Editor’s note: This piece was originally published at The Macroscope.

One of the most interesting developments in American agriculture during the last decade has been the rise of the local food movement.

It’s incredibly popular. People love the idea of eating food that is grown nearby on surrounding farms. It helps increase the sense of authenticity and integrity in our food. Also, the food can often be fresher and tastier. Many folks also like that the supply chain  —  the path food travels from the farmer’s field to the dinner fork  —  is shorter, is more transparent and supports the local economy. And who doesn’t love going to a wildly colorful farmer’s market or a beautiful farm-to-table restaurant and learning more about the farms and farmers who grew our food? No wonder local food is so popular.

Local food can also be good for the environment, especially if it reduces food waste along the supply chain. Many local farms are organic or well-run conventional farms, which can produce many benefits to soils, waterways and wildlife. And, in some places, local grass-fed ranches are trying to sequester carbon in the soil, offsetting at least part of beef’s hefty greenhouse gas emissions. Done right, local food can have many environmental benefits.

Without a doubt, local food has a great set of benefits. But the commonly held belief that reducing “food miles” is always good for the environment because it reduces the use of transportation fuel and associated carbon dioxide emissions turns out to be a red herring. Strange as it might seem, local food uses about the same amount of energy  per pound  to transport as long-distance food. Why? Short answer: volume and method of transport. Big box chains can ship food more efficiently  —  even if it travels longer distances  —  because of the gigantic volumes they work in. Plus, ships, trains and even large trucks driving on interstate highways use less fuel, per pound per mile, than small trucks driving around town.

But don’t feel bad. It turns out that “food miles” aren’t a very big source of CO2 emissions anyway, whether they’re local or not. In fact, they pale in comparison to emissions from deforestation, methane from cattle and rice fields, and nitrous oxide from overfertilized fields. And local food systems  —  especially organic farms that use fewer fertilizers and grass-fed beef that sequesters carbon in the soil  —  can reduce these more critical emissions. At the end of the day, local food systems are generally better for the environment, including greenhouse gas emissions. Just don’t worry about emissions from food miles too much.

Without a doubt, local food has a great set of benefits. And it’s just getting started.

From Local to Super-Local

We have also seen a movement toward what you might call “super-local” food, where people grow more food right in the city. In other words: urban agriculture.

There are commercial scale urban farms popping up, like Growing Power in Milwaukee, that grow food in vacant lots and create badly needed jobs in urban neighborhoods. Others, like Gotham Greens, are growing food in rooftop greenhouses in major cities. People are also starting community gardens in their neighborhoods, where folks can share an area of land  —  maybe in a city park or a school yard  —  to grow fruits and vegetables. And, of course, many people grow super-local food at home, in their yards, or on their patios and decks. In fact, my wife and I have always grown salad greens, herbs, vegetables, and a wide range of fruits at our place  —  whether in a tiny yard converted to gardens and orchards in Saint Paul, Minnesota, or a variety of potted vegetables, herbs, and fruit trees on a deck in San Francisco. It tastes great, and there is a lot of satisfaction in doing it yourself. And I love that our daughters grew up  —  even as city kids  —  knowing a little bit about where food comes from.

While it’s not a silver bullet solution to all of our global food problems, [local food is] an exciting, powerful development, and it can have important nutritional, social, economic and environmental benefits if done well.But, despite these great advances, we need to remember that urban food can’t feed everyone. There’s just not enough land. In fact, the world’s agriculture takes up about 35 to 40 percent of all of the Earth’s land, a staggering sum, especially compared to cities and suburbs, which occupy less than 1 percent of Earth’s land. Put another way: For every acre of cities and suburbs in the world, there are about 60 acres of farms. Even the most ambitious urban farming efforts can’t replace the rest of the world’s agriculture. Fortunately, urban farmers are smart and have focused their efforts on crops that benefit the most from being super-local, including nutritious fruits and vegetables that are best served fresh. In that way, urban food can still play a powerful role in the larger food system.

So there’s a lot to be excited about with local food. While it’s not a silver bullet solution to all of our global food problems, it’s an exciting, powerful development, and it can have important nutritional, social, economic and environmental benefits if done well.

Taking It Too Far: Hyper-Local Food and Indoor “Farms”

Local food is a very welcome development. But can we take it too far?

Yes, I’m afraid we can  —  especially when we start to grow food indoors with energy-intensive, artificial life-support systems.

