As Japan’s new hybrid electric Emerald Ace splashed into the Pacific Ocean last month, a new class of commercial ships entered service.
Emerald Ace is a massive ship: stretching more than two football fields long, weighing 60,200 tons, and capable of carrying 6,400 passenger cars on a single journey. Yet it’s most impressive cargo may also be its most modest: 324,000 of Panasonic’s lithium-ion batteries (similar to those in your laptop) in the hold, as well as 768 solar power panels on deck. That’s enough power, about 2.2MW hours, to run the entire ship’s electrical systems (if not its engines) without burning a drop of fuel.
Emerald Ace is among a number of new commercial ships integrating multiple power systems that replace the exclusive reliance on diesel or bunker fuel oil. None are just electric (or solar powered): The energy needed to cross an ocean is far too great to rely on renewables alone. Yet solar panels can recharge batteries on long voyages, partially or entirely running the ship’s electrical systems, then allow the switch over to electric in port, eliminating shoreside emissions and expensive fuel.
Emerald Ace is just the latest in a rapidly improving electric marine technology. In 2009, the ship Auriga Leader was outfitted with 328 solar cells and nickel-hydrogen batteries that supplied about 1% of the ship’s electric demand and .05% of its propulsion power.
Yet even that was about a century overdue. Similar to the unfortunate fact that the earliest cars were primarily electric or biofuel powered, electric boats were taking their maiden voyages as early as the 1800s. At Chicago’s 1893 World’s Fair, electric vessels ferried thousands of people in comparative comfort relative to the sooty steamships of the era.
Now that the past is finally catching up with the present, the U.S. Navy’s "Next Generation Integrated Power Systems" looks like it may be the future. The military is far ahead of the commercial sector in converting its fleet to electric propulsion (diesel electric submarines, in fact, have been around for decades). In 2009, the Navy launched its advanced amphibious assault ship, Makin Island, which combines efficient gas turbines and electric motors as well as traditional combustion engines. On its first voyage from Mississippi to San Diego, the ship saved 900,000 gallons of fuel relative to a conventional ship, optimally balancing the different power systems. Over the life of the ship, the Navy predicts, the system will save about $250 million in fuel costs.
For now, commercial fleets may content themselves with solar panels and batteries. As fuel costs rise, turning to electric ships may prove profitable.