Skip to Content
77 Mass Ave

Desalination by sunlight

A passive system could provide cheap drinking water off the grid.

A completely passive solar powered desalination system developed by researchers at MIT and in China could provide more than 1.5 gallons of fresh drinking water per hour for every square meter of solar collecting area. Such systems could potentially serve off-grid arid coastal areas to provide a low-cost water source.

passive solar-powered desalination system
COURTESY PHOTO

The system uses multiple layers of flat solar evaporators and condensers, topped with transparent aerogel insulation. It then desalinates the water in stages, with each stage harnessing heat released by the previous stage–heat that would usually be wasted. In this way, the team’s demonstration device can achieve a world record efficiency level in converting the energy of sunlight into the energy needed to induce water evaporation.

The device is essentially a multi-layer solar still, with a series of evaporating and condensing components like those used to distill liquor. Its flat panels absorb heat and then transfer it to a layer of water, which begins to evaporate. The vapor then condenses on the next panel and gets collected, while the heat from the vapor condensation gets passed to the next layer.

The team used a 10-stage system for the proof-of-concept device, which was tested on an MIT building rooftop. The system delivered pure water that exceeded city drinking water standards, at a rate more than double that previously produced by any such passive solar-powered

desalination system, says Evelyn Wang ’00, professor of mechanical engineering and department head, who led the research.

The team, which included Lenan Zhang, SM ’18, and Lin Zhao, PhD ’19, estimates that a system to serve the needs of a family might be built for around $100.

Keep Reading

Most Popular

Rendering of Waterfront Toronto project
Rendering of Waterfront Toronto project

Toronto wants to kill the smart city forever

The city wants to get right what Sidewalk Labs got so wrong.

Muhammad bin Salman funds anti-aging research
Muhammad bin Salman funds anti-aging research

Saudi Arabia plans to spend $1 billion a year discovering treatments to slow aging

The oil kingdom fears that its population is aging at an accelerated rate and hopes to test drugs to reverse the problem. First up might be the diabetes drug metformin.

Yann LeCun
Yann LeCun

Yann LeCun has a bold new vision for the future of AI

One of the godfathers of deep learning pulls together old ideas to sketch out a fresh path for AI, but raises as many questions as he answers.

images created by Google Imagen
images created by Google Imagen

The dark secret behind those cute AI-generated animal images

Google Brain has revealed its own image-making AI, called Imagen. But don't expect to see anything that isn't wholesome.

Stay connected

Illustration by Rose WongIllustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.