Terminal tractors – vehicles that move massive cargo loads at seaports around the world – spend up to four-fifths of their time sitting still with their engines running, waiting to be put to use. Given that fact, why not retrofit the prevalent diesel-burning versions to make them plug-in hybrids?
The converted tractors are being tested at an SSA Marine terminal at the Port of Long Beach, Calif., and future tests are scheduled for ports in New York City, Houston, Savannah, Ga. and Mobile, Ala., said Andra Rogers, EPRI's senior project manager of electric transportation.
It costs about $80,000 to convert a diesel terminal tractor to a plug-in hybrid, but a converted tractor will save about 80 percent of its fuel usage, or about 3,000 gallons of diesel a year, giving it a payback of about six years, EPRI estimates.
And that's not counting the reduction in carbon dioxide emission and pollution that would come from burning less fuel, as well as the reduced maintenance and life-cycle costs that come from running engines less frequently, Rogers said.
The hybrid tractors can carry the same loads – about 96,000 pounds – as their diesel counterparts, since they use their diesel engines when they're moving and switch to electric when idling, EPRI reports.
Ports, and the shipping industry they serve, aren't as publicly visible sources of pollution as on-road cars and trucks. But the global shipping industry accounts for a significant share of the world's greenhouse-gas emissions – about 4.5 percent, according to a U.N. study reported by the Guardian newspaper last year.
Only a fraction of that can be contributed to on-shore activity at ports. Still, ports have been linked to high levels of pollution and contamination of nearby communities, and that's led to government and industry action to clean them up, such as a $28 million project at the Port of Oakland, Calif. aimed at cutting diesel truck emission by up to 85 percent, the San Francisco Chronicle reported last month.
Ideas for making ports cleaner and more energy-efficient include onshore systems to capture emission from ships at port and plates installed in roadways that capture kinetic energy (see The Next Green Wave: Ports).
The big cranes that move cargo containers can also be harnessed for extra energy. Vycon Energy has developed a flywheel that can capture the kinetic energy of port cranes as they lower cargo containers to give them a boost on their next lift (see Generating Power With Gravity).
As for electric transportation, ports typically have lots of 240-volt connections, making charging a simpler task, EPRI noted.
The US Hybrid plug-in terminal tractors are just one of several technologies EPRI is looking into for what it calls "non-road electric transportation," Rogers said. That could include airports, warehouses and truck stops, where long-haul semi tractors can spend 10 hours a day idling and wasting fuel (see Quallion Seeks DOE Grants for 'Anti-Idling' Batteries).
Warehouse forklifts have been popular targets for conversion to electric or fuel cell systems, since they are refueled (or recharged) at the sites they work at – avoiding the quandary of building a network of charging or alternative fueling stations (see Green Light post and Battery Makers Target Forklift Market).
Buses are another popular choice for switching from fossil fuels, since they are generally refueled or recharged at central terminals (see The Bus With Plug-and-Play Batteries and Valence: Electric Buses and Trucks First, Cars Later).
Learn how to differentiate your company through greener product lines at Greening the Supply Chain on September 17 in Boston.