Seawater is so highly concentrated that drinking it will dehydrate a human being, ultimately leading to death.
But the earth is so abundant with oceans that harnessing the power of desalination—the process of converting seawater into drinkable water—may be the key to solving global water crises.
With about 70% of the earth's surface covered in mostly seawater, it is no wonder that governments, NGOs, and private companies are exploring ways to make desalination a more widespread method of water purification.
It’s a very promising frontier in the water purification space, but it’s not without its challenges.
This article will cover what desalination is, how it can help drought-stricken areas, its challenges, and possible solutions for the future.
What is Desalination?
Desalination is the process of converting seawater into drinkable water by removing the salt content. The technology behind the desalination process is continually being innovated, but there are three main methods that are particularly worth covering.
Thermal, or flash, desalination is a type of distillation method that extracts potable water from seawater through the process of evaporation. Intense heat is used to convert seawater into steam, condensing the steam into clean water and leaving the concentrated salt brine behind.
Some of the challenges of thermal desalination are its high oil consumption necessary to maintain heat and the large amounts of salt-heavy brine left behind as a byproduct, often requiring more energy to be pumped back into the ocean.
While thermal desalination is the earliest method of desalination, there has been a significant shift toward more energy-efficient methods of desalination due to its high energy demands and excessive byproducts.
Membrane purification technology—predominately reverse osmosis—is currently the premier method of desalination due to its effectiveness and lower energy costs. Reverse osmosis works by using water pressure to pass seawater through a molecular membrane where only the H20 molecule can fit, leaving all the salt compounds behind.
While reverse osmosis is much less energy-intensive than thermal desalination, it still requires large amounts of electricity and revenue to maintain.
Electrodialysis Reversal, or EDR, is a method that uses electrical nodes to attract and capture charged salt particles, leaving only clean water.
While EDR is a promising venture for desalination, its high electricity requirements present a challenge.
Challenges and other factors
The type of desalination method used largely depends on factors such as cost, energy availability, infrastructure, and the salinity of the water source. The ongoing challenge for desalination technology is the energy and cost required to maintain the process, especially for large community applications.
But despite the energy challenges, innovators understand its potential in solving many of the world's water problems and continue to develop new strategies for improving the technology.
Can Desalination Solve the Water Crisis?
With nearly half of the world’s population currently living in water-stressed areas, desalination is proving to be a major help to the growing problem of water scarcity.
About 20,000 desalination plants are currently in operation worldwide, with the Middle East and Asia-Pacific regions experiencing the most growth. The largest desalination plant is in Ras Al Khair, Saudi Arabia, and produces 1,036,000 cubic meters, or 273 million gallons, per day.
The United States also has several active desalination plants, the largest in Carlsbad, CA, capable of producing 50 million gallons of clean water per day and responsible for 7% of San Diego County’s water.
Altogether, a total of 177 countries are currently running desalination plants, providing a cumulative amount of 95 million cubic meters of freshwater per day. While still far from perfect, desalination technology looks to be the common area where most countries around the world are focusing their attention on the pursuit of water sustainability.
Future of Desalination Technology
As water engineers and scientists explore innovative ways to improve desalination, new methods, such as solar desalination, nanofiltration, and graphene desalination are emerging.
Solar desalination involves harnessing the sun as a power source to solve the energy-intensive process of desalination. Neom, a 26,500 km-long smart city being constructed in Saudi Arabia is projected to use solar desalination technology to purify its water.
Nanofiltration is similar to reverse osmosis but constructs the membrane of special materials allowing for even smaller pore size, essentially small enough for only the H20 molecule. Its use in desalination is currently an area of rigorous study.
Graphene is a special arrangement of carbon atoms that allows for very innovative technological processes and is a promising component for the future of desalination. Graphene membranes may allow for more efficient desalination mechanisms than traditional reverse osmosis membranes.
Small-scale Desalination for Home
While desalination is a frontier prominent on the world stage, individuals can experience the benefits themselves through small-scale desalination devices.
Companies such as Quench Sea and Rainman make portable desalination devices that can be used for small-scale applications.
QuenchSea is a portable desalination device that uses reverse osmosis to convert seawater to drinkable water at a rate of 4 Liters or 1 Gallon per hour. The device is ultralight and requires no electricity to operate. The RO membrane itself will last between 6 to 12 months and produce up to 1,000 liters of fresh water before needing replacement.
Rainman Water Maker
The Rainman AC is a portable desalination unit that also uses reverse osmosis technology but incorporates the use of electrical power, producing up to 140 liters (37 gallons) of fresh potable water per hour.
Power comes in 230VAC/50Hz or 115VAC/60Hz options and is designed to run off of a minimum of a Honda 2kW generator.
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