After decades of experiments, U.S. Navy scientists believe they may have solved one of the world's great challenges: how to turn seawater into fuel. The development of a liquid hydrocarbon fuel could one day relieve the military's dependence on oil-based fuels and is being heralded as a game changer" because it could allow military ships to develop their own fuel and stay operational 100 percent of the time, rather than having to refuel at sea. The new fuel is initially expected to cost around $3 to $6 per gallon, according to the U.S. Naval Research Laboratory, which has already flown a model aircraft on it. The Navy's 289 vessels all rely on oil-based fuel, with the exception of some aircraft carriers and 72 submarines that rely on nuclear propulsion. The breakthrough came after scientists developed a way to extract carbon dioxide and hydrogen gas from seawater. The gasses are then turned into a fuel by a gas-to-liquids process with the help of catalytic converters. The next challenge for the Navy is to produce the fuel in industrial quantities. It will also partner with universities to maximize the amount of CO2 and carbon they can recapture. "For the first time we've been able to develop a technology to get CO2 and hydrogen from seawater simultaneously. That's a big breakthrough," said Dr. Heather Willauer, a research chemist who has spent nearly a decade on the project, adding that the fuel "doesn't look or smell very different."