Seawater Desalination: Benefits and Environmental Challenges

Seawater desalination offers hope for water scarcity but poses environmental challenges that need urgent attention.

### The Bitter Truth Behind Seawater Desalination: Benefits and Environmental Challenges
* 💧 Despite the vast amount of water on Earth, only about **1% is available for drinking** due to the predominance of salty seawater and frozen sources.
* 🌍 Regions marked in red on maps indicate areas suffering from **year-round water scarcity**, highlighting the paradox of **water abundance versus accessibility**.
* 🌡 Many believe global warming will increase rainfall, but climate change is actually **exacerbating dryness in many regions**, leading to a predicted **increase in water scarcity**.
* 🔬 Desalination has been a solution for centuries, evolving from ancient methods to modern techniques like **evaporation and reverse osmosis**, with **over 16,000 plants operating globally today**.
* 🌊 However, the process of desalination generates **significant greenhouse gases**, particularly from fossil fuels used in boiling seawater, raising concerns about its **environmental impact**.
* ☀ Innovative projects like the Solar Dome in Saudi Arabia aim to utilize solar energy for desalination, producing **fresh water with zero carbon emissions** at a **cost-effective rate**.
* The concentrated brine produced during desalination poses a serious threat to marine ecosystems, with many facilities **discharging it back into the ocean without adequate regulation**.
* 🔍 Ongoing research seeks to address these challenges, exploring methods to **reduce brine salinity and recover valuable minerals**, but widespread adoption of these solutions remains a **future goal**.

Oh, amazing! Wow, it's incredible! But there is one thing that both you and I know: behind something sweet, flashy, and grand, there is a bitterness that we either do not know or choose to ignore. Today, I want to talk about the somewhat uncomfortable truth regarding seawater and freshwater. The areas that appear in bright red on the map are regions that suffer from water scarcity all year round. Of course, no one looking at these areas would say, Hey, there’s water all around; why is there a shortage? That’s understandable because 70% of the Earth's surface is covered in water, totaling about 1.3 billion cubic kilometers. However, a staggering 97% of that is salty seawater, which is difficult to drink, and most of the remaining 3% is frozen. In the end, we can only use about 1% of the Earth's water as drinking water. Given this situation, countries that are inherently water-scarce due to their geographical location inevitably suffer from a shortage of drinking water.

There are some people who believe that global warming is making the Earth hotter, causing seawater to evaporate and resulting in more rainfall, thus solving the drinking water problem. However, this is a one-dimensional way of thinking. The climate changes caused by global warming make dry areas even drier, and the large amounts of rain clouds brought about by warming are likely to pour rain only in specific regions at specific times. Therefore, scientists predict that the current climate change will accelerate water scarcity. But as you know, there is a really simple solution: widely desalinating seawater makes the game over. In fact, this method has been used since thousands of years ago. Ancient Greek sailors boiled seawater on their ships and used the condensed water as drinking water, while in ancient Rome, they used clay filters to turn seawater into freshwater. And now, in modern times, we have more advanced methods.

The principles have become more sophisticated and large-scale, but they remain the same. The evaporation method, which cools the steam generated by boiling seawater to create fresh water, and the reverse osmosis method, which filters out salt by passing seawater through a semi-permeable membrane under high pressure, are representative examples. As we can see in this graph, starting in the late 20th century, the number of plants has increased exponentially as the costs of seawater desalination technology have decreased. Currently, there are over 16,000 plants operating in 77 countries around the world. Of course, there are also plants in our country, and above all, Korea is well-known as an exporter of this technology. However, it is important not to misunderstand that just by looking at this number, it may seem like seawater desalination technology is widespread globally. As we can see, most of the installed plants are concentrated in high-income countries such as the Middle East, Europe, and North America. Anyway, the seawater desalination plants installed around the world...

The amount of freshwater produced in desalination plants in a single day reaches an astonishing 100 billion liters. Particularly in Saudi Arabia, a country with no rivers at all, most of the drinking and agricultural water relies on seawater desalination, accounting for one-fifth of the world's freshwater. However, with ongoing projects like The Line, a massive 170 km long linear city that Saudi Arabia is planning, the demand for desalination plants will significantly increase to supply drinking water. Of course, this issue is not limited to Saudi Arabia alone. However, the increase in seawater desalination plants poses a significant problem: the generation of greenhouse gases. As mentioned earlier, the evaporation method of seawater desalination literally involves boiling seawater, which requires a corresponding amount of fossil fuels to be burned to heat vast quantities of water.

the enormous amount of greenhouse gases is generated in the process. Isn't that ironic? Many scientists are searching for solutions, and one of them is solar energy. The Solar Dome project currently underway in Saudi Arabia involves placing a large dome in the middle of the desert, surrounded by mirrors. Seawater is drawn into the dome and stored, and then the light reflected by the mirrors is used to heat the stored seawater, resulting in zero carbon emissions. Additionally, the eco-friendly seawater desalination project installs solar panels in small-scale desalination facilities, where the electricity generated is used to produce fresh water. This project is highly cost-effective, producing fresh water at about 700 won for 1,000 liters. As a result, this technology is already being adopted in some villages in developing countries. However, there is a fundamental issue with seawater desalination technology that is difficult to overcome even with renewable energy.

