Is Seawater Desalination the Solution for the World’s Water Problems?

A study from McGill University, estimates the average Canadian consumes about 329L of water a day, the equivalent of more than 600 standard water bottles (500 ml). Think of your daily routine. In the morning you get up, you have a shower. Flush the toilet. Fill the water for your coffee or tea. Run the dishwasher. At lunchtime, you might boil some pasta. Later you might do some laundry. Before bedtime, you may might run a warm bath or put the kettle on for some hot tea. Sleep and repeat. 

As the population keeps growing, water consumption increases, and it becomes more difficult to access the blue gold in a sustainable way. In the long run, this can create water stress, a phenomenon that occurs when the water demand is higher than its availability. How can we prevent this problem and what solutions are available to us? In cities like Cape Town, South Africa, residents have been encouraged to follow a series of water-saving initiatives, from flushing the toilet when necessary to shower no longer than two minutes. 

But this doesn’t completely solve the issue from repeating itself. Are there any other solutions available? In the past, desalination has been considered a possible option to solve the water crisis. If you think about it, 70% of the Earth's surface is covered by water, and the oceans hold more than 95 % of all Earth water. Turning seawater into drinking water could help populations who face water stress and water scarcity to solve this problem. However, this isn’t as easy as it sounds. 

In today’s episode, Heather Cooley, Director of Research at the Pacific Institute, explains how desalination works, the impacts this can cause to the marine environment, and how unsustainable this practice can be.

For more information about seawater desalination, water stress and the work that the Pacific Institute does Click Here.

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Transcript

David Evans: 0:25

Cape Town is home to 4 million people. And it's a coastal paradise that sits right at the southern tip of South Africa. Cape Town is a global tourist destination, with tourists flocking to its beautiful beaches, scenic waterfront, and the climb Table Mountain. However, in 2018, the city of Cape Town almost completely ran out of water. It was so bad that capetonians were limited to just 50 litres of water every day per person. Now 50 liters sounds like a lot. But considering it takes 15 liters on average for a shower, and the average US citizen uses 300 liters of water a day. 50 liters doesn't get you very far. So capetonians were encouraged not to flush their toilets. They even had competitions to see who could wash their clothes, the least throughout this crisis. Now, what caused this water shortage? And what did Cape Town turn to as a potential way to solve their water crisis? While they also live right beside an ocean? Today, we're talking about another tool in the water tool belt. We'll discuss its strengths, its weaknesses, and its potential role to play in combating the impacts of climate change. In this episode, you'll be hearing from Dr. Heather Cooley from the Pacific Institute. Today we're talking about seawater desalination. Water we doing? And how can we do better? your one stop shop for everything water related from discussing water to use and the organisms that depend on it for all the global issues that you really never knew all had to do with water. I'm your host, David Evans from the aquatic biosphere project. And I just want to ask you something. What are we doing? How can we do better? Water stress is one of these buzzwords in the water world. water stress occurs when we take more water out of a system then is going back into that system. So for example, if you have a glass of water, and it's half full, if every minute you add five drops of water, and then every minute, you're also taking a pretty big sip of water, eventually, the glass is going to be empty. Now, that's basically what water stress is. But on a landscape level, around a city around a country, it's actually more common than you might think. So you don't have to live in a desert to be water stressed. Almost every state in the United States is water stressed to some degree. Even Canada has areas that are under water stress across the country. But we still consider ourselves a water rich nation for some reason. It's really sad, but one in four people around the world live in an area that's water stressed, it might surprise you that some of the major cities in the world are actually at risk of running out of water. In the next few years. The City of London is set to run out of water. Actually all of England is set to run out of water. Within the next 25 years. Melbourne Australia had a huge drought for over a decade from 1997 to 2009. But guess what, because of deforestation around them, they're not actually able to gain the headwaters back. And so they are also really in danger. Other cities Beijing, China, Sao Paulo, Brazil, Jakarta, Indonesia, Tokyo, Japan, some of these might surprised to hear that they're really water stressed areas and they are on track to run out of water in the next couple of years. This issue starts to snowball out of control, as populations continue to grow. And as our climate increases in its very ability, sometimes now we're getting extremely long droughts, and some areas of the world are getting more and more rain. And we just have no way of predicting this as the climate is changing. This all leads to more water stress on different areas of the world. water stress impacts human health. Water plays a huge role in sanitation, food production, and we all need drinking water. It also impacts socio economic development. Water is a basic input in almost everything that we produce. It impacts the environment, if the rivers run dry, it has enormous effect on all living systems. And another impact that is really coming to light is it impacts political stability, it's increasingly playing a role in conflict. If we want to work towards world peace, eliminating water stress is a key factor. So you probably guessed it by now. But yes, the area around Cape Town is water stressed. Not only that, but it was also in a three year long drought and needed rain badly. The drought accelerated the city's water issues, so that they had to act quickly. So they did, Cape Town took drastic actions, everything from banning the filling of swimming pools of washing cars to finding households with high water use. This was great as a decreased demand for water, but it certainly didn't increase the supply. Capetown was lucky, they were able to work out agreements to buy water from other areas until the rains finally came. The problem is, they aren't out of the woods yet, and are still predicted to run out of water sometime in the next few years. Unless they take drastic action to increase their water supply. Soon. The city hurried to install new wells to access deep underground aquifers, and to build seawater desalination plants to provide the city with fresh water. I mean, they live right beside an ocean. That has to be the way to go. So tell me understand this, I reached out to an expert to understand if building seawater desalination plants is the way forward.

