Japanese construction firm Shimizu Corp has unveiled a proposal for an underwater city that draws energy from the seabed to accommodate human life.

Based on an artist’s rendering, the futuristic ‘Ocean Spiral’ structure will be divided into three sections.

A floating sphere with a diameter of 500 metres, located just beneath the surface of the sea, will house business and residential zones and hotels.

Known as the “Blue Garden”, the sphere will contain 75 floors and is expected to accommodate a population of 5,000, with 4,000 permanent residents and 1,000 visitors.

Attached to the Blue Garden is a 15 kilometre long spiral that descends to an “Earth Factory”, located on the seabed.

The factory will use micro-organisms to turn carbon dioxide into methane, while power generators located along the ocean spiral will use differences in seawater temperatures to create additional energy – a process known as ocean thermal energy conversion.

Desalinated water produced using hydraulic pressure will be pumped into the residential pod and food is produced via deep-sea aquaculture.

The plan is to build the frame for the sphere and its tower using a resin concrete covered in triangular acrylic sheets and reinforced using semi-transparent fiberglass cross-bracing ribs.

Despite their reputation for dreaming up ambitious schemes, Shimizu Corp insist Ocean Spiral is more than just a pipe dream and believes the required technology could be ready in as little as 15 years.

The project is drawing on experts from Tokyo University, government ministries and energy firms to turn Shimizu’s blueprint into a reality.

Courtesy The Guardian and Gizmag