As I reported recently, ten towns in northern NSW and the Southern Downs in Qld are at high risk of running out of water. Indeed news.com reports that Stanthorpe could be dry by Christmas, with nearby Warwick at risk of running out in 17 months’ time.
Nature worked out how to extract water from desert air with the evolution of the Namibian fog beetle (above). The image is from my files, so I’ve posted about it before, I reckon about 10 years ago. I googled and found this article:
Along the southwestern coast of Africa in the Namib Desert where rainfall can be as little as 10 millimeters each year, four beetles have learned to get a drink from the fog that tends to roll in from the sea:
- When the fog rolls in, the beetle stands atop the dunes on tiptoe. It then sticks its rear end up into the humid morning air. Fog droplets strike and then cling to the beetle’s back. Or humidity can condense into water right on the insect’s shell. When the drops there grow large enough, they roll off the beetle’s back and down to its mouth for a refreshing drink.
A large part of the trick is in the shapes of the tiny bumps on the shells, which have flatish tops with rounded edges. Scientists have actually tweaked the shape to maximise the water extraction.
Recently New Scientist ran an article by Nic Fleming How to suck water from desert air and quench the planet’s thirst. It has another story from the Cuchumatanes mountains of Guatemala where nets up to about twice the size of a car parking space supply villagers with up to 200 litres of freshwater a day:
The article has yet another story, that of Omar Yaghi, who started life as a Palestinian refugee in a refugee camp in Jordan, where in a family of 10 you had to think of every drop of water you used. Eventually he came to be working at the University of California, Berkley, on complex synthetic materials known as metal organic frameworks (MOFs). There he came up with MOF-5, a zinc-based polymer which was stable to an impressive 300˚C. Incredibly the gaps in this material gave it an internal surface area of 2900 square metres – nearly half a soccer pitch – per gram. That was in 1999.
MOFs have a variety of industrial applications. Later in 2013 when working on another project Yaghi noticed an MOF that was especially good at absorbing water. He surveyed the field and came up with a system that looked like this:
To speed up the process a cold surface will cool the air around it and force water vapour to form droplets, but it is power-hungry.
Things have progressed from there:
- Yaghi, who recently set up a company called Water Harvesting Inc., knows he needs to think about economics as well as chemistry if his plans for a household appliance to help those at threat of water scarcity are to come to fruition. To that end, he has been testing MOF-303, which is based on aluminium, a much cheaper metal. In 2018, he reported devices based on this material could produce 230 millilitres of water per kilogram. He says he can boost that to more than 2 litres if he connects solar panels to the device and uses them to successively heat and cool it many times in 24 hours, rather than relying on day-night temperature cycles.
There are others in the field:
- Zero Mass Water, a company based in Arizona, promises to do this using large, solar-powered condensers it calls hydropanels. Two can draw around 10 litres of water per day from the air, even in arid climates, it says.
The problem the company faces is the energy required. It takes about 1.4 megajoules to produce a litre of water, roughly the same amount of energy required to boil the water for 40 cups of tea. On the other hand, the tech does away with the need for infrastructure to send water from place to place, which requires energy to install. This system is also readily scalable – to get more water, just add more panels.
- Late last year, a company called Skywell launched the UK’s first office water cooler that condenses water directly from the air. In future, the firm plans to sell an industrial unit big enough to serve a small town.
Their target market ranges from office water coolers to small town supply, to food production.
I don’t know about the economics, but I do believe that electricity in the post fossil fuel era will be plentiful and cheap.
A Saudi wind project has announced what it says is a world record-low onshore wind levellised cost of electricity (LCOE) of 1.99 US cents per kilowatt-hour (kWh).
Australian utility Alinta Energy is ramping up its push into renewables, citing stunning low costs that will enable dispatchable wind and solar to compete with existing fossil fuel plant.
Apparently these ‘water from air’ technologies only need 20 per cent humidity as a a threshold for viability.
The NS article says the United Nations estimates the number of people living in areas of absolute water scarcity, where available supplies are insufficient to meet demand, will rise from 1.2 billion in 2014 to 1.8 billion in 2025.
Hence the potential is large. Perhaps some Australian towns would do well to investigate the potential, especially for vital services, such as hospitals.