3 Frozen food processing plants earn EPA’s Energy Star

With the help of efficient freezing technology such as ammonia, the three potato processing plants (J.R. Simplot Company’s Aberdeen, Idaho plant, J.R. Simplot Company’s Othelllo, Washington plant and ConAgra Foods Lamb Weston Inc.’s Quincy, Washington plant) perform in the top 25% for energy efficiency nationwide and, on average, use nearly 20% less energy when compared to similar plants across the country. Together, the plants save annually nearly 40,000 metric tons of carbon dioxide equivalent, which is equal to the emissions from the yearly electricity use of 5,000 homes.

For example, at the Aberdeen plant, sprays of hot water blanch the fries and gusts of hot air dry them before boiling oil fries them to a slight crisp. Then they are air cooled by compressed ammonia gas in order to freeze quickly. The plant size is currently 84,084 square feet of processing area, 9,836 square feet of dry storage, fiber storage and batter transfer, and 5,670 square feet of raw receiving area with a 710-ton capacity. The plant is located on 40 acres with an additional 2,460 acres of waste treatment.

Guidelines on refrigeration systems

To receive the Energy Label, the EPA recommends that plants establish a comprehensive energy management program using the Guidelines for Energy Management.

The guidelines include a section on refrigeration systems, “a significant consumer of electrical energy in the U.S. fruit and vegetable processing industry, particularly in the frozen fruit, juice, and vegetable manufacturing sub-sector”. Some of the most significant energy efficiency measures available for industrial refrigeration systems are discussed in the chapter.

According to the guidelines there are some favourable properties that make ammonia the refrigerant of choice, including its high latent heat of vaporization, its classification as a non ozone-depleting substance, the fact that it is non-corrosive to iron and steel, and because ammonia leaks can often be easily detected by smell. Hence, most refrigeration systems in the U.S. fruit and vegetables processing industry use ammonia as a refrigerant.

Suggested energy efficiency improvements to refrigeration systems that can lead to significant cost and energy savings in many fruit and vegetable processing facilities, fall under four main categories and include:

• Refrigeration System Management: Good housekeeping (For example, making sure the control settings for the refrigeration system are easy to find and interpret for ease of system tuning and adjustment, or keeping the doors to cold storage areas closed whenever possible), Monitoring system performance, Ensuring proper refrigerant charge, Checking for refrigerant contamination, Refrigeration system controls, Efficient piping design.

• Cooling Load Reduction: Piping insulation, Minimizing heat sources in cold storage areas, Reducing heat infiltration in cold storage areas, Reducing building heat loads, Free cooling, Properly sized motors, Hydrocooling, Removal of surface water before freezing, Geothermal cooling

• Compressors: Compressor control systems and scheduling, Floating head pressure control, Indirect lubricant cooling, Raising system suction pressure, Adjustable-speed drives on compressor motors, Compressor heat recovery, Dedicating a compressor to defrosting

• Condensers and Evaporators: Keeping condensers clean, Automatic purging of condensers, Reducing condenser fan use, Reducing condensing pressure, Use of axial condenser fans, Adjustable-speed drives on condenser and evaporator fans, Cycling of evaporator fans in cold storage, Demand defrost, Water defrosting