These buildings are self-sufficient

In 2012, as an undergraduate student at the National Institute of Technology Calicut, Swapnil Shrivastav had to suggest an innovative idea for a competition with the theme 'future of water in cities'. Being a Star Wars fan, he offered a moisture evaporator like the one used by residents of the arid world of Tatooine in the popular sci-fi series. Four years later, a dry spell in the monsoon led to an acute water shortage, forcing students to restrict themselves to using just one bucket of water a day. It made him think seriously about his idea for the contest.

So, along with his friend Venkatesh R.Y., Shrivastav developed a prototype that worked on the familiar principles of condensation. When moisture-laden air passes over a cold surface, water vapour condenses into water droplets. Though the prototype worked, it consumed too much energy to be of practical use. Shrivastav subsequently developed a desiccant-based water harvesting system, where a powder absorbed moisture from the air and released it when heated. 

The team presented the idea at the Water Abundance XPRIZE competition in 2018 and was among the top five finalists. It got a grant of $50,000 as well. The following year, they set up Uravu Labs in Bengaluru, and hired two more specialists in the field.

"At any point in time, the air has six times more water than all the world's rivers combined," Shrivastav says. "And this water gets replenished in 8-10 days." It is like drawing water from a well, except the replenishment in the atmosphere is significantly faster. This principle provides an opportunity to decentralise water supply, as the system can be set up in any locality or building. 

The initial system comprised a desiccant coupled with a solar thermal plant that provided heat for extracting water from the desiccant. Over the years, the company has made the system more efficient by using a liquid desiccant and by developing the ability to use any kind of renewable energy. This means that the system can now get electricity that produces heat from any source of renewable energy to power the system. The system can produce 500 litres of pure water per day. By changing the amount of desiccant used, it can generate the same amount of water in different geographies.

Uravu is working to get the system set up in the offices of two Abu Dhabi institutions, the national energy company TAQA and Khalifa University, within a year. It will be among the earliest such installations in the world, providing the capacity for a building to generate its own water. "Technologies where one can extract water from the air, recycle wastewater and perform efficient rainwater harvesting will help in making buildings of tomorrow water-secure," says Shrivastav.