What happens when Japan and United States decide to work together? Something wonderful. At least if reports were true.

Japanese daily Yomiuri Shimbun reported that the Japanese defense ministry is working on a submarine in collaboration with Washington, a 33-foot sub that could run unmanned on a pre-charted course. The Japanese defense ministry, however, denied the report, saying that it is not working on anything at the moment with Washington. It did confirm, however, that it is true that a submarine project is under development.

Called an "unmanned underwater vehicle" or UUV, the submarine will be used for patrolling, designed to follow a course that has been pre-set and then coming back to the base to report. It could last as long as one month under the sea and it would take only a single charge for that to happen.

Ministry sources said that $25 million have already been set aside for the UUV's development which is projected to last five years because it will take that long to create a fuel-cell system that would address the needs of the submarine. As for torpedoes and other weapons, none would be installed on the UUV because it will not be used for military purposes. It will simply be patrolling the waters of Japan and nothing more, using a sonar to detect potential threats in the area. It will not be used actively in efforts to keep China's looming threats at bay.

Why a fuel-cell system instead of going nuclear? Essentially, because it's cleaner. A nuclear-powered submarine can keep running for 50 years which dwarfs the one-month-on-one-charge capabilities of a fuel-cell system but the effects of nuclear power versus fuel cells outweighs its benefits when it's considered that the UUV is only a patrolling submarine. A fuel-cell system is also cheaper in the long run so it's the more cost-effective option for the Japanese defense ministry. And when the country itself is a leading producer of fuel cells, it only makes sense that Japan will be turning to fuel cells for its energy needs.

Fuel cells are an emission-free energy source that produces energy by creating a reaction between hydrogen and oxygen. Because it is not radioactive, it is considered to be an environment-friendly source of energy so it is commonly used for applications where a smaller energy footprint is needed.