Shipping ports are major sources of air and water pollution, due in part to anchored or docked ships using diesel generators to keep their onboard systems powered up. A year from now, however, the Port of Honolulu will be trying out a mobile hydrogen fuel cell unit, as a more eco-friendly and fuel-saving alternative.

The unit will consist of four 30-kilowatt fuel cells, a hydrogen storage system and power conversion equipment, all housed inside a single 20-foot (6.1-m) shipping container that could be floated on a barge, parked on a dock, or otherwise taken where electrical power is needed.

It will be used in a six-month pilot project starting in early 2015, by shipping company Young Brothers Ltd.

"We compared the efficiencies of their diesel engines versus fuel cells, studied the energy efficiencies at various power levels and estimated the savings and reductions in emissions that would be realized if they were to convert to a fuel cell-powered operation," said Joe Pratt of Sandia National Laboratories, one of the partnering groups behind the project. According to Sandia's calculations, the fuel and energy savings should be significant, while the reduction in emissions should be particularly dramatic.

The fuel cell unit is being built by Hydrogenics Corp, while the Hawaii Natural Energy Institute will procure the hydrogen.

If it does indeed turn out to be a practical and affordable solution, other units may be trialled at other ports, with the ultimate goal of developing a commercial product that could be used in a variety of applications.

The US Department of Energy is also looking into replacing diesel generators with fuel cells, for running the refrigeration units in cold transport trailers.