Adding Value

Practical tips for improving profitability in storage

Published in the December 2010 Issue Published online: Dec 09, 2010
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"Value added" has become an often-used buzzword in business today. In a general sense, this is the concept of enhancing or improving the value or worth of something. Whether it's trucks, tractors or potato storage facilities, this idea of `value added' is utilized to maximize profitability. With this concept in mind, many opportunities exist for potato producers, packers and processors to add value to their storage facilities. Investing in climate control equipment, meaning ventilation, refrigeration or control systems-or even modernizing storage management practices-are great ways to "add value" and improve overall profitability.


Upgrade Humidification Equipment

Weight loss, or shrinkage, reduces returns from storage by diminishing both the quantity and quality of marketable potatoes. Shrinkage is often just ignored or accepted as a fact of life, but reducing shrink losses must be a top priority in order to maximize potato quality and profits. Many factors influence shrinkage, but the most critical is the relative humidity (RH) of the storage environment-particularly in the first weeks following harvest. Stored potatoes lose weight by giving up water to the surrounding air (transpiration) and through the process of respiration. Although both processes contribute to the total weight loss, transpirational water loss is by far the greatest contributor. It is important to recognize that transpirational water loss cannot be stopped-only slowed by maintaining high RH levels and providing potatoes with the appropriate volume of airflow.

RH can be simply defined as the amount of moisture (water vapor) in the air at a given temperature, relative to the maximum amount possible at that same temperature. The key to minimizing shrinkage is to establish and maintain the desired RH level throughout the duration of storage. Current Agri-Stor recommendations suggest that a plenum RH of at least 90 percent, and preferably greater than 95 percent, should be maintained. This recommendation assumes that the crop is healthy, with minimum potential of postharvest disease. Humidity management for wet, frosted or diseased potatoes is a complex topic and should be discussed with your professional ventilation system provider.

In order to achieve these recommended RH levels, the storage facility must be equipped with adequately sized and properly functioning humidification equipment. Specific equipment may include ClimaCell evaporative cooling/humidification systems, centrifugal humidifiers and nozzle-based systems. Bear in mind that all humidification equipment on the market today is not created equally. Quality equipment will truly humidify the ventilation air, not simply soak your plenum or ducts with free water. Quality humidification equipment will also operate efficiently and have a long service-life. It is absolutely critical that storage humidification systems have the capacity to meet peak humidity-demand-typically fall and spring/summer-and that all components are functioning properly. Undersized or poorly functioning equipment will have a serious impact on shrinkage, pressure bruising and your profitability from storage.

Keep in mind that excessive shrinkage levels and incidence of pressure bruising go hand-in-hand. Taking steps to reduce shrinkage will also help to minimize pressure bruising. Contact your professional ventilation system provider to evaluate your storage humidification equipment and maximize your profits. An investment in your humidification system will yield returns for many years to come and is a great way to "add value" to any storage facility.


Utilize VFDs

Installing and utilizing energy-efficient ventilation equipment is another opportunity to add value to your storage. Rising energy costs and the availability of incentives or cost-sharing programs from many utilities/energy providers have created a very cost-effective climate for energy efficiency upgrades.

Ventilation system operation is a key factor impacting energy use efficiency and overall profitability from storage. Variable frequency drives (VFDs) are a tool in the storage manager's toolbox that allow for the precise control of fan speed and, therefore, airflow volume supplied to the stored potatoes. For example, a storage fan operating at 80 percent speed will provide about 80 percent airflow, but will reduce energy use by half. A more dramatic example of potential energy savings can be seen with a fan operating at 50 percent speed. This fan will provide about 50 percent airflow, but will reduce energy use by nearly 85 percent.

VFD use allows the storage manager to match the changing airflow requirements of the potatoes over the course of the entire storage season. It is important to recognize that the amount of airflow required at harvest or through the curing phase may be totally different than the amount of airflow needed during winter holding. By matching the airflow delivered to the potatoes with exactly what is required to optimize potato quality-damaging over- and under-ventilation can be eliminated. Modern control systems, such as Gellert's Agri-Star control panel, can assist the storage manager by continuously monitoring the storage environment, automatically adjusting airflow to provide the potatoes with the needed airflow volume for optimum quality and maximum energy efficiency. These control systems will also provide a constant stream of data regarding the storage environment that can be used to evaluate potato health and make the most informed storage management decisions.

When utilized correctly, VFDs can substantially reduce your power bill and help to minimize unnecessary shrinkage and pressure bruising. Data from the University of Idaho, University of Wisconsin and industry sources have documented tremendous benefits from integrating VFDs into nearly all storage facilities.

The positive impact of "adding value" to storage facilities cannot be overstated. Growers, packers and processors that evaluate their storages and storage management practices and implement the needed changes will recognize that they are also adding value to their crop.