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
Abay Yimere
Postdoctoral Scholar in International Environment and Resource Policy, Tufts UniversityFood 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.
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Expanding food cold chains to the world’s least-developed countries can have enormous impacts. But it also raises concerns if it’s not done in a way that avoids contributing to climate change.
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.
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Read more: https://theconversation.com/installing-solar-powered-refrigerators-in-developing-countries-is-an-effective-way-to-reduce-hunger-and-slow-climate-change-195143
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.
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Most recreational vehicle refrigerators use this system because of the simplicity. It’s easy to have three way power so they can run on gas, 12 volts DC or 110 volts AC. Gas uses a small flame while both electric modes use a small resistance heater.
Ther has also been a revolution in micro sized compressed gas cycle refrigeration. A few years ago the US military put out a contract for a very small refrigeration compressor. But then whomever ordered it canceled the order. I assume the project it was for got cut.
So the companies who put the time and money into developing the new compressors put them into production for the civilian and industrial market.
That’s where all those portable 12V refrigerator/freezers that use a tiny compressor instead of inefficient Peltier modules came from.
The compressors are so small that Adam Savage used one to build a refrigerated cooling unit he could fit in the backpack of a spacesuit costume he’s making, and it’s efficient enough to keep a person cool for hours using a lithium-ion battery.
Refrigerators? Before they have reliable electricity?
Even a discussion of work-around engineering seems quaint but impractical.
The cart of consumer goods will follow the horse needed to pull it. For electricity that means fuel, generators, long delivery infrastructure and “last mile” hook ups. That technology will govern what Africa looks like in the future. Estimates online suggest that around 40% of the people in Africa have no access to electricity.
They are now where China was in the first half of the 1900’s, dreaming about the “big” (important) consumer items: a bike, a watch and a manual sewing machine (70’s in China). A decade later the “big” list had grown to five: a refrigerator, sewing machine, bicycle, TV and a washing machine.
China was electrified by the 1950s, by which time U.S. citizens had most of these things, but it took them 30 more years after their infrastructure was in place to actually be in a position to buy such goods. Now, with 100% electrification, Chinese urbanites rival our own for their wealth and consumer spending. They own cars, second apartments, take vacations in Vietnam (when Xi lets them out of their houses), and spend leisure hours on WeChat.
Cart before the horse.
There’s a California couple who recently relocated to North Idaho. They had a successful shop doing custom work on off road vehicles, did some AirBnB rental, flipped a few houses (did one on a TV show), built and sold a shipping container house, and various other stuff, much of it they covered on their Ambition Strikes YouTube channel.
At their Idaho property it would have cost $20,000 just to bring a power line to the place. Then there would have been the costs of connecting it up plus the never ending electricity bill.
They opted to spend $50,000 on a large solar array and battery bank, big enough to power arc welders and a CNC plasma cutting table.
They recently found out just how long their system would last in constant overcast conditions. Two weeks before it shut down. But they’d planned for that with a military surplus diesel generator. In five hours the generator had their battery bank recharged, while also running whatever they were using in their house.
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
yeah sure. and cows consume thousands of gallons of water. same garbage thinking. i suppose it’s a good thing rotting vegetation on the forest floor doesn’t generate CO2 or methane.
Believe me, where people are starving, there is no food waste. Zero. There are no left overs. You dont need fridges.
Many RV’s and boats have absorption fridges. The Amish also love them, they can build them in their own communities and run them off biogas. I live in a small RV, and I used one for years until the coils blew. (they rely on gravity to cycle, thus are a bit sensitive to being tilted. An occasional issue in an RV, not so much in a stationary application)
I’m currently using a 12v electric fridge, running (mostly) off solar, no less. that chews up about 300Wh of power a day. You’d need at least a 150w of solar panels and about 2.4kwh of battery to run that reasonably , You *could* build that DIY for $600-700, but you would be swapping batteries every year or two. I have 3 times that in solar and twice the battery, with batteries that will last years, and I feel comfortable leaving it run for a few days if I’m not in the RV, but my system cost $2700, and I *still* had to run the generator several times last week because it was unusually cloudy all week. Solar is very nice for the right applications, but you do have to understand it’s limitations.
Also, to correct a minor bit of incorrect info above: The mechanism of absorption fridges isn’t chemical. It’s pretty much just physical phase change. To understand how they work, imagine cooling a room with a swamp cooler. You blow air over a wet pad, the water evaporates, and cools the room. Except, now the room is humid, so you put a bunch of that desiccant crystal stuff in the corner to suck up the excess humidity. When the desiccant is saturated, you take it outside and heat it up to drive off the water. Being frugal, you put something on the pot you are heating the desiccant in to re-condense the water being driven off back into a liquid. Then you bring the re-charged desiccant back to your room, and pour the water back in your swamp cooler. Ta-DA!, you have a closed cycle. This is exactly what an absorption fridge does, except they use liquid ammonia because it freezes at a much lower temperature, so you can run a freezer. (the water in such a fridge is actually the “desiccant” for ammonia. Which is handy, since it’s a liquid, and you can circulate it past the the heat source by natural convection, without moving parts, like pumps. )
Don’t tell this any fridge making company.
They will hire a killer.