Earlier this year, we looked at the future of water — specifically, how we’ll get enough of it to meet all our needs. And those needs are many. Not only do we use water to quench that mighty thirst we work up after a long, hard day of thinking about the future — we also use it in everything from manufacturing to agriculture. And while there’s a lot of water here on this rock, much of it isn’t easily accessible or is incredibly salty.
Taking salt out of seawater is one way we can address this problem. But the two primary methods we rely on to remove salt require a lot of energy, infrastructure and money. You can boil seawater and allow the water vapor to condense into fresh, drinkable water — that means pouring in energy to heat water up. Or you can use expensive, porous membranes that allow water to pass through but block the passage of salt particles. Now, scientists may have another alternative that’s less expensive and more efficient.
It’s called electrochemical mediated seawater desalination. It removes salt from seawater on a microscopic scale. It’s also experimental and so far can only remove about 25 percent of the salt from seawater. It starts with a plastic chip filled with seawater. The chip has a tiny channel cut into it that has two branches. Where the two branches meet is an electrode. Researchers apply three volts of electricity to the electrode, which neutralizes chloride ions and creates a local electric field. This field acts like a traffic controller, directing salt down one branch of the channel and fresh(er) water down the other side.
At this scale, the method wouldn’t be very useful even if researchers could remove 99 percent of the salt from the water. That’s because we’re talking about very tiny amounts of water. In one minute, this method can produce only 40 nanoliters of water. A nanoliter is one-billionth of a liter — even if you were just a little parched it would take about 70 weeks for you to create enough slightly-less-salty water to fill a shot glass.
If the researchers can address the problems of scalability and increase the efficacy of the approach, we could have a low-energy method for making fresh water. We’ll still have other problems to resolve, such as what to do with all that briny water that’s left over after the desalination process. But water shortages may become a thing of the past.