As U.S. biotech firm Moderna announced this week that its COVID-19 vaccine had more than 94.5% effectiveness in clinical trials, another U.S. firm, Stirling Ultracold, is touting a novel cooling technology that can keep that vaccine at its required low temperature (-20°C/-4°F).
Stirling Ultracold’s system can also accommodate the -70°C (-94°F) temperature required by the COVID-19 vaccines developed by Pfizer, which announced a 95% efficacy rate in its trials this week. (Another refrigeration provider, Mirai Intex, is also marketing ultra-low-temperature (ULT) air-cycle systems that can handle the Pfizer vaccine.)
Stirling Ultracold is already equipping pharmaceutical companies, a delivery service, a testing facility and a U.S. state health department with ULT fridges to store COVID-19 vaccines.
“We understand that we’re in a unique position to be an integral part of a global public health effort, and we’re working around the clock to ensure vaccines will arrive to everyone safely and with as little product loss as possible,” said Dusty Tenney, CEO, Akron, Ohio (U.S.)-based Stirling Ultracold, in a statement.
Stirling Ultracold’s ULT does not use traditional vapor compression. Instead, it employs a “free-piston Stirling engine” design that uses a reciprocating piston and displacer, along with a continuous, gravity-driven thermosiphon to cool the cabinet interior. The system uses 10g of helium (R704), which is compressed and expanded in the engine, and 90g of the hydrocarbon ethane (R170), which is chilled in the thermosiphon.
According to Sterling Ultracold, its upright and undercounter ULT freezers use less than one-third the electric power of standard compressor-based ULT freezers; its SU780XLE freezer is certified by the U.S. Environmental Protection Agency’s ENERGY STAR program for energy-efficiency.
Fleet of freezers
Stirling Ultracold says it is working with several pharmaceutical companies in COVID-19 vaccine development to build a fleet of ULT freezers capable of storing the approved vaccine once available.
It is also working with the Department of Health for North Dakota, one of the four U.S. states tapped to model local COVID-19 vaccine preparedness, to ensure its communities are equipped with reliable ULT freezers.
“Our main objective is to safely deliver the approved vaccine to our communities with as little loss as possible, and for that reason ultra-low temperature storage will be an integral part of our strategy,” said George Gerhardt, Emergency Preparedness Program Representative, State of North Dakota Department of Health, in the Stirling Ultracold press release.
Stirling Ultracold is also partnering with Infinity Biologix, a genomics testing facility, which will be storing COVID-19 vaccines for New York Presbyterian Hospital, in New York City.
In September, the New York Times reported that United Parcel Service (UPS) was constructing a “freezer farm” in Louisville, Kentucky (U.S.), which contain rows of upright Stirling Ultracold freezers, each capable of holding 48,000 vials. A similar UPS center is being built in the Netherlands.
To help less developed countries that do not have the transportation and power needed to store and transport a vaccine to remote locations, Stirling Ultracold has designed a system that can plug into any 110V-240V outlet worldwide, and run on 12V DC power adapter; it is also portable, weighing 46lbs (21kg).