Methodology & Assumptions

Assumptions:

2.645 short tons = one empty teu
Emissions:
Truck: 161.8g CO2/st-mile
Rail: 22.94g CO2/st-mile
Ocean: 11000 TEU (12.5 gCO2/t-km) 6000 & 4500 TEU (16.6g CO2/t-km)
1 Nautical Mile = 1.852 kilometers
1 Kilometer = .621371 miles
1 short ton = .907185 metric tons

Fuel Prices:
Ocean: Bunker fuel index price as of 12/17/2012
Truck: Highway Diesel Prices as of 12/17/2012
Rail: Diesel prices as of 12/17/2012
Barge: Currently Undocumented


Formula:

Ocean Component (Nautical miles x emissions of CO2 based on size of vessel) + Inland Transportation (miles from port to destination x emissions of CO2 based on choice of barge, rail or truck)


Sources:

Ocean Distance: Distance: Sea Distances Voyage Tracker http://sea-distances.com
Road Distance: Google Maps http://googlemaps.com
Rail Distance: US Federal Railroad Administration http://www.fra.dot.gov
Emissions for Truck and Rail: EPA SmartWay Shipper Tool http://www.epa.gov/smartway/documents/partnership/shipper/partnership/42...
Emissions for ships: Second IMO Greenhouse Gas Study 2009 http://www.imo.org/blast/blastDataHelper.asp?data_id=27795&filename=GHGS...
Diesel Prices: http://www.eia.gov/petroleum/gasdiesel/
Bunker Fuel Prices: http://www.bunkerworld.com