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The use of energy by the major modes of freight transportation has become of increasing concern in setting transportation policy. This report complements previous Congressional Budget Office (CBO) studies of the relative energy efficiency of the major modes of urban passenger transport and of intercity passenger transport. It was prepared at the request of the Commerce, Transportation and Tourism Subcommittee of the House Committee on Energy and Commerce. In keeping with CBO's mandate to provide objective and impartial analysis, the study offers no recommendations.
Richard R. Mudge of CBO's Natural Resources and Commerce Division prepared
the study under the supervision of Damian J. Kulash and David L. Bodde.
Valuable comments were received from representatives of the Association
of American Railroads, the American Trucking Association, the Coal Slurry
Pipeline Association, and the National Waterways Conference, and from the
following individuals: Axel Rose of Oak Ridge National Laboratory, Edward
Gregory of the Department of Energy, John Pollard of the Transportation
Systems Center, and Samuel E. Eastman. Other suggestions came from Peter
Tarpgaard, Allen Kraus, and Richard Weissbrod of CBO. Francis Pierce edited
the manuscript and Kathryn Quattrone prepared the paper for publication
with help from Paula Mills.
Alice M. Rivlin
Director
February 1982
SUMMARY
CHAPTER I. INTRODUCTION
CHAPTER II. ANALYTICAL APPROACH
CHAPTER III. ESTIMATED ENERGY EFFICIENCIES OF FREIGHT TRANSPORTATION MODES
APPENDIX A. DESCRIPTION OF INPUT DATA
APPENDIX B. MAJOR SOURCES
| TABLES | |
| 1. | ESTIMATES OF BASIC COMPONENTS OF ENERGY USE FOR SIX MODES OF FREIGHT TRANSPORTATION |
| 2. | RELATIVE IMPORTANCE OF BASIC COMPONENTS OF ENERGY USE FOR SIX MODES OF FREIGHT TRANSPORTATION |
| 3. | SUMMARY MEASURES OF ENERGY EFFICIENCY FOR SIX MODES OF FREIGHT TRANSPORTATION |
| 4. | ESTIMATES OF ENERGY USE OVER THE SHORT TERM FOR SIX MODES OF FREIGHT TRANSPORTATION |
| 5. | POTENTIAL ENERGY SAVINGS FROM SWITCHING FREIGHT TRAFFIC TO MORE EFFICIENT MODES |
| A-1. | ESTIMATES OF PROPULSION ENERGY REQUIREMENTS FOR RAILROADS |
| A-2. | FIELD MEASUREMENTS OF RAIL FREIGHT PROPULSION ENERGY USE |
| A-3. | ESTIMATES OF PROPULSION ENERGY REQUIREMENTS FOR INTERCITY TRUCKS |
| A-4. | ESTIMATES OF PROPULSION ENERGY REQUIREMENTS FOR WATER TRANSPORTATION |
| A-5. | ESTIMATES OF PROPULSION ENERGY REQUIREMENTS FOR AIR FREIGHT |
| A-6. | ESTIMATES OF PROPULSION ENERGY REQUIREMENTS FOR PIPELINES |
| A-7. | ESTIMATES OF PROPULSION ENERGY REQUIREMENTS FOR COAL SLURRY PIPELINES |
| A-8. | SUMMARY ESTIMATES OF PROPULSION ENERGY REQUIREMENTS |
| A-9. | ESTIMATES OF VEHICLE MANUFACTURING ENERGY |
| A-10. | SUMMARY ESTIMATES OF VEHICLE MANUFACTURING ENERGY |
| A-11. | ESTIMATES OF GUIDEWAY CONSTRUCTION ENERGY |
| A-12. | SUMMARY ESTIMATES OF CONSTRUCTION ENERGY |
| A-13. | ESTIMATES OF VEHICLE AND INFRASTRUCTURE MAINTENANCE ENERGY |
| A-14. | SUMMARY ESTIMATES OF VEHICLE AND INFRASTRUCTURE MAINTENANCE ENERGY |
| A-15. | ESTIMATES OF CIRCUITY FOR INTERCITY FREIGHT TRANSPORTATION |
| A-16. | SUMMARY ESTIMATES OF CIRCUITY FOR INTERCITY FREIGHT TRANSPORTATION |
This report examines the relative energy efficiency of the different modes of freight transportation. It finds that in terms of energy per ton-mile, oil pipelines are easily the most efficient of the modes of transportation considered. Inland barges rank second, although for some uses railroads are of comparable efficiency. Trucks use more energy than railroads, and cargo planes are at the bottom of the efficiency range (see Summary Table). But these simplified comparisons must be modified in several ways.
