Updated on March 11, 2024


Created on August 6, 2016


Upcoming Update

Coolar is a vaccine refrigerator powered by heat instead of electricity

Developed By
  1. Coolar
Tested By
  • Coolar
Content Partners


Product Description

The Coolar system is a medical refrigerator that uses warm water generated through solar energy to provide an affordable, durable, and sustainable solution for vaccine, medicine, and food storage in regions with unreliable or expensive electricity. Coolar is currently in a prototype stage.

Target SDGs

SDG 3: Good Health and Well-Being

Target Users (Target Impact Group)

Public Sector Agencies, NGOs

Distributors / Implementing Organizations

This product is a prototype as of June 2017 and no distributors or implementors have been established, although Coolar is in the process of teaming up with industry partners and developmental organizations like Doctor's Without Borders to bring the solution to market. Coolar is supported by Bayer cares foundation, Expo 2020 Dubai UAE and others

Competitive Landscape

Direct competitors include Sure Chill Vaccine Refrigerator BLF100 DC.

Manufacturing/Building Method

The product is still in the prototyping stage    

Intellectural Property Type

Select Type

User Provision Model

The product is not yet commercially available

Distributions to Date Status


Gross storage capacity (L)


Holding Temp (°C)

Above 0 degrees C

Holdover Time (days)


Number of Shelves


Power Requirements

Solar Heat

Vaccine storage capacity (Liters)

180 and 200 liters

Design Specifications

The Coolar system uses warm water through solar energy. The system does not require batteries or electronic components, nor rotating parts. It does not use any hazardous refrigerants or lubricants.  Coolar is designed to be economical, durable, and a sustainable solution for vaccines, medicine, and food storage in regions with unreliable or expensive electricity. It also produces 10x low carbon emissions How it works The absorption cooling cycle Evaporation Part of the water evaporates in the evaporator due to low pressure in the system. The resulting evaporation cooling effect cools the storage compartment. Absorption The absorbent attracts vapour, binds it on its surface and frees up space in the evaporator. In that space more water evaporates, so multiplying the cooling effect. Drying Once the absorbent’s surface is filled with vapour, the cooling is paused temporarily. In order for the process to be repeated the absorbent must be dried. Condensation By heating, the absorbent is then dried and all of the vapour is released from its surface. The vapour then condenses and flows back into the evaporators. This completes the cycle.

Product Schematics

Technical Support

Provided by the manufacturer

Replacement Components




Manufacturer Specified Performance Parameters

The manufacturers performance parameters are :
Grid Independent

Powered by solar thermal energy it operates independent from electricity.

Long-lasting & Robust

System requires no short-lived batteries and contains no easy to break electronics or rotating parts.


No running costs as it is powered by hot water from abundant solar heat.


CO2 emissions are 10 x lower compared to conventional fridges.


Uses no hazardous materials, which makes it unproblematic upon disposal.


Enables reliable cooling for people without access to stable electricity.

Vetted Performance Status

In the spring of 2019, The company successfully installed and operated its Coolar refrigerator prototype on the island Tenerife. During the field test, the refrigerator operated completely independent from the electricity grid and managed to reliably cool the storage compartment inside the refrigerator cabinet to below 8°C, even as outside temperatures reached up to 36°C. This is the first successful field test of a refrigerator operating with a solar heat-powered continuous adsorption cooling system that only uses water as the refrigerant.


In developing nations, up to 75% of vaccines are damaged due to storage at too high or too low a temperature. Delivering damaged vaccines does not effectively influence disease control according to Coolar website

Complementary Technical Systems


Academic Research and References

Kühn, R., Göller, C., Goerdten, P., Mähne, K., Römer, J. and Schrecker, S., 2020. Performance evaluation of a double-lift concept for an adsorption refrigerator for high ambient temperaturesISHPC 2021 Proceedings, p.69.

Hess, Jan, “Climate-KIC showcases Coolar, Prosumergy, MotionTag, Pendula and Orkess at ECO16 Berlin“, ECOSUMMIT, 2016

Coolar, “Coolar Field Test on Tenerife successful“, 2019

Compliance with regulations


Evaluation methods

Field Testing

Other Information

Coolar has won various awards including Global Innovator by Expo 2020 Dubai’s Expo Live programme

Comments from the Community


  1. Pritpal Singh says:

    minor typo in “Target regions” “followed misspelled.

  2. Steve Harston says:

    I interpret the “Safety” category differently than the owners of this product did. I don’t know which is correct but I interpret it as what are the hazards of using the device. For example, if caustic Phase Change Material is used in their ice packs or if high voltage is required to run their system than these should be called out here

  3. Steve Harston says:

    Other than a picture and a link to their website, there practically isn’t any information provided on this product. When I go to their website there is additional information and it appears that they have enough information to fill out many of the empty categories on the E4C page.

    However, in general I have concerns about this technology working sufficiently well to keep vaccines cool. Concerns include: 1. In order to get the water to evaporate you need relatively high temperatures or low pressures. This is actually quite difficult to do just by using solar power (and not using solar panels). One of our partners has worked extensively for a number of years to refine a system that boils water to power a system in Africa simply by using the sun. This was a surprisingly difficult feat and with the reduced cost and increased efficiency in solar panels it was more practical to switch to solar panels. 2. When you factor in the energy that can be practically captured by the sun, the inefficiency of the cooling cycle, the inefficiency of the cooler insulation, and the temperature that it is required to hold it is unclear if their technology is capable of meeting their reported specs on their website. 3. If they are capturing the sun’s heat, there isn’t any information or even renderings of their “heat capture” system. They haven’t addressed the size that this apparatus will need to be, how to maintain efficiency as the sun tracks across the sky, and how to address a cloudy day (or week).

    To be clear, I’m not saying that it doesn’t work — in fact, I would be excited if they did get it to work and I would want to help them make progress if it does — but based on my experience and the limited information they have provided I have doubts of this being a practical approach to keep vaccines cold. On the other hand, even if they don’t have all of the pieces figured out but they do have the adsorption element figured out it could be a great piece to be posted on the E4C website. But since it currently appears to be an incomplete system it is not sufficient to be considered a “vaccine cooler”.

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