Coolar’s solar-powered refrigerator uses water and adsorption technology rather than compressors.
Artists impression of how a Coolar unit would look at a remote health clinic. Credit: Coolar.
Two decades ago, Greenpeace and the United Nations Environment Program developed Solar Chill, a solar-powered vaccine chiller based on a compressor system using isobutane refrigerant. Since then, about 100,000 have been deployed in remote, off-the-grid locations around the world.
German startup Coolar, based in Berlin, has taken a different approach, developing a new solar-powered refrigerator that uses only water and adsorption technology to achieve stable cooling for vaccines in off-the-grid locations.
Coolar plans to ask the World Health Organization (WHO) for approval of its technology after receiving feedback from pilot tests in Kenya later this year. Given the need for an eventual COVID-19 vaccine throughout the world, its timing couldn’t be better.
The idea for the Coolar technology came to Founder and CEO Julia Römer in 2014 while she was studying for a degree in industrial engineering at the Berlin Institute of Technology (Technische Universität Berlin). For her Master of Science thesis, she investigated the idea, based on the theoretical possibility of scaling down industrial-sized adsorption systems to something refrigerator-sized, suitable for vaccine storage, and other medical uses, anywhere in the world where electricity is a scarce commodity. She concluded that it was feasible, and Coolar was born.
The first fully functioning prototype – a single-cycle mini-bar refrigerator demonstrator – was ready at the end of 2015. That was the year she won second prize (€10,000/US$11,292) in the Darboven Idee Competition for women with promising business concepts.
Since then the Coolar team has worked on improving its prototypes, demonstrating compatibility with 32°C (89.6°F) ambient temperatures in 2018, and recently showing compatibility with outside temperatures of up to 43°C (109.4°F).
The company carried out a successful field test in Tenerife (in the Canary Islands) in the spring of 2019. An upgraded vaccine refrigerator prototype will be tested this summer in Berlin, and later in different locations in Kenya, once worldwide COVID-19 travel restrictions have been lifted.
Funding for the test, and for bringing it to market, comes from the European Union’s Eureka Eurostars research and development funding program, with additional funders as well.
One of the important criteria for vaccine cooling is to achieve a stable temperature between 2°C and 8°C (35.6°F-46.4°F). “If [vaccines] are getting too warm, they deteriorate, but if they freeze they're dead so you cannot do anything with it,” Römer explained. “Normal refrigerators have evaporator temperatures under zero degrees, like -15°C to -20°C, so you can easily freeze vaccines, or cool them way too far, whereas our system is a naturally freeze-free alternative.”