August 30, 2019 • 24 mins
What is desalination? What are some of the methods used to get salt out of water? Why isn't desalination in wider use? Join Jonathan and Chris as they explore the tech behind desalination in this episode with Erik Hanson of General Electric.
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Episode Transcript
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Speaker 1 (00:04):
Welcome to tech Stuff, a production of I Heart Radios,
How Stuff Works. Hey there, and welcome to tech Stuff.
I'm your host, Jovian Strickland. I'm an executive producer with
How Stuff Works and iHeart radio and I love all
things tech. And you know, sometimes here on the show,
(00:24):
I can get a little salty, which is why we're
looking at this classic episode tech Stuff Gets Salty and
originally published on October one, two thousand twelve. And you know,
I'm being all ki and everything, but yes, this is
an episode. It's about desalination, the process of removing salt
from water and the technology behind it. I hope you
(00:46):
enjoy this classic episode. So, Chris, one of the big
issues facing the world today is access to clean, drinkable water,
and so we wanted to talk to someone who's an
expert in a particular form of processing water to make
something that isn't drinkable into drinkable water, and we have
(01:07):
with us from ge Eric Hansen. Eric, welcome to the
to the podcast very much. We're excited to have you here,
and we're going to talk a bit about desalination, which
is a process where we're removing things like salt and
other minerals from water so that you have clean drinking
water as an as a byproduct, really the other one
(01:28):
being the the salt the salute. So we want to
talk a little bit about the process that you guys
use over at g the things that you're looking into,
and um, how that has changed over the years. So
to really start off, what what are the greatest benefits
of desalination. Um, it's a great question. Uh. You know,
(01:51):
the world today uh bases you know, ever increasing challenges
and stresses on water supplies. But the good news behind
that is the Earth's surfaces sent water. So even though
less than one percent of that is accessible as fresh
water today, the rest of it is is seawater, and
(02:12):
we do have the technologies today to turn that into
usable water. So in fact, those technologies have been around
for a really long time. Uh. You know, even hundreds
of years ago, people would boil water, capture the steam
from that water, and use the condensation from that that
steam as purified water. So the concepts of of desalinating
(02:37):
water using heat or thermal technologies, those aren't new concepts.
They've been around for a while. Desalination has been going
on for a long time and even up through the
most of the nineties, UH, thermal technologies were still very prevalent,
albeit a little bit more advanced than just simply boiling water.
(02:58):
But the concepts were still the same. Up the water,
capturing the steam, and condensing it. Sure, in the in
the nineties, different technologies started being applied. UH. Instead of
heating up the water and boiling it, what we started
doing was applying membranes, special kinds of very advanced filters. UH.
(03:21):
These membranes are able to remove the salts from the water,
UH with much less energy. Takes a lot of energy
to boil water. So using membrane technologies, we've been able
to reduce the amount of energy it takes to remove
the salt from water. And over the last twenty years
there have been just a lot of advances in that
in that field, which I'm sure we'll go into a
(03:43):
little bit more in our conversation. Sure, making the cost
of desalinating water come down, UH, you know every year, right,
And so you're talking about these these semi permeable membranes.
Essentially we're looking at a process of reverse auso osis
really um forcing the using pressure essentially to force water
(04:06):
that has various minerals and salt in it. Through this membrane,
the membrane separates out the minerals the salts, and the
water passes through. Normally, when you have a membrane between
a solute and a solvent, the solvent is going to
pass through the membrane until there's a an equilibrium there
(04:26):
and osmosis pressure is osmotic pressure is built up. So
in this case, we're actually applying energy on one side
so that we get water on one end of the
membrane and everything else is on the other. Is that
that sort of a bird's eye view of what that
technology is all about. Yeah, you described it very well.
You know. One of the biggest difference between membrane filtration
(04:48):
and the types of filtration that most people are familiar with.
It's when most people think of a filter, they imagine
a barrier of some kind with one stream of water
flowing into it, things being removed by that barrier, and
then one stream of water flowing out the other side,
and then after a while you have to do something
to get all this stuff you've removed off that barrier.
