Slowly but steadily the U.S. Navy is maintaining a course for electric-drive propulsion as a way to save fuel costs, reduce ship lifecycle expenses and provide the extra power needed to run advanced radars and weapons the service is planning for its future fleet.
Navy officials have been touting recent successes in developing electric propulsion options. Service brass and research leaders paint a vision of plugged-in ships patterned after such hull designs as thedestroyer class.
“We're excited about hybrid-electric drive,” says Lawrence Schuette, director of innovation for the Office of Naval Research (ONR). “We've been working on ways to reduce fuel consumption. We're looking at pulling a generator right off the main shaft. We want to offer the same capability we have today at less cost, especially total ownership cost.”
The biggest electric propulsion success, Navy officials say, was the recent voyage of the LHD-8 USS Makin Island, a Wasp-class amphibious assault ship, from the Huntington Ingalls Industries (HII) shipyard in Pascagoula, Miss., to San Diego.
With the voyage, electric propulsion proved technically feasible. The concern now is funding for such power systems.
“We've had success with the technology,” said Rear Adm. Frank Morneau, deputy director of expeditionary warfare, during a break at a conference for expeditionary forces in March. The challenge now will be on the financial side. He acknowledged that every program and technology will have to prove itself worthy of investment in the current economic climate. But theis funding hybrid and electric-drive efforts. “I don't anticipate they will be pushed off.”
The Makin Island is the only ship of its class powered by LM 2500+ gas-turbine engines and electric drive. The ship also is the only LHD with all-electric power, using no steam on board.
The Makin Island used its electric drive 67% of the time on the Pascagoula to San Diego voyage, saving 900,000 gal. of fuel worth $2 million. Each ship equipped with electric drive will save the Navy $250 million in lifetime costs.
Electric-drive vessels will be part of the Navy's “Great Green Fleet” of energy-efficient ships scheduled to sail in 2016.
The Green Fleet underscores the Navy's focus on conserving energy and developing ships and programs to make more efficient use of energy, as well as incorporate alternative means of powering equipment.
Part of the benefits, Navy officials say, comes from the reduction in the number of sailors needed on board ships to maintain traditional power plants. This will play a major part in reducing ship lifecycle and ownership costs.
The showcase ship for electric drive will be theZumwalt-class destroyers. Although the class has been reduced from its initial fleet of two dozen to three, there will be enough ships, according to the Navy and contractor executives, to show the benefits of electric drive.
Even with the smaller fleet, though, Zumwalt backers say the DDG-1000 will make a difference. “There will be three globally deployable ships,” says Bill Marcley, DDG-1000 program manager and vice president of total ship mission systems forIntegrated Systems, one of the prime contractors. “One of the primary functions will be 24/7 naval surface fire support.”
But Navy officials don't have to rely on the performance of the Zumwalt-class ships to see the benefits of electric drive. There's already discussion about incorporating electric drive in the Burke-class Flight III upgrades now being mapped out. A Naval Sea Systems team set up last year is reviewing possible design changes and requirements for the Arleigh Burke destroyers for propulsion and power upgrades to accommodate radar and related equipment enhancements.
Navy officials see the Arleigh Burke hull frame as a natural for electric drive. The ONR “ship-of-the-future” literature includes a graphic resembling a DDG-51 ship that incorporates electric-drive technology as part of the organization's hybrid-drive-propulsion ship project.