Do Mobile Farms Guzzle More Gas Than They're Worth?

There’s a new trend of promoting local agriculture by growing vegetables in the back of a truck and driving it around. But—like everything—moving all that pro-local-food dirt comes at an environmental cost.

Truck farming is all the rage. Not the farms where 16-wheelers haul away produce to distant markets. Farms growing in the vehicles themselves.

First, there was designer Marco Castro’s small test plot aboard the BioBus. He was demonstrating to the Metropolitan Transit Agency that it was possible to wheel around commuters under a verdant carpet of greenery (we covered this here). Then came "Truck Farm" a mobile garden education effort in Brooklyn, as well as a similar project sprouting in Chicago.

Now we have Lulu’s Local Eatery in St. Louis. Wishing to create a one-of-a-kind "tasty, locally sourced and organic food" food truck, owners Lauren Loomis and Robbie Tucker raised $3,000 on Kickstarter for a garden roof, inspired by the aforementioned BioBus.

Loomis is now growing parsley, oregano, mint, strawberries, and some vines on her roof. If all goes well, she plans to expand the garden, convert to biodiesel, and install solar panels. "How much more local can you get if you put the garden on top of the truck?" she says in an interview with local TV station KSDK. "If we can grow a garden on the roof of our truck, think of the possibilities."

Well, let’s consider then. Raising awareness of local food is great. Although it’s often better to raise crops where they grow most efficiently, there are plenty of social and environmental benefits that go along with local food. Teaching kids about agriculture is also laudable.

But local food—the mobile kind in particular—is not always better for the environment.

We asked Except, a Dutch environmental consultancy, to run the numbers on (mobile) truck farms. The firm has been working to grow more sustainable food for cities through its Polydome project, a finalist in the 2012 Buckminster Fuller Challenge. Eva Gladek, Except’s director, agreed to calculate the energy required to operate a mobile farm. She looked at the efficiency of a medium-sized truck carrying about 10,000 pounds of moist topsoil traveling an average of about 10 miles daily (maintenance and drag were not considered).

Gladek estimated that this cut fuel economy by 30%, which means getting only seven miles per gallon instead of 10. Over the course of the year, that would burn 156 more gallons of fuel (compared to garden-free) and emit an extra 1.5 tons of carbon dioxide. That is more than Lulu’s strawberries will ever absorb. For a full-size bus, fuel efficiency might decline as much as 60%.

So, trucking around your farm to show inner-city kids where their food comes from is great. But if you’re concerned most about trying to help the environment, leave the farm on the farm. It’s all about trade-offs.

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  • IanC

    Interesting piece! Although the math gave me a few chuckles: if my old 1986 Dodge (pictured above), rated when it was born as a 1/2 ton capacity pickup, had had 10,000 pounds (or 5 tons) of soil in it as suggested above, then it would've had a very tough time indeed getting down the block! That said, I'm sure the open bed and the few hundred pounds of soil didn't do wonders for its already lackluster MPG rating. (Surprisingly, having the garden in the back meant I actually drove it a lot less than I used to — meaning fewer gallons burned per year, and a lot more public transportation...if we had more automobile gardens would we drive less?) 

    But more to the point: I'd be the first to admit that it'd be laughable to propose that fossil fuel-burning cars should bear the burden of growing our food, so this critique (which has been aired before: http://www.huffingtonpost.com/... has always struck me as rather straw man. Most of us trucking around gardens in our pickups are doing so because we believe our environmental problems run much deeper than carbon-counting: too many young people are growing up without healthful food or a connection to the natural world, and we need all the out-of-the-box thinking we can muster to get them excited about something as fundamental - and overlooked - as growing a bit of one's own food. 

    - Ian Cheney
    Truck Farm