|The APL China moves into San Francisco Bay.|
Global shipping company APL, the world’s eighth-largest container carrier, will test a new cold-ironing system to reduce in-port emissions at US seaports.
With financial support from the Port of Oakland (California), the Bay Area Air Quality Management District and Pacific Gas & Electric (PG&E), APL will test the new system for 18 hours aboard the 863-foot container vessel APL China.
Cold-ironing—also known as alternative marine power—isn’t new. Vessels connect (plug-in) to a clean shore-side electrical power source while docked, enabling them to shut down their diesel-powered generators. That would eliminate more than 1,000 pounds of exhaust pollutants in a single containership port call.
Because of the potential environmental benefits, port authorities and air quality regulators have embraced cold-ironing. But the maritime industry has been wary, citing safety, operational and cost concerns in making cumbersome cable connections from ship to shore—especially for the large percentage of the world’s existing container fleet that hasn’t been constructed with cold-ironing in mind.
To reduce those concerns, engineers at APL devised a plan to connect a single high voltage cable from a shore-side power source to the vessel’s bow thruster circuit. The bow thruster is a propeller mounted in a ship’s bow to push it sideways during docking.
The bow thruster is driven by a high-voltage electrical motor. The motor is connected to the rest of the vessel’s low-voltage power system through a high-voltage cable and transformer. When the shore-side power source is connected to this circuit in the bow, the electricity can be back fed through the cable and transformer to the vessel’s main switchboard to power the entire ship.
By using the high-voltage circuit, the vessel-to-shore connection can be made with one 3-inch diameter cable instead of 10 cables, as in other cold-ironing designs. This reduces the cost and complexity of making the connection each time the vessel is docked. Furthermore, using the bow thruster transformer eliminates the need to install a costly additional transformer to facilitate cold-ironing.
Because a ship’s auxiliary engines are shut down during cold-ironing, APL estimates that it can eliminate 1,000 pounds of nitrogen oxides (NOx) emissions, 70 pounds of sulfur oxides (SO2) and 15 pounds of particulate matter in a single 24-hour port call.
The plan also offers benefits that could accelerate the adoption of cold-ironing in the industry, according to APL:
The cost to retrofit vessels for cold-ironing would be about $225,000, far less than original industry projections of $1.5 million.
Safety is assured on two counts: 1) only one, relatively small cable is required to connect a vessel to shore power and 2) the ship’s transformer can run in parallel with the portable power source, allowing the vessel to switch over to shore power without temporarily cutting power.
Vessels should be able to connect to shore-side power at any port worldwide.
APL plans to test the cold-ironing concept at Middle Harbor Terminal next month with its technical partners: Progressive Electric, of Los Angeles; and Wittmar Engineering and Construction Inc. of Signal Hill, Ca. The APL China will be connected to a portable generator powered by liquefied natural gas.
During the test, APL will determine if the vessel’s transformer can handle the continuous load from a shore-side power source. If the test is successful, APL will begin to assess broader application of the cold-ironing concept.
We’ve seen a number of innovative proposals to curb vessel emissions. We’re taking part in this test because it holds the promise of significant benefits for air quality in and around the port.—Omar Benjamin, Executive Director of the Port of Oakland
In March, APL announced a voluntary decision to use cleaner-burning low-sulfur fuel in APL vessels berthed at the Port of Seattle. Last December the shipping line said it will test fuel emulsification—injecting water into diesel fuel—to reduce vessel emissions.