Fresh water plucked out of thin air. It鈥檚 an ambitious goal, but to win the 聽teams have to suck two tonnes a day from the atmosphere in a cheap and sustainable way.
XPrize, a non-profit that organised the competition, announced the five teams through to the final round today, coinciding with World Water Day. The finalists are from the UK, Australia, India and the US, and were selected from an initial field of 98 based on results from their prototypes.
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Final testing will happen in July. Teams must produce at least 2,000 litres of water a day using renewable energy at no more than 2 cents (1.4 pence) per litre. Whichever group extracts the most at the lowest cost will be awarded $1.5 million.
The World Health Organisation says people need at least 20 litres of water a day for drinking and basic hygiene but increasing demand from growing populations, climate change and pollution are rapidly depleting global fresh water supplies. The UN also published a report this week predicting that by the middle of the century 5 billion people will have poor access to water.
XPrize hopes to incentivise solutions that can serve communities of roughly 100 people at a time. 鈥淏y 2025 two out of three of us are going to live in water scarce regions聽,鈥� says Zenia Tata at XPrize. 鈥淲hat we鈥檙e trying to do is to unlock this hidden source of water in a cost-effective and sustainable way.鈥�
The finalists have a variety of solutions. London-based Veragon already builds machines that condense water from the air by cooling it. To supercharge the process, they teamed up with Imperial College London start-up ThinAir, who have developed a surface material that boosts condensation efficiency, which they expect to nearly treble water production.
Laura Dean, who leads the team, says they expect to produce more than 5,000 litres of water a day. Their solution will have a large upfront cost of $200,000, thanks to the $150,000 solar energy system powering it, but spreading the initial outlay over the machine鈥檚 10-year lifetime makes the cost per litre less than 1 cent, she says.
Indian team Uravu is focused on a simple, low-maintenance solution using a silica gel whose structure lets it passively suck water vapour from the air聽. Water is collected at night and during the day solar collectors channel heat from the sun to warm the gel, releasing the vapour again. This hot, water-saturated air passes through a series of tubes where it turns back into water.
The machine costs around $600 to $800 and produces 10 to 15 litres of water a day, but the design is modular so they will link together multiple units to meet the 2,000 litre benchmark.
Atmospheric water generators are already used for military and disaster response applications. But they have proved too expensive for day-to-day water production and typically run on fossil fuels or grid electricity. The technology works best in humid areas where you might expect water isn鈥檛 a problem. But these regions frequently suffer water scarcity due to things like low rainfall, water access issues and pollution.
