Shifts in rainfall caused by climate change, in addition to escalating water demands of a global world population, are setting the earth on track for a water crisis. The UN predicts that by 2025 2.4 billion people will live in regions of intense water scarcity, forcing as many as 700 million people from their homes by 2030. This has led to many people to focus their attention onto the earth’s oceans in hopes of finding water. The only problem is that all of this water has extremely high salt content, making it impossible to drink. While desalination is already in use in some areas, salt-removal remains expensive, so it’s difficult to implement in poorer parts of the world. However, recent innovations could bring costs down and make this technology more accessible and affordable. Solar-powered disks, in addition to a new wonder material, are making it efficient, cheap and accessible.
Since at least the 4th century BC, people have been experimenting with ways to take the salt out of water; Aristotle wrote about Greek sailors using desalination, and in the 1800s the English started using desalination plants. Yet most modern desalination plants use a different technique, with pumps that force pressurized saltwater from the ocean through special sheets, which contain molecule-sized holes that allow water to pass through while blocking salt. Membranes are rolled, then stuffed into long tubes with additional layers that direct water flow and provide structural support. The process, known as “reverse osmosis”, makes 1 liter of fresh water out of about 2.5 liters of salt water.
While still less than 1 percent of freshwater usage, desalinations plants’ production is two-thirds higher than it was in 2008. They currently supply water to more than 300 million people worldwide, a number that’s expected to grow. However, there’s a limit to these energy savings. It takes a lot of energy to produce, and is typically only viable when it’s cheaper than the next alternative water source. This is particularly difficult for places where electricity is hard to come by, such as Africa. However, cost is the main obstacle. The upfront cost of desalination membranes is minimal, but these membranes are made from a synthetic material that dissolves when exposed to chlorine, but also breeds a biological matter that can clog up works without chlorine, creating an endless catch 22. Researchers have begun to experiment with other materials, such as graphene oxide and carbon nanotubes. Although these save money in the long run, their high upfront costs remain an issue.
In more underdeveloped areas where electricity is hard to come by, researchers have been researching with the ancient Greek method, namely evaporating and condensing water. This system runs on sunshine, using more light-absorbing material to power the entire process. Such a process would be more effective for smaller desalination needs.
If desalination can be mastered, some researchers have suggested that it can supply irrigation water to coastal floating farms, which in turn could bring agriculture to arid coastal regions. While radical, it could be accomplished with recent technological advancement. These floating, solar-powered farms would lay anchor along coastlines and suck up seawater, which in turn would be desalinated. This would work particularly well in dry coastal regions with plenty of sunshine, such as the Middle East, North Africa and Australia. Admittedly, these would be expensive, so the most important thing would be to make the entire process cost-effective.
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