US Navy plans a $25bn electric destroyer fleet

The US Navy has announced plans for a new generation of electrically propelled destroyers and hinted that all of its surface vessels - and possibly its submarines as well - will eventually use electric drive systems.

Initially, the Navy plans to built 32 destroyers at a cost of around $25bn. It says that the electric drive systems will be smaller, more efficient, quieter, and "stealthier" than conventional propulsion systems. The ships will need less maintenance and their crews will number just 95 instead of the 300 needed for today`s destroyers.

The electric destroyers will still use diesel engines or gas turbines, but instead of driving the propeller via bulky and difficult-to-maintain reduction gears, they will drive generators powering electric motors.

The motors will drive the propellers directly, varying their speed independently of the engines which will be able to run efficiently at a constant speed. The absence of reduction gears and the short drive shafts will make the vessels quieter and harder for submarines and mines to detect.

The new drive configuration also means that the various components will not have to be aligned along the bottom of the ship - the generators for example, could be placed anywhere in the ship, freeing up space for other uses.

Spreading the generators around a ship will also make the electrical system less vulnerable to damage in times of war. And because the engines will be generating power both for the drive and for other ship installations, just four engines will be needed instead of the seven found on a typical destroyer today.

The Navy has budgeted $250m over the coming six years to fund the development of the drive technology. Two teams of contractors are bidding for the work. The first electric destroyer is expected to enter service in about ten years` time.