A portion of today's video
is brought to you by Larq. Many researchers are looking for
ways to improve desalination and other freshwater tech to help
us solve the freshwater crisis, like what we’re seeing in the southwest
US and other parts of the world. There’s some promising advances in both efficiency and
quality compared to what’s currently available. With these new technologies we can pluck the water
from the air at the push of a metaphorical button, so are they finally the answer we’re looking for?
Let’s see if we can come to a decision on this. Fresh water is THE great equalizer: no matter
who you are or what your background is, water is crucial to our survival and way of life.
While many of us have this fundamental resource literally “on tap”, not all of us are so
lucky, and more of us may face that same dilemma in the near future. Just take a look
at the worsening drought in the southwest US, where some areas are seeing some of the worst
dry spells they’ve had in the past 1,200 years. Record heat, major soil moisture loss, and historically low reservoirs are only some
of the symptoms that are likely to stick around. It’s not just the US, either. The World Health
Organization reports that 785 million people lack even basic drinking-water
services, and by 2025, half of the world’s population will be living
in water-stressed areas or conditions, and it’s predicted that ¾ of the world’s population
will suffer from freshwater shortages by 2050. Even though water covers 70% of the Earth’s
surface, only 2.7% of that is freshwater, and only 0.3% can be directly used by humans as-is.
This is going to be a problem close to home. So we have two options: either stretch the
water we already have, or find it somewhere else (preferably in that 97% worth of
water previously unavailable to us). We already have some idea of how to do
this via techniques like water harvesting (collecting rainwater runoff) and desalination
(removing dissolved salts from otherwise undrinkable water to make it suitable for human
consumption). Desalination has been a huge target, especially for coastal and/or rural communities
who are tempted to use the giant wealth of water that’s already practically in their backyards. Those desalination technologies
are generally one of three types: thermal (aka distillation), membrane (like
reverse osmosis) and charge-based (which use ion exchange processes). Thermal tends to be
good for desalinating a lot of water at once, to the tune of several thousand cubic meters a day
(which makes it appealing at industrial levels). Charge-based desalination is better for brackish
water sources along with small-scale systems (more along the lines of a few hundred cubic
meters a day). And membrane technologies, perhaps the most well known of the bunch, can be
optimized for practically any production level, making it one of the most commercially utilized
desalination technologies on the market. So why aren’t there desalination plants
everywhere? Well, we’re still trying to find the right flow. For one, desalination
is an energy-intensive process, which can make it costly in areas not flush with energy
funding (like Saudi Arabia). You also have to consider the environmental impacts from brine
runoff (aka the residual water that holds all that extra salt and other gnarly stuff
after the desalination is said and done). On top of all of that, the technological limits
of the desalination tech we have currently all seem to have made desalination seem nearly
dead in the water–at least, at first glance. There are quite a few researchers determined to
change this. Among the many projects underway, two in particular have made some exciting
headlines–and have interesting results to back them up. While they’re just two of many, these
could be the building blocks of what’s to come. While they may not be the solution
to solving large scale water needs, they do give us an indication of the
direction for fresh water technology, especially for more targeted applications. One
of the advances gets freshwater at the push of a button WITHOUT filters, and the other can pull
water out of the air without a power source, even in the middle of a desert.
But are they worth the hype, and what role can they play in the
freshwater crisis? Let’s take a deeper look. Before we get to an incredible,
lightweight, portable solution from MIT, I’d like to share another option you get for
your home today from today’s sponsor LARQ. 186 million Americans are drinking water with lead
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the water every 6 hours to keep it that way. It’s been fantastic for us. Use the link
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pure water today. Thanks again to LARQ and to all of you for supporting the channel.
