Electricity-independent medical refrigerators

Coolar is raising investment to pilot electricity-free cooling systems powered by solar heat

The Coolar system uses warm water that is easy to generate through solar energy and easy to store in a water tank. It does not require any short-lived batteries or electronic components, nor rotating parts. It does not use any hazardous refrigerants or lubricants.

This way, the Coolar system can provide the most economical, durable and sustainable solution for vaccine, medicine and food storage in regions with unreliable or expensive electricity.

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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.

Coolar’s system powers refrigerators that run independent from the electricity and instead with hot water from solar heat, which makes them close to carbon neutral.
The refrigerator will enable doctors and health professionals to preserve lifesaving medicine and vaccines in a reliable and eco-friendly way.
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The Adsorption Cooling Cycle

1. 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.

2. Adsorption

The adsorbent 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.

3. Drying

Once the adsorbent’s surface is full of vapour, cooling temporarily pauses. In order for the process to be repeated, the adsorbent has to be dried.

4. Condensation

By heating the adsorbent is dried and all vapour is released from its surface. The vapour condenses and flows back into the evaporator, which completes the cycle.

Seeing Is Believing

Helping health workers preserve lifesaving medicines by providing electricity independent refrigerators.

Watch our founder and CEO Julia Römer explain our mission for the Cartier Women’s Initiative Awards 2018.

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