In 2020, Prime Minister Narendra Modi asked Danish energy company Vesta Wind Systems to explore the possibility of extracting water from air. Four years on, a clutch of companies around the world are working on the principle. In India in the meantime, “hawa se pani” has been achieved without the help of wind turbines.
Air-to-water technology, also known as atmospheric water generation, is being touted as a solution to the planet’s water scarcity crisis.
India is no exception. With 18 per cent of the world’s population but only 4 per cent of global water resources, water stress in India is steadily intensifying. According to an estimate by Niti Aayog, 600 million Indians experience extreme water stress and by 2030, the country’s water demand can outstrip supply. The 2024 Groundwater Quality Report released by the Central Ground Water Board revealed that 70 per cent of India’s water sources is contaminated. Also, groundwater levels are depleting at an alarming rate what with 60 per cent of the country’s agriculture and 85 per cent of drinking water needs depending on it.
On the other hand, the water present in the atmosphere can be considered a nearly inexhaustible resource. At any given time, approximately 13,000 cubic kilometres of fresh water is present in the atmosphere, which is naturally replenished through the daily water cycle.
Atmospheric water extraction needs minimal infrastructure, is easy to install and takes up little physical space. During an emergency, portable water harvesting units can be moved to the area where safe drinking water is required. In addition, atmospheric water generation will not harm the environment.
The devices, known as atmospheric water generators (AWGs), extract water from the air and convert it into potable water through condensation and desiccation.
Condensation is the deposition of a liquid (or solid) from its vapour, usually upon a surface that is cooler than the surrounding gas. Think of a glass of ice-cold water with water droplets on the outside of the glass on a summer day. Or dewdrops on grass blades on a cool morning.
In desiccation, chemical substances are used to remove water vapour from air. Desiccants such as silica gel and activated alumina are used in air conditioners to decrease humidity. One of the leading manufacturers of atmospheric water generators, Akvo, is based in Howrah, Calcutta’s twin across the Hooghly.
Says Navkaran Singh Bagga, CEO of Akvo, “The most abundant source of freshwater is our Earth’s atmosphere. We at Akvo replicate the natural process of condensation by simulating dew formation in a machine. After all, the atmosphere is the largest river around us.” Akvo’s technical expert Ashis Jha explains how the machines work. First, air drawn into the machine is filtered to remove contaminants such as dust or suspended particulate matter. Then the air is cooled to its dew point, causing water vapour to condense into droplets. The collected water is filtered through an ultraviolet sterilisation process and stored in dispensers or tanks .
Water dispensers in various shapes and sizes are manufactured at Akvo’s Ankurhati Industrial Park at Howrah. The smallest ones can generate up to 50 litres of water per day and work best at temperatures between 15°C and 55°C and relative humidity of 30 to 99 per cent. The largest ones can dispense 1,00,000 litres of water per day. Says Bagga, “Atmospheric water generators offer decentralised, renewable and sustainable solutions in water-scarce areas. Moreover, the water is free from contaminants, including harmful microbes and pesticides.”
Akvo has installed them in cities such as Chennai, Bangalore and even Abu Dhabi. “We also installed a portable unit, which can be moved around in trailers, for the Philippines Port Authority.” Ports in the Philippines are frequently battered by typhoons, which is why they need a robust water supply system.
That said, atmospheric water generators face several challenges. The foremost is that most use a condensation process that doesn’t work when the ambient temperature is below 18°C or the relative humidity is below 30 per cent. To tackle this, newer machines are utilising desiccation technology. “The desiccant, often a salt solution or solid material, captures water vapour from the air. Then the water is extracted from the desiccant,” says Amit Kumar, a professor of mechanical engineering at NIT Surat, who has done a lot of work on this technology.
Kumar is working on a technology that can combine both condensation and desiccation. He is a consultant scientist of Maithri Aquatech, a company that partners with the Indian Institute of Chemical Technology (IICT) under the Council of Scientific and Industrial Research (CSIR). Maithri, based in Hyderabad, has major clients in the public sector, including defence, and has gained recognition from the Union ministry of water.
Maithri is Akvo’s competitor, as are Israel-based Watergen and Bangalore-based Uravu. Bagga, however, is not bothered about competitors. He thinks that with skyrocketing water scarcity in the country, there’s a huge emerging market for many players.