(05:10):
So membrane technology doesn't exactly work that way. You still
have a barrier and it's the membrane. But in membrane technology,
the feed stream is actually flowing across the membrane, so
you have one stream in, but then you're applying pressure,
so some waters making it through the membrane. That's the
purified water without much salt in it, and all the salt,
(05:32):
all the salt is staying on the other side of
the membrane. So in membrane technology, instead of one stream
in and one stream out, you actually have one stream
in but two streams out, the saltier stream, so that
saltier stream the brine. I know that that has caused
some problems in the past simply because Brian, you know,
what do you do with that after you've gone through
(05:53):
the desalination process Now, Brian, because it has this concentrated
amount of salts and minerals in an it's actually denser
than seawater. So if you were too simply dump that
brine into the sea, then it would it would sink
to the bottom of the sea floor where it could
potentially cause damage depending upon the environment that you're in. Uh,
(06:16):
can you talk a little bit about some of the
approaches to to take care of that problem. I know
there's some about mixing the brine in with other water
that's going to be running into the sea, so it
it dilutes it. So I mean, if you step back
and look at the desalination process, you know, from from
(06:36):
thirty feet, uh, it can simply be considered really part
of the normal water cycle, the hydrological cycle. So yes,
there's water with more salt going back into the ocean,
but the water that's purified and it's then used, uh,
ultimately that goes back into the ocean as well, whether
it comes through municipal wastewater and sanitary supers and it's
(07:00):
treated you know, in many other ways. You know that
water all does essentially return to the hydrological cycle at
some point. So you know, from a high level, the
mass balance is fine. The oceans aren't going to get
saltier because of this, because we are returning the purified
water back to the oceans at some point as well.
So really, the the more immediate concern is just that
(07:24):
very point at which you're introducing the brine back into
the ocean, and depending on the characteristics of the seabed
and what's living in that area. Uh, sometimes there are
special considerations that are taken. Uh. And you know, there
are many different ways you can return the brine back
into the ocean. You can just have a pipe that
(07:45):
puts it right into the ocean. You can create an
elaborate grid of pipes underneath the seabed to uh, to
blend it a little bit better. There's a number of
different methods. And even though desalination may seem like a
niche to some people, there are actually quite a few
specialties within it. And uh, you know, really thinking through
(08:08):
how the brine is going back into the ocean and
how it's going to affect marine life is uh is
quite a science in itself. But you know, there's been
a ton of progress on that really in just the
last ten years. And you know, I think in nearly
all cases we're now able to come up with with
special schemes and and the right technology to blend up
without harming marine life. Fantastic. Hey there it's Jathan from
(08:31):
two thousand nineteen. We're gonna take a break from this
salt extravaganza and here from our sponsor. Well, moving on
to another question. What what's the greatest barrier to adoption
(08:52):
of desalination? I mean, why, uh, what's keeping this technology
from being more widespread and used in more areas of
the world. You know, I think there are you know,
you could probably classify it into two different barriers. One
of one of them is, uh is more perception. Uh.
You know, there are some areas where the public still
(09:15):
isn't really that on board with it yet, just for
you know, things they've read in the news and their
own ideas about it. Other parts of the world are
doing this uh often uh you know, in the Middle
East or in Southeast Asia. You find de cell plants
all over the place. They have largely solved all the
environmental issues that people should be worried about. Um. You know,
(09:38):
but some people are slower to adapt than others, and
it takes a while to to come to terms with
with some of that mentally. UM. So that you know,
that's a harder problem to solve. The easier problems to
solve really are are the energy problems, because when you
do desalination, it isn't the cheapest way to get water.
If there's other uh supplies of water of alable to
(10:00):
you uh that don't have so much salt in them,
they're most likely going to be less expensive than desalination.
So today people are doing desalination really only in areas
where they don't have a lot of other alternatives, where
they're in a water scarce area and they simply need
to do it. So driving down the energy cost is
really the primary goal and desalination it has been for
(10:24):
the last twenty years, and there have been a lot
of different improvements over the last really fifteen years that
have really made progress in driving that down UH, and
they're in a number of different areas. Obviously, the amount
of energy that you need to drive the salt out
of the water is a big deal, and you can
lower that through advances in the membrane chemistry, so actually
(10:48):
improving the membranes. You can do it through advances in
the efficiencies of pumps UH, and you can also do
it through advances in energy recovery devices. So there's a
you know, a number of different area is that that
people are working on. And then in addition to that,
you know, simply the operation of these plants, you know,
it requires a the amount of of manpower just to
(11:11):
keep these things running. So we've also been making a
lot of improvements and innovations and the pre treatment to
these plants. So as as the pre treatment to the
water gets better, they're lower operating costs as well. So
lots of different levers to pull in order to lower
the operating costs. You know, I was wondering a little
bit about the equipment itself. I mean, the process itself
(11:32):
seems pretty uh, pretty straightforward, but um, you know, is
