Posted May 31, 2006
Editor's note: Subsequent to the publication of this feature, Sierra learned that there was a calculation error in the original paper on which the article was based, "The Load Less Traveled," (Leopold Center for Sustainable Agriculture, 2002). In addition, Sierra's own calculations failed to account for the differing fuel-energy values of gasoline (light truck), diesel (commercial truck), bunker oil (ship), and jet fuel (air). We also neglected to cite the weight of our example produce; e.g., the potato was large, weighing one pound. Together, these errors led us to significantly overstate the amount of fuel needed to move the items to market.

What follows are the Leopold Center's recalculations of the fuel requirements to transport various produce to market. Remember that for the purpose of this example, the "market" was designated to be Des Moines, Iowa.

Calculations for estimating energy (fuel) requirements to transport various produce:

1. Estimates for transport of goods by various modes:

   Mode of transport	Energy requirement	Source
   Ship	80 kcal/ton/km	Pimentel et al., 2004
   Truck	820 kcal/ton/km	Pimentel et al., 2004
   Air	6,995 kcal/ton/km	(See "References" below for explanation)

   kcal = kilocalories

2. Convert to kcal/ton/mile:

   Ship: 50 kcal/ton/mile
   Truck: 510 kcal/ton/mile
   Air: 4,372 kcal/ton/mile

3. Input distances traveled by produce and mode of transport, from source to Des Moines food store:

   • Apple (Iowa) – 60 miles by light truck (gas)
     
   • Apple (Washington) – 1,722 miles by commercial truck (diesel)
     
   • Grapes (California) – 1,887 miles by commercial truck (diesel)
     
   • Grapes (Chile) – 5,585 miles by ship (residual fuel oil); 1,683 miles by commercial truck (diesel)
     
   • Potato (North Dakota) – 558 miles by commercial truck (diesel)
     
   • Potato (Idaho) – 1,246 miles by commercial truck (diesel)
     
   • Pineapple (Costa Rica) - 1,211 miles by ship (residual fuel oil); 1,466 miles by commercial truck (diesel)
     
   • Pineapples (Hawaii) - 2,551 miles by plane (kerosene jet fuel); 1,683 miles by commercial truck (diesel). (Only specialty Hawaiian pineapples are shipped by air. Most come in the same fashion as the Costa Rican fruit, by sea and truck.)

4. Calculate the kcal needed per pound of produce transported:

   • Apple (Iowa) – 15
   • Apple (Washington) – 439
   • Grapes (California) – 481
   • Grapes (Chile) – 139 by ship; 429 by truck
   • Potato (North Dakota) – 142
   • Potato (Idaho) – 317
   • Pineapple (Costa Rica) 30 by ship; 373 by truck
   • Pineapple (Hawaii) 5,576 by plane; 429 by truck

5. Fuel-energy values of various fuels:

   Oxygenate gas (truck) – 123,000 BTU/gallon
   Distillate fuel oil - #2 Diesel (truck) – 139,000 BTU/gallon
   Kerosene jet fuel (air) – 135,000 BTU/gallon
   Residual fuel oil (ship) – 150,000 BTU/gallon

   Conversion: 1 BTU = 0.252 kcal

6. Convert to cups of fuel per pound of produce transported:

   • Apple (Iowa) – 0.01
   • Apple (Washington) – 0.2
   • Grapes (California) – 0.22
   • Grapes (Chile) – 0.06 by ship; 0.2 by truck (0.26 total)
   • Potato (North Dakota) – 0.065
   • Potato (Idaho) – 0.14
   • Pineapple (Costa Rica) 0.01 by ship; 0.17 by truck (0.18 total)
   • Pineapple (Hawaii) 2.62 by plane; 0.2 by truck (2.82 total)

7. Weights of produce pictured:

   • Apple (Iowa) – .6 pounds
   • Apple (Washington) – .6 pounds
   • Grapes (California) – 1 pound bunch
   • Grapes (Chile) – 1 pound bunch
   • Potato (North Dakota) – 1 pound
   • Potato (Idaho) – 1 pound
   • Pineapple (Costa Rica) – 3 pounds
   • Pineapple (Hawaii) – 3 pounds

8. Volume of fuel needed to transport produce:

   • Apple (Iowa) – 0.048 ounces (0.288 teaspoons)
   • Apple (Washington) – 0.96 ounces (5.76 teaspoons)
   • One-pound bunch of grapes (California) – 1.76 ounces (3.5 tablespoons)
   • One-pound bunch of grapes (Chile) – 2.1 ounces (4.2 tablespoons)
   • Potato (North Dakota) - 0.52 ounces (1 tablespoon)
   • Potato (Idaho) - 1.12 ounces (2.25 tablespoons)
   • Pineapple (Costa Rica) - 4.32 ounces (0.54 cup)
   • Pineapple (Hawaii) - 67.68 ounces (0.529 gallons)

References

1. D. Pimentel, A. Pleasant, J. Barron, J. Gaudioso, N. Pollock, E. Chae, Y. Kim, A. Lassiter, C. Schiavoni, A. Jackson, M. Lee and A. Eaton. 2004. "U.S Energy Conservation and Efficiency: Benefits and Costs." Environment Development and Sustainability 6: 279-305.

Transport by air

To arrive at the energy used to transport goods by air for the Hawaiian pineapple calculation, we used the total fuel consumption of jet fuel and the total revenue ton-miles by air to arrive at the figure of 6,995 kcal/ton/km (or 4,372 kcal/ton/mile).