Evaporative Cooling Can Combat Food Loss

Covering an evaporative cooling chamber.
Covering an evaporative cooling chamber.
Empowering People.Network

Blog post as originally posted by Empowering People.Network


Food insecurity remains one of the most burning development challenges, as Food and Agriculture Organization notes – roughly one-third of the food produced globally gets lost or wasted every year. Whilst in the developed world it is mostly a waste journey from refrigerators to landfills, for millions in the developing regions, it is lost in farms due to poor storage, pest infestations and lack of uninterrupted energy or appropriate transportation. Simple evaporative cooling technologies have come a long way to significantly address these challenges, yet the application of this approach has been stunted with misconceptions and lack of investment. Eric Verploegen is a research engineer who leads MIT D-Lab’s research on evaporative cooling for vegetable preservation, breaks down the myths around evaporative cooling and suggests approaches that benefit underserved communities.

What is the significance of evaporative cooling in developing regions?

In developing regions with hot and dry climates, evaporative cooling technologies have the potential to provide a cost-effective solution for preserving certain products such as vegetables and leafy greens. These technologies are particularly attractive when cooling technologies that rely on electricity are either not available or not affordable.

How did you realize that this is best suited for developing regions?

There are a lot of misconceptions about the suitability of evaporative cooling technologies. It is well established that evaporative cooling is only effective when the ambient relative humidity is low and that there are limits in the temperature decrease that can be achieved. A portion of D-Lab’s work on this technology is specifically focused on suitability research and communications. I am equally interested in giving people advice on when not to use evaporative cooling – it is not appropriate for storing meat, dairy, or medicine (not cold enough), and can’t be used for anything anywhere that it is cool and humid. To help communicate all the important details about how and how not, where and where not to use evaporative cooling, I co-authored the  Evaporative Cooling Best Practices Guide (2018), which includes a section outlining the suitability of evaporative cooling technologies. Also, it is worth noting that more sophisticated machines that reply on the principle of evaporative cooling are widely used in highly-developed economies for many industrial, commercial, and residential applications.

Eric Verploegen (seated) kicks off an evaluation of evaporative cooling technologies with researchers at the World Vegetable Center in Bamako, Mali. (Photo credit: Lauren McKown)

With the long history of this technology, why is it still not a widely used cooling solution?

While a majority of people in many arid regions such as the West African Sahel already use evaporative cooling methods for storing and keeping drinking water cool, awareness is low about its suitability for preserving specific vegetables, fruits, and leafy greens. Furthermore, there is a lack of locally-relevant information on how to construct evaporative cooling devices and few businesses are distributing affordable and effective products in the regions where they can provide maximum value.

Do you think there are any new approaches that could increase the uptake of evaporative cooling techniques?

Yes, there are over 100 million people living in the rural areas of the Sahel, and combined with other arid regions of Africa and South Asia, there is a large enough market for these technologies.

The approaches used at varying scales can be grouped as follows:

World Vegetable Center staff members installing a data logging sensor on a clay pot cooler in Mopti, Mali. (Photo credit: World Vegetable Center)

  • Dissemination of information directly to users for ‘Do IT Yourself’ construction and use through digital channels (best practices guide, videos, etc.), extension agents, and training workshops.
  • Training and support to local entrepreneurs for the construction and sales of evaporative cooling devices.

We are working with partners to explore the efficacy of training workshops including ones that teach the construction and use of a specific clay pot-in-pot cooler design along with a combination of general design skills and the basic principles of evaporative cooling to enable participants to construct devices from locally available materials. Another training workshop combines instruction on the construction of evaporative cooling devices with business and entrepreneurship training focused on selling evaporative cooling devices in local markets

Where have you successfully tested and implemented cooling systems? Is it easy and practical for the local community to replicate it in large numbers?

In partnership with the World Vegetable Center, we conducted an evaluation of evaporative cooling technologies for improved vegetable storage in Mali. The results showed that clay pot coolers and brick evaporative cooling chambers of various designs improved the shelf life of vegetables by providing a stable storage environment with low temperature and high humidity, and the additional advantage of protection from animals and insects. The typical evaporative cooling designs are easy to construct if guidance is provided. But we haven’t yet quantified the kind of scale of use that can be reached through training – that research needs to be undertaken and is part of my five-point call to action. Building an evidence base of what does and does not work is critical to advancing the use of evaporative cooling. We are currently collaborating with organizations in Kenya, Nigeria, Burkina Faso, and Gujarat, India to test the performance of locally-made devices and looking to expand distribution efforts so that their usefulness can be evaluated.

You are exploring collaboration with epNetwork member Evaptainer, what is the potential of entrepreneurial models for disseminating these technologies?

Models ranging from locally made products sold by local entrepreneurs to mass-manufactured products sold globally have the potential for scaling the use of evaporative cooling. We are working with our partners to identify who can benefit from these technologies and what specific products and distribution models are best suited for those potential users. Some people may be best reached through agricultural extension programs with information for constructing cooling devices with materials they already own or can easily acquire, while for others, buying a customized evaporative cooling chamber from a local entrepreneur might be preferable. And in some case, purchasing a lightweight mass-manufactured evaporative cooling device like the Evaptainer might make the most sense.

How far do you think this technology can go to provide a long-term answer to fight hunger?

The unrealized potential for evaporative cooling to reduce food loss, increase access to nutritious food, and increase incomes is significant. Unfortunately, very little attention and very few resources have been directed towards this. Investment in developing and researching as well as dissemination approaches are critical for increasing confidence among users and the development sector actors. The sector should be working towards a broad understanding of where and how this technology can be applied, by gathering examples of success stories and resources for learning, replication, and fostering a community of individuals and organizations that can serve as ambassadors for these solutions. Embracing this approach – and mobilizing significant and targeted investment – will enhance large-scale outreach.


Eric Verploegen, Research Engineer, Food-Water-Energy Lead, joined MIT D-Lab in 2014 to expand its research efforts in the area of off-grid energy. Currently, his two main areas of work are related to evaporative cooling for vegetable preservation and D-Lab’s Energy Needs Assessment Toolkit, supporting organizations to identify the most pressing energy needs in the communities where they work. He has a background in materials science and received his Ph.D. in Polymer Science and Technology from MIT in 2008.

Blog post as originally posted by Empowering People.Network


Eric Verploegen, MIT D-Lab Research Engineer