the is the equipment itself large? Does it take up
a lot of space or or does it require a
lot of high pressure to to make it work? Yeah,
the two different things. In terms of size. It doesn't
take up really any more space than a traditional water
treatment plant for the same capacity would. But the big
(11:55):
difference is pressure. The more salt that you have dissolved
in any in any given amount of water, the higher
the osmotic pressure of that water, something Jonathan referred to
in his earlier explanation. So the more salt, higher the
osmotic pressure, the more pressure you need to apply to
(12:15):
the water to drive the salt out of it. So
take for example, the Middle East in the Gulf, in
the Middle East, that's really some of the saltiest water
in the world. So on detail plants, they're running them
as high as as eighty p s I, which is
(12:35):
pretty high pressure. Uh. In other parts of the world,
like say the Caribbean, the water is a little less salty,
still absolutely seawater, but it's not quite as stalin as
as the Middle East. So there you because it has
slightly less salt, you can use slightly less less pressure. Now,
are these plants often um sort of piggybacked onto other
(12:59):
plants like pour generation. I was wondering if there was
a lot of cogeneration going on with desalination plants. Yeah,
that's a great question. Uh. And this is actually one
of the reasons that g is is uh, you know,
so active in this market. Uh. You know, there's just
an inex Uh. There's a there's a obvious tie between
(13:20):
energy and water. So to produce energy, you know, power
plants need water to produce energy. In fact, almost ten
percent of all global water withdrawals go to the production
of water, so it's a pretty significant amount. Uh. And
then the reverse of that is to desalinate water, you
need energy to do it. So power plants and deesel
(13:41):
plants are are are very linked. In the past, when
the technologies were more thermal based, that was another advantage
of tying the plants together because many power plants, especially
power plants in the past, had a lot of waste heat,
so they could use some of that heat uh for
the thermal desalination. Power Plants today are much more efficient,
(14:04):
so there isn't so much waste heat coming from them. Uh.
And the membrane technologies come to a point where really
that's the propol and technology for desalination. So we're not
seeing them tied together as much anymore because of waste
heat from the power plant, but we are seeing them
tied together simply because the power plant needs water, uh
and the decail plant needs power. Excellent. Hi, it's Jonathan
(14:28):
two nineteen again. I decided that I needed to get
a little salt, so I came back to visit this episode.
While I'm doing that, let's take another quick break. So
what is ge doing to make desalination more feasible to
(14:49):
address water scarcity issues? So we're working in a number
of different areas. We've worked a lot in the past
on the membranes, and uh, you know, there are really
some very high quality membranes now used in this salimation. Uh,
they're not at entitlement yet. There are still some games
to be made there UM, but they're they're getting close.
(15:09):
The membranes are very efficient today. UM pre treatment is
very important. So when when we talk about membranes and
how they take the salt out of water, they're great
at taking the salt out of water, but they aren't
great at taking suspended solids out of water. So you
don't want to put salt or sticks or stones or
anything like that into a membrane. That's bad for it.
(15:29):
So pretty much every membrane plant in the world has
some kind of pre treatment in front of it to
take the suspended solids out before it gets to the membranes.
UH and G has been leading in this area as well.
We have some terrific advanced prefiltration another type of membrane
called an ultrafiltration membrane, and it it provides really superior
(15:51):
UH suspended solids removal, so that the water that gets
to the the reverse us most of the membranes is
as clean as it can be, still salty, but it's
had everything else removed and that makes the life of
those membranes last a lot longer, which in turn lowards
the overall cost of ownership. UM. Then the other pieces
(16:11):
of the pumping side, there are a lot of different
kinds of pumps in the marketplace. The most efficient types
of pumps are positive displacement pumps. If you think of
pumping water, you can imagine you have a fixed geogray
fixed geometry of water. The most efficient way to raise
the pressure of it is just to push on it
um and that works today in in relatively small sizes,
(16:36):
but as plants get larger and larger um there aren't
so many good positive displacement pumps. So instead what people
use their centrifugal pumps. So that's more like spinning the water.
The water that gets thrown to the outside has a
higher pressure. So you know, we've been working developing a
new pump which is a positive displacement style pump, but
(17:00):
is much larger than other positive displacement style pumps on
the marketplace. That's a pretty new product for us, but
we expect that within the next year we're gonna start
seeing more of more of that pump out in de
cel plan and that's going to knock as much as
another ten percent of the energy off, so that when
we get that fully commercialized, not in the marketplace, it's
(17:22):
gonna lower the electrical costs by about ten percent more,
which is really significant when you're talking about, you know,
the cost of desalination. Sure. So, so that's sort of
leads into what do you see as the future of desalination?
Where do you see us going in another few years,
like another decade or two decades. Yeah, that's a great
(17:42):
question and a hard question because there are many many
technologies out there today. Uh. You know, I I think
most people in the industry, myself included, really see reverse
osmosis as continuing to be the most prevalent technology, uh
for at least the next five or seven or ten years. Um.
(18:04):
It's certainly possible that some other technologies could could come along.
