A company in Abu Dhabi is attempting rainmaking using arrays of 10-metre towers that emit ions – negatively charged particles – which attach to cloud condensation nuclei, particles around which water vapour condenses. This new technology has yet to be proven, but is similar to the old practice of cloud seeding: the theory is that ionizing condensation nuclei allows them to survive longer, giving water droplets more time to form.
The seawater greenhouse uses seawater and sunlight to grow food and flowers in arid coastal regions such as Australia, Oman and the Canary Islands. Wind blows through porous cardboard walls over which seawater is trickled, creating cool humid growing conditions. Moving across sun-heated pipes, the evaporated seawater condenses as freshwater for irrigating crops within the greenhouse and vegetation without, helping to green the landscape.
A Swedish company has come up with a solar-powered water purification system that promises to deliver 100,000 litres of clean water a day by using solar power to filter dirty or salt water. The upfront cost of installing the system is high, but over the 20 years that the system should continue to function, it averages out at less than $0.03 per litre of clean water.