From Watts Up With That?
Essay by Eric Worrall
If only people like International Environment and Resource Policy Post Doc Abay Yimere talked to the engineering department before discussing technology solutions.
Installing solar-powered refrigerators in developing countries is an effective way to reduce hunger and slow climate change
Published: January 20, 2023 12.36am AEDT
Postdoctoral Scholar in International Environment and Resource Policy, Tufts University
Food loss and waste are major problems around the world. When food is tossed aside or allowed to spoil, it makes economies less productive and leaves people hungry.
It also harms Earth’s climate by generating methane, a potent greenhouse gas. Food loss and waste accounts for 4% of global greenhouse gas emissions. If food waste were a country, it would be the third-largest emitter in the world, ahead of India and behind only China and the U.S.
Existing refrigeration systems release hydrochlorofluorocarbons, or HCFCs, and hydrofluorocarbons, or HFCs, which are extremely potent greenhouse gases. Producing electricity with fossil fuels to power these systems also worsens climate change. For these reasons, exporting traditional cold chains to developing countries is not environmentally and socially sustainable.
Instead, developing countries need cold chains that run on renewable energy and use alternative refrigerants with lower climate impacts. As a scholar focusing on sustainable development, green growth and climate change, I believe that expanding cold chains in the developing world – particularly sub-Saharan Africa – will not only benefit the environment but also provide important social benefits, such as empowering women.
A friend uses solar power to run his fridge – 10KW of solar panels + a battery backup, to run two household fridge freezers and a freezer. Total cost about $10,000 USD of solar panels and battery – for one family of four. Even so, he has to switch over to grid power a few times per year, when a prolonged period of cloudy weather prevents his battery charging.
The cost of the battery alone is a showstopper. Without the battery, my friend’s solar fridges would be close to useless. With the battery, they only let him down sometimes. But how many poor Africans can afford a $10,000 family fridge? Or even a $3000 family fridge?
There is a better solution – an absorption refrigerator.
Absorbtion refrigerators are simple, cheap, 1920s technology, which can be driven by any source of heat – including, but not limited to solar energy. They used to be very common – my grandpa had a kerosene powered cooler chest size portable absorption fridge he kept into the back of his pickup truck, for camping trips.
The following video from 1939 explains how an absorption fridge works.
Absorption fridges don’t need electricity, and have no moving parts, though they can use electricity to supply the heat they need to operate. A fire, normally propane or kerosene, drives a cyclic series of chemical reactions which keeps the interior of the fridge cold.
Such fridges could easily be adapted to use a wood fuelled fire box, they only need a source of heat – it doesn’t matter how the heat is produced. They don’t use CFCs, the cooling cycle uses ammonia, water and hydrogen – so they could be recharged with minimal effort in the field using cheap chemicals.
Such fridges could be assembled by a competent welder from a blueprint. Africa has plenty of skilled machine welders and metal workers, nothing gets thrown away in Africa until it is truly beyond repair. Like I said, there are no moving parts, there are no expensive, difficult to obtain components – just an arrangement of gas tight pipes and radiators.
All skilled African tradesmen would need is the knowhow to assemble the fridge, out of parts they likely already have in their worksheds.
By all means run the absorption fridge on solar power, when sunlight is available – a cheap solar concentrator would be enough, they wouldn’t need expensive solar panels. A molten salt heat reservoir, like the salt in an off peak electric powered wall heater, could possibly be used to keep the refrigerator running at night, or the owner could light up the firebox, and power the fridge from coal or wood after the sun goes down.
Of course, some of the absorption fridges might be adapted by the owners to work on fossil fuel, even if they didn’t start out that way – so maybe that rules them out as a perfect “climate solution”, even if they would be an incredibly cheap and accessible solution to Africa’s cold food storage problem.