The path to zero-food-mile cooking

A food mile is the distance an ingredient covers between the place it grows and the plate it lands on. The phrase came out of British food campaigning in the early 1990s, and pushing the number toward zero has an obvious appeal: grow the food where it will be eaten, and the trucks, flights, depots and cold stores between farm and kitchen drop out. A handful of restaurants have started to try it, usually with a bed on the roof or a spare room fitted with lamps.

A grow room in the basement

In February 2013 DNAinfo Chicago described one version run by the Chicago chef Homaro Cantu. It was a basement room about the size of a walk-in closet, where arugula, kohlrabi, basil and broccoli grew from seed under LED lights, with a miracle berry bush among them. Scraps from the kitchen went into compost, the compost was steeped in water and aerated, and that liquid watered the plants. The chef was experimenting with colored light for different crops, and he told the paper the room had saved him about $2,000 a week in food costs since it went in a year earlier.

That setup shows what indoor growing does well. Herbs and leafy crops are cut young, weigh almost nothing and fade quickly once harvested, so they gain the most from a short trip.

Why small greens come first

Microgreens make the strongest case. They are the seedlings of vegetables and herbs, cut within a few weeks of sowing, when the first leaves have opened. In 2012 researchers from the U.S. Department of Agriculture and the University of Maryland measured vitamins and carotenoids in 25 kinds sold commercially and published the results in the Journal of Agricultural and Food Chemistry. Red cabbage seedlings carried the most vitamin C, and as a group the seedlings generally held higher concentrations than the mature leaves of the same plants listed in the USDA nutrient database.

They are also costly to buy and bruise easily in transit, which makes them the crop where a restaurant’s own trays pay back first.

On the roof

A roof swaps electric light for weather. Uncommon Ground, a restaurant on Devon Avenue in Chicago, has a roof farm certified organic in 2008 and widely reported as the first rooftop farm in the country to earn that certification. Its 2013 season was its best so far, about 1,100 pounds of fennel, garlic, potatoes, lettuce, kale, hops and grapes, with seedlings started in a basement grow room and carried up in spring. Even in that record year, as DNAinfo reported in October, the roof supplied only a small part of the produce the kitchens went through.

New York has gone bigger. Brooklyn Grange began farming about an acre of roof in Long Island City in 2010 and opened a second roof farm at the Brooklyn Navy Yard in 2012, selling to restaurants as well as the public. At that scale the roof becomes a farm that happens to be in a city, and the food still travels, only a few miles instead of a few hundred.

What the zero saves

Transport is the part of a food’s footprint that growing on site removes, and it is smaller than the phrase suggests. A 2005 study for the British environment department, The Validity of Food Miles as an Indicator of Sustainable Development, found that distance alone was a poor measure of sustainability. How food moves matters as much as how far. Air freight carried about 1 percent of the tonne-kilometers of British food transport and produced about 11 percent of its carbon dioxide. The same work found that tomatoes trucked up from Spain could take less energy than tomatoes grown out of season in heated British glasshouses, and that shoppers’ own car trips were a large share of the kilometers driven for food.

A grow room brings its own meter. Lamps, fans and pumps draw power from the grid, so an indoor crop trades diesel burned on the highway for electricity spent imitating the sun. For basil that would otherwise be flown in, that can be a fair exchange. For onions or potatoes, which keep for months and ship cheaply by the ton, it seldom is.

Where it stops

Space runs out first. A roof or a former office can keep a garnish station supplied; it cannot fill a walk-in. Calories run out next. Grains, beans, meat, dairy and oil make up most of what a menu serves, and they need fields and pasture. Then there is labor: someone has to seed, water, cut and scrub trays every week, and through a Chicago winter the roof beds sit idle. A roof also has to carry the weight of wet soil and standing water, which is a question for a structural engineer before anyone orders seed.

Within those limits the payoff is real. Greens cut minutes before service have lost nothing to a cooler or a truck, and a kitchen that grows even a small share of its produce has a reason to waste less of it. Zero food miles for a whole menu is out of reach for any restaurant. For the handful of leaves that travel worst, it is already happening a few steps from the pass.