Water, Water, Everywhere—They Hope
Water, Water, Everywhere—They Hope
Water, Water, Everywhere—They Hope
Some 300 million to 500 million people in the world have no access to safe water at all, and perhaps 2 billion have inadequate access, “so it’s a big deal internationally,” says Greg Blonder, a College of Engineering visiting researcher and an ENG professor of the practice of mechanical engineering from 2015 to 2021.
One group of BU engineering students attempted to come up with an innovative way to address the crisis: creating a water harvester that would pull moisture from the air to provide potable water without great effort or expense.
“When we saw the numbers, that kind of hit home for us,” said team leader Gayatri Sundar Rajan (ENG’22). “One of the first things we have to do in this proposal is say why this is a problem, what is the scale, who would benefit. And the numbers are staggering.”
Besides Sundar Rajan, the team members were Tess Ravick (ENG’22), Carla Sheridan (ENG’22), and Trevor Melsheimer (ENG’22). The water harvester was their required ENG Senior Design Project, and for Sundar Rajan and Melsheimer, it was also their Keystone Project for Kilachand Honors College.
People are affected by two types of water scarcity, either geographic (there just isn’t a lot of water in the area) or economic (it’s too expensive to access or process to make potable).
A cubic yard of air, even on a dry day, contains a gram of water, but on a regular day in warmer climes in Africa or Asia, it would contain 10 or 15 grams of water, says team faculty advisor Blonder, who had taught the students in a class last year. “If you have a way of extracting that, you can make water in the desert.”
After exploring several ideas, they chose the water harvester project, Sundar Rajan said, because “everybody on our team was interested in the energy and sustainability space and also interested in humanitarian engineering applications.”
Their prototypes used a cheap chemical desiccant, calcium chloride (CaCl₂), to draw moisture from the air. The unit itself acted as a solar oven, using the natural heat of the sun to boil the water back out of the desiccant. That vapor was then to be collected through condensation. No fuss, muss, or power source required.
The team recently finished up a full-size prototype—think of a small refrigerator—and then had to test it out. “Because our system is a passive solar oven essentially, we need to test it outside when we have a clear day,” she said. “We need to see how hot that oven gets and how much of that water can condense.”
More than a few companies are seeking similar solutions, she said, but many existing attempts to solve the problem use high technology, costly or fragile equipment, or have other logistical issues that would hinder their use in remote or poorly resourced areas. The BU team’s solution was intended to be simpler and easy to implement and even to be easy to swap out some materials to use locally available resources.
“We’re looking at a low-cost, low-energy, culturally conscious solution,” said Sundar Rajan.
The question was, would it work? Watch the video and find out.
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