SA-born engineer's vintage fridge could be key in vaccine rollout

As countries scramble to find freezers capable of storing vaccines, one ultra-old fridge developed by a South Africa-born engineer could become a crucial element in the country's war against Covid-19.

The fridge was developed by David Berchowitz, chief technology officer of US-based firm Stirling Ultracold. The company's freezers are capable of preserving vaccines such as the Pfizer-BioNTech vaccine, which needs to be kept at -70°C.

With SA in line to receive millions of doses of the Pfizer vaccine, portable freezers will be critical equipment.

Speaking from his office in Athens, Ohio, US, this week, Berchowitz said he was delighted that his company had something to offer. "We know that Pfizer is recommending the deeper temperatures, and we have freezers that can easily achieve those temperatures," he said.

The company's fridges are powered by heat engines in which a cycle of expanding and compressing gases converts heat energy into mechanical work.

"We are the only company using this technology that can achieve these deep temperatures using very little energy," Berchowitz said.

Ultra-low-temperature freezers can typically cost from $10,000 (R145,000) to $15,000, Tim Root, marketing chief of Stirling Ultracold, told Bloomberg News.

The engines are named after their inventors, Scottish clergyman Robert Stirling and his brother James, who built their first air-operated engine in 1816. "The technology of the time could not quite deliver the promise of the invention," said Berchowitz.

The technology was forgotten until the 1960s, when a handful of scientists in the UK and US realised they could build a mechanism that could link to the cycle without any mechanical linkages.

Berchowitz, who at the time was studying aeronautical engineering at the University of the Witwatersrand, was asked by a colleague to investigate the Stirling engine technology.

As a result of his research, Berchowitz was offered a job in the US in 1979. His continued work on gas engines led to Stirling Ultracold, the company he founded in 2008.

Berchowitz had been actively working on cold-chain solutions for preserving vaccines, but the pandemic took the company by surprise. Demand for Stirling's freezer engines soared and the estimated waiting time for new orders is six to eight weeks, the New York Times reported.

Prospective investors studied Stirling's prospects, which in turn saw the company receive a capital injection of an undisclosed amount that it plans to use to buy new equipment and expand production, the paper said.

Company staff, meanwhile, have been putting in long hours to ramp up production. Stirling's South African agents have not received any inquiries yet.

Meanwhile, negotiations for SA to receive 20-million doses of the Covid-19 vaccine are still going on, Business for SA health working group chair Stavros Nicolaou said on Monday.

"The plan for 20-million doses of the Pfizer vaccine is still on the table but it hasn't been concluded," he said. "I guess government is going to look at [the vaccine's] performance with the [501.V2] variant."

Data released this week indicated that the Pfizer vaccine offers up to 90% protection against the 501.V2 variant. Deliveries of the vaccine are expected to start in the second quarter of the year.

SA also anticipates getting a further 117,000 Pfizer shots in the first quarter from the Covax facility, Reuters reported.

Pfizer said it could deliver its vaccine directly to vaccination centres in SA but did not give details on how this would be done.

While materials such as vaccines have previously been transported in containers of dry ice or liquid nitrogen, both are currently in short supply, Stirling said.

Both methods also require special personal protective equipment and training for the people handling them.