Tree fruits vary in shelf life, and the shelf life of all tree fruits is extended when kept under refrigeration. Pome fruits keep fresh for the longest time under refrigeration – about four months – when temperatures are just right. Stone fruits are only storable for a week or so and are very sensitive to the temperature and prone to chilling injury. They require lower temperatures than most pome fruits.
For many apple growers with direct market sales, a refrigeration unit is a must for sales during the winter months, after pick-your-own operations have shut down, and customers seeking local apples for holiday meals and winter eating.
But maintaining those apples is going to use a lot of energy. Refrigeration can be responsible for more than 50 percent of an orchard’s electricity use, according to Daniel Ciolkosz, P.E., agriculture engineering, Penn State University. Reducing the amount of energy cold storage requires is a prudent way to cut costs, while being environmentally savvy.
“Energy efficiency, if it can improve the bottom line of a farmer, is a very important part of saving money and being sustainable on the farm,” Ciolkosz said during a presentation for the Farm Energy IQ’s (FEIQ) training program. FEIQ was developed by Extension specialists from Penn State, Rutgers and University of Vermont, and received funding from the Northeast Sustainable Agriculture Research and Education (SARE) grant.
Finding ways to decrease fuel use by optimizing field operations, to save electricity costs by improving refrigeration units, and to decrease electricity use while better managing water needs via a well-maintained irrigation system are the primary ways to become more energy efficient in the orchard, Ciolkosz said.
While refrigeration is a big user of electricity, fuel use for field operations typically consumes the most energy in the overall orchard operation. Typical fuel use can amount to three-fourths of the farm’s entire energy use, according to data from a Penn State Extension farm audit.
Ciolkosz called fuel use “a missing part of energy use for tree fruit production.” Often overlooked, equipment fuel efficiency can reduce overall fuel expenses. Selecting – and maintaining – fuel efficient tractors, sprayers and other equipment, and matching the power and size of the equipment to the job at hand, can reduce fuel consumption.
Penn State Cooperative Extension’s Orchard Block Fuel Use Calculator is available online. It provides growers with a tool to easily estimate fuel use and cost, as well as cost of fuel per bushel of production.
Irrigation systems utilize about 4 percent of a typical orchard’s electricity use. While not a huge portion, these systems are often wasting electricity. Optimizing the system can make a difference in a farm’s energy efficiency, and an improved irrigation system can impact water usage and improve fruit yield and quality.
“Irrigation systems in general … are not very efficient on farms,” Ciolkosz said.
Once an irrigation system is in place, farmers may not think too much about its operation. Yet making mechanical improvements and upgrades to more efficient components, maintaining cleanliness of the system and matching the size of the system to the actual needs of the orchard, are all ways to improve efficiency.
Irrigation pumps are one area in which energy savings can be realized. Oversizing pumps is a big waste of energy. The capacity of the pump should match the needs of the irrigation area to correctly deliver the right amount of water to the crop. Replacing worn pump parts and lubricating and cleaning the pump to decrease wear and protect against dirt and moisture can increase energy efficiency.
The efficiency of a pump is based upon “how much of the energy we put into the pump actually turns into water energy,” Ciolkosz said. Investing in a pump test is a good way to begin optimizing the system and saving money. Also, an irrigation system should be designed with minimal right angles and turns. “Minimize kinks and elbows,” he said.
Providing uniform irrigation with an even wetting front that penetrates down to the root zone is the goal. As a general rule of thumb, 1 inch of water per week, from rain and irrigation combined, is the target. Moisture sensors help deliver the correct amount of water to the soil. These can range from simple tensiometers to state-of-the-art computerized systems for precise control.
As noted before, refrigeration is a necessity for many orchard growers, as it makes a big difference in the quality of the product, Ciolkosz said. “It’s all about moving heat from one space to another” by using fluid and manipulating its temperature.
Cold storage units should be well insulated. Doubling the amount of insulation can decrease heat loss by half. Insulation degrades over time, so maintaining or replacing it, as well as replacing worn strip curtains and sealing any leaks, is a good place to start saving. “It doesn’t matter how good your insulation is unless you take care of those details,” he said. “Insulation holds the cold air in. (It) works really well, unless there are leaks.”
Keeping coils and fans clean, checking refrigerant levels and using efficient fans can offer significant savings. Defrost controls, along with anti-sweat controls in doors, which decrease condensation when humidity is high, can operate only when needed, rather than cycling on regularly.
Electronically commutated motors “tend to be a really good option for energy savings” and also produce less residual heat, Ciolkosz said.
Another step would be to capture any residual heat generated by the refrigeration system with a waste energy recovery system. That captured heat can then be used to meet other energy needs on the farm. While solar, wind and biofuels are renewable energy alternatives that many farmers may wish to explore, simply taking energy efficient steps can make every orchard operation a more sustainable one.