To save fuel, the U. S. Navy contracted with General Electric Energy’s Power Conversion unit to convert one of its latest ships, the USS Makin Island, to hybrid power. At speeds above 12 knots, power comes from twin gas turbines, the same type of engines that power Boeing 747s. At lower speeds, the gas turbines become extremely inefficient. So at slow speeds, the ship relies on six diesel generators powering a pair of 10,000hp motors. According to GE, Navy ships like the Makin Island spend less than 30% of their time cruising at top speed from one location to another. The vast majority of time the ship is in harbor, or it stays on station deploying and supporting aircraft and troops.
During a sevenmonth test, the Makin Island saved 4 million gallons of fuel worth $5 million. Based on this figure, the Navy estimates the switch to a hybrid system will save the Navy $250 million over the life of that one ship. The Navy plans to have GE convert two more ships to hybrid operation, including the latest largedeck amphibious assault ship, the USS Tripoli.