There is still the issue of concentrated brine. Many people focus on the freshwater produced through various processes of seawater desalination. However, have you ever thought about what happens to this highly concentrated saltwater? Unfortunately, most of it is simply dumped back into the ocean. For example, in the case of reverse osmosis, when 2 liters of seawater are passed through a semi-permeable membrane, the amount converted into freshwater is about 1 liter, which is roughly 50%, while the remaining 1 liter becomes concentrated brine, most of which is released back into the sea. A report written by the Korean Environment Policy Evaluation Institute in 2018 points out this problem. In the United States alone, 48% of seawater desalination facilities discharge concentrated brine directly into the ocean. Particularly, the concentrated brine in high-temperature and high-salinity conditions poses a problem in itself, but water with high salinity also has a low capacity for dissolved oxygen.

If concentrated water flows into the sea, there is a growing concern that it could destroy marine ecosystems. In fact, experiments that exposed marine organisms to high concentrations of concentrated water showed that the species richness of fundamental organisms in the ecosystem, such as phytoplankton and seaweed, significantly decreased. Moreover, there were cases of mortality in fish like flounder, as well as reduced growth rates, lower reproductive rates, and diminished ink defense abilities in cephalopods like squid. It was confirmed that the survival and reproduction rates of shellfish, such as oysters and clams, decreased when exposed to concentrated water. However, the bigger problem is that despite this situation, it is very rare for the discharge status of concentrated water to be made public. Except for some regions like the United States, Australia, and Japan, the reality is that most places have minimal standards or regulations regarding the discharge of concentrated water.

Ultimately, even if we solve the greenhouse gas problem with renewable energy technology, if the technology and regulations regarding brine treatment are not properly established, seawater desalination technology will struggle to gain acceptance. However, as always, scientists are once again searching for answers. There are simple methods, such as mixing wastewater from nearby sewage treatment plants with brine to lower salinity before discharging it further away. Recently, research has been underway to efficiently extract useful minerals like lithium and magnesium from brine. There is also research on energy recovery technology that involves installing a semi-permeable membrane between highly concentrated brine and fresh water, generating electrical energy from the osmotic pressure that occurs there. However, most of these studies are still in the early stages, and it is expected to take time for them to become widespread. Personally, I believe that seawater desalination is a technology that is essential for the era of the iPhone.

There are disadvantages such as the occurrence of real-time costs and concentrated water, but when you think about it, is there any technology developed by humanity that has no drawbacks? However, I believe that when innovative technologies are introduced to a large audience, the underlying disadvantages must be adequately mentioned. There is a clear difference between society knowing about these issues and accepting the technology versus being unaware and accepting it. Science is a window to see the world. This has been Science Dream. Thank you.

해수담수화 기술은 정말 물 부족 위기의 해결사일까?(ft.비용이 문제가 아냐!)

과학으로 재미와 지식을 더해 드리는 채널입니다.
한 때는 과학을 좋아했던, 지금도 과학을 좋아하는, 
그리고 앞으로 과학을 좋아할 사람들이 제 채널과 함께였으면 합니다.
문의: sciencegive@gmail.com

과학드림 [Science Dream]

The Uncomfortable Truth About Water Scarcity

Water scarcity affects regions with bright red markings on the map, despite the Earth's 70% water coverage.

Salty seawater makes up 97% of the Earth's water, with only 1% available for drinking.

Global warming's impact on rainfall is complex, potentially worsening water scarcity, while desalination of seawater offers a historical and modern solution.

The Global Impact of Seawater Desalination

Seawater desalination methods, such as evaporation and reverse osmosis, have become more sophisticated and widespread, with over 16,000 plants operating in 77 countries.

The technology's growth is driven by decreasing costs, with high-income countries like the Middle East, Europe, and North America hosting the majority of the plants.

While desalination provides a significant amount of freshwater, it also raises concerns about greenhouse gas emissions due to the fossil fuels used in the process.

Solar Energy's Role in Seawater Desalination

The Solar Dome project in Saudi Arabia aims to use mirrors to heat stored seawater, resulting in zero carbon emissions.

The eco-friendly desalination project is cost-effective, producing fresh water at 700 won for 1,000 liters and is being adopted in developing countries.

However, the issue of concentrated brine from desalination processes, which is often dumped back into the ocean, poses a significant environmental problem.

The Impact of Concentrated Water Discharge on Marine Ecosystems

Concentrated water flowing into the sea is harming marine ecosystems, leading to decreased species richness and mortality in key organisms like fish and cephalopods.

The discharge of concentrated water is often not publicly disclosed, with minimal regulations in most regions.

Scientists are exploring methods to mitigate the impact, such as mixing wastewater with brine and extracting useful minerals, but these solutions are still in the early stages.

Innovative technologies often have disadvantages, such as real-time costs and concentrated resource use.

It's important to adequately mention these drawbacks when introducing new technologies to a large audience.

Society's awareness of these issues plays a crucial role in accepting the technology.