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Coolar: refrigerators powered by heat instead of electricity

Berlin, Germany
Year Founded:
Organization type: 
for profit
Project Stage:
$100,000 - $250,000
Project Summary
Elevator Pitch

Concise Summary: Help us pitch this solution! Provide an explanation within 3-4 short sentences.

When electricity is scarce, reliable cooling of medicine and vaccines poses a challenge.
Coolar turns the problem - heat - into the solution, by powering a refrigerator with 60°C hot water (i.e. from solar heat) instead of electricty!
It's the most reliable, sustainable & economical refrigerator.

WHAT IF - Inspiration: Write one sentence that describes a way that your project dares to ask, "WHAT IF?"

What if reliable and sustainable cooling could be made available to everyone - improving basic health care and dietary options for people living off-grid - without the use of CO2-intensive generators or hazardous batteries and refrigerants?
About Project

Problem: What problem is this project trying to address?

1,4 billion people in the world have no electricity, many more only have unreliable access. This also means no access to cooling. Cooling however is needed for storing lifesaving vaccines and medicine. In developing regions up to 75% lose potency because of faulty cooling before they are used. Cooling is often CO2-intensive (10% of global emissions), without stable electricity grids pollution gets worse due to generators and hazardous batteries.

Solution: What is the proposed solution? Please be specific!

By evolving adsorption refrigeration technology from industrial scale applications to fit "small" applications like refrigerators, Coolar has developed a cooling system that can tap into heat from any source to power a normal refrigerator with 60°C heat instead of electricity. Coolar's system can tap into a variety of heat sources, but the most abundant source for powering medical refrigerators in developing regions is heat from the sun. Wherever electricity is scarce or not available at all, energy storage is crucial. As the system is powered by hot water instead of electricity it can use robust and reliable isolated water tanks to store energy - no hazardous batteries needed! It uses water as refrigerant and contains no moving parts!


EIT Change Award 2015 - Coolar co-founder Arno Zimmermann was a nominee; Off-Grid Experts Award 2015 - nominee in the category "best product"; JJ Darboven IDEE award 2015 - 2nd place; StartGreen Award 2015 - finalist (final is on Nov. 19th)
Impact: How does it Work

Example: Walk us through a specific example(s) of how this solution makes a difference; include its primary activities.

Imagine a remote health centre in Mali. It has no connection to a central electricity grid and relies on a diesel generator for power. The vaccine refrigerator consumes most of the electricity. Until 3 months ago, they had a photovoltaic system, and did not have to rely on expensive, often delayed fuel delivery. About once a year the batteries gave in to the hot climate and had to be replaced, but overall it was a much more cost-effective system. 3 months ago the in-demand photovoltaic collectors were stolen over night. The manager won't invest in new ones, just to have them stolen again. Coolar provides the solution. It stores energy in solar hot water tanks that are much more robust than batteries, it is cheaper, and noone will steal it.

Impact: What is the impact of the work to date? Also describe the projected future impact for the coming years.

As specified in the example, most remote health centres and communities rely on diesel generators or photovoltaic to power refrigerators. These need short-lived, expensive and hazardous batteries or expensive and often unreliable fuel supply. Coolar allows those centres to save money on batteries and fuel, prevent pollution from discarded batteries and mitigate CO2 emissions from generators. Furthermore, as the Coolar system uses water as its refrigerant, it has a no-freeze guarantee. This is a big advantage, considering that currently 30% of vaccines spoil due to accidental freezing in the cold chain in developing regions. Deploying Coolar refrigerators will not only improve the current health systems energy efficiency and reliability. It will also establish a precedent for a "green" alternative cooling technology that could inspire a more sustainable development path for the region.

Spread Strategies: Moving forward, what are the main strategies for scaling impact?

Coolar is aiming to get the World Health Organization's PQS certification to have its system approved as grid-independent medical cold storage system. With this Coolar can supply refrigerators to large organisations that provide procurement services to remote health facilities around the globe (i.e. UNICEF supply division). With this reach it will be possible to extend basic health care to regions in >50 nations. Coolar will test 5-10 units in pilot projects with our partners - representatives of the Philippine's department of energy, Doctors without Borders and Health Builders - in 2016.

Financial Sustainability Plan: What is this solution’s plan to ensure financial sustainability?

Coolar will be able to sustain itself via the revenues it generates through the sale of medical cooling systems to developmental organisations and national health agencies. Long-term Coolar is aiming to cooperate with a large player in the domestic refrigerator market and generate revenues i.e. through licensing its technology. The money earned in richer countries will then be channeled into donating additional medical cooling devices to projects

Marketplace: Who else is addressing the problem outlined here? How does the proposed project differ from these approaches?

There are a couple of technologies availlable to provide off-grid refrigeration. However, all of these require electricity, which in remote areas is susceptible to outages.Right now projects in remote regions require either a steady supply of fuel for a diesel generator, which is expenisve and hard to guarantee, or a photovoltaic system with batteries, that tend to break within 1-2 years in hot climates, are environmentally hazardous, as well as expensive and hard to replace. As Coolar's system is powered by hot water it can tap into the abundant solar heat and store energy in isolated tanks.

Founding Story

Coolar's inventor Julia Römer first contemplated applying adsorption refrigeration technology, that she knew from engineering components for industrial-scale adsorption chillers in a previous employment, in 2012. She attended an entrepreneurial summer school hosted by the EIT Climate-KIC programme for EU clean-tech innovation and thought a refrigerator as the application, where this ecologically sustainable cooling process could have the biggest impact. The idea wouldn't leave her mind and she later decided to devote her industrial engineering master's thesis to a technological feasibility study of her idea. The outcome was promising, in 2014 upon graduation she started building a team.


Julia Römer - Co-founder responsible for technology development Julia is an industrial engineer by training and the inventor of the Coolar adsorption refrigeration system. Together with Arno she initiated the project in the summer of 2014. She has previously developed patents for industrial-scale providers of alternative cooling technology and is furthermore very active in sustainability and environmental protection related advocacy. She is a member of the board at Germany's largest environmental NGO, the BUND (Friends of the Earth Germany). Arno Zimmermann - Co-founder responsible for product development Arno is an expert in ecologically sustainable product development, which he consulted on during is time at Ernest & Young and principles of which he applied to product development projects that he worked at in Nest Labs (before it got acquired by Google) and Bayer AG. His position at Coolar makes him a serial entrepreneur, as he also was a co-founder of CupCycle - an eco-friendly coffee cup rotation and recycling project - where he and his team realized a succesful exit. Christoph Göller - Co-founder responsible for business development Christoph's background is in business, economics and China studies. He has previously worked in product marketing and marketing at Bosch in Taipei, where his team also marketed compressors for cooling applications across the entire Asia-Pacific region. He is very passionate for the marketing of technology products. After joining he was the first to identify the opportunity the Coolar system can realize in developing regions and delivered research that proved it a feasible business model. Kilian Mähne - Co-founder responsible for manufacturing and quality control Kilian is a talented craftsman that has previously maintained a glider clubs entire fleet of glider planes, is a mechanical engineer by training and contributed most to building Coolar's first prototypes. As an engineer with a focus on automotive technology he is knowledgeable when it comes to large-scale production and quality management and is currently working on preparing the Coolar system for series production.
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