Coolar — an electricity-independent medical refrigerator

Living off the grid, without access to stable electricity, carries consequences beyond simply not being able to switch on the lights at night. In hospitals and clinics across developing regions, the inability to rely on electricity — or a complete lack thereof — translates into profound shortcomings in the provision of life-saving treatments. 

Many vital medical supplies — including, blood, certain drugs, and vaccinations — must be stored at low temperatures in order that their properties are preserved and they work as intended when they’re needed. This necessity is typically served by refrigerators not unlike those found in kitchens. 

In a design that is essentially unchanged since the early twentieth century, conventional refrigerators rely on vapor compression systems. These typically require electricity, not least to power compressors and fans. Additionally, they rely on so-called refrigerants — chemicals which are central to cooling processes but can contribute to global warming and present challenges for safe, clean disposal of refrigerators on account of their being hazardous substances. 

Altogether, the common refrigerator is far from an ideal solution for developing regions. 

It was against this background that Julia Römer co-founded Coolar in 2014, with the goal to develop a better solution for off-grid refrigeration of medical supplies. William Steel interviewed Julia Römer for Cleanleap. 

Working with a small team of dedicated engineers, Coolar are developing a refrigerator system (see below) that runs independently from electricity, and without much of the apparatus you’ll find in your classic refrigerator. 

Nothing More Important

Coolar is a Berlin-based company in its infancy — only later this summer will its first prototype be field-tested — but the team have made great strides in development of a working model.  

Coolar’s origins begin with Römer. As an industrial engineering student specializing in technical chemistry she attended a summer school on climate innovation, and was involved in development of a cooling solution similar to that which Coolar now features. 

Reflecting on that experience, she says: “I always thought that the idea of using heat to cool things was, well, really cool. I thought this was amazing, and surely could be used in many applications. The fridge immediately came to mind — so I worked with that for those five weeks.”

“Close to the end of my masters, I continued with the idea for my thesis. But the solution remained interesting and had gained attention. We had shown the solution was technologically feasible. I thought, ‘What next? Well, I should really do something with this.’ So around spring 2014, we founded Coolar.”

“It became clearer and clearer that there was a market for this solution. And probably the most valuable good for it comes when we consider medicine and vaccines — it can save lives. There’s nothing more important.”

Now an intrepid start-up, Coolar received much needed support from the Climate-KIC — the EU’s main initiative promoting climate innovation solutions. From Climate-KIC, Coolar has received financial support, office space for its core team of seven, and an invaluable network of contacts. 

Inner Workings of Coolar

Coolar has been developed with remote and/or developing regions without access to electricity in mind. Indeed, the Coolar system’s autonomy — or ability to work independent of fixed, established infrastructure —, together with its departure from traditional refrigerants, is central to its innovation.

So how does it work? 

Coolar relies on adsorption cooling processes to cool its inner compartment. Simply speaking, when liquids evaporate they produce a cooling effect — it is this physical process that the Coolar system leverages to reduce the temperature of its storage compartment to what we’d expect inside a refrigerator.

Römer explains: “Because of the low pressure within the system, water — in the evaporator — evaporates; and as it does there’s a cooling effect. But this alone isn’t enough. So we added an adsorbent material — a silica gel — at the back. This material soaks up more water vapor, and retains it on its surface. The effect of this means more cooling — enough for our needs.” 

“As the adsorbent material’s surface fills up — and cannot hold more water — it basically needs to be dried out to allow the cooling process to continue. So at that stage we add heat — using a heat exchanger — to release the vapor. The water vapor then condenses and flows back into the evaporator to continue in the cycle.”

“It’s all a closed loop system, working with water in different phases, levering the effects of temperature and pressure differentials. So we don’t need any pumps or compression. None of that.”

It’s a smart solution, and one that the team have demonstrated in their prototypes to achieve temperatures between 2 to 8 degrees Celsius — enough for vaccines and other medical supplies. 

Römer is no stranger to adsorption based cooling technologies, having first worked with them as a student developing components providing similar cooling systems for industrial applications. “These were much larger units though,” she says. “What we’ve had to do is shrink that technology down into something more useful for a hospital or clinic.”

While the prototype pictured above goes to show the team’s success in shrinking down the technology; that design is purposefully small — for use in pitching and exhibitions. In actuality, Coolar are working with retrofitting larger, 180 litre size refrigerators with their technology. Even here though, the original dimensions of the refrigerator essentially remain the same after the team’s modifications.

Having figured out solutions to miniaturization, there were further challenges to overcome. Those industrial cooling units mentioned earlier use electricity — not an option for Coolar. 

“Because we need more than ambient, room temperature for drying the adsorbent surface, we’re using solar thermal technologies to warm water,” says Römer.

Of course, to ensure the refrigerator’s working without the sun, the team is planning on building in some added security: “We imagine incorporating a thermal water storage tank into the system, so that the fridge can continue to operate at night, and through cloudy days. We’re developing a second closed loop, autonomous system for this.”

Towards a Product

Looking towards the coming months, the Coolar team are preparing for some exciting field-testing of the Coolar system. “Our first test, towards the end of summer, will be at a climate-chamber in Berlin — that will allow us to test the system under a really wide range of conditions. After that, we’re going to install a Coolar in a hospital in Ethiopia.”

Image: The Coolar Team - Julia is stood third from the left, at the front

The Ethiopia field-testing will take place over three months and provide an opportunity for gathering vital user data about how Coolar functions. Since actual medical supplies cannot be used, the test unit will be used like a regular refrigerator, for foods, drinks and the like. 

According to Römer, this is actually an ideal situation. To help control temperatures, medical refrigerators cannot be opened up on a whim. Because the Coolar being tested in the hospital will be opened and closed far more frequently, if the system works as intended under these conditions it’ll demonstrate a very high level of functionality and durability, indicative that it’s up for the task of safely storing medical supplies.    

Römer is optimistic for the future of Coolar. The results of the climate chamber testing and field-tests in Ethiopia will undoubtedly prelude some refinements in the design of Coolar, but “soon enough,” she says, “provided everything goes well, we’ll begin to look at manufacturing on a small serial scale.” Nevertheless, more field-tests will follow on from Ethiopia, next year. There are, after all, many variations and circumstances in which Coolar technology may be applied. 

But all in good time. For now, the team has a busy schedule; not least since they’re approaching the end of their partnership with Climate-KIC and are already looking towards gaining capital to support their endeavors and getting Coolar to market. 

To that end, we’d encourage anyone interested in jumping over to Coolar’s website for more information.