Moisture Harvesters for all?

I’m not easily impressed by reports of some newly invented uber-box, but a new paper in Science reveals an amazing little device from MIT: “Water harvesting from air with metal-organic frameworks powered by natural sunlight”

“… an efficient process for capturing and delivering water from air, especially at low humidity levels (down to 20%), has not [yet] been developed. We report the design and demonstration of a device based on porous metal-organic framework-801 [Zr6O4(OH)4(fumarate)6] that captures water from the atmosphere at ambient conditions using low-grade heat from natural sunlight below one sun (1 kW per square meter). This device is capable of harvesting 2.8 liters of water [5 British pints] per kilogram of MOF daily at relative humidity levels as low as 20%, and requires no additional input of energy.”

Sadly the Science paper is behind a paywall. But ScienceDaily has a good write-up.

At present, the device…

* is still only a working prototype. The “proof of concept harvester leaves much room for improvement”. But… “Rooftop tests at MIT confirmed that the device works in real-world conditions.”

* needs a mesh pad made… “of zirconium metal and adipic acid”.

* might work best when there’s direct sunlight to warm it.

* it looks like it would need to work with a bug screen and anti-fungals in a real-world deployment. Flies and mites can come in very small sizes, and in a dry environment would be attracted by the moisture: would a fine-meshed bug-screen let enough moisture in overnight?

Apparently zirconium cost about $14 per pound in 2010, according to figures I found, so it is not some incredibly rare metal. It’s also durable in the presence of moisture, since it’s apparently used to cap dental fillings. “Adipic acid” is also common, annually produced in the billions of pounds as a precursor in making nylon. It doesn’t melt before 152 degrees centigrade. The working device used about two pounds of the mixture in a pad. How long the pad remains viable isn’t stated, but the materials sound durable. If the pad can be made to last six months in a desert summer before gumming up its latices with microscopic fungi or other similar blockages, and the starter box costs $95, then it’ll sell like hot cakes. Or, in this case, like hot boxes.

As with all such world-changing devices, we probably want to be alert to unintended consequences of mass deployment as early in the development process as possible. Especially in terms of drinking water with a trace of zirconium or aluminium. Think: the Ancient Romans and their lead water pipes, for instance. But some nano-mesh or other would presumably filter unwanted metal traces out of the water.

But it looks good, very good. And is also well-timed, in terms of offering a simple technology that could help nudge along measures such as a green wall along the southern edge of the Sahara, or even help to water the smallholdings of the coming billions in Africa. It’s also simple like-a-bicycle, which means there should be lots of opportunities for home-brew tinkerer iterations of the sort that took humanity from the ungainly old Penny Farthing and ‘boneshaker’ bicycles to the perfected modern Safety Bicycle form we know today. For instance, might it be possible to block fungi colonisation of the mesh by using light, since apparently “Blue light (470 nm) effectively inhibits bacterial and fungal growth”?


“Who’s The Denier Now?”

I spotted a strong lead article in the crusty old magazine of the American right, The National Review, “Who’s The Denier Now?”. The new article is a bit ‘American Politics stodgy’ at the start, but the final half is a cracker. Here are some highlights…

“Softened by years of punching down at their opponents’ worst arguments, they became addicted to asserting that “science says so,” and they are now lost when it doesn’t.” [In this context] “Statements about climate change are no longer being policed for their accuracy, but rather for the degree to which they help or harm the activist agenda.”

[Any statement which questions science’s ability to very accurately model man-made influences on the global process of greenhouse warming …] “crosses a red line for activists, because the precision with which climate models can describe what is happening links directly to the precision with which they can describe what will happen”. [And in the resulting overheated media environment … ] “The scope of viewpoints that constitute ‘denial’ is rapidly expanding to swallow all opposition to favored policies.”

There’s a lot more in the article itself, and there’s also a weightier recent article in the journal Foreign Affairs, from the same author.

I was however disappointed that Oren Cass has been suckered by the false establishment media consensus which has been generated around the recent CNBC interview. A false consensus that waves the interview snippet about as if it somehow ‘proves’ that Pruitt holds some sort of ‘anti-science’ position. Here’s Cass in The National Review article…

“EPA Administrator Pruitt confused matters greatly with comments to CNBC last month that went beyond his testimony about “precision” and “debate” and suggested that human activity was not the primary cause of recent warming”

But as I’ve shown quite carefully here on this blog, in a line-by-line fisking of the CNBC transcript, all of Pruitt’s CNBC statements were congruent with the accepted mainstream science on the process on greenhouse warming. Pruitt’s choice of words, in a snatched minute at the end of a quick-fire TV studio interview, might have been better. But he was ‘denying’ nothing in terms of the science, as far as I can see.