A recent project at the University of Arkansas aimed to characterise the energy uses in a broiler processing facility and to identify specific measures to improve energy efficiency.

The process of quantifying power requirements and energy usage was separated into two levels, referred to as a high level and a detailed level. The high level included analysis of 12-month energy usage records for the plant and available 15-minute electrical interval data from the utility company, in order to gain an overview of total energy consumption.

Electricity was used for refrigeration, conveyors, lighting, air conditioning, pumps, compressed air and other mechanical drives. Natural gas was used for production of steam, and further used to generate hot water for processing and sanitation, as well as for space heating.

The production process was split into individual unit operations, which were monitored in the detailed level.

The major processes include RKP (Receiving, Killing, and Picking), Evis (Evisceration), Offal (collection and removal of non-edible parts), 2nd process (sizing, cutting and deboning), pack and ship, utilities (chilled ammonia, compressed air, waste water) and boilers (steam production).

Electrical energy for each of the individual unit operations was monitored over three separate data collection intervals, each consisting of two-week periods, between November 2012 and January 2013. Natural gas energy was measured with some novel non-invasive data collection methods during April 2013.

Recorded sub-metered power consumption data on weekdays from individual unit operations matched the 15-minute interval data within three per cent, indicating that sub-metering captured the major consumption of electrical usage.

Utility usage - including the production of chilled water and compressed air - was the largest energy user of electricity, followed by Offal, RKP and Evis operations.

On a total energy (MMBtu) basis, natural gas usage for steam generation by boilers was higher than site electricity consumption.

Energy efficiency recommendations included:

• insulating steam pipes and valves
• installing an automatic blow-down system to improve boiler efficiency
• adding variable speed motors and drives to the cooling towers of the refrigeration system
• upgrading to energy-efficient lighting
• upgrading to a more efficient air compressor for the plant air system, etc.

These measures have guaranteed pay-back periods of two years, with some leveraging of utility rebate programmes.

Several additional energy-saving measures were investigated during the course of this project. Although most of the measures in this category represent viable technologies, they are either too costly to implement or are more difficult to estimate the energy savings due to uncertainty.

The addition of temperature or occupancy sensors to the cooling shed will allow the automation of the cooling fans with reduced running hours. This measure may warrant further investigation to determine the magnitude of running-hour reduction.

Because of the amount of hot water used for scalding and clean-up, it will be more efficient to generate hot water directly and avoid the intermediate step of producing steam. It was difficult to estimate the efficiency improvement of this measure due to the existing boiler system deficiencies. Recognising that this is a costly system change, it should to be considered when a boiler change-out is required.

Results from this project demonstrated that cost-effective energy saving opportunities are available in poultry processing plants and warrant investigation.

The project was carried out by Dr Yi Liang (Biological and Agricultural Engineering Department, University of Arkansas System Division of Agriculture, Dale Bumpers College of Agricultural, Food and Life Sciences) and Dr Darin Nutter and Chase Harding (University of Arkansas Mechanical Engineering Department) and sponsored by US Poultry & Egg Association.

March 2014