Traditionally, banks of single speed fans have been used to circulate air through the pile of stored potatoes to remove field heat after harvest and to remove the products of respiration during the storage period. The highest ventilation rate is required at cool down thus the fan capacity is sized accordingly.

by Tudor Vintiloiu

Research by the University of Idaho suggests that a low constant airflow is more desirable than periods of high airflow followed by periods of no airflow.

Variable Speed Drive Fans

Variable speed drive (VSD) controllers on fans allow continuous air circulation at a lower rate during the holding periods, which saves a significant amount of energy and reduces demand loads. A 1995 study in Maine estimated a 55-60% energy savings was possible with VSD fans. A more recent study (2003) in Idaho reported energy savings ranging from 33% for potatoes stored for 60 days, up to 45% energy savings for potatoes stored more than 125 days.

The Idaho VSD study, quoted by the University of Wisconsin, reported 0.4% to 1.7% lower shrinkage losses in a side-by-side comparison of storage facilities with constant speed fans and variable speed fans. “The percentage may seem small but on a 100,000 cwt storage facility the reduction in shrinkage would provide an additional USD2000-USD8000 in income,” the researchers point out.

No differences in potato quality were observed with the use of VSD controls in any of the studies.

Sealing and Insulation

Adrian Cunnington, head of storage research at AHDB, shared some insights for assessing and improving potato stores in a dedicated webinar.

“The loss of approval of CIPC will inevitably mandate change within the potato industry. For many it may mean using alternative sprout suppressants, such as mint oil, maleic hydrazide or ethylene. Others, particularly in the fresh sector, may choose to go chemical-free, moving to varieties with a longer dormancy period, or by storing at lower temperatures. For all, though, optimizing storage conditions and reducing operating costs are likely to be high priorities. Taking some simple steps to improve store efficiency may help to offset the potential increase in operating costs resulting from the use of more expensive sprout suppressants, or greater use of refrigeration.”

You can read the rest of this article in your complimentary e-copy of the July/August Issue of Potato Processing International magazine, which you can access by clicking here.