Japanese construction firm Shimizu Corporation has developed a series of bold architectural plans for the world of tomorrow. Here is a preview of seven mega-projects that have the potential to reshape life on (and off) Earth in the coming decades.

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- Luna Ring

In response to the ever-growing demand for energy, Shimizu has developed plans for the Luna Ring, a project that seeks to transform the Moon into a massive solar power plant.

Luna Ring's 11,000-kilometer (6,800-mile) "solar belt" spans the Moon's equator

Electricity collected by the Luna Ring's enormous "solar belt" is relayed to power conversion facilities located on the near side of the Moon. There, the electricity is converted into powerful microwaves and lasers, which are beamed at Earth. Terrestrial power stations receive the energy beams and convert them back to electricity.

Luna Ring feeds power to energy-hungry Earth

The solar power plant is built mainly using lunar resources. Moon rocks and dust are used to manufacture building materials such as cement, bricks and glass fibers. Water is produced through a chemical process involving lunar soil and hydrogen.

Large machinery and equipment from Earth is assembled in space and landed on the lunar surface for installation. Much of the construction is performed by robots controlled by people on Earth, and a team of human astronauts is stationed on the Moon to supervise the robot operations. [More]

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- Green Float

Shimizu's Green Float project seeks to build "botanical" cities that float like giant lily pads in the equatorial Pacific, where sunlight is plentiful and the impact of typhoons is minimal.

Lily pad-like cities at sea

Each floating island features a 1,000-meter (3,300-ft) central tower. The lower section of the tower serves as an industrial area with offices and factories employing 10,000 workers, while the upper section functions as a residential area for 30,000 people. Another 10,000 residents live at ground level, in low-rise townhouses near the beach.

Green Float islands are 3 kilometers (1.9 mi) in diameter and support a population of 40,000

The typical Green Float island landscape consists of forests, grasslands, waterways and reservoirs. A portion of the land is set aside for agriculture and some of the shallow beaches are used for cultivating seafood, making the islands 100% food self-sufficient.

The eco-friendly Green Float cities rely on a variety of natural energy sources, including wave, wind and solar power, as well as ocean thermal energy conversion.

Green Float islands join to form a floating metropolis

Green Float islands are built upon a floating base of connected hexagonal tubes that each weigh 7,000 tons and measure 20 meters (65 ft) across and 50 meters (165 ft) deep. The primary structural material for the honeycomb-like base, as well as for the island's buildings, is magnesium alloy. Seawater -- which is composed of 0.13% magnesium by weight -- is an abundant source of magnesium. One ton of the material can be extracted from 770 tons of seawater. [More]

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- Mega-City Pyramid

Shimizu's proposed Mega-City Pyramid is a self-contained city for one million people.

The Mega-City Pyramid stands 2,000 meters (1.25 miles) high

The pyramid-shaped hyperstructure is an assembly of skyscrapers suspended within a skeleton of 350-meter (1,150-ft) long shafts made from lightweight materials (such as carbon and glass fibers).

Residential buildings (left) and office complexes (right) inside Mega-City Pyramid

The skyscrapers within the Mega-City Pyramid are home to residences, offices, research institutions, shopping and entertainment centers, and other facilities. The connecting shafts, which measure from 10 to 16 meters (30 to 50 ft) in diameter, contain the city's plumbing, electrical and communication systems, as well as a network of trains, escalators and moving walkways.

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The proposed hyperstructure has a footprint of approximately 8 square kilometers (3 sq mi), and it features an open-air construction that allows sunlight to reach the interior. A network of optical fibers transports sunlight into poorly-lit areas.

Construction of the massive Mega-City Pyramid is facilitated by robots and automated assembly systems, as well as by the use of standardized parts and materials. [More]

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- Space Hotel

To capitalize on the coming boom in space tourism, Shimizu has developed plans for a space hotel in low-Earth orbit.

Shimizu Space Hotel, located 450 kilometers (280 mi) above Earth

The hotel -- which is powered entirely by solar energy -- features a microgravity recreational area where guests can enjoy sports, dining, and gazing at the Earth and stars. The 64 guest rooms and 40 staff rooms are situated in a ring measuring 140 meters (460 ft) in diameter. The ring rotates at a speed of 3 rpm to produce an artificial gravity of 0.7 g in the rooms. A 240-meter (790-ft) elevator shaft connects the hotel facilities with the docking port. [More]

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- Lunar Bases

For the more adventurous offworld traveler, Shimizu has developed plans for lunar bases.

Lunar bases are the key to establishing a long-term human presence on the Moon

Shimizu's proposed bases feature a modular design of interlocking hexagonal units that can be arranged both horizontally and vertically. The modules are built using concrete made from lunar soil and rock. Tele-operated robots and automated assembly systems are used to construct the bases. [More]

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- Urban Geo-Grid Plan

Back on Earth, Shimizu's Urban Geo-Grid Plan seeks to reduce urban congestion and improve the overall efficiency of Tokyo by placing a variety of city functions underground.

Urban Geo-Grid Plan puts much of Tokyo underground

The plan -- which covers an area extending from central Tokyo to the Boso Peninsula on the opposite side of Tokyo Bay -- consists of a vast underground network of so-called "grid points" and "grid stations." Grid points incorporate community facilities such as grocery stores, exhibition halls and public bathhouses, while the larger-scale grid stations incorporate office buildings, hotels, shopping centers, and train stations. An extensive underground transportation network connects the grid points and stations. Moving all these facilities underground frees up an enormous amount of street-level space that can be set aside for parks. [More]

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- Desert Aqua-Net Plan

The Desert Aqua-Net Plan seeks to make the desert habitable by constructing a network of lakes and waterways.

Desert Aqua-Net Plan brings water to the desert

The plan involves creating artificial lakes in low-lying desert areas. Islands are constructed in the middle of the lakes, which are filled with seawater channeled inland through canals. The canals connect the lakes to form an extensive water network.

Located 150 kilometers (95 mi) apart, the artificial lakes measure 30 kilometers (20 mi) in diameter and 20 to 30 meters (65-100 ft) deep. The canals running between the lakes measure 50 meters (165 ft) wide and 10 meters (35 ft) deep

The lakes reduce temperatures and increase humidity in the surrounding areas, creating a comfortable and mild environment. Seafood and biomass resources (such as algae and seaweed) can be cultivated in the saltwater lakes, and the canals can be used to transport people and goods between the cities built on the artificial islands. [More]