That's not a great example - surface parking lots and their runoff are fucking horrible for the environment

So, it's probably a good example then, since we currently accept the building of parking lots.

The point is, people are always writing letters to the editor and what-not when some green tech has some environmental impact, far more than they do over their city making another parking lot or any of a million other things. I assume it's because it triggers some notion of hypocrisy. c.f. wind turbines and dead birds.

How about we put our energy into fighting cars and parking lots first, before we worry about solar-powered desalination that could potentially save the Western states from the over-extraction of water that's turning them into dust bowls?

I'm not going to lose any sleep over that. Permeable concrete exists, but it's just not worth the maintenance cost in most places

https://en.m.wikipedia.org/wiki/Pervious_concrete

That's pretty cool. Personally, I'd prefer small roads and outdoor parking lots to be au naturel unpaved. Zero construction cost, and I imagine the maintenance cost is just trimming grass.

Only works if the natural soil is remarkably solid or the traffic negligible. Unpaved roads with more than very modest traffic generally need routine grading (repairing corrugations by scraping it over with a levelling blade) and re-graveling

Accurate. And, if there is significant rain and/or snowmelt, roads can quickly become impassable (see: "mud season" in New England, and surely many other places)

Won't they become unusable when it rains?

It's a good example then. Given that a Walmart parking lot is societally acceptable, fresh clean drinking water probably will be too.

Carbon-based energy is socially acceptable, as are completely unsecured computing devices and mass corporate surveillance, but that isn't the standard of a good idea. If it was, we wouldn't want a forum like HN.

What's the problem with parking lots?

"Fucking horrible" is unquantifiable. Policy decisions need to be based on figures.

Unfortunately, in reality many policy decisions are based on enough many people thinking X is "fucking horrible".

On a tangential note, I don't why paved outdoor parking lots are built[1]. It seems to be an entirely pointless exercise in aesthetics to me. I've parked on unpaved spots (in large parks near hiking trails, etc), and never had an issue.

We really should have more unpaved outdoor that is simply trimmed semi-regularly if or when the plant growth gets too big.

[1] Unless you're in a sandy or snowy area, where shoveling the sand or snow is difficult on an unpaved surface.

Unpaved parking lots tend to lose their plant growth when frequently used, after which the parking lot turns to mud in wet weather, which then results in stuck cars and dirt getting into stores with the customers that walked through that mud.

Pure soil wouldn't be a good option. Anything that's subject to high traffic, whether foot or vehicular, will also be subject to soil compaction which implies water pooling. That's a long way of saying those parking lots will turn into mud lots. At a minimum you could grade and gravel them, going the extra mile to crush the gravel so it stays in place longer. I do this with the driveway at my house because it rains a lot where I live. Paving would arguably last a lot longer and probably be more bang for my buck, but not having a place for water to go and having a basement is not a good combination.

On my driveway we only tend to get clovers and really resilient weeds. So, either really shallow rooted plants or weeds with absurdly strong roots. You're not likely to get native plans to grow unless you section off parts of the area for maintaining living soil.

To give a visceral example- There's an episode of Clarkson's Farm where the customers that parked in the grass at his farm shop need to get their cars pulled out of the mud by a tractor.

Just talking out my ass here, but can't it be combined with, say, treated wastewater?

We're taking the salt out of the water in order to "drink" it, but the reality is that most of it gets used for irrigation or toilets or whatever, and eventually returned either as groundwater or to the ocean.

In some cases, yes. I know we had a temp desalination running here for a while, and they just mixed the brine with sewerage outflow.

Obviously it depends on the location of the sewerage outflow relative to the location of the plant.

Of course this only matters at scale. For the suitcase sized device mentioned in the article the amount of brine generated is negligible.

It may be better to just treat the waste water and skip the desalination in that case.

Isn't the reject ratio typically closer to 75%? At least, my filter at home has a reject ratio of 75%, which means the wastewater is only ~33% more ppm than the starting water.

Yeah that'll be right for a small scale unit, I think it's just that large commercial-scale RO plants have better reject ratios.

The salty sea water could even become the water to flush your toilet with as one use for the waste?! I agree with the above, the scale of the proposed system shouldn't lead to sealife issues.

I don't think running saltwater through a toilet is straightforward. You would need higher quality parts, more frequent valve maintenance, and downstream waste processing equipped to handle the salt.

Just as a reference, 80% of toilets in Hong Kong are flushed with seawater: https://en.wikipedia.org/wiki/Water_supply_and_sanitation_in...

Sailboats use sea water in their toilets all the time but using it would require two systems, one fresh and another brackish. Very doable but more expensive. I believe they've also use grey water for toilets and plants but again it requires splitting the systems and having storage.