By Nina Shen Rastogi
Monday, November 1, 2010; 3:28 PM
My city suddenly seems to be awash with food trucks and food carts - a major boon to my weekday lunch routine. But whenever I'm standing there, waiting for a slice of pizza, falafel or kimchi quesadilla, I always feel a twinge of guilt as I hear the generator chug away. Should I? Would buying my lunch at an actual restaurant make my meal any greener?
The Lantern comes from a people fiercely devoted to street food (stinky tofu from the Shilin Night Market - now that's fine dining). So she's relieved to say that, as far as she can tell, there's no strong environmental reason to shun your local street vendor.
The truck-vs.-restaurant battle won't be won on the stove top. The equipment they use is often quite similar, except that restaurants typically rely on piped-in natural gas to heat their fryers and griddles, while trucks and carts use tanks of propane. When burned, propane emits a bit more carbon dioxide than natural gas does, per unit of heat it generates. But unignited natural gas contains 95 percent methane, while propane contains none. If methane reaches the atmosphere - through leaky pipes or equipment, or burners that don't light properly - it's a far more potent greenhouse gas than carbon dioxide.
That generator is a greater concern: The onboard electricity - used to run lights, fridges, exhaust hoods, microwaves and air conditioning - is likely to be dirtier per kilowatt-hour than the electricity powering a restaurant. The small generators favored by carts and trucks are very inefficient compared with a power plant. They may run on gasoline, propane or diesel, but regardless of fuel choice, they spew more hydrocarbons, carbon monoxide, nitrogen oxides and particulate matter than a power plant.
Onboard generators also emit more carbon dioxide than utility-delivered electricity. According to one emissions expert, the kind of generators typically used on food trucks and carts might emit 1.5 to 3 times as much of the carbon dioxide, per unit of electricity, as the average power plant. That's just a ballpark figure, though; there isn't much decent information on this topic, since portable generators are small potatoes in the grand scheme of climate change. And, of course, these estimates depend on your utility's specific fuel mix: If you're buying breakfast sandwiches from a food truck in a coal-heavy state, the truck's generator won't look quite so bad compared with the local power plant.
While food trucks may create more emissions for every kilowatt-hour they use, they don't need to maintain a dining area and all the modern comforts it entails. In the average full-service restaurant, lighting, heating, ventilation and air conditioning can account for 41 percent of the establishment's total energy use.
Once the lunch crowd leaves, the comparison gets more complicated: Trucks and carts often must be driven back to a commissary, where they dispose of their wastewater and used cooking oil, and receive other maintenance. Sometimes commissaries have food-prep areas and fridges as well, all of which you'd need to consider when tallying a truck or cart's overall footprint.
Indeed, there are so many other issues to consider that, without more studies, it seems impossible to say whether restaurants or street vendors have a distinct advantage.
For instance, there's the question of driving. The Lantern isn't convinced that driving is an environmental deal-breaker for food carts and trucks: With the exception of ice cream trucks, street vendors don't spend a lot of time puttering around city streets, since their income relies on their being parked as long as possible. In cities where people hop in their cars to grab lunch, a well-located street vendor can turn many drivers into walkers, giving the mobile kitchen a distinct environmental edge.
So at this point, the Lantern will issue one of her regular calls to young environmental analysts looking for thesis topics: Food trucks are hot! Please study them and then present us with your findings!
In the meantime, dear hungry reader, remember that there are simpler ways to reduce the environmental impact of your lunch, regardless of where you buy it.
First, eat less. (At the very least, don't buy more than you can finish.) Second, scale back on meat and dairy. And if a van with tasty falafels is parked right outside your office building and the only decent restaurant is a 10-minute drive away, then by all means: Keep on truckin'.
Is there an environmental quandary that's been keeping you up at night? Send it to firstname.lastname@example.org.