Water is the foundation of our life. Our bodies are made up of 60% water. And we need clean, safe drinking water to survive, to grow our crops, and to move our waste stream.
71% of our planet’s surface is covered in water. In number, it is actually 332.5 million cubic miles which are covered by the ocean.
And the ocean water is around 366 billion, billion gallons. That’s over 48 billion gallons of water for every person on Earth.
But today, one out of three people doesn’t have access to safe drinking water. We can say that 20% of the world’s population has no access to clean, drinkable water.
And some reports say that by 2050, more than half our population will be living in water-stressed areas. That’s over four billion people.
These aren’t just issues in developing countries. Water scarcity is a worldwide issue. The worst-affected areas are the arid and semiarid regions of Asia, the Middle East, and North Africa.
It’s hard to imagine, but 96.5 % of water is found in our oceans. It’s saturated with salt and it is undrinkable. And most of the earth’s freshwater is locked away in glaciers or deep underground which means less than 1 percent of it is available to us.
So why can’t we just take all that sea water, filter out the salt, and have a nearly unlimited supply of clean, drinkable water? Why can’t we solve the world’s water crisis by desalinating sea water?
So how does Desalination works?
Desalination is the process of removing the excess salt and other minerals from water to obtain potable freshwater suitable for animal consumption or irrigation, and if all of the salt is removed, even for human consumption.
It’s been practice for years. In fact, it’s a natural process. It occurs when the sun heats the ocean and freshwater evaporates off and it falls again as rainfall.
If you mix salt into water, it dissolves. And if you could watch microscopically while you did that, you’d see that the water is actually breaking apart the salt into charged particles that chemically interact with the water.
So saltwater is chemically a new solution. It’s not just water with some salt grains floating around in it. And that’s why desalination is a fundamentally tricky process. The two main types of desalination are thermal desalination and reverse osmosis.
Thermal desalination is the oldest form of desalination. It’s basically boiling water and then capturing the steam and turning that into freshwater.
But in the 60s, UCLA was able to develop a process called reverse osmosis which has now started to dominate the market.
One of the main difference between the two is that reverse osmosis doesn’t use heat, doesn’t boil anything. It really just pressurizes the water to a tremendous amount and forcing it through a membrane where it doesn’t want to go. It wants to stay with the salt. But with this high pressure, it is forced to separate from the salt.
So due to this process, desalination starts to become a very attractive option. That is why the vast majority of desalination efforts right now are happening in places like the Middle East and North Africa.
In fact, the Middle East has been a leader in desalination so far. Saudi Arabia, United Arab Emirates, Kuwait, and Israel heavily rely on desalination as a source for clean water.
They are rich with fossil fuels, but also experiencing extreme water scarcity. These countries make up currently one percent of the world relying on desalination to meet water needs. But the UN has predicted that by 2025, 14 percent of the world will rely on desalination to meet water needs.
So desalinating the water is a great measure in the fight against water scarcity. Its reliability is becoming critical.
And if you have a desalination plant, energy, and sea water, you can reliably get clean water. But it’s not a cure-all. There are concerns about the amount of energy required, how much it costs, and its environmental impacts.
Concerns about Sea Water Desalination
Some experts see the sea water desalination as a key solution but others think that it is expensive, it has impacts on the marine environment and so we should pursue alternatives first.
Desalination requires a tremendous amount of energy to basically break up that bond between the water and salt. Sea water desal can be twenty-five times as energy-intensive as other freshwater approaches.
Historically, the hindrance for sea water desalination has been cost. It has been cost-prohibitive.
The Claude “Bud” Lewis Carlsbad desalination plant outside of San Diego is the largest of its kind in the Western Hemisphere and has been operating since 2015, producing 50 million gallons of clean water a day. It’s in San Diego County because of its dry, arid climate.
The county has historically imported nearly all of its water from the Colorado River and Northern California. And in San Diego, in Carlsbad plant, they are spending twice as much for sea water desalination as they do on imported water.
The Carlsbad Plant is operated as a public/private partnership where the plant is 100 percent privately financed and in long term, fixed-price water purchase agreement with the public water agency. And they are recovering their investment over time through the sale of water.
In United States, there is a huge deficit in the infrastructure. And it’s time that the private sector should also invest in it.
Experts say that there’s a huge opportunity in water in a way that both protects the ratepayers and also allows for the investment of private capital.
