Grabbing Water from Thin Air
There was a robust group chat on the risk some African immigrant take in their quest for greener pastures. Some of them undertake dangerous journeys through the desert. And which often prove fatal when they run out of food and water. In a hot day, a person can lose upwards of between 1 to 1.5 litre of water through sweating per hour.
The world famous Indian nonviolent activist and leader, Mahatma Gandhi, once made food fast lasting up to 21 days at the age of 74, intermittently taking some water.
Humans can withstand up to 70 days, according to the record set up by the political prisoner, Terence MacSwiney who went without food for 74 days. A standoff that culminated to his death on the 74th day.
But staying without water is another story, I think the record for the longest a person had stayed without water is 18 days. A record set by an Austrian, Andreas Mihavecz in 1979. A mistake from the police who forgot they kept him in a holding cell underground. The record is not 100% without water as he desperately licked water off the walls of the room for survival. He lost about 24kg of his weight when another officer discovered him. He was lucky to be alive.
The human body is made up of about 60% water; the water is vital for the daily working of the various organs in the body. Hence, a stranded human is more likely to die from dehydration, lack of water, than from food.
So in the chat, a contributor sent a link to a technological company marketing a device that can fetch water from air. The device will come in very useful for both the daredevil immigrants and anyone up to an adventure along the desert. The link was to a startup called Fontus.
I immediately abandoned the conversation as I head over to the site. On getting to their webpage I saw:
WITNESS THE WORLD’S FIRST SELF FILLING WATER BOTTLE
JOIN US AND BE A PART OF HISTORYFontus
Well, I wanted to be part of that history. I decided to check on how the device plans to carry out the plan. But before I did that, a simple google search revealed that the startup had raised more than $340k from Indiegogo contribution. Indiegogo is a crowdfunding website, a goto site for many startups, charities, etc. looking for funding. That amount raised by 1438 backers surpassed the $30,000 goal by 1151%.
The product got into the Top 20 of the 2014 James Dyson Award. An annual award set up by billionaire inventor and businessman, James Dyson to reward new problem-solving ideas and innovation. MOM, an inexpensive incubator later won the award.
That development piqued my interest the more. These guys must be up to something fantastic.
The design named after the Roman god of water and springs, Fontus, is a self-filling bottle made up of a container with a cooling condenser at the top, a flexible solar mat and a storage battery.
The bottle houses the water which drips down from the cooled air which condenses the water. The flexible solar PV mat powers the cooling condensation unit. The bottle also filters out big contaminants like bugs and dust from entering the container.
When hot, humid air gets cool, it condenses and forms water droplets. The solar panel supplies the power for the cooling, much the same way the air conditioner in our homes gets its power from the electric company.
The fontus bottle, adapted for a hiking bike and has two compartments; the upper cold area, and the lower hot area.
Inbetween these two compartment is a Peltier element which provides the cooling. A Peltier element is a form of cooling/heating which employs the use of static part (thermoelectric materials), unlike the vapour-compression technique which has moving parts and therefore requires more energy to function.
A look at the claim of 0.5liter of water harvest in an hour appears too good to be true. And in my experience, most things that seem too good to be true usually ends up being just that.
A Graph of Water Saturation Over a Range of Temperatures. Image credits: By Wikipedia user GregBenson under CC-BY-SA-3.0 licence from Link]
If you take a look at the graph showing the different saturation of water over a wide range of temperature or the relative humidity, you will notice even at 100% saturation or dew point, at 40-degree Celsius there is about 50g of water is present in a kilogram of air. The quantity of water available in the air decreased by half at 50% relative humidity, i.e. we can only get 25g of water available per kilogram of air.
The claim of Fontus able to collect up to 500ml in about 2 hours runs into a snag. Imagine the weather is like 20-degree Celsius and the relative humidity is, say 30%, that means the quantity of water per cubic meter of air is less than 5g or exactly 4.3g/kg.
Remember if we assume standard temperature and pressure, air weighs in at 1.204 kg/ cubic meter (m3) under at 20 degree celsius and pressure of 1013 hectopascals (hPa).
At sea level, the water density is 1/cm3; therefore the 50g of water obtained at 100% relative density gives us 50ml of water per cubic meter of air. Consequently, it will be next to impossible to harvest 500ml at almost 16%, at 20 degree Celsius, the water vapour obtainable at that range within 120 minutes.
That aside, let us take a peep at the power requirement, a look at the fontus model shows a small flexible solar mat. I own a 14w Anker portable solar panel, and the dimension is 670 x 282 x 5mm when opened fully. A 50W solar panel falls into the average size of 505 mm x 650 mm x 25 mm.
A mere look at the solar panel in use by Fontus shows it is not up to this size, that means the capacity cannot be more than 60w.
A typical humidifier will require an energy of 1Kwh to extract about a litre of water. That is 1000w is the energy need per hour to pull a litre of water out of the air. You will agree with me that the power requirement of the "magic" water maker is far from that even with the Peltier element and all.
To be fair to them, they are not the only ones with such hard-to-achieve claims to their product; others include Waterseer, which may not work as many hoped according to this article by Popular Science, Zero Mass Water which was busted by a Youtuber etc.
The good news with all these attempts is that it pushes people to talk about it and hence draw more critical attention to the problem. The more an issue is out there, the better the chances of coming up with a solution.