Dr. Heather Cooley, The Pacific Institute: 7:17

Yeah, so my name is Heather Cooley, and I'm a research director at the Pacific Institute. Our mission is to create an advanced solutions to the world's most pressing water challenges. When I say I work in water, often their first question is, well, what about desalination? Clearly, that's the solution. And you know, I can sort of see, you know, oceans cover about 70% of the Earth's surface and much of that water, about 97% of that water is found in the ocean. There's a lot of interest, but there are major drawbacks that really limit widespread use. First, it's expensive. The second it's it's energy intensive. And third, it can have some major impacts on the marine environment.

David Evans: 8:02

Okay, so maybe I jumped the gun a little bit on this one. Do you mind Heather, just explaining a bit about seawater desalination, and how it even works?

Dr. Heather Cooley, The Pacific Institute: 8:13

Yeah, so seawater desalination is the process of removing salts and other minerals from water taken from our oceans. It typically occurs through either thermal or membrane processes. With thermal desalination or thermal processes, what you're really doing is you're using heat to distill fresh water from seawater, you could sort of think of the sun and doing this all the time, right, it's heating up water in our oceans, that creates vapor that then falls over the land as freshwater. So you know, most of the early plants use these thermal processes, but nearly all new plants are using sort of membranes, and specifically they're using reverse osmosis membranes. And with reverse osmosis, seawater is pressurized, and then it's forced through a semi permeable membrane. So you know, the water molecules are small enough to pass through the membrane, whereas the salts are too large and are left behind. So from that inflow that you're having of that ocean water, you then have two streams, you have sort of a freshwater stream, and then you have a very sort of hyper sailing brine. And for every two gallons of seawater, you have about a gallon of fresh water and then a gallon of the of the hyper sailing brine that you then need to dispose.

David Evans: 9:35

seawater desalination isn't anything new. And it's been improving a lot over the years. Starting with thermal really intense fossil fuel use to be able to produce the heat that's needed to boil the water to create the vapors that we can then condense to form freshwater. There's a shift now towards using more reverse osmosis plants. They're more energy efficient than the thermal plants, but they still take a huge amount of energy. One of the major problems with seawater desalination is your leftover with this really super salty sailing brine. During the desalination process, you end up with fresh water and the super salty brine All of the salt from the freshwater is now put back into the salty brine. So the salty brine is twice as salty as normal seawater. And this becomes a problem when you have to do something with this huge amount of salty brine, is it going to hurt our oceans?