But beyond environmental costs of producing the energy needed to power these plants, there is another concern that is arising due to desalinating the clean water.
Brine as a Byproduct
Brine is hyper salty water. Sea water desalination plants that use reverse osmosis typically operate at 50 percent efficiency which means that if you take in two gallons of sea water, you’re going to produce one gallon of freshwater and one gallon of hyper saline brine.
As desalination efforts grow, it’s not clear what should be done with these huge amounts of brine. Globally right now, the world is producing over 37 billion gallons a day.
And typically, the most brine is in one way or another emptied back into the ocean. Brine also has its drawback as it has a much higher salt concentration than regular sea water; it has the potential to do other things like a sink to the seafloor and wreak havoc on the plants and animals found there.
Besides with this all, the intake of sea water also could destroy local marine life.
But Poseidon Water, which operates the Carlsbad plant, says the regulations in California provide sufficient environmental protection.
Numerous studies have been done in California and around the world which shows that the increase in the level of salinity will not harm marine life.
But a recent study published in 2018 showed that we’re producing even more brine than we thought. For every liter of desalinated water, we produce 1.5 liters of brine. In other words, we are producing more brine than we produce desalinated water.
And while some places like California have robust regulations regarding brine in place and it’s not clear that as a whole the industry is taking its disposal seriously enough.
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Currently, they are disposing of the brine in a way that we use to do to dispose of the industrial wastewater about 40-50 years ago.
So if desalination uses a huge amount of energy which is very expensive compared to other options and in the end, we’re producing more potentially harmful brine than clean water, so why do we continue to pursue it?
Desalination has its drawbacks, but one of the benefits is that it’s a fairly stable and known process particular for dealing with sea water. You can be confident that it will supply you with water when you need it. Reliability is the key. And water scarcity is a complex, difficult problem.
Climate change is affecting everything and introducing growing uncertainty. Weather is variable, but if you have a desalination plant, energy, and sea water, you can reliably get clean water.
But desalination undeniably uses a large amount of energy. And for some, it’s just fundamentally difficult to advocate for a technology that would be adding to our ever-growing and mostly fossil fuel-based energy needs.
High Energy Cost and Impact
Desalination plants need high energy to produce fresh water. And for me, energy provides us services. It heats our homes, it lights our offices and buildings.
And if we think of energy as a service that could give us water. And for some context, you know, the average person in the U.S uses about a hundred gallons of water per day.
Let’s take an example, if I were to produce that hundred gallons per day with sea water desal, that would be the same electricity consumption that my home would require over an hour.
So to kind of put things in context, we should start to think about our energy resources and where do we invest it? And how important is water?
So it’s clear that desalination is not the solution to water scarcity. It’s one of the options to narrow the gap between water supply and demand.
But for some communities around the world, it’s already making an enormous local impact.
Israel Case Study
Desalination is one tool of many. And for it to have maximum impact, it must be implemented alongside other techniques.
And Israel is the perfect example of this. They invested quite a bit in sea water desalination, but they also made investments in efficiency such that their water use on a per-person basis is far lower than we see in the United States.
So they used water efficiently which delayed their need to build a plant and when they built it, they build it a bit smaller than they would have. So they saved a little bit for their community.
I think sea water desalination is an option. And we should do the cheaper, less environmentally damaging things first.
And also use the water more efficiently, which can save water, save energy, can have less environmental impact.
And while we are giving most of the attention to sea water desalination, there is an another similar measure we can use for treating many other sources of water like wastewater or brackish water.
The volume of wastewater, if that’s all collected and recycled, it will be almost equivalent to five times the volume of water that passes through Niagara Falls each year.
And if we look at the desalinated water which we produce globally, on an annual basis is almost equal to half of the volume of the water that passes through Niagara Falls.
And we can also desalinate the brackish water. It is not as salty as sea water, but it’s saltier than freshwater. In this case, the energy requirements substantially will be less simply because there’s less salt.
Conclusion:
So there are many ways to fight the water scarcity. And Desalination is an important tool in the fight against water scarcity. Its reliability is becoming ever more important, but it’s not a cure-all and other techniques should always be implemented alongside it.
Desalination is already vital for many water-scarce communities around the world. And as climate change continues to transform our planet, the balance between concerns about energy use and the ability to reliably get clean water is going to evolve.
At this point, it is evident that “Sea Water Desalination” is not a sustainable option. But how exactly desalination will fit into the future of lean water is yet to be seen.
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