It sounds like a distant dystopian crisis: a world where global food and water supply chains buckle under the strain of overpopulation and climate change, before being contaminated by weapons of mass destruction unleashed in a desperate fight for access to what little is left.
While the crisis may not be as unrealistic or far away as it seems, scientists are already coming up with potential solutions. One is the curiously named metal organic frameworks (MOFs), a powder of nano-engineered crystals with an apparently endless variety of uses.
One teaspoon of these crystals contain the surface area of an entire football field, and scientists have been able to customise them to absorb and store vast quantities of a desired substance.
In 1998 Prof Omar Yaghi, a chemist who now works at the University of California, Berkeley, made a key breakthrough that built on earlier work by Prof Richard Robson and Bernard Hoskins who showed it was possible to craft structures that can be imagined as metal scaffolding at a molecular level, bound together by organic links.
Less than two decades later, MOFs are being applied to purposes that even he could not have imagined, many of which would be particularly handy in a world falling apart – such as fabrics that can protect against chemical weapons, devices that can artificially replicate photosynthesis to transform carbon emissions into oxygen, and glowing crystals that can detect and trap contaminants in water.
Yaghi himself has developed a MOF that enables the harvesting of moisture out of the sky, and unlike other technologies that can already do this in high-humidity areas, the device using Yaghi’s powder works in the dry desertified conditions that are gradually expanding around the globe.
“We are living in an uncertain time,” Yaghi observes, “and fresh water is going to be one of the most precious and sought-after resources to humanity.”
In 2014, Yaghi reached out to MIT mechanical engineer professor Evelyn Wang about creating a machine capable of using his MOF technology. Wang and her team developed a transparent box with a top surface painted black to absorb solar heat, which prompts a reaction that delivers enough drinking water for a person’s daily needs with 1kg of the powder, even in areas of 20% air humidity.
“During the night, these MOFs soak up the water from air, and when the sun comes up, the MOFs will release water to be collected due to the warmth of the sun,” Yaghi says. “Then these empty MOFs will be ready to absorb water from the air at night again.”
Yaghi hopes these devices will enable people to access what he calls “personalised water” – off-grid and free of any impurities.
MOFs can be applied to just about any purpose. The obstacle has long been producing enough of them at a cheap enough cost to be of any practical use. Some cost upwards of $10,000 per kilo to produce at a painstakingly slow pace.
Over in Australia, at the CSIRO, Professor Matt Hill is leading the charge to find a way to make what he calls his “magic powder” commercially viable.
When he and his team first started pitching MOFs to companies in 2008, Hill says there was plenty of interest: “People asked ‘could you just send us a bit to try out – maybe 50kg?’. The trouble was, we could only produce a teaspoon a week.”
Today CSIRO’s startup MOFWORX can produce 10kg per hour on their pilot reactor (named Mindi, after a giant serpent of Indigenous Australian mythology that was said to spit out white powder) using a continuous process 20 times more efficient than the conventional batch process.
In September 2016, the first ever commercialisation of a MOF was announced by another Australian – Paschal McCloskey, the CEO of UK-based MOF Technologies, a spin-out company from Queen’s University Belfast.
The MOF in question can capture and store a gas that inhibits the hormone that prompts fruit and vegetables to rot, allowing for the safe storage of such foods for up to 12 months. This would enable further efficiencies for a food production process already being hampered by climate change.
McCloskey says it is already in use in the US where fruit and vegetable storage provider Decco Worldwide has achieved FDA approval to roll it out, and is undergoing approval processes in countries across Europe and Africa.
The company has 15 different MOFs they are seeking to commercialise, including two that MOF Technologies hopes to sell to carbon-intensive industries as a way to capture and convert carbon emissions.
MOF Technologies have expanded their production facility in preparation for capacity of between five and 10 tonnes of MOF production per year from 2018.
The obscure and complicated nature of the technology makes it “tricky to get the foot in the door with big companies”, concedes MOF Technologies commercial director Phil Patterson, but he has found a pitch that resonates: “I tell them it has the highest surface area of any material known to man – that usually gets their attention.”
An American Chemical Society study released early this year found that MOFs were approaching the projected costs of $10/kg for natural gas storage – the Advanced Research Projects Agency-Energy target – while a Royal Society of Chemistry study identified that further commercialisation of MOFs would require refinement of downstream processing, as methods used at the laboratory scale limited production rates.
Back at Berkeley, the father of these super-absorbent structures believes scientists have “just scratched the surface” of the “essentially limitless” applications of the technology.
Yaghi says it is “a pleasure to see that chemistry could combine molecular beauty and function in such a brilliant way as demonstrated by MOFs”.
“Imagine, any slight change of the metal ions, the organic components, the shape and topology, or the combination of them could give you a completely different MOF to be used for different purposes. I am not surprised at all to see MOFs being applied to so many different purposes, and I believe more amazing things are going to come.
“We have shown the world how it works; the rest is just fine tuning.”
