Let's start off easy.
When I was a kid I saw a series with Alby Mangels, the Bush Tucker Man. He is a survivalist type of guy that lives his life out in the Australian Bush and Deserts. On this episode, he got fresh water by digging a hole and filling it with leaves, placing a cup in the middle, stretching plastic over the top with a rock in the middle, and then sleeping as the water in the leaves evaporated and condensed against the plastic, trickling down to fall into the cup. Genius.
Diagram 1.
I was about 7 or 8 and was wondering at what scale this idea could work at to produce fresh water to make the deserts green (environmental issues were big when I was a kid 30 years ago, lucky we solved them all...). So, I thought about if the 'hole' was a large catchment area by the sea that allowed a thin layer of salt water in and had a large black plastic sheet as the membrane for the condensation.
Once closed off, the sun would heat the water to evaporate it and the sheet would catch it and it would run into a pipe that would take it to a storage tank. From this point, it could be used for a range of purposes including creating hydroponic gardens.
There would of course also be a byproduct of sea salt in the catchment area left from the process that could be scraped away and sold for additional income.
Diagram 2.
What I am thinking is to make a very low cost system that could produce 'fresh enough' water to either grow plants or in times of need such as drought or war situations etc. Besides the scraping of the salt, it would be a relatively passive system that requires very little energy (maybe a solar pump) to produce relatively large quantities of water each day.
Potentially, there is still too much salt in the water and may require a secondary process of distillation to make it suitable for drinking.
So, before shooting it down :) see if you can answer some of these questions and consider anymore that may be necessary to get a working model up and running for testing.
Let's say the catchment area is 10 x 10 meters.
What depth of water may be optimal considering the heat of the sun in a coastal desert area.
How much fresh water could it potentially produce in a day
How much Salt in a day
Could the area be floating in the water or would it need to be secured to the land
What is a good way to get the water into a tank
Is the water pure enough to drink
Is it pure enough to grow plants in a greenhouse
How much could it grow and how many people could it support
Is it viable for a small community
Could it be done without any electricity
Ok, so there are plenty of questions and you can add your own as you see fit. This is more for the Engineering, Maths and Environment type people perhaps but it would be interesting to get any ideas that may add to the concept. If your solution is to 'buy a desalinator and put it on a solar generator' blah.... boring.
When I was a kid, I imagined ways that the system might passively pour fresh water into the deserts and over the space of centuries it would create a new localised ecosystem. As said, I am not a very bright person when it comes to these kinds of things :)
I am really hoping that people will play along with this and test their skills to see if they can solve the many various problems associated. Hopefully it generates some discussions in the comments sections of this and the linked posts. It is meant to be fun and educational!
If you write posts based on this, link them in the comments section so I can have a read and add a little value if I can. Hopefully others will too. Tag steemstem and sci-curious and we will see how this plays out.
Perhaps this is easy for some, hard for others but, everyone can problem solve and add their ideas.
Enjoy the challenge.
Taraz
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