ONR Sails into Propulsion System Development

The Office of Naval Research (ONR) is developing fuel cell propulsion systems for future ships. ONR is also funding development of a method to extract hydrogen from diesel fuel to take advantage of the relative low cost of the fuel and the Navy’s established infrastructure for buying, storing, and transporting it.

“The Navy’s shipboard gas-turbine engines typically operate at 16% to 18% efficiency because Navy ships usually sail at low to medium speeds that don’t require peak use of the power plant,” says ONR program officer Anthony Nickens. “The fuel cell system that ONR is developing will be capable of between 37% to 52% efficiency.”

Fuel cells will permit design of a “distributed” power system, since they can be dispersed throughout the ship instead of being co-located with the ship’s shaft.

At the Department of Energy Idaho National Engineering and Environmental Laboratory in Idaho Falls, ONR is testing a 500kW diesel fuel reformer compatible with a proton exchange membrane fuel cell. Reforming diesel is complicated due to the sulfur present. The integrated fuel processor heats and vaporizes the diesel, then the sulfur in it is converted into hydrogen sulfide. The hydrogen sulfide is then exposed to zinc oxide, oxidizing the sulfur into sulfur dioxide and separating it from the hydrogen.

ONR is looking at designs to reduce the size of the processor, which consists of an arrangement of valves, water-gas shift reactors, an oxidizer, and other components.