Such off-grid, low-carbon innovations could provide much-needed cooling methods for about 2 billion people living without reliable power or unable to afford conventional products, said Larry Bentley of Engineers Without Borders USA (EWB-USA).

The non-profit runs a competition that backs low-cost, energy-efficient cooling systems suitable for developing countries.

If the technologies work and are commercially viable, they would make life easier for the poor, from India to Mali, by helping keep food, medicine and people cool as the world warms.

“Affordable refrigeration in off-grid communities will be more than a cool drink. It will, in a small way, change the world,” because of wider benefits such as improved nutrition and education, Bentley told the Thomson Reuters Foundation.

Globally, temperatures have already risen by about 1.1 degrees Celsius above pre-industrial times and could climb further if the world does not step up efforts to curb planet-heating emissions, scientists have warned.

Warming is fast approaching the most ambitious goal of 1.5C (2.7F) set in the 2015 Paris Agreement on climate change, beyond which lie rising seas, catastrophic weather events like droughts and floods and the loss of species, according to scientists.

A recent study led by Columbia University warned that extreme heat and humidity are increasing around the globe, threatening millions of lives and economies in places where it could become fatal to work outdoors.

Surviving in these conditions would require adapting buildings to provide shade and cooling, and minimising outdoor labour during the hottest hours, experts said.

But poor people cannot afford to stop working, nor can most buy air conditioners, which use 20 times as much power as running a fan and could exacerbate climate change.

Hotter temperatures also mean fresh produce spoils more easily, slashing the incomes of small farmers.

Julian Kruger from German start-up Solar Cooling Engineering said that, on Kenya’s coast, people suffer up to five power cuts per day, and farmers selling milk or fisherman selling their catch “have a huge problem”.

The company, also an EWB-USA grantee like New Leaf, is developing a solar-powered ice-maker that can produce 100-120 kg of ice a day based on its existing cooling unit the size and weight of a small suitcase.

The new ice-maker will run on farm waste like straw, cow dung cakes, biomass pellets, wood and hay. Photo by Kevin Doncaster/Flickr

Bentley and competition co-organiser Andrew Dowdy said their passion for off-grid solutions was born from years of overseas assignments and volunteering with EWB-USA, which took them to bush clinics and accommodation in Africa and Asia that had little or no electrical power.

“Fresh bread will mould in high heat and humidity in about three days,” said Bentley, recalling a trip to rural Papua New Guinea where only one house in the whole community had solar lighting.

Last August, EWB-USA launched a $300,000 “Chill Challenge” to fund the development of prototypes for low-cost community refrigerators and ice-makers.

The focus on larger products was intentional because many people would still struggle to buy even cheap individual refrigerators, and this way, households can band together to buy them or vendors can sell the ice, the organisers said.

Earlier this month, it selected seven proposals – from India, Germany, Britain and America – out of 43 submissions.

The winners told the Thomson Reuters Foundation the grants of about $40,000 each would allow them to buy key components and accelerate technology development. Costs are still being worked out but they want their products to be affordable, they added.

New Leaf Dynamic Technologies now hopes to deliver a working product in four to five months instead of a year or two.

Its new ice-maker will run on farm waste like straw, cow dung cakes, biomass pellets, wood and hay, and use a refrigerant with “zero global warming potential”, said Akash Agarwal, who founded the company with his father.

“We have lots of ideas but to convert them into products, there’s some amount of capital needed. If there’s access to funding, we can expedite the process,” he said.

Another winning team from Imperial College London is also working on an ice-maker powered by solar thermal collectors and developed by business partner Solar Polar, which is currently being tested in the United States and India.

The final product will be a box with chambers and tubes but no mechanical or moving parts, said Christos Markides, who leads Imperial’s Clean Energy Processes Laboratory.