Can Sea Water Desalination Save The World?

Despite desalination's drawbacks (high energy use, high cost, environmental impacts), it remains pursued because it provides a fairly stable and known process for reliably supplying water in water-stressed regions when energy and seawater are available

“Desalination has its drawbacks, but one of the benefits is that it's a fairly stable and known process particular for dealing with ocean water. You can be confident that it will supply you water when you need it. Reliability is the key.”

Reverse osmosis does not use heat or boil water; instead, it pressurizes water to tremendous amounts and forces it through a membrane to separate it from salt despite the water's chemical preference to remain with the salt

“reverse osmosis doesn't use heat, doesn't boil anything. You're really just pressurizing the water to a tremendous amount and you're 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.”

Reverse osmosis was developed at UCLA in the 1960s and has since come to dominate the desalination market, replacing thermal desalination as the preferred method

“But in the 60s, we were able to develop reverse osmosis processes at UCLA and these have now started to dominate the market.”

Water scarcity is a complex, difficult problem being affected by climate change, which introduces growing uncertainty about future water availability and supply

“Water scarcity is a complex, difficult problem. Climate change is affecting everything and introducing growing uncertainty.”

San Diego County has historically imported nearly all of its water from the Colorado River and Northern California due to its dry, arid climate

“The county has historically imported nearly all of its water from the Colorado River and Northern California. In San Diego, in Carlsbad example, they are spending twice as much for seawater desalination as they do on imported water.”

Historically, the main impediment to widespread seawater desalination adoption in North America has been cost, as desalination has been prohibitively expensive compared to alternative water sources

“Historically, the impediment for sea water desalination being more abundant or popular in North America has been cost. It has been cost prohibitive historically.”

The Claude Lewis Carlsbad desalination plant outside San Diego is the largest of its kind in the Western Hemisphere, has been operating since 2015, and produces 50 million gallons of clean water per day

“The Cloud 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.”

Desalination plants produce huge amounts of hyper-salty water called brine as a byproduct, with seawater desalination plants using reverse osmosis typically operating at 50 percent efficiency, producing one gallon of fresh water and one gallon of hyper saline brine from two gallons of seawater input

“They're not just outputting clean desalinated water. They're also producing huge amounts of hyper salty water, called brine, as a byproduct. Seawater desalination plants that use reverse osmosis typically operate at a 50 percent efficiency in that if you take in two gallons of seawater, you're going to produce one gallon of fresh water and one gallon of hyper saline brine.”

A 2018 study showed that desalination produces even more brine than previously thought: approximately 1.5 liters of brine for every liter of desalinated water, meaning overall production of brine exceeds production of desalinated water

“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, overall, we are producing more brine than we produce desalinated water.”

For some communities around the world, desalination is already making an enormous local impact, though it remains a small fraction of global water supply and will likely remain so

“But for some communities around the world, it's already making an enormous local impact. It's currently a pretty small fraction of the water supply globally and probably will remain so.”

Communities can use water more efficiently to save water, energy, and reduce environmental impact, making efficiency a superior first approach compared to desalination

“They can use water more efficiently, which can save water, save energy, can have less environmental impact.”

Brackish water desalination requires substantially less energy than seawater desalination because brackish water has lower salt content than ocean water, making less salt removal necessary

“we don't want to lose sight of other sorts of desal, brackish water, which is, you can think of brackish water is it's not as salty as ocean water, but it's saltier than freshwater. It's that whole space between and there the energy requirements are substantially less simply because there's less salt. So less salt, less stuff to remove, less energy.”

Desalination processes similar to reverse osmosis can be applied to treat many other water sources beyond seawater, including wastewater, representing significant untapped potential

“And while most attention is given to seawater desalination, a similar process can be used for treating many other sources of water like wastewater.”

Ninety-six point five percent of Earth's water is found in oceans and is saturated with salt and undrinkable, while most freshwater is locked in glaciers or deep underground, with less than 1 percent available for human use

“ninety six point five percent of that water is found in our oceans. It's saturated with salt and undrinkable. And most of the earth's freshwater is locked away in glaciers or deep underground. Less than 1 percent of it is available to us.”

Seventy-one percent of Earth's surface is covered in water, totaling 332.5 million cubic miles or 366 billion billion gallons, providing over 48 billion gallons per person on Earth

“Seventy one percent of our planet's surface is covered in water. Three hundred and thirty two point five million cubic miles of it. Three hundred and sixty six billion billion gallons. That's over forty eight billion gallons of water for every person on Earth.”

