A new study shows that cruise ships docked in Charleston could reduce their carbon monoxide emissions by as much as 97 percent by plugging into the onshore power grid instead of idling their engines.
The report is fodder for an ongoing debate about the future of the Holy City cruise ship industry, sparked by the S.C. State Ports Authority's plan to build a new $35 million cruise terminal in the historic district and by city leaders' refusal to enforce caps on cruise ship traffic. Environmental and community groups have filed lawsuits in the matter and pushed SPA to consider incorporating power grid plug-ins in the new terminal design, as has been done at seven other U.S. ports including one in Brooklyn, N.Y., but SPA has refused to make the change. As a result, cruise ships will continue to run their engines at the Charleston port to power lights, air conditioners, refrigerators, and other equipment. In the new study, which was published Monday, these onshore electrical needs are referred to as the "hotelling load factor."
The study, published Monday, was commissioned by the Charleston-based Southern Environmental Law Center and prepared by the Pittsford, N.Y.-based Energy and Environmental Research Associates, LLC. In estimating emissions, it used methodologies similar to ones used by the U.S. Environmental Protection Agency and the California Air Resources Board.
Under current conditions, according to the report, a switch to onshore power would reduce emissions of carbon monoxide by 92 percent, nitrogen oxide by 98 percent, small particulate soot by 34 percent, and carbon dioxide by 26 percent. The study found that a 2,000-passenger Carnival ship emits 68.3 metric tons of nitrogen oxide per year in the time it idles at the Charleston terminal, whereas the same ship using shore-based power would emit only 0.8 metric tons in Charleston.
The study also looks forward to the year 2019, when Carnival will be operating larger 3,500-passenger ships that are expected to emit more pollutants. By then, the South Carolina utility SCE&G is also expected to have shifted toward natural gas and nuclear power generation, leading to lower emissions from the currently coal-based onshore power source. As a result, the study finds that the emissions cuts from switching to on-shore power would be even more dramatic in 2019: Carbon monoxide emissions would be reduced by 97 percent, nitrogen oxide by 99 percent, small particulate soot by 71 percent, and carbon dioxide by 36 percent.
SPA representative Allison Skipper says she has not seen the report yet, but that her organization "believes Carnival to be operating legally in Charleston" under federal MARPOL (Maritime Pollution) Annex VI emissions standards. Those standards, which went into effect in 2005, placed limits on ships' emissions of nitrogen oxide and sulphur oxide.
The Coastal Conservation League, a vocal proponent of onshore power for Charleston cruise ships, is touting the report as support for their side in the debate. "People in Charleston are not anti-cruise," says Katie Zimmerman, a program manager at CCL. "They just want a fair look at options used in other ports to manage cruise impacts and protect human health, and shore power is one of them."