Towards an Energy Standard of 'Local'
A couple Saturdays back a favorite vendor was selling strawberries at my local farmers' market, and knowing they represented the tail end of the season I indulged in a pint. I polished off the sweet berries while wandering by other booths, checking in with a few farmer friends before buying eggs from one who pasture raises his hens with the utmost care. It was a glorious morning.
For those of us interested in the intricacies of food systems, farmers' markets are great places to test hypotheses. In The Energetics of Food Distribution I noted the comparative efficiencies associated with shipping larger quantities of food over longer distances. That post didn't paint small-scale, localized food distribution in a very positive light, and after thinking about how best to characterize efficiency when comparing transport strategies over varying distances I thought it worthwhile to dedicate another post to the issue, this one informed by data collected from several local farmers.
The graph below presents the fuel required to deliver 100 pounds of food for several small farms to my local farmers' market relative to a semi truck transporting 40,000 pounds of food 3,000 miles to Vermont from the Central Valley of California. Recall that the semi truck in The Energetics of Food Distribution achieved the highest efficiency per unit food delivered for a set transport distance, but of course transport distance isn't constant when comparing long distance shipments to local vendors. If transport distance shrinks enough, food distributed via less efficient means will end up using less fuel. For most of the vendors I surveyed - I collected information on the weight of food they brought to market, their round-trip travel distance and the fuel efficiency of their truck or van - the amount of fuel used per unit food delivered was lower than the semi from California, sometimes much lower.
In the 1970s a faculty member at the University of Illinois named Bruce Hannon suggested that since energy was a vital production input for goods and services, perhaps we should use embodied energy as a standard of value rather than the good or service's price in dollars . I've always thought this an intriguing idea, one readily adaptable to the context of food distribution. Today the term 'local' in local food is defined in many ways by many organizations, although in the United States the 2008 Food, Conservation and Energy Act defines 'local food' as any food that travels less than 400 miles to its point of sale or was produced within the state where it's sold. Rather than relying on such an arbitrary political definition, perhaps we should define 'local' as the distance a small farm can transport its products while still requiring less fuel per unit food than a semi truck delivering from afar? This threshold distance will vary depending on where the semi is coming from as well as how heavily loaded the local farmer's delivery vehicle is, but I think that such a distance can be discerned for most regions and I suspect it will be far less than 400 miles.
In the graph above for instance, the only vendor who required more fuel per 100 pounds of food than the semi from California was a meat vendor who drove 84 miles round-trip, or 42 miles one way. His longer travel distance is compounded by the fact he only brought 150 pounds of meat to sell that day, but he'd need to bring four times as much product just to equal the fuel efficiency achieved by the truck from California and that doesn't seem likely. The diversified farm that used 0.8 gallons traveled 50 miles round trip, or 25 miles one way, and all other vendors I surveyed had shorter travel distances. The two vegetable farmers traveled only 2.5 miles to the market, and the amount of food they brought to sell on the day I did my survey is far below normal for them as their growing season is just ramping up. Setting aside the variation in the amount of food that vendors bring and the type of food as discussed in More on the Energetics of Food Distribution, it seems that travel distances beyond a 30 mile radius risk not beating the semi's performance, at least here in Vermont.
In The Energy Cost of Local Food I presented data showing that small-scale, local farms often don't enjoy an advantage over larger-scale producers in terms of their energy demand per calorie of food produced. It appears that, at least for farms that don't travel far to deliver their products, the energy use associated with distribution isn't what's hurting them. It's most likely on-farm energy use, which usually requires an energy input-output audit to study with enough detail to craft meaningful efficiency strategies. I think there's still plenty to learn about the energetics of locally produced food and plenty of room for efficiency gains on and off the farm for those farmers and communities willing to invest in this area, and hope this and similar posts will inspire progress towards this goal.
- Bruce Hannon. (1973) An energy standard of value. The Annals of the American Academy of Political and Social Science, Vol. 410, No. 1, Pages 139-153.
Teaser photo credit: Flickr/churchstreetmarketplace
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