One of the Georgia Port Authority’s (GPA) top priorities is responsible stewardship of the environment. This has been demonstrated by the conversion of ship-to-shore container cranes from diesel to electric power, as well as gradually changing other container handling equipment to cleaner burning ultra-lowsulphur diesel fuel.
Moving from diesel to electricity
As a next step in developing more sustainable operations, the Port of Savannah has begun the transition from diesel to electrically powered rubber-tyre gantry (RTG) system. This makes the GPA the first in North America to introduce this cleaner and more efficient method of operation.
Just over 18 months ago, the GPA and our partners started an effort to solve a problem for our port, and in turn most major ports in America. How can we transfer our yard crane fleet to a cleaner form of energy without reducing mobility and efficiency on the terminal?
The new electrical rubber tyre gantry (ERTG) system was developed with the help of partners Konecranes, Conductix-Wampfler and Georgia Power, which provided the cranes, the new power system and the electrical infrastructure, respectively. Early on, we knew that if we simply converted the diesel burning rubber tyred gantry cranes to electric, we would certainly have reduced emissions, but in the process we would also have reduced mobility and therefore efficiency of the cranes.
Developing a hybrid solution
That’s when our team went back to the drawing board to develop a new hybrid crane that provides the emission benefits of an electricpowered crane with the flexibility to move across terminal. Custom built to a GPA design, the ERTGs are powered through 480 volt conductor rails installed on the container yard. While relying on electrical power to handle containers, our ERTGs use diesel generators to move from stack to stack and row to row. Using a retractable arm, the ERTGs will switch via an auto-engage system between diesel and the electrical grid. The ERTGs will also capture power when lowering boxes – energy which is currently lost under diesel power. This innovative system regenerates power back to the electrical grid, powering itself for 18 minutes each hour.
All functions of the ERTG – including linking to the conductor rails – are performed automatically or by the crane operator without other assistance. The conversion of the cranes to electrical power will result in an overall energy savings, reducing fuel consumption by 95 per cent, with a corresponding reduction in emissions. Additional benefits to our new ERTGs include increased reliability, better performance and less downtime. Crane reliability is increased because the motors, drive systems, and all critical electrical components are perpetually energised, thereby reducing potential moisture damage. Maintenance and repair of diesel generators constitutes a significant portion of equipment downtime. Additionally, the conversion will reduce the overall staff hours required to provide maintenance on the cranes. In the end, fewer hours of diesel-powered operation will mean reduced maintenance costs and extended diesel life.
Further developments planned
Long term plans call for retrofitting the Garden City Terminal’s fleet of diesel-powered RTG cranes with retractable arms to link to the conductor rail system, bringing the total number of ERTGs to 169 by 2022. Repowering the RTGs will be a multi-year initiative, requiring new cranes to be ordered with electric power capabilities, and some older cranes to be retrofitted. When complete, the ERTG fleet will allow the GPA to avoid the use of 5.97 million gallons of diesel each year. This will result in a net saving of nearly US$10 million each year, even after the purchase of electricity is factored in.
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