Pimentel and Hall (Food and Energy Resources, Academic, 1985) indicated that:
"Transport of food products in the US is estimated to be about 60% by
truck and about 40% by rail. Based on energy requirements for truck and
rail transport the energy required to move 1 kg of food product is
calculated to be approx 0.5 kcal/km. Assuming 640 km [400 miles] is the
average distance that goods are moved, then the energy input is about 350
kcal/kg.
"Frequently however, much greater energy inputs are required for
transporting foods from production areas to far distant marketplaces.
Consider the journey frequently taken by a 0.5 kg head of lettuce that
has a food energy value of only about 50 kcal. When this head of lettuce
is transported by truck from California to NY, a distance of 4827 km, the
energy expended is about 1800 kcal of fossil energy. This means that just
for transport, about 36 kcal of fossil energy are expended per kcal of
food energy in the lettuce." pg. 22
But I don't have their primary source for this data.
Hector Valenzuela
Vegetable Extension Specialist
Horticulture, University of Hawaii at Manoa
3190 Maile Way, No. 102
Honolulu, HI 96822-2279
Tel. 808-956-7903
Fax. 808-956-3894
hector@hawaii.edu
http://agrss.sherman.hawaii.edu/hort/