Environmental Engineering Reference
In-Depth Information
13 Transportation
INTRODUCTION
Along with carbon footprint, “food miles” have become part of the general population's
jargon,but, do food miles really matter? Certainly, they do matter but not in the context that
they are generally used. The belief that “eating local” mitigates emissions significantly, as
embraced by some movements (e.g., locavores), has small impact when compared with other
impacts in the food supply chain. In terms of emissions of greenhouse gases, food transporta-
tion is on average 11 percent responsible for the total emissions generated during food produc-
tion, processing, and distribution in the United States (Weber and Matthews, 2008). Emissions
from transportation vary by the type of food product (i.e., shelf stable, fresh refrigerated, or
frozen), method of transportation (e.g., sea freight, river vessel, train, truck, or plane), size of
the transporting vehicle (e.g., pickup truck versus semi-trailer truck), and distance.
When looking at energy consumption, food transportation accounts for 14 percent of the
total energy consumed during the whole cycle from agricultural production to restaurants and
home consumption (Fig. 13.1). When compared across all commodities, according to data for
the United States, in 2002 transportation of food represented 21.6 percent (in ton-miles) of all
commodity products shipped in the United States (Table 13.1).
Still, transportation is an important issue and will become even more important in the near
future as the availability of fossil fuels starts to decline. If we overlook just for a minute the
environmental issues created by emissions from transportation, one of the unique qualities of
transportation of goods is the exclusive reliance on petroleum-derived liquid fuels. No matter
what transportation method is used to move goods on long or short distances, and get them
delivered, diesel is currently the only fuel of choice (gasoline is used on a small scale, mainly
for local delivery).
It can be argued that diesel could be substituted by natural gas in the near future, but they
are both unsustainable resources that eventually would come to an end. Therefore, even when
transportation accounts only for 14 percent of the energy from “farm to fork,” it is weak link
in the food supply chain. What is more, using natural gas as a substitute for current fuels to
maintain business as usual is not the best alternative in the long run. Natural gas is a premium
feedstock for the production of chemicals, plastics, and fertilizers, so burning natural gas as a
fuel is not the best use of the resource.
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