This is interesting:
The U.S. Navy is adding a hybrid-electric drive to its 34 newer Arleigh Burke-class guided missile destroyers, in essence turning them into floating Priuses. Hybrid drive cars, like the Prius, use batteries that are recharged by the conventional engine and that allows the use of more efficient (under certain conditions) electric motor. On the Burkes The added electric motor will help propel the ship at speed of up to 24.1 kilometers per hour, speeds at which the four LM-2500 gas turbines on the ship have much less efficiency. ...
When the Burke program began in 2008, the Navy was driven more by high oil prices (well over $150 per barrel). While the price has dropped (to $40), the Navy is continuing the program. In this case, the green technology will actually make a lot of sense operationally. In this case, the hybrid drive will buy 60 more hours of on-station time between at-sea refueling.
This will begin in the 2015-16 fiscal year. I love the Prius comparison. It's so environmentally responsible!
Sure, if oil is expensive, allowing the ships to operate on an electric drive rather than the gas turbine at lower speeds will help on the fuel budget. And add a whole 60 hours of sailing time.
But unless I'm way off, the reason for adding electrical generating power is to allow the hull to evolve for future systems that will gobble electricity far in excess of the ship's design.
My understanding of a drawback of our decision to simply build more Burke class ships rather than the new DD-1000 (aka Zumwalt, DDG-1000 ,or DD(X) way back) is that the latter generates electric power for systems under development while the Burke destroyers can't do that, limiting their growth potential.
So adding electric power allows the ship to be updated with new energy-hungry systems.
Electric armor, for one (quoting Strategypage here):
For several years, up until 2003, the U.S. Navy mentioned electromagnetic armor, or DAPS (Dynamic Armor Protection System) being developed for the planned CVN-21 class of carriers. The basic technology behind DAPS was not complex. Areas above the waterline would have two layers of thin armor, separated by a small air space. The two layers of armor would be electrified, and when the armor was hit by a shaped charge (favored for cruise missile warheads) the jet of superhot plasma, formed by the shaped charge warhead going off, would be broken up by the electromagnetic field formed when the two layers of armor were forced together. The big problem with DAPS was the huge amount of electricity required when the system was turned on. However, in the next decade or so, warship power plants are expected catch up with the needs of DAPS systems.
And electric rail guns, for another (quoting the Weekly Standard):
All of the technologies discussed so far have already been successfully tested, but the DD(X) is also designed to allow for the rapid deployment of technologies still in the pipeline. The Navy hopes to fit these ships with an electromagnetic rail gun by 2020. The rail gun would be capable of firing a guided projectile up to 267 nautical miles[.]
Or laser weapons: (Quoting AP):
The Navy's laser technology has evolved to the point that a prototype to be deployed aboard the USS Ponce this summer can be operated by a single sailor, he said.
Or weaponized AESA radars (quoting Strategypage):
AESA is able to focus a concentrated beam of radio energy that could scramble electronic components of a distant target. Sort of like the EMP (Electromagnetic Pulse) put out by nuclear weapons. The air force won’t, for obvious reasons, discuss the exact “kill range” of the of the various models of AESA radars on American warplanes (the F-35 and F-22 have them). However, it is known that “range” in this case is an elastic thing. Depending on how well the target electronics are hardened against EMP, more electrical power will be required to do damage. Moreover, the electrical power of the various AESA radars in service varies as well. The air force has said that the larger AESA radars it is developing would be able to zap cruise missile guidance systems up to 180 kilometers away.
That AP article is still live, and it notes the electricity problem:
Producing enough energy for a rail gun is another problem.
The Navy's new destroyer, the Zumwalt, under construction at Bath Iron Works in Maine, is the only ship with enough electric power to run a rail gun. The stealthy ship's gas turbine-powered generators can produce up to 78 megawatts of power. That's enough electricity for a medium-size city — and more than enough for a rail gun.
I'm just saying that marginal increases in on-station time or saving money on fuel seem like minor side benefits to this program that will power new systems that will make the Burke class viable for decades into the future.