We’re now seeing what you could call “hyper-local” food, where crops are grown inside a building, whether a warehouse, an office building, a grocery store or even a restaurant. In the last few years, a number of tech companies have designed indoor, industrial “farms” that utilize artificial lights, heaters, water pumps, and computer controls to grow stuff inside. These systems glow with a fantastic magenta light  —  from LEDs that are specially tuned to provide optimal light for photosynthesis  —  with stacked trays of plants, one on top of the other.

Some of the more notable efforts to build indoor “farms” include Freight Farms in Boston. And a group at MIT is trying to create new high-tech platforms for growing food inside, including “food computers.” These folks are very smart and have done a lot to perfect the technology.

At first blush, these “farms” sound great. Why not completely eliminate food miles, and grow food right next to, or even inside, restaurants, cafeterias or supermarkets? And why not grow crops inside closed systems, where water can be recycled, and pests can (in theory) be managed without chemicals?

But there are costs. Huge costs.

First, these systems are really expensive to build. The shipping container systems developed by Freight Farms, for example, cost between $82,000 and $85,000 per container — an astonishing sum for a box that just grows greens and herbs. Just one container costs as much as 10 entire acres of prime American farmland — which is a far better investment, both in terms of food production and future economic value. Just remember: Farmland has the benefit of generally appreciating in value over time, whereas a big metal box is likely to only decrease in value.

Second, food produced this way is very expensive. For example, the Wall Street Journal reports that mini-lettuces grown by Green Line Growers costs more than twice as much as organic lettuce available in most stores. And this is typical for other indoor growers around the country: It’s very, very expensive, even compared to organic food. Instead of making food more available, especially to poorer families on limited budgets, these indoor crops are only available to the affluent. It might be fine for gourmet lettuce, or fancy greens for expensive restaurants, but regular folks may find it out of reach.

Finally, indoor farms use a lot of energy and materials to operate. The container farms from Freight Farms, for example, use about 80 kilowatt-hours of electricity a day to power the lights and pumps. That’s two to three times as much electricity as a typical (and still very inefficient) American home. And on the average American electrical grid, this translates to emitting 45,000 pounds (20,000 kilograms) of CO2 per container per year from electricity alone, not counting any additional heating costs. This is vastly more than the emissions it would take to ship the food from someplace else.

And none of it is necessary.

But, Wait, Can’t Indoor Farms Use Renewable Energy?

Proponents of indoor techno-farms often say they can offset the enormous sums of electricity they use by powering them with renewable energy  —  especially solar panels  —  to make the whole thing carbon neutral.

But just stop and think about this for a second.

Any system that seeks to replace the sun to grow food is probably a bad idea.These indoor “farms” would use solar panels to harvest naturally occurring sunlight and convert it into electricity so that they can power artificial sunlight. In other words, they’re trying to use the sun to replace the sun.

But we don’t need to replace the sun. Of all of the things we should worry about in agriculture, the availability of free sunlight is not one of them. Any system that seeks to replace the sun to grow food is probably a bad idea.

Also, These Indoor “Farms” Can’t Grow Much

A further problem with indoor farms is that a lot of crops could never develop properly in these artificial conditions. While LED lights provide the light needed for photosynthesis, they don’t provide the proper mix of light and heat to trigger plant development stages  —  like those that tell plants when to put on fruit or seed. Moreover, a lot of crops need a bit of wind to develop tall, strong stalks for carrying heavy loads before harvest. As a result, indoor farms are severely limited and have a hard time growing things besides simple greens.

Indoor farms might be able to provide some garnish and salads to the world, but forget about them as a means of growing much other food.

A Better Way?

I’m not the only critic of indoor, high-tech, energy-intensive agriculture. Other authors are starting to point out the problems with these systems, too (read very good critiques here, here, here and here).

While I appreciate the enthusiasm and innovation put into developing indoor farms, I think these efforts are, at the end of the day, somewhat counterproductive.

Instead, I think we should use the same investment of dollars, incredible technology and amazing brains to solve other agricultural problems  —  like developing new methods for drip irrigation, better grazing systems that lock up soil carbon and ways of recycling on-farm nutrients. We also need innovation and capital to help other parts of the food system, especially in tackling food waste and getting people to shift their diets toward more sustainable directions.

With apologies to Michael Pollan, and his excellent Food Rules, here are some guidelines for thinking about local food:

  • Grow food. Mostly near you.
  • But work with the seasons and renewable resources nature provides you.
  • Ship the rest.

An interconnected network of good farms  —  farms that provide nutritious food with social and environmental benefits to their communities  —  is the kind of innovation we really need. And the local food movement is making much of this possible. View Ensia homepage