Shore-power for cruise ships is feasible

January 29, 2011

Ms. Katie Zimmerman

Coastal Conservation League

P.O. Box 1765

Charleston, SC 29402

Dear Ms. Zimmerman,

I enjoyed your presentation on cruise ships a few weeks back at the Charleston Surfrider Foundation chapter meeting. Although the main focus of that presentation pertained to discharge from cruise ships visiting Charleston, the issue of dockside energy use also piqued my interest. Specifically, I was curious to determine how much energy is consumed by cruise ships and the subsequent shore power requirements to terminate their practice of burning fuel oil while in port.

A 2010 report by the Alaska Department of Environmental Conservation1 provides some informative insights for comprehending this issue. During one week (20-26 July 2008) at the peak of the tourism season, 23 cruise ships were documented docking in Skagway, Alaska. Fifteen of these 23 cruise ships were classified as “large” (capacity >2500 persons) that typically docked for 13.5 hours each during which time they typically burned 620 gallons of marine diesel fuel per hour.

According to the Energy Information Administration2, a gallon of diesel and home heating oil contains 138,690 British Thermal Units (BTUs), which is the equivalent of 40.6 kilowatts. Therefore, at 620 gallons per hour and 13.5 hours docked, each of these cruise ships consumed roughly 8,370 gallons of diesel and 340.2 megawatts (25.2 MW/hr) of energy while docked.

With respect to cruise ships visiting Charleston, the State Ports Authority estimates that no more than 104 cruise ships will dock in Charleston annually3. Taking this estimate at face value and applying the typical consumption estimates for large cruise ships in the Alaska survey, we can estimate that the 104 cruise ships visiting Charleston annually would require approximately 35.4 gigawatts of shore power to satisfy their docking needs. To put that estimate into perspective, the same amount of electricity could be produced by the 615 MW coal-fired Williams station in Goose Creek in less than 2.5 days of continuous operation.

Eco-Cents strongly supports weaning ourselves off of fossil-fuels and as such, the reference to the Williams station is only provided for scale. Ideally an alternative energy fuel would be utilized for meeting the shore-based power needs of these cruise ships. The most direct substitution for petro-diesel fuel is bio-diesel fuel, which also requires minimal ship retrofits and dock upgrades. Southeastern Biodiesel located in North Charleston already provides fuel for local shrimpers. At 8,370 gallons of diesel per cruise ship docking, 870,480 gallons (i.e., 2,385 gallons produced every day of the year) would need to be produced to offset the estimated annual marine diesel consumption of 104 cruise ships docked in the Port of Charleston.

A true shore-based electricity grid could be also constructed, but this endeavor would require much greater capital investment in infrastructure changes both by the cruise ship industry to make their ships compatible with “cold ironing” as well as potentially by the City of Charleston to retrofit the cruise ship terminals to support these high voltage power lines. Major ports along all three coastlines of the United States have made or have plans to make such upgrades4; thus, there is a precedent for doing so, particularly as it relates to the cruise ship industry. Solar electric power is touted as a viable cruise ship fuel in California; however, at a cost of slightly more than one million dollars per megawatt of generating capacity5 it is not an inexpensive proposition. Considerably more logistical details would also need to be worked out in order for solar (or wind or even tidal) energy solutions to be effective for cruise (and container) ships at the Port of Charleston than would be required for bio-diesel, but these considerations represent hurdles rather than barriers. Such projects also represent precisely the types of “innovation” and infrastructure “investments” lauded by President Obama in his State of the Union address this past week. As such, these investments deserve due consideration, particularly if their energy could be fed directly into the local electrical grid during periods when ships were not docked.

In conclusion, clean and reasonably affordable alternatives to burning petro-diesel fuel exist for vessels visiting Charleston; thus, economic and environmental gains are not mutually exclusive. Given the vitality of the Port of Charleston to the Southeast U.S. and efforts to deepen the Port to accommodate even larger vessels later this decade, the actions we take (or fail to take) now have great ramifications on our future health and well-being. While the suggestions presented herein are neither complete nor infallible, the challenges that they present pale in comparison to not improving the status quo of unabated and wasteful consumption. I sincerely hope that you will share the calculations and projections that I have presented herein with a diverse audience, so that sensible discussions on energy issues may ensue. As the Eco-Cents mantra states, smaller footprints are achievable with affordable steps, and I greatly appreciate your taking that to heart.


Michael Arendt, Owner and Centsible Sleuth

Cc: Mayor Joseph P. Riley

Councilwoman Kathleen Wilson

Byron Miller, State Ports Authority