When salt is mixed into water, it dissolves into charged particles that chemically interact with the water at a molecular level, making salt water a chemically new solution rather than simply water with floating salt grains

“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 salt water is a chemically new solution. It's not just water with some salt grains floating around in it.”

Weather is variable, but if you have a desalination plant, energy, and seawater available, you can reliably obtain clean water regardless of climate variability or drought conditions

“Weather is variable, but if you have a desalination plant, energy, and sea water, you can reliably get clean water.”

One out of three people do not have access to safe drinking water, and projections show that by 2050, more than half the global population will be living in water-stressed areas, affecting over four billion people

“today, one out of three people don't have access to safe drinking water. Some projections will show by 2050, more than half our population will be living in water-stressed areas. That's over four billion people.”

At the Carlsbad desalination plant, water agencies spend approximately twice as much for seawater desalination as they do on imported water from the Colorado River and Northern California

“In San Diego, in Carlsbad example, they are spending twice as much for seawater desalination as they do on imported water.”

The vast majority of current desalination efforts are occurring in the Middle East and North Africa, regions that are rich with fossil fuels but experiencing extreme water scarcity

“Which is why the vast majority of desalination efforts right now are happening in places like the Middle East and North Africa. Rich with fossil fuels, but also experiencing extreme water scarcity.”

The two main types of desalination are thermal desalination (boiling water and capturing steam) and reverse osmosis (pressurizing water through a membrane)

“The two main types of desalination are thermal desalination and reverse osmosis.”

Ocean water desalination can be twenty-five times as energy intensive as other freshwater approaches, due to the tremendous amount of energy required to break the chemical bond between water and salt

“It requires a tremendous amount of energy to basically break up that bond between the water and salt. Ocean water desal can be twenty five times as energy intensive as other freshwater approaches.”

Desalination facility water intake operations can destroy local marine life by drawing in millions of gallons of seawater daily

“In addition, because these facilities are taking in millions of gallons of seawater a day, the intake itself could destroy local marine life.”

There are some communities for which desalination is a fairly significant contribution to water supply and can be quite important at the local level

“There are, though, communities for which it is a fairly significant contribution. It can be quite important at the local level.”

The volume of wastewater, if collected and recycled, would be approximately equivalent to five times the volume of water passing through Niagara Falls each year, representing enormous potential for water recovery

“The volume of waste water, if it's all collected and recycled, that is almost equivalent to five times the volume of water that passes through Niagara Falls each year.”

Ocean water desalination undeniably uses large amounts of energy, making it difficult for some to advocate for a technology that would add to growing energy demands when energy is already needed for heating homes and lighting buildings

“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 energy needs.”

Desalination efforts globally produce over 37 billion gallons of brine per day, with most brine emptied back into the ocean where its higher salt concentration can sink to the seafloor and harm marine life and plants found there

“Globally right now, we're producing over 37 billion gallons a day. Most brine is in one way or another emptied back into the ocean. But because it has a much higher salt concentration than regular seawater, it has the potential to, among other things, sink to the sea floor and wreck havoc on the plants and animals found there.”

In water-scarce regions, energy provides services to enable water production, and the energy needed to produce 100 gallons per day via ocean desalination equals approximately one hour of residential electricity consumption, which compares favorably to other energy expenditures

“I think when we start to look into these water-scarce worlds, we start to think about well 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 for some context, you know, the average person in the U.S. uses about a hundred gallons of water per day. If I were to produce that hundred gallons per day with ocean water desal, that would be the same electricity consumption that my home would require over an hour.”

Today, desalinated water in Carlsbad costs approximately twice as much as imported water, but the imported water is produced from systems built a half-century ago where all capital investment has been paid off, making cost comparisons misleading

“You're comparing apples and oranges because that imported water is coming from systems that were built half a century ago where all the capital investment has been paid off.”

By prioritizing efficiency measures first, Israel delayed its need to build desalination plants and was able to build smaller plants than would otherwise be necessary, generating real cost savings for the community

“So they did those things first, so that they aren't wasting that very expensive water. That then delayed their need to build a plant. And when they built it, they could build it a bit smaller than they would have. So there's a cost, a real cost savings there to the community.”

A desalination plant should be viewed as a low-risk but expensive option to hedge risks in a community's water portfolio, particularly useful for managing supply uncertainty

“I would almost look at it as a safe bet, you know, to hedge your risks. A desalination plant is your low risk option in your portfolio. Kind of expensive, maybe, but it's going to deliver.”

