this post was submitted on 04 Mar 2024
35 points (97.3% liked)
Technology
971 readers
30 users here now
A tech news sub for communists
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
I think it's all about energy efficiency. Places with no access to clean water often also have no access to reliable energy sources.
right but is this actually better than desalination plants and pipes to pump it further inland? my gut says no, this is just like several other previous machines promising to do the same thing with horrific efficiency compared to desalination plants that already struggle with efficiency. maybe 20, 30+ years in the future we will be able to use machines that directly suck water out of the air efficiently, but desalination still seems like your best bet, especially since desalination continues to improve.
Your gut is right. After a quick search, it seems that the power consumption of a seawater desalination process is less than three kilowatt hours per meter squared for a large-scale plant.
However, the downside of desalination plant will be the cost of the infrastructure and the time it might take to have it up and running. With the "water extraction from air" machine, the cost is lower(I assume) and the size is smaller(Height: 259 cm, Width: 610 cm and Length: 224 cm). Seems like it might be quick to have this MoP up and running faster than the desalination plant while costing a ton of energy in the long run.
funny that my response to you directly was so similar! I would say, back of napkin math, that desalination being over 150x efficient than these new machines would make up the deficits so extremely quickly that it's not even worth considering the long-term costs between the 2, the desalination plants beat these dehumidifiers that much more quickly.
After checking this dude's website, it needs 475 Kwh/m3 in a desert condition which is a lot of energy.
With this in mind, using the data within this website, to achieve a daily 100 kWh electricity output, the people interested in this device will require 50 to 52 solar panels, each rated at 400 Watts. Now, if we multiply this times 5, they might 250 solar panels to deliver that kind of power.
In a hypothetic scenario, what could be done to make this practical?
Unfortunately, nothing really. The thermodynamics are just severely unfavourable. Water is an amazing coolant, by far one of the best. It takes up an insane amount of energy to vapourise. That Unfortunately also means it takes up a lot of energy to turn it back.
It would make more sense to focus on developing conventional technologies and reforestation in the Sahara. That path is a lot more viable
to give you an idea of the level of efficiency we're aiming for desalination with the latest tech rn, this paper from 2020* is saying that these news techs are shooting for under 3 Kwh/m^3^ power usage. so we would need a bare minimum 158x reduction in power usage just to match the most experimental of desalination techs. Now, it doesnt need to get quite this low to match desalination because of the problem with dealing with all the waste products from desalinating waste water, but it still means we need to get pretty close to that. so, what could be done to make this practical? a leap in tech akin to the level of progress we've seen in semiconductors, which seems very unlikely to me at this point in time. so, we will needs at bare minimum, 2 or 3 decades, if not centuries (if it's possible at all) to match that.
*I admit this is just one paper I found in like 10 seconds of searching, but this matches with other stuff I've read about desalination vs de-humidification in the past. still, maybe we'll all be super surprised and there's some secret to easily drawing water out of the atmosphere that we're all missing and we'll discover and it will usher in a new age of easily accessible fresh water.