Towers could harvest water from fog in driest cities

GIANT mesh towers designed to catch droplets from fog could provide a vital source of water in Peru’s climatestressed cities.

A 20-metre (66ft) tall prototype will be unveiled in the capital Lima this summer as part of a rollout that may eventually provide the driest megacity on Earth with up to 3.6 million litres (6.3million pints) of fresh water a year.

Lima’s rapidly growing population of more than 10 million relies on just a quarter of an inch of rain a year and glacier meltwater from the Andes. The World Health Organisation estimates that by 2025 half of the world’s population will live in water-stressed areas.

But the hills of Lima have plenty of thick fog that floats above the city, creating small oases known as lomas, dense with vegetation.

Alberto Fernandez, a Chilean designer currently researching a PhD at University College London, was inspired by mesh fog catchers installed on rural hillsides in South America in recent years. He said: “I developed a tower that can go inside the cloud,” making them around a hundred times more effective at capturing water.

The first prototypes will capture around 1,000 litres of water a day. The design consists of a spiral structure made from aluminium wrapped in copper mesh, with a plastic skin.

The water will be used for agriculture, and will need to be filtered for use as drinking water. “The problem of water resources is an issue that is growing year by year,” Mr Fernandez added.