A speaker (likely from Poseidon Water) argues that waiting 5-10 years for major technological breakthroughs to reduce desalination costs is not justified, because such breakthroughs will not materially reduce infrastructure building costs, which are a substantial part of total desalination project expense

“Standing down for 5 or 10 years, hoping there's some major breakthrough in the technology is not going to materially reduce the cost of building infrastructure. That's not unique to desal and water. It's true of all public infrastructure.”

The desalinated water globally produced annually is approximately equal to half the volume of water passing through Niagara Falls each year

“And if we look at the desalinated the water, 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.”

Saudi Arabia and United Arab Emirates together produce approximately one-fourth of all desalinated water currently produced on the planet

“Just two countries, Saudi Arabia and UAE, they produce one fourth of the desalination water that is produced currently on this planet.”

Desalination alone is not a comprehensive solution to the world's water problems, and where regions are water-rich, desalination does not make economic or practical sense

“It's clear that desalination alone is not going to fix the world's water problems. Up in some places where you're just water rich, desalination probably won't make the most sense.”

Desalination is one tool of many, and for maximum impact, it must be implemented alongside other water supply techniques

“Desalination is one tool of many. And for it to have maximum impact, it must be implemented alongside other techniques.”

The primary factors to evaluate for desalination viability are whether freshwater supply is available and, if insufficient, whether desalination is needed to augment the supply

“Broadly speaking, what you want to look at for desalination is where's my freshwater coming from and do I have enough of it? And if I don't have enough of it, do I need to augment supply? Desalination then starts to become a very attractive or interesting option.”

The Carlsbad Seawater desalination plant is operated as a public/private partnership with the private sector financing the plant in exchange for a long-term fixed-price water purchase agreement with the public water agency, allowing the private sector to recover investment through water sales

“The Carlsbad Plant is operated as a public/private partnership with the Carlsbad Seawater desalination plant. In the proposed Huntington beach seawater desalination plant, we're proposing a public/private partnership where the plant is 100 percent privately financed and then we enter into a longterm, fixed-price water purchase agreement with the public water agency. Essentially, we're recovering our investment over time through the sale of water.”

The private sector must invest in desalination and other infrastructure because local, state, and federal government cannot be expected to pay for all infrastructure needs, creating a substantial opportunity for private capital investment in water

“There's an infrastructure deficit in the United States. There's certainly an infrastructure deficit in California. And you can't expect local, state and federal government to pay for all of it. The private sector is going to have to invest private dollars. And I think there's a huge opportunity in water in a way that both protects the ratepayers and also allows for the investment of private capital”

While California has robust regulations for brine disposal in place, it is unclear whether the desalination industry globally is taking brine disposal seriously enough, with current disposal methods similar to industrial waste water disposal practices from 40-50 years ago

“And while some places like California have robust regulations regarding brine in place, it's not clear that as a whole the industry is taking its disposal seriously enough. Currently, we are disposing of brine in a way which we use to dispose of industrial waste water about 40-50 years ago.”

Desalination is not a solution to water scarcity but rather one option to narrow the gap between water supply and demand

“Desalination is not the solution to water scarcity. It's one of the options to narrow the gap between water supply and demand.”

Communities should prioritize cheaper, less environmentally damaging water supply options first, treating seawater desalination as an option only after other approaches have been exhausted or are unavailable

“I think we do the cheaper, less environmentally damaging things first. That seawater desalination is an option. In some communities, they don't have other options. Others, though, do have other options.”

Desalination is already vital for many water-scarce communities around the world, and as climate change continues to transform the planet, the balance between concerns about energy use and the need to reliably obtain clean water will evolve

“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.”

Desalination is an important tool in the fight against water scarcity, with reliability becoming increasingly important as climate change transforms the planet, but it should not be viewed as a cure-all and other techniques should always be implemented alongside it

“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.”

The United States has a substantial infrastructure deficit across water, transportation, and housing that requires immediate investment, not delayed implementation pending technological improvements

“We have a huge deficit. We need to start building not just water, but transportation and housing. Now, not 5 or 10 years from now.”

People spend more on a daily Starbucks coffee than they do on a month's supply of desalinated water, but many consumers are not aware of this price comparison

“people go out and they buy a venti Starbucks every day and spend more on that than they do for a month's supply of desalinated water. And they don't realize it.”

Poseidon Water argues that California regulations provide sufficient environmental protection and numerous studies show that salinity increases from brine disposal will not harm 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 that show that level of salinity increase will not harm marine life.”