[mhb]

As to the necessary CO2, he imagines this would come from power stations and other industrial processes, such as cement-making, that produce the gas in large quantities as exhaust. This would restrict diffusiophoretic water plants to industrial cities—but, since such cities are huge sources of demand, that is hardly a problem.

[ChuckMcM]

I read that, but noted it suffers from 'scientist' blindness. These industrial processes, that are producing CO2 in large quantities, don't have an economical way to capture and cleanse that CO2 to allow for then shipping and selling it (or giving it) to this guy to clean water with it.

If they could capture the CO2 they could already resell it economically as there are lots of uses for it. There was some work in 2012 in Canada on that [1] but it hasn't gone well (here we are 5 years later and there aren't any products yet). There has been work on recapturing the CO2 in new plants, but that doesn't help our 'industrial cities' that are sitting on a bunch of existing infrastructure they cannot afford to refresh given they haven't fully depreciated the existing infrastructure.

[1] https://www.scientificamerican.com/article/can-co2-be-captur...

[ams6110]

What is the current process for producing "pure" CO2 gas for sale e.g. as dry ice, or for use in food/beverage or for other industrial purposes? Unlike e.g. nitrogen or oxygen, concentrating it out of the atmosphere would seem to be inefficient as it's only roughly 0.04%.

[URSpider94]

It's typically captured either from processes that make ammonia or hydrogen from methane (with CO2 being the only major byproduct), or by capturing the output from large-scale fermentation.

Source: http://www.uigi.com/carbondioxide.html

[hwillis]

Note that the gases coming out of a power plant are mostly nitrogen

[URSpider94]

True, CO2 capture from power plants and cement kilns is not yet reality.

That said, this process should work (if perhaps less efficiently) with less pure streams, since it should just depend on the partial pressure of CO2. Other gases like oxygen and water vapor should just be spectators in the process.

[yuhong]

The fun thing is that burning hydrocarbons also itself produce water too!