While larger vessel sizes carrying cargo through an expanded Panama Canal could reduce CO2 emissions as much as 23 percent, other factors such as increased voyage distance and waterborne emissions essentially negate these GHG reductions, according to a new Environmental Defense Fund (EDF) study.
The peer-reviewed Panama Canal Expansion: Emission Changes from Possible U.S. West Coast Modal Shift, published in a special issue of the journal Carbon Management, studies the environmental opportunities presented by the expansion of the Panama Canal, slated for completion in 2014, for the intermodal container shipping industry.
The report evaluated whether a modal shift of east coast-bound cargo onto larger ships through an expanded canal offers net emission reductions compared with the land-freight truck/rail network via the west coast.
Ocean transport is more carbon-efficient than truck or rail, according to EDF, and the study authors — scientists at the School of Marine Science and Policy at the University of Delaware, along with EDF transportation analysts — expected that the use of larger ships and more water routes would reduce the CO2 footprint of freight transported through an expanded canal.
However, the authors found that diverting cargoes from transportation modes with higher emissions per ton-mile (the emissions released by moving one ton of freight one mile) may not provide emission benefits. When taking future cargo volumes into consideration and assuming a 10 percent diversion from the west coast to the east coast (see chart), the effects of the expansion on CO2 emissions appear to be negligible because of longer distances traveled, the report concludes.
In 2010, Mitsubishi Heavy Industries designed a large fuel-efficient container vessel that it says reduces carbon-dioxide emissions by 35 percent compared with conventional container carriers and will be able to carry 14,000 6-meter equivalent unit containers and travel through the Panama Canal after the waterway’s expansion.
A report published in October in the journal Environmental Science & Technology found putting a speed limit on cargo ships as they sail near ports and coastlines could cut their GHG emissions by up to 70 percent. While cargo ships make up less than 5 percent of the total ocean-going fleet, they emit more than 21 percent of the CO2 from the international shipping industry, according to the journal.