Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportation's Role in Reducing U.S. Greenhouse Gas Emissions: Volume 1
Figure 2.9
Rail Trends: a) Greenhouse Gas Emissions, and b) Revenue
Freight Ton-Miles and Fuel Efficiency
1990 to 2006
Greenhouse Gas Emissions (MMT CO2e) 2.9a
60
50
40
30
20
10
Passenger Rail
Freight Rail
0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Source: U.S. EPA (2008). Inventory of Greenhouse Gas Emissions and Sinks: 1990 to 2006.
Revenue Freight Ton-Miles (in Millions)
2.0
1.5
1.0
0.5
0.0
Revenue freight ton-miles (millions)
2.9b
Fuel Usage (Gallons per Ton-Mile)
0.0035
Fuel Usage (gallons per ton-mile)
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
0.0030
0.0025
0.0020
0.0015
0.0010
0.0005
0.0000
Sources: Bureau of Transportation Statistics. National Transportation Statistics (Freight Activity and Fuel
Efficiency).
Marine
Figure 2.10a depicts greenhouse gas emissions from the broad range of marine
activities: recreational craft, inland waterway, marine coastal, and international
shipping. Greenhouse gas emissions from marine sources appear rather volatile
in some years in Figure 2.10a. This fluctuation is most likely due to issues with
data collection and interpretation, including the challenge of separating the
domestic and international components of fuel consumption estimates. These
issues may also reflect the nature of ship refueling strategies, which take
advantage of price differences among countries to buy fuel at the least expensive
port. As shown in Figure 2.10b, domestic waterborne freight tonnage decreased
from 1990 to 2006, while international waterborne imports and exports increased
significantly as the Nation’s international trade grew. Because of the complex
nature of some routing, such as multiple stops to exchange cargo and routing
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