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Backup Power for Critical Refrigeration

In recent years, the storage and distribution of cold goods has become increasingly important in logistics and commerce. The ongoing pandemic has given cold-chain logistics an important role in COVID-19 response. This article summarizes the confluence between cold-chain logistics and backup power systems.

Trends In Refrigerated Grocery Distribution

Even before the pandemic, refrigerated distribution services faced increasing demand. The business press routinely spoke shortages of truck drivers and even cold storage facilities. In the interim, food retailers have seen increasing demand for fresh and organic foods ordered online, and even for preassembled meal kits. This has led to increasing demand for cold-chain logistics.

The impacts of a power outage at these facilities is spoiled product, reduced revenue, frustrated businesses, and disappointed consumers. Emergency power systems offer solutions that provide refrigeration loads with the critical backup power they need. Figure 1 illustrates a conceptual arrangement. This ASCO Power Technologies case study provides further detail.
Temperature excursions during cold-chain distribution could result in unsaleable product. In turn, business continuity planning and customer satisfaction goals could make backup power for cold storage systems increasingly important. As the epidemic spread In Spring 2020, online shopping increased across many sectors. This was true for food and groceries before declining some over the following summer months. But given the trend towards increased pre-COVID volume of prepared and fresh foods together with increases in online shopping resulting from the pandemic, it is easy to see that cold storage could be an increasingly important part of retail strategies.

Cold-Chain Refrigeration in Pharma

Many pharmaceutical products require cold-chain logistics. Through distribution to point-of-use, many medicines require cold temperatures throughout their life cycle. Along with the food industry, pharmaceutical companies have implemented monitoring solutions to ensure that temperatures stay within prescribed limits during product transport and storage. Digital data loggers that record temperatures throughout the distribution process are an important part of this solution.

Notably, bulk cold storage has been required at manufacturing and distribution facilities. Temperatures as low as -50°C (-58°F) have been required for medicines and vaccines. To this end, reliable bulk cold storage equipment requires reliable backup power.

Like the food industry, the need for cold-chain pharma transport services has risen in recent years. Shippable refrigerated equipment and dry ice-packed containers each play roles in distribution logistics. One challenge – wastage resulting from temperature excursions. If temperature guidelines are violated, vaccines cannot be used. It is estimated that some vaccines experience wastage of up to 20%, a problem that has cost an estimated $34 Billion annually.

Requirements for COVID-19 Vaccines

In November of 2020, pharmaceutical companies announced promising results for COVID-19 vaccines. These companies are working with health authorities to manufacture, distribute, and administer vaccines worldwide. There’s much to celebrate in this news, but complex distribution and storage challenges must be managed.

First, some of these vaccines must be kept very cold, at temperatures as low as -80°C (-112°F). Ultra-cold freezers and special coolers that hold dry ice are used to store and transport vaccines at these temperatures. Pharmaceutical and medical facilities are expanding their refrigeration capacities. Airlines and shippers such as DHL, UPS, and FedEx are establishing or expanding freezer farms. In the USA, some vaccines may be distributed through a government-coordinated distributor; others may be shipped overnight directly to point of use.

Additional challenges face areas of the world underserved by modern power grids and special cold storage systems. Dry ice will play an important role there, where ice-packed containers must be transported to remote areas. In the most remote areas, point-of-use facilities may need to rely on this packaging to keep vaccines viable for days.

All the elements of cold-chain vaccine distribution will increase the demand for, and importance of, dry ice. Because the unavailability of dry ice could prevent people from being vaccinated, it is important to consider whether dry ice facilities have or need access to backup power to support uninterrupted vaccine distribution.

Backup Power Considerations for Critical Refrigeration

Refrigeration systems can range from refrigerated warehouses for food storage to cold rooms and pharmaceutical-grade freezers. When specifying backup power equipment for electric-powered and compressor-driven critical refrigeration, it is important to remember that these are motor loads that can be subject to inrush currents when switching between power sources. Where sufficiently large, inrush currents can open breakers or damage load equipment. Approaches for limiting or avoiding these currents during transfer of load to an alternate power source include:
  • In-phase transfer
  • Motor load disconnect circuits
  • Delayed transition transfer switching
  • Closed transition transfer switching
More information about these approaches is available in the ASCO Power Technologies document entitled Transferring Motor Loads Between Power Sources, which is summarized in the video entitled Transferring Motor Loads.


Changing consumer preferences and a shift to online grocery retailing had increased the demand for refrigerated warehousing and logistics. With the emergence of the COVID-19 pandemic, these trends accelerated as additional consumers shopped from home. Recent vaccine developments will again increase the importance of, and the demand for, refrigerated storage solutions and dry ice. Because a successful vaccination campaign will require careful vaccine preservation, backup power systems could play an important role in avoiding spoilage that could further enable successful vaccine distribution.


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Case Study: Lidl- 50+ US Supermarkets, ASCO Power Technologies, Inc., 2019, https://download.schneider-electric.com/files?p_enDocType=Customer+success+story&p_ File_Name=asc-cs-lidl.pdf&p_Doc_Ref=ASC-CS-TS-LIDL50-US-SM, Accessed November 25, 2020.

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Covid-19 Vaccine Delivery Will Present Tough Challenge to Cargo Airlines, Wall Street Journal, October 5, 2020, https://www.wsj.com/articles/covid-19-vaccine-delivery-will-present-tough-challenge-to-cargo-airlines-11601890203?mod=searchresults_pos8&page=1, Accessed November 25, 2020.

Now, ‘Freezer Farms’ for Potential Covid-19 Vaccine Delivery, Pharmaceutical Commerce, August 4, 2020, https://www.pharmaceuticalcommerce.com/cold-chain-focus/now-freezer-farms-for-potential-covid-19-vaccine-delivery/, Accessed November 25, 2020.

How to Ship a Vaccine at –80°C, and Other Obstacles in the COVID Fight, New York Times, September 18, 2020, https://www.nytimes.com/2020/09/18/business/coronavirus-covid-vaccine-cold-frozen-logistics.html?action=click&module=Top%20Stories&pgtype=Homepage, Accessed November 25, 2020.

'Mind-Bogglingly Complex': Here's What We Know About How COVID-19 Vaccine Will Be Distributed When It's Approved, USA Today, September 8, 2020, https://www.usatoday.com/story/news/health/ 2020/09/06/covid-vaccine-complex-distribution-supply-chain-follow-approval/5712053002/, Accessed November 25, 2020.

What is a Cold Chain?, UNICEF Supply Division, Undated, https://www.unicef.org/supply/what-cold-chain, Accessed November 25, 2020.

Vaccine Storage Issues Could Leave 3B People Without Access, AP News, October 19, 2020, https://apnews.com/article/virus-outbreak-pandemics-immunizations-epidemics-united-nations-fc4c536d62c5ef25152884adb1c14168

Shortage Of Dry Ice Could Chill Coronavirus Vaccine Distribution, WBUR, September 4, 2020, https://www.wbur.org/commonhealth/2020/09/04/covid-vaccine-dry-ice-shortage, Accessed November 25, 2020.

Transferring Motor Loads Between Power Sources, ASCO Power Technologies, Inc., 2020, https://download.schneider-electric.com/files?p_enDocType=White+Paper&p_File_Name=asc-ts-wp-119-motorloads.pdf&p_Doc_Ref=asc-ts-wp-119-motorloads, Accessed November 25, 2020.

White Paper Video - Transferring Motor Loads, ASCO Power Technologies, Inc., 2020, July 22, 2020, https://www.youtube.com/watch?v=l75DQDUwvhg&t=19s, Accessed November 25, 2020.

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