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Simple, solar-powered water desalination (2020)

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

#191

Post by jvanderbot »

tenfourwookie wrote: post #190
afterburner wrote: post #189

Earlier quoted context omitted.

A trillion? Well I guess efficiency doesn't concern you...

It's wild ass guess, but imagine a drone fleet capable of delivering that quantity of water on demand. We will see this in our lifetimes. Rain on demand.

I don't think we will. Except in the case of fighting fires in remote areas, if you want water in some area, you use pipes.

For fighting remote fires, we already have piloted vehicles and in some cases uncrewed vehicles delivering water in bursts ... so perhaps.

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

#192

Post by crackercrews »

hans_castorp wrote: post #160
ComodoHacker wrote: post #98

Earlier quoted context omitted.

It's an example of a good old scientifically flavored clickbait. The energy efficiency of anything cannot exceed 100% (until I missed something groundbreaking in physics).

How can it be "click bait" if neither the title nor the headline contains that number? You have to read at least the first three paragraphs of the article to stumble about that number. The focus of the article is on the inexpensive design, not on its efficiency

The HN title has been changed. It used to refer to the 385 percent claim. Probably GP thought this was from the title.

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

#193

Post by afiori »

alpaca128 wrote: post #118
wcoenen wrote: post #30

Earlier quoted context omitted.

The 100% level refers to a system where all energy goes to heating up water in order to evaporate it, and then letting it cool down to condense it. All the energy that was spent to heat up the water, is lost to the environment in the "cooling down" step. If some of the heat is instead recovered during condensation to heat up the next batch of water, then you have >100% efficiency.

Unless you ignore energy sources from the environment you cannot exceed 100% efficiency. And that would be incorrect, applying that same standard to photovoltaic panels would result in infinite efficiency. That doesn't make any sense. Edit: Also, when you take heat/energy from a previous step in the process, you also need to account for the energy put into that previous step. In the end that will again be As someone…

the full sentence is:

the [..] device can achieve an overall efficiency of 385 percent in converting the energy of sunlight into the energy of water evaporation.

it seems quite clear how the 3.85 ratio is obtained

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

#195

Post by mixmastamyk »

jedberg wrote: post #164
amn79 wrote: post #134

Earlier quoted context omitted.

Why release the salt back into sea water? This is salt production alongside desalination.

We already have a massive oversupply of salt from existing desalination. The cost of table salt is basically all transportation at this point.

Can be buried also.

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

#196

Post by SamBam »

adolph wrote: post #155
faceplanted wrote: post #127

Earlier quoted context omitted.

The Deja vu sensation of this conversation happening almost identically 2 days ago (everything from wondering how >100% efficiency works, someone explaining it's from the environment, and then someone else explaining efficiency is inappropriate and COP exists) is kinda wild.

Nothing to worry about. Its people alpha-testing the Copilot internet commenting plugin.

Can't wait for all our text input boxes on the web to be GPT-3-enabled, and then all comments on HN and Reddit and Twitter will be just people accepting the defaults, and it will end up just being GPT-3 talking to itself, and we can all go back to doing something productive.

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

#197

Post by maximus-decimus »

kingsuper20 wrote: post #174
celticninja wrote: post #99

Earlier quoted context omitted.

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?

If their toilets used clean water, then I have a much more efficient way to produce clean water : drink from the toilet and shit in a hot house.

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

#198

Post by ghshephard »

MauranKilom wrote: post #110
ghshephard wrote: post #87

Earlier quoted context omitted.

Back of the envelope - say that you could get 7-8 hours of sunlight a day that could destill water. That would mean ~50 liters/day. ~20 Days to get 1m^3. Reverse Osmosis costs approx $0.50/m^3 water, so your payback on a $100 system would be ~200 * 20 Days or 4,000 Days to equal what you could get for spending $100 on buying water from a reverse osmosis system. The objective here isn't large scale economics, but self…

Looking at a 10+ year time frame, I feel that maintenance cost would become the dominating factor. For both.

The Reverse osmosis cost estimate was based on a 10 year committed Hyflux Desalination commercial contract with the PUB in Singapore (from about 5 years ago, so might be less expensive now, actaully) - so includes maintenance costs.

Regardless - this isn't a scale able solution, but doesn't need to be - should work fantastic for a small family with negligible environmental impact.

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

#200

Post by Gravityloss »

pfdietz wrote: post #132

An issue with desalination systems of this type (that have water vapor in a carrier gas, so called HDH or Humidification-Dehumidification desalination systems) is the retardation of mass transfer to the cold surface by the carrier gas. Multieffect distillation (MED) systems usually operate without a carrier gas for this reason, but this means they operate below atmospheric pressure, so they have to be sturdy to resis…

The opposite of bubbles, mist, might also work. Extremely high surface area.
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