With financial support from the Port of Oakland, the Bay Area Air Quality Management District, and Pacific Gas & Electric (PG&E), APL will begin using shoreside electric power when its 863-foot ship, the APL China is docked. Connecting to shore-based electricity to power the onboard systems while the ship is docked could eliminate as much as 1,000 pounds of exhaust pollutants during a single containership port call.
The maritime industry has been wary of cold ironing, says APL, because of safety, operational and cost concerns associated with making the cable connections from ship to shore.
Most of the world’s existing container fleet hasn’t been constructed with cold ironing in mind. Ships operate with both high-voltage and low-voltage systems. APL engineers devised a plan to connect a single high-voltage cable from the shoreside power source to the vessel’s bow thruster circuit. (The bow thruster is a propeller mounted in the ship’s bow to push it sideways during docking.) The thruster is driven by a high-voltage electric motor which is connected to the vessel’s low-voltage power system through a high-voltage cable and transformer. With shoreside power connected, this circuit can be back fed through the cable and transformer to the vessel’s main switchboard to power the entire ship. This approach allows the shoreside connection to be made through one three-inch cable vs. 10 smaller cables used in other cold ironing designs.
Using the method APL has developed, the cost to retrofit vessels for cold ironing is about $225,000 vs. the original industry estimates of $1.5 million. In addition, the set up is safer because there is only one cable needed to connect the ship to the shore and the ship’s transformer can run in parallel with a portable power source, allowing the vessel to switch to shore power without the need to shut down power temporarily.
“We’ve seen a number of innovative proposals to curb vessel emissions,” said Omar Benjamin, executive director of the Port of Oakland. “We’re taking part in this test because it holds the promise of significant benefits for air quality in and around the port.”