And you know, honestly, if there are other technologies that
will dramatically lower the cost of desalination, that would be
great for the planet. Um. But I you know, I
think over the next five or seven years, what we're
going to see is people figuring out how to link
the cell plants more to other renewables. So already we're
(18:27):
starting to see people thinking about how do you combine
a de cell plant with wind turbines and a wind farm,
or how do you combine a de cell plant with
a solar farm. You know, it turns out that a
lot of places in the world but neat desalination, places
that are water scarce, are also places that have quite
(18:48):
a bit of sun. So there there's some nice natural
links between, you know, combining solar with de cell. In
some ways, there's also challenges because you know, in addition
to having a sun, you know, some of these places
also have a lot of sand and it's dusty and
and dust and solar don't don't always hair so well.
The dust coats the panels and they become less efficient.
(19:10):
But you know, now we're talking about some pretty um
discreet challenges. You know, people are doing this now, they're learning,
they're getting better at it. There's not a lot of
solar plus D cell or wind plus D sell out
there today, but I think in the next five to
ten years we're probably gonna start to feel a lot
more about Yeah, it's really exciting and to give our
(19:31):
listeners an idea of the impact that these sort of
technologies have made so far. Uh, it wasn't that long
ago that the estimated population that could not get access
to clean water was around twenty but according to the
World Health organization. They had a two thousand twelve report
(19:52):
which took numbers from and took a look at that.
They said that it's is still a massive problem. Still
s million people lack access to safe drinking water, according
to this report, and that's a you know, that's a
sobering number. But the silver lining here is that that's
that's half of what it was before, so that the
(20:14):
numbers of people who are getting access to safe drinking water,
they're on the rise, which I mean, that's obviously the
way we want to see this trend go. So it's
exciting to see this sort of technology combined with the
efforts of other organizations out there dedicated to making sure
that that people across the world get access to this water. Yeah.
(20:35):
I couldn't agree more. You know, one of the statistics
that that I often hear is that today it's one
and every six people today doesn't have access to clean water,
which is, as you said, really a sobering number. Um.
You know, I I think there's an interesting combination here
where you read a lot about this today. You know,
(20:57):
ten years ago you didn't generally see water articles in
mainstream media, and today, you know, every week you're going
to see an article in mainstream media talking about water scarcity,
and you know, it is a serious problem and it
is alarming. But the plus side of this publicity is
(21:18):
that they're more entrepreneurs, more large companies like GE, just
more people out there starting to think about what are
some possible solutions, uh, And there's lots of them. You know.
Desalination is a great example of ways that we can
solve water scarcity. Water reuse is another great example of
ways that we can solve water scarcity. Water reuse is
(21:40):
just taking water that's already been used for one purpose, uh,
and treating it and cleaning it up and finding a
way to use it for another purpose. So, you know,
I think all the current press that we hear about
water scarcity is actually helping to feed a pipeline of
new innovations and new ideas that will actually helps all
the problems in the long run. Fantastic, Eric, Uh. That
(22:05):
that's a great look at the desalination process and what
g E is doing to to really push this technology forward.
And we really appreciate you coming on the show and
talking with us. It's been a really educational experience for
me and especially as as as liberal arts majors whose
whose background and engineering is saying, Wow, that's cool. Uh,
(22:28):
it's really great to get people like you on our
show to talk about this and and give our listeners
this uh this sort of Uh look, is there anything
else you would like to say before we wrap up? Well,
you know, Jonathan Chris, I'd just like to say thanks,
thanks for having me on the show. Um. You know,
at ge we're doing a lot of really interesting and
innovative things to solve the very problems that we were
(22:50):
just talking about for the last half hour. Uh. You know,
one of the great things about being in this kind
of business is when you come up with innovations, you
can actually see you that they're helping people. Uh. So
you know, it's it's a rewarding business to be and
Geez very committed to it. We're investing a lot and
solving problems today and in the future, and and uh,
(23:12):
you know, I love talking about it and I'm really
excited about where this can all go over the next
couple of years. And that wraps up this classic episode
of tech Stuff where we learned all about desalination. There's
been a lot more work on that over the last
few years and maybe I'll do a follow up episode
to talk about this and the challenges around desalination and
(23:35):
how we need to really be cognizant of those challenges
before we pursue desalination on a grand scale. It turns
out it's a lot more complicated than just taking salt
out of water. I hope you guys uh enjoyed the episode.
If you have suggestions for future topics for tech Stuff,
feel free to reach out to me the email addresses
(23:57):
tech stuff at how stuff works dot com, or pop
on over to our website that's tech stuff podcast dot com.
You will find links to all of our old episodes.
I say old, I should say classic, gorgeous Pristine episodes,
and you will also find links to where we are
on social media, and you'll find a link to our
(24:19):
online store, where every purchasing make goes to help the
show and we greatly appreciate it, and I'll talk to
you again really soon. Tech Stuff is a production of
I Heart Radio's How Stuff Works. For more podcasts from
my heart Radio, visit the i heart Radio app, Apple Podcasts,
(24:40):
or wherever you listen to your favorite shows.