Dr. Heather Cooley, The Pacific Institute: 10:36

You know, typically with plants, the easiest way for them to dispose a brine is through an open ocean outfall. Essentially, they take the brine it not only frankly, has salts in it, it has some of the chemicals that are used in the in the treatment process itself. It has some of the marine organisms that are killed, it has those in it as well. And it's very heavy, it's dense. And so what happens is it's released and it tends to sink, and it then spreads out on the bottom.

David Evans: 11:08

You know, those cocktails that you see pictures of that have different layers of liquids on top of each other, and then you try to make them yourselves and it never seems to work out the way you planned it? Well, this is kind of like that, that's based on density. When we have this super salty liquid, we put it back out in the ocean, it's actually more dense than the ocean water around it. So it ends up sinking right to the bottom, like it does, if you do it correctly in your fancy cocktail drink. Now, the problem with having a super salty layer at the bottom of the ocean is that all living organisms in the ocean have a salt tolerance, they have an amount of salt in the water that they really like. And if it gets too high or too low, then they don't do so well. So if you take a saltwater fish, and you put it in a freshwater aquarium, it's not going to do very well because it needs that salt level so that it can survive. On the flip side, if you double the amount of salt in that water, then that organism still is going to suffer because it's not in its ideal salt tolerance, we really don't know much about our oceans to begin with, let alone How adding millions of gallons of super salty brine, how that will affect marine environments. So we really need to know more about what are the potential environmental effects that we could be dealing with sooner rather than later. The way that we get rid of this super salty layer is mixing in the oceans. And this happens over time. It's usually a very slow process, though. But there are ways to increase the mixing, you can make sure the pipe that takes the brine from the plant to the ocean, make sure it doesn't end up in an enclosed Bay or a really calm area, you want the brine end up in the open ocean, or an area that has a lot of turbulence so it increases it's mixing with the rest of the water. You can also install diffusers along the pipe so that small amounts of the brine get led out along the way. And it just increases the mixing speed. And unfortunately, these mitigating factors have a cost that's associated with them. So it's not always a first choice to do it.

Dr. Heather Cooley, The Pacific Institute: 13:28

There's also been some interest in turning the waste into a resource and moving towards zero discharge plans. There are things in that brine that are of commercial value, potentially, there's sodium hydroxide or hydrochloric acid, you know, those are so things can be recovered. And then actually used in the desalination process itself. There are metals like lithium or uranium that are in that there's the salts, as you sort of mentioned, for road salts, for example, there are parts of the world where road salts are not in my part of the world,

David Evans: 14:04

here in Canada.

Dr. Heather Cooley, The Pacific Institute: 14:08

So you know, the big obstacle, there is really the cost, I mean, recovering all of that is far more expensive, obviously, than just discharging it into the ocean. But there is an environmental cost that we often don't account for with discharging into the ocean. So how do you how do you sort of integrate that into the decision making? So you know, I think there's work being done on it there. There are some I would say some constraints, it does often require more land area, there's been a lot of analysis to try to see what's cost effective. Thus far, nothing's really sort of driving it yet, but there are opportunities out there.

David Evans: 14:47

Alright, so what have we learned so far, water stressed areas of the world are in trouble. These issues are serious. And as populations increase, and the climate becomes more unpredictable, this problem will only get worse. And if you have the luxury of being near an ocean and have the money and electricity to invest in desalination technology, then you have some options. The problem with this is that now we are using up a lot of energy pumping potentially even more greenhouse gases into our atmosphere which Just perpetuates this problem. It's expensive, and we're unsure about the scale of the environmental effects. Okay, so I'll be the first to admit, I guess I thought the solution to Cape town's problem was a little too obvious. I mean, it's an entire ocean for crying out loud. But there are lots of places around the world that are water stressed, and they aren't near an ocean. What are some of the other strategies that we can use to combat water stress?

