81–90 of 644 posts
While on the issue of water: Some countries have floods in one part, and drought in the other. The floods are so bad that large numbers of people die. Here's a great challenge that should be worked on: how to capture the flood water and use it to mitigate the droughts. Could something like Elon Musk's Boring company concept fix this?
I was surprised how cheap it is. Desalinated water costs ~50 cents per 1000 liters [1]. That's about the same amount of water as a typical American household uses per day. 50 cents per day for a fully desalinated water supply is... incredibly cheap. If you're interested in water policy and water management / engineering, I cannot recommend enough reading the book "Let There Be Water: Israel's Solution for a Water-Sta…
Don't forget food, industrial, etc
It's not difficult. It's just energetically uphill. Undoing entropy costs energy. Second Law of Thermodynamics.
Exactly, desalination is very popular in arid countries. With renewable prices trending down, it's getting cheaper too. Basically, don't use consumer grid prices because those still include a fat profit margin for the energy suppliers and their sunk investment in legacy expensive generation using gas, coal, or nuclear. If you are within 40 degrees of the equator, which is where you'd find most arid places, solar is a…
A large desalination plant means large patches in the sea where life is not sustainable.
BTW, if an average US house really needs 1m^3 per day, that's appalling. These past years, my house has used less than 10m^3 per year and per person. 30× less. I'm afraid most US homes will keep wasting drinkable water and pressure society on building desalination plants, rather than halve (at least!) their water usage and protect the environment.
The energy costs are a bit of a red herring depending on local conditions. In California we currently "curtail" i.e. discard a huge amount of renewable energy in the spring season. If we can seasonally apply that energy to desalination, and store the fresh water for later, it is essentially a huge time-shifting battery that stores excess spring energy for the summer.
Earlier quoted context omitted.
I'd guess that if anything they'd increase the pressure to raise the boiling point. That way things dissolve in it faster and the water doesn't evaporate away.
On this topic the 14 minute episode "How Do They Make Maple Syrup?" from the PBS chemistry show 'Reactions' may be of interest: https://youtu.be/nSRCDiKMEJc
Earlier quoted context omitted.
In 2022, 85% of the country's drinkable water was produced through desalination of saltwater and brackish water. If there is a real need, and a will to address it, we have everything we need to to it. https://en.wikipedia.org/wiki/Water_supply_and_sanitation_in...
>In 2022, 85% of the country's drinkable water was produced through desalination of saltwater and brackish water. Israel does this by burning massive quantities of fossil fuels: https://en.wikipedia.org/wiki/Energy_in_Israel#/media/File:E... It's not even remotely economical without huge government subsidies. Completely untenable with current technology for poorer countries, or anyone that cares at all about carbon e…
Is it just me, or did this article dance around the question? I am not a physicist but let me give it a stab: except for a few specialized steps like UV or oxidizing heavy metals, most filtration is mechanical. A series of filters with smaller and smaller pores capture more and more of the mess in the water like bacteria and particulates while UV breaks down viruses, the oxidizer precipitates out metals, and so on. N…
> It takes less energy but produces a concentrated liquid waste stream that must be disposed of.
This implies that creating a concentrated waste stream is a problem unique to reverse osmosis. It isn't. No matter what you do you're going to end up with a bunch of salt that you have to get rid of somehow.
Is it just me, or did this article dance around the question? I am not a physicist but let me give it a stab: except for a few specialized steps like UV or oxidizing heavy metals, most filtration is mechanical. A series of filters with smaller and smaller pores capture more and more of the mess in the water like bacteria and particulates while UV breaks down viruses, the oxidizer precipitates out metals, and so on. N…
I've heard that this brine is toxic. Does this make disposal an issue? Is the toxicity true or hyperbole? I mean, do we know how bad it is, and if we can do anything safely with it? It seems like "salt" is useful in a lot of contexts, including industrial, so can we do something with the brine besides disposing it somewhere?