Modifying Factors
Oil pipelines use only 500 BTUs (British Thermal Units) per ton-mile (280 ton-miles per gallon of diesel fuel), but they are limited by their very specialized function. The efficiency of inland barges (990 BTUs per ton-mile or 140 ton-miles per gallon on average), is likewise offset by the roundaboutness or circuity of most rivers. Also, significant amounts of energy may be required to bring cargo to a waterway system: grain and other farm products are sometimes trucked 200 miles to a river, increasing energy use per ton-mile by 50 percent or more.
The efficiency of rail transportation varies considerably depending on the commodity and the level of service provided; at one extreme, unit trains designed to carry only coal typically require less than 900 BTUs per ton-mile of cargo (155 ton-miles per gallon), while at the other extreme high-speed short trailer-on-flat-car (TOFC) trains use about 2,000 BTUs per ton-mile of cargo (68 ton-miles per gallon).
Intercity trucks require on average about 3,400 BTUs per ton-mile of cargo (41 ton-miles per gallon), twice the rail average and 1.7 times that for rail TOFC. It is not surprising that trucks require more energy since they provide a generally higher level of service than rail.
An even higher level of service, and hence greater energy need, is characteristic of air freight. In planes devoted to air freight, over 28,000 BTUs per ton-mile of cargo may be required (5 ton-miles per gallon), although freight carried in the belly of a passenger plane may require only 3,900 BTUs per ton-mile of cargo (35 ton-miles per gallon).
A specialized new mode of freight transportation is the coal slurry pipeline; this appears to require about 1,270 BTUs per ton-mile of coal--although this conclusion is based largely on engineering studies.
Components of Energy Use
These energy estimates include all of the energy consumed in transportation--that is, not only the energy used in propelling a vehicle but also the energy used in manufacturing and maintaining it, and in building the guideway over which it moves. In addition, they make allowance for "circuity"--the extent to which a vehicle's route departs from a straight line. The amounts of energy used for propulsion and for circuity are by far the most important, accounting between them for more than 70 percent of the energy used by most modes of transportation.
For rail and barge transportation, propulsion consumes between 35 and 50 percent of all energy used. For intercity trucks, propulsion accounts for about 60 percent, and for airlines about 90 percent, of total energy use. Circuity requires about 45 percent of barge energy, 35 percent of rail energy, and 20 percent of intercity truck energy, the differences corresponding largely to the extent of each mode's transport network. On the other hand, circuity accounts for less than 10 percent of energy use by airlines and pipelines. With a few exceptions, none of the other components of energy use--vehicle manufacture, guideway construction, and maintenance--accounts for more than 10 percent of total energy use.
Other Factors
Factors such as speed, terrain, and type of cargo have a major influence on energy use. For example, a train carrying only coal is much more efficient per ton-mile cargo moved than a mixed train carrying various manufactured goods in boxcars, many of them empty. Similarly, upstream barge traffic requires more energy than barges moving downstream.
Finally, energy is only one of the concerns that enter into the setting of transportation policy. Of more importance, usually, are the total costs of each mode of transportation, the service qualities it possesses, the effects it may be expected to have on regional development, and the way in which it is financed.
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