In 2015 a series of droughts started to dry up this dam, the source of almost half of the water
available to Cape Town, South Africa. In this satellite time-lapse you can literally see the stored water decrease month by month. In 2018 the city
was approaching "day zero". Shorthand for the day the taps run dry and people would
have to queue to get water rations. Cape Town was the first
major city to risk running out of water, but it's not going to be the last. Jakarta, London, Beijing, Tokyo could all face their
own day zero in the coming decades. “Most parts of the
world at least for a month a year are experiencing some water stress or water scarecity." “The gap between demand
and supply of water is narrowing down.” Our planet is awash with water. More than one billion
trillion liters to be precise. The problem is
that 97% of Earth's water is salty and most of the
freshwater is frozen in ice caps. Less than 1% of the
Earth's water is drinkable. That makes one
solution especially promising: Desalination seems
a pretty straight forward solution: you take that undrinkable
salt water, you remover the salt, and you have an unlimited
supply of freshwater. So, why are we not building
more desalination plants? Desalination is a natural
process that's been known for millennia. As already Aristotle noted,
the sun dissolves ocean water into vapor, which then condenses
again and falls back as rain. His compatriots took note. Greek sailors
boiled seawater for long trips. Romans used clay filters to trap salt. These are still the two
basic principles used today. Thermal desalination uses heat. Salt's boiling point
is a lot higher than water, so if you boil salt water, only freshwater
will evaporate, leaving all the salt behind. Membrane desalination uses pressure. Saltwater, here colored in red for clarity, is pressed through a
membrane that is only partially permeable. Freshwater can pass through, here colored in blue,
but the salt is trapped on the other side. The technology didn't
improve much until the 19th century, when industrialization and
population growth encouraged more research. “Population growth is the main
driver for increasing water scarcity.” Manzoor Qadir
is an environmental scientist with over 30 years’
experience in water management. “Say, for instance, the
Middle East and North Africa region. That region has a population of about
five percent of the world's population, but just has one percent
of the global water resources.“ And soon, another factor could
make desalination even more crucial: As the climate warms
more water will evaporate. And as Aristotle noticed, more vapor equals
more clouds, equals more rain. But that rain won't fall evenly. This map shows how precipitation
will change as the climate warms. Regions in purple will get
more rain, those in orange less. Now compare it with this other map. The red dots here show areas
that already today don't get enough water. Dry areas like California and
the Middle East will see even less rainfall. Other countries like India will have
more rain in the monsoon season, but less in the dry season,
when people need it most. This will make desalination
even more popular. "And that has really started to explode,
let's say since the late '80s and '90s. But especially in the last
20 years, you've seen a big acceleration." Edward Jones is a Ph.D. researcher who has put together a "state-of-the-art
outlook on the status of desalination." "Nowadays we have
around 16.000 desalination plants which are producing
more or less 100 million m3 per day.“ But take a closer look at this map. "If you look at how much desalinated
water we produce on this globe, currently, 71% is
produced in high-income countries.“ That's because desalination is very costly. Boiling billions of liters
of water takes a lot of energy. “In the Middle East, the availability of oil and especially
fossil fuels makes the thermal processes cheaper, but for other types it can
be 25 or 30 times more expensive.” But that energy doesn't
have to come from fossil fuels. A startup in Berlin
has a sustainable alternative. “My name is Ali Al-Hakim, I am the co-founder and CEO of the company Boreal Light. I moved from West Germany to Berlin...
Let me just drink a glass of water. Do you also want to drink something?“ “Your water?“ “If you like.“ “Yes, please!“ “So the water comes from
the borehole tank to the system. And after that, it's going through the buster pump. With 40 bars of the water
is pressured to the membranes. It's clean,
desalinated water, with green energy.“ Green energy:
that's the key to the company's success. You are looking at of their plants in Kenia. These solar panels
keep the cost of water low in villages like this,
where electricity is not available. “We get the water for free, we get the electricity
from solar and wind for free, so we can now produce
one thousand liters for fifty cents. This price is actually competitive [with]
clean water from rivers or from boreholes.“ But there's another problem. What do you do with this water? “We forced all of this salt out of the
water to produce our freshwater. But now the salt is still
contained within our substance, but it's just in a smaller
volume, so it's more salty.” This water is called brine. “At the global level, we produce more
brine than we produce desalinated water.“ “You've got your pipe that's
coming out of the desal[ination] plant. You're discharging hypersaline water here, and as it flows out it will
sink because it's more dense.“ “The salinity and the temperature
can also deplete the oxygen available and this is what's
causing the organisms more damage, just the lack of oxygen.
They are basically suffocating.“ Brine can also contain
chemicals harmful to sea life. “There needs to be a better plan
for the industry of dealing with this brine. We are producing
more waste with no plan.“ But what if this waste
could become a resource? Tomatoes, seaweed, and
certain fish can tolerate high salinity. Boreal lights uses
brine to cultivate them in tubs like this. "There's also the opportunity
for salt recovery and for metal recovery." "At the moment technologies
are available for brine management, but those are on a very small scale. The challenge is how we can transform
those small-scale technologies into a large-scale operation.“ Desalination is not a magic formula. The process must become more efficient before low-income countries can afford it. Plants must convert from fossil fuels
to renewable energies to limit emissions. And the whole industry needs to come upÂ
with a plan to deal with this brine. But plants like this are already
a lifeline for many communities. “It's very important to
realize that desalination is here to stay. We really need to work towards
solving the challenges of desalination.“ “This is a gradual process
this will not happen overnight. But I can see that there is a push there is a willingness to harness
the potential of desalinated water.“ Today Cape Town is doing a lot better and the dam is almost full. The city was rushing to build
desalination plants to avoid day zero. But the solution was not
desalination or any other technology. Citizens became water-wise. They radically
changed their water use, and valued water for the essential
and irreplaceable substance that it is. Fun fact: The amount of
desalinated water we produce every year is comparable to half the water
that falls off the Niagara Falls every year. That's it from us. As you can
guess from this quick time-lapse, these videos take a lot of time.
If you liked it, please give it some love. Share, subscribe, press the like button. And stay tuned. We have more
videos like this coming out every Friday.
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