Now back to the new freshwater advances. First, from our friends at MIT, we have a
new, lightweight and portable desalination unit that can generate clear, clean
drinking water without the need for filters or high-pressure pumps. The device
itself is about the size of a suitcase, weighs less than 22 pounds, and requires less
power to operate than a cell phone charger. Most commercially available
portable desalination units rely on high pressure pumps to push
the salty water through the filters, which not only makes it hard to make into a
compact device, but it also requires extra maintenance and energy to keep everything
running smoothly. MIT’s device, on the other hand, uses a two-step setup including ion
concentration polarization (or ICP, for short). ICP applies an electrical field to membranes
placed above and below a channel of water. (think of these like electrified bumpers on
a bowling lane). These membranes then repel positive or negatively-charged particles (like
salt, bacteria, and viruses) as they flow past. These charged particles are then funneled into a
second stream of water which is discharged at the end of the process. ICP doesn’t usually remove ALL
of the salts flowing in the middle of the channel, so the researchers added a round of
electrodialysis to remove those stubborn residual salt ions. Researchers found the optimal
setup to include a two-step ICP process where water flows through six modules in the first
stages, three modules in the second stage, and is followed by a single electrodialysis
process to finish out. This setup minimized the energy usage required while also making
sure that the process was self-cleaning. This means this device falls squarely under the
“charge-based” desalination techniques . Most rely on filters and other membrane techniques, which
not only require strong pumps to operate, but also are prone to fouling and buildup on the pores by
the salts and contaminants it’s meant to remove. The more contamination in the filter, the harder
the pump has to work. As a contrast, in MIT’s device, the water never actually flows through the
electrified membranes, which means you don’t need to worry about pressure OR particulates–basically
a win-win. Even if particles get trapped, researchers can reverse the polarity of the
electric field and electrostatically “sweep” those particles off the membrane easily. The best part …
the device can be driven by a small portable solar panel, and at the end of the day, the estimated
cost of the unit is in the ballpark of around $50. What about the communities who aren’t close
to the shoreline–are they out of luck? Not if the scientists at the University of
Texas at Austin have something to say about it. Researchers have developed a low-cost gel
film (all made from abundant materials) that can pull water from the
air, even in drier climates. Let’s be clear: the idea behind this isn’t really
new. In terms of “pulling drinking water out of thin air”, it’s a pretty old trick. In fact,
hydropanels have already beaten this gel to the market. Crudely put, they’re basically a
dehumidifier strapped to the back of a solar panel. More specifically, these panels use solar
power to convert water vapor in the air into a liquid state, collecting it into a reservoir
where the water is mineralized for consumption. It’s really straightforward. As I
said, it’s basically a dehumidifier. This water harvesting gel aims to do pretty much
the same thing, with one major change: there’s no electricity required. A single kilogram of this
gel can generate more than six liters of water per day in areas with less than 15% relative humidity,
and up to 13 liters in areas with up to 30% relative humidity. That makes it especially
useful in drier areas like the southwest US, and the research was funded by the US Department
of Defense’s Defense Advanced Research Project Agency (DARPA) in part to find ways to provide
drinking water for soldiers in arid climates. It’s made from a mix including renewable cellulose
and konjac gum, whose open pore structure and hydrophilic nature (at room temperature)
speeds up the moisture capture process. The thermo-responsive cellulose is also hydrophobic
when heated, which helps to release the collected water immediately while also minimizing the amount
of energy you need to keep the reaction going. It’s a relatively simple reaction, which
researchers believe to be one of this gel’s biggest strengths. Making more of the gel is
fairly simple too: all you need to do is mix the precursor, let it set for two minutes, then
freeze dry. You can peel the gel off and use it immediately after that, and the gel itself is
flexible and moldable, so you can make it in a variety of shapes and sizes. The researchers
ultimately envisioned this as something that people could buy at your local hardware store
and use in their own homes–even in the desert! For sure, these two projects–while extremely
cool–aren’t exactly breaking the status quo by themselves. However, they do represent
some interesting developments going on in the industry at large. So let’s explore
that a bit: are they too good to be true? First, let’s take a closer look at
MIT’s portable desalination device. Keep in mind, this project is one that
has been in the making for over 12 years. Now that an official prototype has been tested,
we need to ask: can we finally get efficient, effective desalination at the push of a
button? How excited should we be about this? Well, there’s one thing to be excited
about: we have an actual field test, not just a small-scale experiment in the
confines of the lab. Researchers Yoon and Kwon field-tested the device at Boston’s Carson Beach,
literally putting the feed tube in the water and getting a cup of clean, drinkable
water in a matter of thirty minutes. Not only that, but that cup of water exceeded
World Health Organization quality guidelines while cutting the amount of suspended
solids by a factor of at least 10. Not bad! Of course, the device needs to generate
more than one cup of water at a time: the prototype generates drinking water at a rate
of about 0.3 liters per hour, and it only requires 20 watts of power per liter . According to the
U.S. National Academies of Sciences, Engineering, and Medicine, a man living in a temperate region
would need about 3.7 liters of water per day. That means the prototype would need
about 12 hours to collect enough water. This device bucks the trend of using reverse
osmosis for portable desalination devices, which actually makes sense in a lot of ways. Charge-based desalination techniques are
more suited for brackish water feeds, and they also tend to have higher water recovery
rates (85-90%) than reverse osmosis does (25-80%). Since we don’t want a drop to go to waste,
that adds up fast. As an added bonus, the system would also remove many contaminants,
viruses and bacteria at the same time. Reverse osmosis is usually considered the most
promising option for smaller systems and places like islands and coastal communities, so the
fact that ICP is challenging this status quo is a pretty big deal. Converting seawater to potable
water usually takes a lot of electrically-powered pumps, well-maintained filters, and access
to a reliable power source–something that’s not in huge supply in places like
coastal communities and disaster areas. We’re often impatient to turn small-scale
energy advances to a larger scale, but in this case, the device’s small-scale
nature is actually one of its biggest strengths. The device’s portability and low-maintenance
design makes it perfect to deploy in remote and resource-limited areas, such as rural communities,
cargo ships, or places hit by natural-disasters. You could use it day-to-day in a village.. Factor
in the low expected cost of this device–about $50 each–and you could potentially deploy a BUNCH
of them at a time in those areas in need, once they’re commercially available. We do still have to ask, though: what
environmental impacts would this have? While small, this device is still shadowed by
desalination’s unfortunate reputation in this regard. Brine discharge (aka the discharge with
high levels of salt products) is a common problem, and a lot of energy is usually needed
to achieve a near-zero liquid discharge (like thermal desalination methods). You can
add extra steps to mitigate the brine problem, but as the desalination
method gets more complicated, it also gets more costly, and you
introduce more room for error. ICP device’s second deionization process seems to
combat this problem, but we might need more info on how to handle potentially damaging discharge.
