How Covering Reservoirs With A One-Molecule-Thick Film Could Alleviate Droughts

As the West runs out of water, an MIT professor thinks he’s figured out how to reduce evaporation in massive reservoirs by 50%.

How Covering Reservoirs With A One-Molecule-Thick Film Could Alleviate Droughts
[Top photo: Kushch Dmitry via Shutterstock]

The world needs more water, or it’s going to run out. Yet most water conservation strategies, such as repairing faulty pipework in cities or improving management of watersheds upriver, don’t really change much about how the existing system works.


MIT professor Moshe Alamaro‘s focus is more directed. He wants to cover a few hundred reservoirs so the water in them doesn’t evaporate so readily. His idea is to cover the biggest reservoirs with a one-molecule-thick film derived from palm oil or coconut oil. He thinks it could reduce evaporation by 50%, if done properly.

Alamaro isn’t the first person to think of suppressing evaporation to conserve water. Hydrologists have been toying with the concept for at least 70 years. The problem is that wind tends to move any film from the upwind side of a lake to the downwind side. A film that should last up to five days is useless in a matter of hours because it’s no longer spread across the full surface.

Flickr user Konrad Summers

Alamaro gets around that problem in two ways. First, he plans to constantly monitor reservoirs from drones and satellites to build up an hourly picture of whether his “monolayer” is still where it should be. If not, floating diffusers will issue more coating to the surface automatically. “Based on images of the reservoir, we would dispatch a marine drone to those portions of the reservoir that are not covered and/or the portion that is already degraded,” he says.

Second, he thinks evaporation suppression will work only in certain circumstances, chiefly on the biggest lakes, like Lake Mead, outside Las Vegas. “What I suggest is to supply this on very large reservoirs where it takes a few days for the monolayer to arrive at one side. By that time, it will have degraded,” he says. You can’t really stop the layer from moving; all you can do is ensure it’s being useful in some part of a lake, and then fill in the rest of the area.

The oil is likely to make no difference in the taste of the water, or cause any local environmental impacts. It’s also cheap, so constantly respraying isn’t an issue. The real cost is in the overhead monitoring and round-the-clock analysis. Alamaro, who’s formed the More Aqua startup, has done tests in his lab and now wants to take the idea to a real lake in the West. He’s trying to persuade the Bureau of Reclamation or a state water department to help him out. “Everyone wants to take credit for the things that are done, but everyone else wants someone else to take the first step,” he says, ruefully.

Another evaporation suppression company, Flexible Solutions International, ran a $325,000 test on Lake Arrowhead, in Canada, last July to October. There was less evaporation than normal, though it struggled to prove its coating was the reason. Daniel O’Brien, Flexible Solutions’s president, told Nature its film would cost $160 per acre-foot of water, which is considerably less than the consumer price for the same.


Apart from the U.S. Southwest, Alamaro also sees markets in Mexico, India, China, Egypt, and Pakistan, all of which have hot, dry climates and growing water security issues. But he needs more funding before he can get to any of those places.

About the author

Ben Schiller is a New York staff writer for Fast Company. Previously, he edited a European management magazine and was a reporter in San Francisco, Prague, and Brussels.