While water covers two-thirds of the Earth, 96.5% of it is in the oceans. Desalination processes can refine this saltwater into something drinkable, but past systems have come with a range of issues. Recently, though, researchers have developed ways to desalinate seawater with the help of solar energy.
There are varying approaches to solar desalination, each using sunlight at a different step in the process. Researchers at Australia's Monash University developed a system that uses a metal-organic framework (MOF) to filter out salt and other impurities. The MOF adsorbs the impurities in 30 minutes, then sunlight removes the adsorbed particles from the MOF.
A recent invention from the Korea Institute of Science and Technology works differently. This desalination approach uses sunlight to evaporate seawater, passing it through a hydrophobic membrane that filters out the salt. When this vapor cools, it condenses back into a liquid form as clean drinking water.
These solar desalination techniques can produce hundreds of liters of potable water a day. Since they rely on solar power, they're also energy-efficient, helping them address water scarcity and sustainability issues.
Obtaining clean drinking water through desalination is far from a new process. Ancient cultures boiled seawater to remove impurities, and large-scale thermal desalination has existed since the 1930s, but has traditionally been inefficient. While these desalination processes are effective, they tend to consume vast amounts of energy.
Generating enough heat to evaporate water on a large scale requires a substantial amount of energy. Since most electricity comes from fossil fuels, these larger desalination plants often contribute a considerable amount of carbon emissions. As the climate crisis grows more urgent, this level of energy consumption is unsustainable.
Solar desalination occurs on a smaller scale than other techniques, but is far more efficient. Both the Australian and Korean approaches use less energy than even reverse osmosis, which itself is more than twice as efficient as traditional thermal distillation.
Solar desalination could be an answer to one of the world's most pressing issues: water scarcity. Despite there being enough freshwater on Earth to serve the entire population, approximately 20% of humans have limited access to it, with industries like agriculture and food manufacturing contributing to water pollution and now looking for more sustainable ways to provide food and water for the world.. That means more than a billion people have trouble getting potable water, a necessary resource.
The world's oceans can provide more than enough water to meet global needs if people can desalinate it. As natural freshwater sources become scarce and the population proliferates, this source becomes even more appealing. Solar desalination techniques would allow water-scarce communities to take advantage of this water without sacrificing energy efficiency.
Roughly 40% of the global population lives near a coastline, making desalination a relevant option for more than 2 billion people. If solar desalination could meet that scale, it could make water scarcity a thing of the past. Even if it doesn't serve the entire population, handling that amount would reserve enough water to meet global needs.
Maintaining current global usage levels will require expanding access to potable water. At the same time, turning to high-energy processes can lead to environmental issues with carbon emissions, negating any positive effects. Solar technology accounts for both sides of the equation.
Solar desalination techniques are still in their infancy, but early results look promising. By turning to sustainable methods like this, the world can ensure everyone can access clean water and preserve the environment.