(Granted, we likely wouldn’t see the large-scale damage done by major desalination plants, but
that shouldn’t give us license to ignore it completely). Does this device remove non-charged
pollutants that don’t have an electric charge, like industrial pollutants? Earlier iterations
of the project indicate that it doesn’t. The final product may require at the LEAST
a charcoal filter to cover its bases there. There’s still some room to grow, and the
researchers are eager to keep up that momentum. They’re hoping to make the device more
user-friendly, scalable, and energy efficient in the future, and they’re hoping to do so
via a startup that researcher Han plans to launch in order to commercialize the technology.
(For renewable-tech fans that bemoan how these advances tend to get stuck in the lab, having
a push towards the market is a welcome change). As for the University of
Pennsylvania’s water harvesting gel: did we mention you can use
this in the DESERT? Sorry, not trying to drive that point into the
sand; but it’s just a really cool feature, and one that makes this gel especially effective
in the areas hit hardest by recent droughts. Like the MIT device, this gel also
seems to be a small-scale solution, possibly to supplement households or small
businesses. Its 6-liter yield is only the start, according to the researchers. You could use
thicker films or absorbent beds to optimize and increase the amount of freshwater
they produce, and since the film itself is flexible and moldable, the application
possibilities are practically endless. This certainly isn’t the only tech out there
that pulls water out of thin air, but those other solutions tend to be energy-intensive,
and they don’t produce much either. The fact that this gel works without an energy
source is huge in that regard. (You can speed up the reaction thermally, but it’s not required;
you can practically “set it and forget it”.) How about the environmental impact? That’s
something we’d have to study in more detail. The ingredients themselves are reported to be
nontoxic, and unlike desalination techniques, you’re not going to get that sickly salty brine
that causes havoc once it's discharged. Many of the ingredients are biodegradable (like cellulose
and konjac gum), so once the gel mold exhausts its lifespan, there could be some promising
environmentally-friendly disposal options. Of course, that brings up another
big unknown at this point: what is this gel’s lifespan? Unfortunately,
that’s not something that’s been reported yet. That will make a huge difference in how
easily this technology can be scaled up, because if you’re constantly needing to
replace a mold that has lost its vitality, that could make this “easy” solution just as
cumbersome as its hydropanel counterparts. While the researchers envisioned this
gel as something that people could someday buy at a local hardware
store and use in their own homes, there is some scalability to explore here. The
gel’s simple reaction makes it straightforward to use (which means less time tinkering
with filters, mechanical parts, and other complicated maintenance items that could
hamper larger-scale applications). The low cost is also a huge bonus. The materials themselves cost a
measly $2 per kilogram. Compare that to the rising costs of fuel and electricity, and that makes
this low-energy alternative pretty appealing! You may be wondering: is this enough? Unlike other exciting advances – like
fluorinated nanotubes for desalination membranes, wick-free solar set-ups, and a low-energy
battery electrode deionization system from the University of Pennsylvania – the
two technologies we’ve talked about here actually have prototypes in place
and are ready to be used in the field immediately (or at least, once the
business side of things is figured out). Will these solve the world’s water crisis?
Maybe not by themselves, and maybe not as is. However, they can help provide real-world relief
(more than some places are getting) to areas hit the hardest by dwindling drinking water resources. They could provide clean drinking
water after a natural disaster, such as a hurricane or earthquake. And they also
show where this type of research is heading. So are you still undecided? Do
you think technologies like these, even if they’re more targeted solutions,
have a place to make a difference? Jump into the comments and let me know and be
sure to check out my follow up podcast Still TBD where we’ll be discussing some
of your feedback. If you liked this video, be sure to check out one of these videos over
here. And thanks to all of my patrons for your continued support. And thanks to all of you
for watching. I’ll see you in the next one.
