Environmental Engineering Reference
In-Depth Information
LOCALLY PRODUCED VERSUS TRANSPORTED
Popular belief is that locally produced food has a lower environmental impact than food trans-
ported from other centers of production. But it all depends on the product itself, the transporta-
tion mode, the distance transported, the production method, and part of the world.
The type of product makes a difference. Foods with low-bulk density have more chances of
having a lower impact when produced locally than when transported from long distances. For
instance, it is likely than the impact is lower when wheat flour is transported and the bread
produced locally instead of transporting the already made bread for long distances.
As discussed previously, all transportation modes have different impacts in terms of energy
consumption and emissions. So without specifying the transportation method, distance does
not have much bearing on any analysis. In addition, locally produced fresh produce is nor-
mally transported in low tonnage pickup trucks that have much higher fuel needs per tonne of
product transported than trailer trucks.
The production method is also crucial. Is it really better, from the environmental view-
point, to grow tomatoes in a green house in a cold weather region? Or it is better to grow
them in a temperate climate and transport them. Does it produce less impact to grow apples
locally and store them in controlled atmosphere warehouses for out of season times? Or is the
impact lower when they are produced in the opposite hemisphere and transported by ships
and trucks?
There is not a general rule to determine what has the lowest impact when comparing locally
produced versus transported food. The most accurate answer will come from analyzing prod-
ucts on individual bases for individual regions and markets using the Life Cycle Assessment
(LCA) methodology presented in Chapter 4. When conducting an LCA for a particular prod-
uct besides transportation all the factors involved from production in the fields to consumption
need consideration.
SUMMARY
In the United States, food transportation accounts for 14 percent of the total energy consumed
during the whole cycle from agricultural production to consumption. Food is transported by
plane, truck, rail, and vessels, which can be only one transportation mode, but more frequently
involves a combination. As a general rule, the longer the haul the more massive and less ver-
satile the transportation mode. As a corollary to the general rule, the more massive and slower
a transportation vehicle is, the less energy it uses per unit of product transported. The opposite
is generally true as well. Lighter vehicles capable of higher speeds can deliver products faster,
but they are penalized with higher energy consumption.
Food miles is an indicator of the distance food has traveled from where it was produced to
the consumption point. This indicator is used often because of its simplicity. But food miles
do not indicate important factors such as transportation mode and fuel consumed. A more
adequate indicator is ton-miles per gallon, or tonne-km per liter, which indicates how much
fuel it takes to transport 1 ton of product for 1 mile. Another indicator is energy intensity that
considers the energy used to move a mass for a certain distance.
Transportation accounts for upto 14 percent of the total energy consumed during the whole
cycle of the food supply chain from agricultural production to consumption, and it is one of
the weakest links in food production and distribution because of the exclusive reliance on fos-
sil fuels, especially diesel.
