Karen Bleier/AFP/Getty Images
A Norfolk Southern freight train rumbles through Luray, Virginia February, 18, 2012. Freight trains deliver goods to and from the inland port at Front Royal, Virginia.
First a riddle...Why did the train carrying biofuels cross the border 24 times in 13 days and never unload any cargo? Stumped?
OK. Here's the answer: To earn millions of carbon credits.
John Nicol, an investigative journalist from the Canadian Broadcasting Corporation, is here to explain.