Dr. Heather Cooley, The Pacific Institute: 15:49

While there's a lot of enthusiasm about seawater desalination, you know many who kind of work on these issues and even who have pursued desalination really see it as a supply of last resort. You know, many areas still have less expensive options that have fewer social and environmental impacts, things like water conservation and efficiency, we lose a lot of water in our water distribution systems, for example, through leaks, fixing those leaks, putting in high efficient showerheads and toilets and replacing you know, water intensive lawns with low water use landscapes can go a long way, and are much less expensive than then desalination. There's water recycling, and reuse, for example, is another option, you know, many of our systems are built, we use water once, and then we throw it away. There's an option of taking that water, treating it and reusing it, whether you're using it for things like irrigation or for industrial processes, but we're also seeing increasingly people using it to recharge groundwater to be reused for drinking water. So you know, desalination is an option and and it's one that communities rely on. But as I noted, it's very expensive, energy intensive and the marine impacts.

David Evans: 17:07

So turns out, water stress can be dealt with, there are many ways to do that. And desalination is just one of those many ways. Now, it doesn't work for everyone. And it may be a while before, it's necessary in some cases, but it's one of the tools in the water toolbelt to help us get through a water crisis. Now, before we wrap everything up here, Heather, do you have anything to add about seawater desalination? And where people can find out more information about this technology? And what's happening around the world with it?

Dr. Heather Cooley, The Pacific Institute: 17:41

Frankly, one of the benefits of seawater desalination is that you can sort of turn it on, right. So it's independent of hydrologic conditions and so that that's a benefit. That's a benefit worth paying something more for. There's a lot of wonderful groups out there working to solve these problems. And whether it's from a government perspective, an NGO perspective, or increasingly, you know, companies are, you know, trying to do better around sustainability. So, you know, there are a lot of opportunities. If you're interested in learning more about desalination and about our work, I would, I would encourage you to look at our website, we do a lot of reports, particularly on desalination, we track a lot of projects. It's all available at no cost.

David Evans: 18:25

So there you have it, go check them out at Pac i n st.org. The Pacific Institute has so many awesome resources about water efficiency, seawater desalination, you name it, they're looking into it. So go check them out. They have great resources, and I'll leave a link in the show notes for their website as well. Thanks for listening to this episode. If you enjoyed this episode, please hit the subscribe button, so you don't miss any of our future episodes coming out. sometime soon, we will be releasing a deep dive episode, our whole interview with Heather Cooley from the Pacific Institute. This Wednesday, you'll be sure to want to check that out because Heather talks so much more about water stress, seawater desalination technology, and how to get into a position. I like her. I had such a great time chatting with her. And I think you'll really enjoy it. And that's our show for today. Thank you so much for listening. Please subscribe so you don't miss any of our future episodes coming out. Leave us a rating and review. It means so much to us to hear back from all of our listeners. I'm the host and producer David Evans. And I just like to thank the rest of the team from the aquatic biosphere project specifically to Paula olman, Sophie Cervera and Ann Bettini. Thanks for all of our help to learn more about he aquatic biosphere project nd what we're doing here in lberta telling the story of ater. Check us out at www.aqua icbiosphere.ca. And if you ha e any questions or comments abo t the show, we'd love to he r them. Email us at conservati n@aquaticbiosphere.org. Please d n't forget to like subscribe a d leave us a review. It really h lps us out. Get excited for n xt Monday when we release our n xt episode. All about a carp a d their invasion across the U ited States and what they're d ing to try to get into C nadian waters. We talking to t e people who are trying to s op them, and the people who a e documenting what's going on. S you'll hear from author Andre Reeves, who wrote the book o Asian carp. They'll hear fro Kevin Irons, the fisher biologist chief out of the stat of Illinois. And you'll eve hear from Chuck Shea, a engineer from the US Army Corps who's in charge of th underwater electric fence that' keeping them out of the Grea Lakes. Tune in you will want t miss it. Thanks for listening t the water we doing podcast an until next time, it's been splas