Welcome to tech Stuff, a production of I Heart Radios,
How Stuff Works. Hey there, and welcome to tech Stuff.
I'm your host, Jovian Strickland. I'm an executive producer with
How Stuff Works and iHeart radio and I love all
things tech. And you know, sometimes here on the show,
(00:24):
I can get a little salty, which is why we're
looking at this classic episode tech Stuff Gets Salty and
originally published on October one, two thousand twelve. And you know,
I'm being all ki and everything, but yes, this is
an episode. It's about desalination, the process of removing salt
from water and the technology behind it. I hope you
(00:46):
enjoy this classic episode. So, Chris, one of the big
issues facing the world today is access to clean, drinkable water,
and so we wanted to talk to someone who's an
expert in a particular form of processing water to make
something that isn't drinkable into drinkable water, and we have
(01:07):
with us from ge Eric Hansen. Eric, welcome to the
to the podcast very much. We're excited to have you here,
and we're going to talk a bit about desalination, which
is a process where we're removing things like salt and
other minerals from water so that you have clean drinking
water as an as a byproduct, really the other one
(01:28):
being the the salt the salute. So we want to
talk a little bit about the process that you guys
use over at g the things that you're looking into,
and um, how that has changed over the years. So
to really start off, what what are the greatest benefits
of desalination. Um, it's a great question. Uh. You know,
(01:51):
the world today uh bases you know, ever increasing challenges
and stresses on water supplies. But the good news behind
that is the Earth's surfaces sent water. So even though
less than one percent of that is accessible as fresh
water today, the rest of it is is seawater, and
(02:12):
we do have the technologies today to turn that into
usable water. So in fact, those technologies have been around
for a really long time. Uh. You know, even hundreds
of years ago, people would boil water, capture the steam
from that water, and use the condensation from that that
steam as purified water. So the concepts of of desalinating
(02:37):
water using heat or thermal technologies, those aren't new concepts.
They've been around for a while. Desalination has been going
on for a long time and even up through the
most of the nineties, UH, thermal technologies were still very prevalent,
albeit a little bit more advanced than just simply boiling water.
(02:58):
But the concepts were still the same. Up the water,
capturing the steam, and condensing it. Sure, in the in
the nineties, different technologies started being applied. UH. Instead of
heating up the water and boiling it, what we started
doing was applying membranes, special kinds of very advanced filters. UH.
(03:21):
These membranes are able to remove the salts from the water,
UH with much less energy. Takes a lot of energy
to boil water. So using membrane technologies, we've been able
to reduce the amount of energy it takes to remove
the salt from water. And over the last twenty years
there have been just a lot of advances in that
in that field, which I'm sure we'll go into a
(03:43):
little bit more in our conversation. Sure, making the cost
of desalinating water come down, UH, you know every year, right,
And so you're talking about these these semi permeable membranes.
Essentially we're looking at a process of reverse auso osis
really um forcing the using pressure essentially to force water
(04:06):
that has various minerals and salt in it. Through this membrane,
the membrane separates out the minerals the salts, and the
water passes through. Normally, when you have a membrane between
a solute and a solvent, the solvent is going to
pass through the membrane until there's a an equilibrium there
(04:26):
and osmosis pressure is osmotic pressure is built up. So
in this case, we're actually applying energy on one side
so that we get water on one end of the
membrane and everything else is on the other. Is that
that sort of a bird's eye view of what that
technology is all about. Yeah, you described it very well.
You know. One of the biggest difference between membrane filtration
(04:48):
and the types of filtration that most people are familiar with.
It's when most people think of a filter, they imagine
a barrier of some kind with one stream of water
flowing into it, things being removed by that barrier, and
then one stream of water flowing out the other side,
and then after a while you have to do something
to get all this stuff you've removed off that barrier.
