First published in the Daily Maverick 168 weekly newspaper.

A former Potchefstroom boytjie and Wits graduate who has lived in the US for more than four decades has played a leading role at Stirling Ultracold, a company that develops and manufactures the freezers being used for the transportation and storage of Covid-19 vaccines.

Stirling Ultracold chief technical officer David Berchowitz (68) is one of the engineers behind the ultra-low-temperature freezers making headlines across the US and around the world. For more than 45 years he has devoted his professional life to the design and development of the freezers, which are driven by the Stirling technology.

Although the AstraZeneca/Oxford vaccine will be Africa’s vaccine of choice because it is believed to be suitable for healthcare systems in developing countries, other vaccines might also be used here, such as the Pfizer/BioNTech that has to be stored at ultra-low temperatures of -80°C to ensure the genetic material remains effective.

The storage and distribution of temperature-sensitive medicines such as vaccines in the cold chain involve complex logistics – being transported from one manufacturing facility to another and then to logistics sites and finally to hospitals and administration facilities. Other traditional methods of refrigeration are dry ice and liquid nitrogen, but these are rare and there is a risk that they are not viable or safe during the transportation and storage of vaccines.

South Africa faces the additional challenge of interrupted power supply owing to the ever-present threat of load shedding by Eskom.

(Photo: Supplied)

Enter the Stirling Ultracold freezers

The engine works on the principle of compressing gas that causes temperatures to rise and gas to expand. It is its expansion that causes temperatures to decrease.

Berchowitz explained: “When you press a bicycle pump, the temperature rises. If you leave it to relax, the temperature decreases. Stirling managed to separate gas in a separate way to increase the temperature and, if you reduce the pressure, lower the temperature. This is done with a free-moving piston in a cylinder. When power is applied to the engine, a heat pump is created. This… helps to transform an instrument into a cooling engine that will not damage the ozone. We use helium gas, but it is possible to use air. These are natural gases that will not damage the ozone and leave a low carbon footprint because of low energy use,” he said.

“Because it is a gas that you compress and expand, rather than a liquid… you can generate very low temperatures. We use it to get the freezers to around -86˚C…

“The freezers come in three commercial sizes to store vaccines such as the Pfizer/BioNTech, Moderna and AstraZeneca/Oxford vaccines. The temperatures required to store them are -80°C, -20°C and 2°C to 8°C, respectively. There are not many companies that can make freezers that reach those temperatures. Ours do, and they definitely use the least power, because they work on Stirling technology,” Berchowitz said.

Luggable pocket rocket

The smallest of the three freezers, the portable ULT25NEU, is currently the only freezer of its kind that can operate on power from an automotive source or with external batteries during transport.

It can store about 7,000 Pfizer/BioNTech doses with custom racking or about 5,400 Moderna doses without. Berchowitz calls this freezer option “luggable”.

The other freezer in the range is the under-counter SU105UE, which is ideal for pharmacies or clinics because it can store 30,000 doses of the Pfizer/BioNtech vaccine or 10,800 doses of Moderna.

The upright SU780XLE is being used in the giant cold-storage facilities known as freezer farms to store research materials and larger quantities of vaccines in one place until they are ready for distribution. It can store 300,000 Pfizer/BioNtech vaccine doses or 156,000 Moderna doses.

The small portable freezer costs $6,000, the medium costs $9,000 and the large costs $15,000.

By September 2020 sales of these freezers had skyrocketed.

The boytjie from Potchefstroom

Berchowitz, born, bred and schooled in Potchefstroom in North West, studied mechanical engineering at the University of the Witwatersrand in Johannesburg, earning his master’s degree in 1978.

During his years of study, he became acquainted with Stirling technology, and it is this technology that runs through his career like a golden thread.

“I published a research proposal on Stirling technology and someone from the US who was interested in the same research was on my trail,” said Berchowitz. A job offer saw him take up a position at a US company in 1979 to help develop an automotive engine that would be more efficient and capable of operating on many different fuels.

He received his PhD in engineering from Wits in 1984. A move to Athens, Ohio, and a job at Sunpower as its chief engineer provided him with the opportunity to focus on improving Stirling technology.

In 1992, Berchowitz was part of the Sunpower development team that designed a similar freezer that was launched into space inside the Discovery spacecraft. “The freezer went up with ice cream in it, and it came back with the astronauts’ pee,” he joked.

In 1995, Berchowitz founded Global Cooling BV in the Netherlands. It was an intellectual property company that focused on designing low-powered refrigerators for less developed countries.

“In many countries, the unreliable power supply and costs are too excessive to have an ordinary refrigerator, which is essential for basic health and a good quality of life. Ours could work on solar power,” Berchowitz said.

A Japanese company bought licences to manufacture a small freezer. In 2007, Global Cooling raised capital and a former Zimbabwean citizen, Neill Lane, became the executive director of Global Cooling Inc, with Berchowitz as the chief technical officer. That became the present-day Stirling Ultracold.

“Since the vaccines were rolled out, we have been battling to meet the demand for freezers from all 50 US states and nearly 155 countries, protecting more than 140 million doses of Covid-19 vaccine. All I can say is the product is coming into its own now and I’m glad things worked out for me and for us.” DM168

Marzahn Botha is a freelance journalist and photographer.

This story first appeared in our weekly Daily Maverick 168 newspaper which is available for free to Pick n Pay Smart Shoppers at these Pick n Pay stores.