Simple, solar-powered water desalination (2020) • Hacker News Board

Re: Simple, solar-powered water desalination (2020)

#171

Post by kevmo » Fri, Jul 02, 2021, 2:52 PM UTC

underwater wrote: post #52

rorykoehler wrote: post #44

Would it be possible to re-green deserts with this technology? Does anyone know of any studies on using this technology to combat climate change?

Yishan Wong, of Reddit CEO infamy, has been working on this for a few years: https://www.terraformation.com/

I seriously considered taking a job there (I did not for personal reasons, namely not wanting to move) and would recommend looking at them to others.

I think they are poised to be a key player in the forestry and reforestation space in the next 2 decades.

Re: Simple, solar-powered water desalination (2020)

#172

Post by walrus01 » Fri, Jul 02, 2021, 2:53 PM UTC

> which was tested on an MIT building rooftop. The system delivered pure water that exceeded city drinking water standards, at a rate of 5.78 liters per square meter

I would be very interested to see data on this vs. sunlight and climate conditions, in what weeks/month of the year they tested it. I think its effectiveness would be highest at MIT's location from late April to end of September and considerably less in colder/overcast/less sunny weather and winter.

Re: Simple, solar-powered water desalination (2020)

#173

Post by kingsuper20 » Fri, Jul 02, 2021, 3:01 PM UTC

tromp wrote: post #14

carl_dr wrote: post #2

This device "could" produce 1.5 gallons per day, per square metre of solar collecting area. The researchers estimate a system suitable for a family might be built for $100, so double or triple that after profits etc. I assume that the 1.5 gallons was the highest yield they would have had from a single day, had they had a 1 square metre solar panel, and the expected average yield would be less (accounting for cloud co…

The article says "per hour", not per day. Although that would seem able to support dozens of users rather than just 1.

The average US citizen uses 82 gallons of potable water per day.

Re: Simple, solar-powered water desalination (2020)

#174

Post by kingsuper20 » Fri, Jul 02, 2021, 3:02 PM UTC

celticninja wrote: post #99

londons_explore wrote: post #82

Earlier quoted context omitted.

'drinking water' often doesn't mean the water a human literally drinks, but all the clean water necessary for living everyday life (bathing, flushing toilets, washing dishes, cleaning clothes, cooking etc.).

I am pretty sure if you had to get your water from one of these devices you would not be using it to flush toilets or other non-essential use. And actually it does seem like 'drinking water' is actually drinking water and not for all those other uses you mentioned. As 3.7 litres is the amount required for a human male each day. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-h...

>I am pretty sure if you had to get your water from one of these devices you would not be using it to flush toilets or other non-essential use.

Are you suggesting that toilets, showers, washing machines use salt water?

Re: Simple, solar-powered water desalination (2020)

#175

Post by dfilppi » Fri, Jul 02, 2021, 3:10 PM UTC

dystroy wrote: post #149

throwaway894345 wrote: post #147

Earlier quoted context omitted.

Why not release the salt back to the sea? Presumably it would not increase the salt content of the ocean very much considering the vastness of the ocean and the sheer quantity of fresh water that is being added to it by melting glaciers, etc? What am I missing?

The salt you release isn't instantly diluted in the whole ocean and we're speaking, for a plant, of millions cubic meters of salt enriched water per day. The release area is just dying.

That is acceptable

Re: Simple, solar-powered water desalination (2020)

#176

Post by [deleted] » Fri, Jul 02, 2021, 3:13 PM UTC

tonyhb wrote: post #169

civilized wrote: post #159

Earlier quoted context omitted.

>> malignant cancer > it's nice come on dude, have some self-awareness

The only thing I was saying is - just because humans can live everywhere doesn't mean we need to. If you look at any map of the modern world, there is almost nowhere that we haven't transformed into farmland, cities, etc, and it's pretty good (nice) that we have left the uninhabitable islands to nature. We've consumed most of the land, which is both pretty amazing and also quite bad for biodiversity, as everyone know…

[deleted]

Re: Simple, solar-powered water desalination (2020)

#177

Post by SV_BubbleTime » Fri, Jul 02, 2021, 3:15 PM UTC

kevstev wrote: post #166

throwaway894345 wrote: post #147

Earlier quoted context omitted.

Why not release the salt back to the sea? Presumably it would not increase the salt content of the ocean very much considering the vastness of the ocean and the sheer quantity of fresh water that is being added to it by melting glaciers, etc? What am I missing?

Why not just collect the salt, and sell it as... salt? Even if its not ok for cooking, it should be fine for roads? I am sure there are other industrial uses for salt.

Actual salt is rarely used on the roads in the USA anymore. Majority use magnesium chloride now. Don’t know about the rest of the world.

Lots of reasons, pros and cons. I work in automotive and hate it.

Re: Simple, solar-powered water desalination (2020)

#178

Post by SV_BubbleTime » Fri, Jul 02, 2021, 3:16 PM UTC

throwaway894345 wrote: post #162

dystroy wrote: post #149

Earlier quoted context omitted.

The salt you release isn't instantly diluted in the whole ocean and we're speaking, for a plant, of millions cubic meters of salt enriched water per day. The release area is just dying.

This makes sense to me. I wonder how feasible it would be to release the saltier water over a broader area to reduce the salinity in any one area? Also, there are at least some ecological benefits to increasing the amount of fresh water. An extreme example is the lake that appeared in the middle of a desert in the United Arab Emirates. I have no idea how we weigh one against another.

Now you’re paying for salt transportation again.

Re: Simple, solar-powered water desalination (2020)

#179

Post by SV_BubbleTime » Fri, Jul 02, 2021, 3:20 PM UTC

SiempreViernes wrote: post #108

londons_explore wrote: post #104

Earlier quoted context omitted.

Nothing about reverse osmosis can't be scaled down in size or cost. The actual membranes are $9 for enough for 100 gallons per day (retail prices, [1]). High pressure pumps and hoses scale linearly. Solar panels scale linearly. Filters scale linearly. In fact, using this solar fountain [2] as the basis for the design, and switching the pump impeller for a high pressure version, and the nozzle for an RO membrane and h…

Ah, so what you are saying is that this is already deployed on a large scale to solve distributed water issues?

What he’s actually saying is he found some residential grade nonsense from China that only seems economically feasible because of the slave labor and subsidized transport.

Re: Simple, solar-powered water desalination (2020)

#180

Post by adrianmonk » Fri, Jul 02, 2021, 3:28 PM UTC

dsr_ wrote: post #131

squarefoot wrote: post #107

FTA: "Unlike some desalination systems, there is no accumulation of salt or concentrated brines to be disposed of. In a free-floating configuration, any salt that accumulates during the day would simply be carried back out at night through the wicking material and back into the seawater, according to the researchers." The capabilities are freaking interesting, but let's say someone builds a big enough settlement on a…

This chunk from the article is, unfortunately, an outright lie. By definition, removing salt from seawater leaves you with water and salt. The article handwaves the salt away by supposing that the desalinator will float on top of the ocean. In actual production configurations other than towing it behind your sailboat, you will end up with a brine pool that needs to be disposed of, or a concentration in the wicking ma…

I don't think they are talking about the impact on the environment. I think they are talking about the procedures for operating the equipment.

The way I read it, they mean whoever operates this device does not have to periodically go empty some bin/tank of salt or brine.

An analogy would be to a frost-free refrigerator. When you say the freezer compartment of your fridge is frost-free, you don't mean that it never generates frost. You mean it does generate frost, but it also automatically removes it. It's "free" of frost in the sense that you are free of doing a chore that you have to do with a freezer that lacks this feature.