"Solar UFOs" invade Japanese city in water-purification mission

A canal in the Japanese city of Osaka has been invaded by a solar-powered, UFO-shaped floating disc designed to purify the water for the benefit of us earthlings.

It is one of two extraterrestrial-like water purifiers – dubbed Solar UFOs – that have been built by Tokyo-based engineering group NTT Facilities.

Each device is 1.6m high and 5m in diameter, weighing 3.4 tons. Solar panels on the exterior provide the discs with zero-carbon energy.

One Solar UFO resides in Dotonbori canal, which runs along the centre of Osaka, while the other roams in a moat surrounding the 16th-century Osaka Castle.

The company said that each Solar UFO can purify up to 9,000 litres of water per day and is equipped with a built-in filtration system that pumps fresh oxygen into the water.

Cleaned water is moved through the machine's body and out through a nozzle on the top that serves to clean the outer surface of bird droppings and grime. The whale-like action also serves to cool the solar panels, helping to keep output efficiency at a high level.

At night, the Solar UFOs maintain their otherworldly appearance through LEDs that ring the exterior. They switch on when darkness falls, each powered by a 1.3 kilowatt solar battery.

The devices were put into use last week as part of the Aqua Metropolis festival, an event that highlights Osaka's rivers and waterfronts, and runs until 12 October.

Far from seeing the devices as a quirky one-off, NTT said it now plans to dispatch Solar UFOs to clean the waters in and around Tokyo in the near future.