(05:10):
So membrane technology doesn't exactly work that way. You still
have a barrier and it's the membrane. But in membrane technology,
the feed stream is actually flowing across the membrane, so
you have one stream in, but then you're applying pressure,
so some waters making it through the membrane. That's the
purified water without much salt in it, and all the salt,
(05:32):
all the salt is staying on the other side of
the membrane. So in membrane technology, instead of one stream
in and one stream out, you actually have one stream
in but two streams out, the saltier stream, so that
saltier stream the brine. I know that that has caused
some problems in the past simply because Brian, you know,
what do you do with that after you've gone through
(05:53):
the desalination process Now, Brian, because it has this concentrated
amount of salts and minerals in an it's actually denser
than seawater. So if you were too simply dump that
brine into the sea, then it would it would sink
to the bottom of the sea floor where it could
potentially cause damage depending upon the environment that you're in. Uh,
(06:16):
can you talk a little bit about some of the
approaches to to take care of that problem. I know
there's some about mixing the brine in with other water
that's going to be running into the sea, so it
it dilutes it. So I mean, if you step back
and look at the desalination process, you know, from from
(06:36):
thirty feet, uh, it can simply be considered really part
of the normal water cycle, the hydrological cycle. So yes,
there's water with more salt going back into the ocean,
but the water that's purified and it's then used, uh,
ultimately that goes back into the ocean as well, whether
it comes through municipal wastewater and sanitary supers and it's
(07:00):
treated you know, in many other ways. You know that
water all does essentially return to the hydrological cycle at
some point. So you know, from a high level, the
mass balance is fine. The oceans aren't going to get
saltier because of this, because we are returning the purified
water back to the oceans at some point as well.
So really, the the more immediate concern is just that
(07:24):
very point at which you're introducing the brine back into
the ocean, and depending on the characteristics of the seabed
and what's living in that area. Uh, sometimes there are
special considerations that are taken. Uh. And you know, there
are many different ways you can return the brine back
into the ocean. You can just have a pipe that
(07:45):
puts it right into the ocean. You can create an
elaborate grid of pipes underneath the seabed to uh, to
blend it a little bit better. There's a number of
different methods. And even though desalination may seem like a
niche to some people, there are actually quite a few
specialties within it. And uh, you know, really thinking through
(08:08):
how the brine is going back into the ocean and
how it's going to affect marine life is uh is
quite a science in itself. But you know, there's been
a ton of progress on that really in just the
last ten years. And you know, I think in nearly
all cases we're now able to come up with with
special schemes and and the right technology to blend up
without harming marine life. Fantastic. Hey there it's Jathan from
(08:31):
two thousand nineteen. We're gonna take a break from this
salt extravaganza and here from our sponsor. Well, moving on
to another question. What what's the greatest barrier to adoption
(08:52):
of desalination? I mean, why, uh, what's keeping this technology
from being more widespread and used in more areas of
the world. You know, I think there are you know,
you could probably classify it into two different barriers. One
of one of them is, uh is more perception. Uh.
You know, there are some areas where the public still
(09:15):
isn't really that on board with it yet, just for
you know, things they've read in the news and their
own ideas about it. Other parts of the world are
doing this uh often uh you know, in the Middle
East or in Southeast Asia. You find de cell plants
all over the place. They have largely solved all the
environmental issues that people should be worried about. Um. You know,
(09:38):
but some people are slower to adapt than others, and
it takes a while to to come to terms with
with some of that mentally. UM. So that you know,
that's a harder problem to solve. The easier problems to
solve really are are the energy problems, because when you
do desalination, it isn't the cheapest way to get water.
If there's other uh supplies of water of alable to
(10:00):
you uh that don't have so much salt in them,
they're most likely going to be less expensive than desalination.
So today people are doing desalination really only in areas
where they don't have a lot of other alternatives, where
they're in a water scarce area and they simply need
to do it. So driving down the energy cost is
really the primary goal and desalination it has been for
(10:24):
the last twenty years, and there have been a lot
of different improvements over the last really fifteen years that
have really made progress in driving that down UH, and
they're in a number of different areas. Obviously, the amount
of energy that you need to drive the salt out
of the water is a big deal, and you can
lower that through advances in the membrane chemistry, so actually
(10:48):
improving the membranes. You can do it through advances in
the efficiencies of pumps UH, and you can also do
it through advances in energy recovery devices. So there's a
you know, a number of different area is that that
people are working on. And then in addition to that,
you know, simply the operation of these plants, you know,
it requires a the amount of of manpower just to
(11:11):
keep these things running. So we've also been making a
lot of improvements and innovations and the pre treatment to
these plants. So as as the pre treatment to the
water gets better, they're lower operating costs as well. So
lots of different levers to pull in order to lower
the operating costs. You know, I was wondering a little
bit about the equipment itself. I mean, the process itself
(11:32):
seems pretty uh, pretty straightforward, but um, you know, is
the is the equipment itself large? Does it take up
a lot of space or or does it require a
lot of high pressure to to make it work? Yeah,
the two different things. In terms of size. It doesn't
take up really any more space than a traditional water
treatment plant for the same capacity would. But the big
(11:55):
difference is pressure. The more salt that you have dissolved
in any in any given amount of water, the higher
the osmotic pressure of that water, something Jonathan referred to
in his earlier explanation. So the more salt, higher the
osmotic pressure, the more pressure you need to apply to
(12:15):
the water to drive the salt out of it. So
take for example, the Middle East in the Gulf, in
the Middle East, that's really some of the saltiest water
in the world. So on detail plants, they're running them
as high as as eighty p s I, which is
(12:35):
pretty high pressure. Uh. In other parts of the world,
like say the Caribbean, the water is a little less salty,
still absolutely seawater, but it's not quite as stalin as
as the Middle East. So there you because it has
slightly less salt, you can use slightly less less pressure. Now,
are these plants often um sort of piggybacked onto other
(12:59):
plants like pour generation. I was wondering if there was
a lot of cogeneration going on with desalination plants. Yeah,
that's a great question. Uh. And this is actually one
of the reasons that g is is uh, you know,
so active in this market. Uh. You know, there's just
an inex Uh. There's a there's a obvious tie between
(13:20):
energy and water. So to produce energy, you know, power
plants need water to produce energy. In fact, almost ten
percent of all global water withdrawals go to the production
of water, so it's a pretty significant amount. Uh. And
then the reverse of that is to desalinate water, you
need energy to do it. So power plants and deesel
(13:41):
plants are are are very linked. In the past, when
the technologies were more thermal based, that was another advantage
of tying the plants together because many power plants, especially
power plants in the past, had a lot of waste heat,
so they could use some of that heat uh for
the thermal desalination. Power Plants today are much more efficient,
(14:04):
so there isn't so much waste heat coming from them. Uh.
