Japan is preparing to bolt turbines onto barges and build the world's largest commercial power plant using floating windmills, tackling the engineering challenges of an unproven technology to cut its reliance on atomic energy, writes Bloomberg.

Japanese developers - including Marubeni Corp., Mitsubishi Heavy Industries Ltd. and Nippon Steel Corp. - will erect a 16-megawatt pilot plant off the coast of Fukushima.

The Fukushima pilot project will have three floating turbines installed by March 2016 with plans to eventually expand the capacity to 1,000 megawatts in the region, according to the trade ministry. It has set aside 12.5 billion yen (USD150 million) as the ceiling to fund the initial stages of the study.

The environment ministry also plans to set up a 2-megawatt floating offshore turbine in Nagasaki in southwestern Japan by June 2013.

The turbines are mounted on a floating structure that allows them to generate electricity in water depths where bottom-mounted towers cannot be erected easily. The country aims to develop the floating offshore wind turbines for commercialization by March 2017.

In addition to improving cost-efficiency, the biggest technical challenge in erecting floating turbines offshore is ensuring the buoyancy mechanisms are stable, and getting fixed lines to the sea floor which can be extended to depths of 200 meters (656 feet).

A feed-in tariff program due to start in July that guarantees above market rates for clean energy including solar, wind and geothermal could boost the development of wind energy, analysts say.

Land-based wind energy development is limited by Japan's mountains, making offshore developments more viable. The depths of its oceans creates a bigger potential for floating turbine technology, still in its infancy and expensive compared with the more conventional method of deploying fixed versions of the machines.

The energy industry group has set a wind-power installation target of 50,000 megawatts by March 2051, including 17,500 megawatts and 7,500 megawatts in floating and fixed offshore wind respectively.

Production of wind turbines and parts and maintenance services is forecast to grow from an estimated 300 billion yen (USD3.6 billion) a year currently to 500 billion yen in 2030, according to the Japan Wind Power Association.

Due to its geography and earthquake risk, Japan is lagging behind developed nations including the U.S., Germany and Spain in wind energy. It supplied just 0.4 percent of its electricity demand in 2010, according to the International Energy Agency Wind 2010 Annual Report.