A new report from Seattle's Sightline Institute says that one of the arguments for building coal export terminals in Oregon and Washington does not hold water.

Supporters of plans to build new U.S. export terminals for sending Powder River coal from Wyoming to Asia have argued that if we don't build the controversial facilities here, that same coal will simply be shipped through Canadian terminals.

But Sightline—a sustainability think tank—looked at Canadian export capacity and found two things: existing terminals are already shipping about as much as they can and Canadian coal, which Sightline says has higher value than U.S. coal, is likely to have priority if ports expand their capacity.

"An examination of each of BC's three major coal terminals reveals that they cannot provide significant capacity to US coal exports," writes the report's author, Eric de Place.

"Very little US coal from the Powder River can be exported via Canadian ports, particularly in comparison to the volumes planned for export from Oregon and Washington."