And the membrane technologies come to a point where really
that's the propol and technology for desalination. So we're not
seeing them tied together as much anymore because of waste
heat from the power plant, but we are seeing them
tied together simply because the power plant needs water, uh
and the decail plant needs power. Excellent. Hi, it's Jonathan
(14:28):
two nineteen again. I decided that I needed to get
a little salt, so I came back to visit this episode.
While I'm doing that, let's take another quick break. So
what is ge doing to make desalination more feasible to
(14:49):
address water scarcity issues? So we're working in a number
of different areas. We've worked a lot in the past
on the membranes, and uh, you know, there are really
some very high quality membranes now used in this salimation. Uh,
they're not at entitlement yet. There are still some games
to be made there UM, but they're they're getting close.
(15:09):
The membranes are very efficient today. UM pre treatment is
very important. So when when we talk about membranes and
how they take the salt out of water, they're great
at taking the salt out of water, but they aren't
great at taking suspended solids out of water. So you
don't want to put salt or sticks or stones or
anything like that into a membrane. That's bad for it.
(15:29):
So pretty much every membrane plant in the world has
some kind of pre treatment in front of it to
take the suspended solids out before it gets to the membranes.
UH and G has been leading in this area as well.
We have some terrific advanced prefiltration another type of membrane
called an ultrafiltration membrane, and it it provides really superior
(15:51):
UH suspended solids removal, so that the water that gets
to the the reverse us most of the membranes is
as clean as it can be, still salty, but it's
had everything else removed and that makes the life of
those membranes last a lot longer, which in turn lowards
the overall cost of ownership. UM. Then the other pieces
(16:11):
of the pumping side, there are a lot of different
kinds of pumps in the marketplace. The most efficient types
of pumps are positive displacement pumps. If you think of
pumping water, you can imagine you have a fixed geogray
fixed geometry of water. The most efficient way to raise
the pressure of it is just to push on it
um and that works today in in relatively small sizes,
(16:36):
but as plants get larger and larger um there aren't
so many good positive displacement pumps. So instead what people
use their centrifugal pumps. So that's more like spinning the water.
The water that gets thrown to the outside has a
higher pressure. So you know, we've been working developing a
new pump which is a positive displacement style pump, but
(17:00):
is much larger than other positive displacement style pumps on
the marketplace. That's a pretty new product for us, but
we expect that within the next year we're gonna start
seeing more of more of that pump out in de
cel plan and that's going to knock as much as
another ten percent of the energy off, so that when
we get that fully commercialized, not in the marketplace, it's
(17:22):
gonna lower the electrical costs by about ten percent more,
which is really significant when you're talking about, you know,
the cost of desalination. Sure. So, so that's sort of
leads into what do you see as the future of desalination?
Where do you see us going in another few years,
like another decade or two decades. Yeah, that's a great
(17:42):
question and a hard question because there are many many
technologies out there today. Uh. You know, I I think
most people in the industry, myself included, really see reverse
osmosis as continuing to be the most prevalent technology, uh
for at least the next five or seven or ten years. Um.
(18:04):
It's certainly possible that some other technologies could could come along.
