like block size, tree row spacing, planting density, current diesel price and tractor/sprayer type.  The program computes the number of passes and turns required, and the resulting fuel cost based on the equipment used.  By manipulating the variables and trying different combinations, you can determine the most efficient use of fuel in your operation.  For a copy of the calculator, please contact Katie Ellis at kag298@psu.edu or 717-334-6271.

You can also save fuel (and time) by ensuring that your farm equipment is well-maintained.  Quick fixes and neglect will only cause headaches later on – and energy efficiency will suffer, too.  Also, be strategic about tractor and truck usage.  Proper planning will ensure that you save time and money in the long run.

Irrigation

The second biggest use of in-field energy is in crop irrigation, and it is possible to reduce fuel and/or electricity through adjustments to your irrigation system.  There are three areas to investigate in order to cut irrigation costs:  1) soil studies, 2) proper water usage, and 3) pump maintenance.  First, studying your soil structure will help you understand its properties – well-aggregated soils let water enter easily and retain water well.  Planning your plantings based on soil type will help maximize water use efficiency.  Increasing organic matter also helps with the soil’s water-holding capacity.

Proper water usage involves matching irrigation to the crop’s needs.  This depends on many factors such as temperature, relative humidity, wind speed and crop coefficients like tree age, height, cultivar and crop load.  In short, you must determine how much water was taken from the soil and then replace it through irrigation.   This is most easily accomplished through automated soil monitoring systems, but you can take measurements manually and then schedule irrigation needs accordingly.

Finally, energy waste can occur from a lack of pump maintenance.  On average, irrigation systems use 40% more fuel if they are improperly sized, adjusted and/or maintained.  Also, about 25% of electricity is wasted from poor pump and motor efficiency.  Most energy waste occurs at the pump itself:  this occurs from wear, improperly designed fittings or lack of maintenance.  Keeping the pump clean, lubricating when necessary, replacing worn gaskets and protection from the elements all go a long way in maximizing the energy efficiency of your irrigation system.  When using an electric motor, be sure to use a shade to cool the thermal breakers.  Also, drip irrigation can lead to special irrigation problems.  Since lines are easily clogged by soil, algae or particulate matter from chemical treatments, be sure to check filters, pressure and flush the system periodically.

To give yourself a rough cost estimate of your irrigation system, try out the irrigation estimator tool offered by USDA-NRCS: http://ipat.sc.egov.usda.gov/.  You’ll need to enter a bit of information about your operation, and the calculator will tell you approximately how much money you’ll save per season by adding a flow meter, scheduling your irrigation and maintaining/upgrading your system.

Refrigeration

If your farm has on-site cold storage, you already know how energy usage affects profit.  Refrigeration can be a huge energy hog, but there are ways to make it more efficient.  First, try to minimize warm air leakage into the refrigerated space by adding insulation, door flaps and reducing movement in and out of the storage.  Doubling insulation can reduce heat loss by 50%, and remember that polyurethane insulation loses its insulating value over time.  Forklift traffic often degrades insulation near doorways, so repairs may be in order.

Routine maintenance, like cleaning fans and coils, can help maximize system efficiency.  Since lights produce heat, turn them off (and other heat sources) whenever possible, or install time or motion sensors.  If your operation has a use for hot water, set up the system to recover heat from the hot refrigerant.  Also, turn up the thermostat or shut off the storage when not in use.  This sounds obvious, but we’ve all seen it – a storage with half a bin of apples and the refrigeration on full-blast.

If the storage is really inefficient, it may be time to replace the refrigeration system with a higher efficiency unit.  Newer equipment utilizes more energy efficient scroll compressors.  Newer units also employ more efficient controls, like anti-sweat heater and hot gas defrost systems.  If you’re not familiar with the latest systems, you may benefit from an energy audit; this can help you calculate the payback time and potential energy savings.

Energy Audits

A third-party energy assessment can help you identify ways to save energy throughout your operation.  A fresh set of eyes can sometimes spot inefficiencies, from simple fixes like switching out old light bulbs to finding major energy hogs.  A special audit opportunity is offered through the “Pennsylvania Farm Energy Audits Program,” a partnership between USDA Rural Development, Capital Resource Conservation and Development Council, Center for Dairy Excellence and Penn State Cooperative Extension.  

USDA will offset the cost by paying 75% of the energy audit, leaving only 25% of the cost to the farmer.  The audits are carried out by Penn State agricultural energy specialists or specially trained private consultants, depending on the location of the farm and availability of personnel.  Since an energy audit is the required first step for many funding programs, this offers growers an excellent opportunity to assess their on-farm efficiency.  For more information about the application process, visit http://extension.psu.edu/energy/farmers-landowners/pa-farm-energy-audits-program.