And you know, honestly, if there are other technologies that
will dramatically lower the cost of desalination, that would be
great for the planet. Um. But I you know, I
think over the next five or seven years, what we're
going to see is people figuring out how to link
the cell plants more to other renewables. So already we're
(18:27):
starting to see people thinking about how do you combine
a de cell plant with wind turbines and a wind farm,
or how do you combine a de cell plant with
a solar farm. You know, it turns out that a
lot of places in the world but neat desalination, places
that are water scarce, are also places that have quite
(18:48):
a bit of sun. So there there's some nice natural
links between, you know, combining solar with de cell. In
some ways, there's also challenges because you know, in addition
to having a sun, you know, some of these places
also have a lot of sand and it's dusty and
and dust and solar don't don't always hair so well.
The dust coats the panels and they become less efficient.
(19:10):
But you know, now we're talking about some pretty um
discreet challenges. You know, people are doing this now, they're learning,
they're getting better at it. There's not a lot of
solar plus D cell or wind plus D sell out
there today, but I think in the next five to
ten years we're probably gonna start to feel a lot
more about Yeah, it's really exciting and to give our
(19:31):
listeners an idea of the impact that these sort of
technologies have made so far. Uh, it wasn't that long
ago that the estimated population that could not get access
to clean water was around twenty but according to the
World Health organization. They had a two thousand twelve report
(19:52):
which took numbers from and took a look at that.
They said that it's is still a massive problem. Still
s million people lack access to safe drinking water, according
to this report, and that's a you know, that's a
sobering number. But the silver lining here is that that's
that's half of what it was before, so that the
(20:14):
numbers of people who are getting access to safe drinking water,
they're on the rise, which I mean, that's obviously the
way we want to see this trend go. So it's
exciting to see this sort of technology combined with the
efforts of other organizations out there dedicated to making sure
that that people across the world get access to this water. Yeah.
(20:35):
I couldn't agree more. You know, one of the statistics
that that I often hear is that today it's one
and every six people today doesn't have access to clean water,
which is, as you said, really a sobering number. Um.
You know, I I think there's an interesting combination here
where you read a lot about this today. You know,
(20:57):
ten years ago you didn't generally see water articles in
mainstream media, and today, you know, every week you're going
to see an article in mainstream media talking about water scarcity,
and you know, it is a serious problem and it
is alarming. But the plus side of this publicity is
(21:18):
that they're more entrepreneurs, more large companies like GE, just
more people out there starting to think about what are
some possible solutions, uh, And there's lots of them. You know.
Desalination is a great example of ways that we can
solve water scarcity. Water reuse is another great example of
ways that we can solve water scarcity. Water reuse is
(21:40):
just taking water that's already been used for one purpose, uh,
and treating it and cleaning it up and finding a
way to use it for another purpose. So, you know,
I think all the current press that we hear about
water scarcity is actually helping to feed a pipeline of
new innovations and new ideas that will actually helps all
the problems in the long run. Fantastic, Eric, Uh. That
(22:05):
that's a great look at the desalination process and what
g E is doing to to really push this technology forward.
And we really appreciate you coming on the show and
talking with us. It's been a really educational experience for
me and especially as as as liberal arts majors whose
whose background and engineering is saying, Wow, that's cool. Uh,
(22:28):
it's really great to get people like you on our
show to talk about this and and give our listeners
this uh this sort of Uh look, is there anything
else you would like to say before we wrap up? Well,
you know, Jonathan Chris, I'd just like to say thanks,
thanks for having me on the show. Um. You know,
at ge we're doing a lot of really interesting and
innovative things to solve the very problems that we were
(22:50):
just talking about for the last half hour. Uh. You know,
one of the great things about being in this kind
of business is when you come up with innovations, you
can actually see you that they're helping people. Uh. So
you know, it's it's a rewarding business to be and
Geez very committed to it. We're investing a lot and
solving problems today and in the future, and and uh,
(23:12):
you know, I love talking about it and I'm really
excited about where this can all go over the next
couple of years. And that wraps up this classic episode
of tech Stuff where we learned all about desalination. There's
been a lot more work on that over the last
few years and maybe I'll do a follow up episode
to talk about this and the challenges around desalination and
(23:35):
how we need to really be cognizant of those challenges
before we pursue desalination on a grand scale. It turns
out it's a lot more complicated than just taking salt
out of water. I hope you guys uh enjoyed the episode.
If you have suggestions for future topics for tech Stuff,
feel free to reach out to me the email addresses
(23:57):
tech stuff at how stuff works dot com, or pop
on over to our website that's tech stuff podcast dot com.
You will find links to all of our old episodes.
I say old, I should say classic, gorgeous Pristine episodes,
and you will also find links to where we are
on social media, and you'll find a link to our
(24:19):
online store, where every purchasing make goes to help the
show and we greatly appreciate it, and I'll talk to
you again really soon. Tech Stuff is a production of
I Heart Radio's How Stuff Works. For more podcasts from
my heart Radio, visit the i heart Radio app, Apple Podcasts,
(24:40):
or wherever you listen to your favorite shows.
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