BERLIN -- At the furthest end of a century-old beer brewery yard in Berlin, a shipping container with a greenhouse on top hums with the gentle sound of pumping water.
Inside the container are two large vats and a fish tank, which looks barely large enough to hold the dozens of tilapia squirming around inside. Upstairs, rows of tomatoes, peppers, lettuce and even flowers line the walls amidst the zen-like sounds of trickling water.
The fish and produce are all part of a symbiotic farming method called aquaponics, which takes wastewater from the fish and filters it to feed the plants above, before recirculating it back down to the fish. Not only does the system solve the problem of animal waste, but it uses about one tenth of the water required for traditional agriculture. It also has the potential to help both fish and vegetables grow bigger faster.
Though the system may date back to the Aztecs, aquaponics is gaining modern traction in places where food transport and water are costly.
Here in the middle of Berlin, the single container farm functions as a prototype for Christian Echternacht and Nicolas Leschke, founders of the social business Efficient City Farming (ECF). Together, the two are looking to bring large-scale aquaponic farming to cities by making it profitable.
"The idea is to give every city access to sustainably grown produce," Echternacht said. "In the U.S., transport costs are often the biggest unnecessary overhead on food prices -- but here in Berlin, we're also looking to minimize water consumption."
A single container farm can feed two or three families for a year. But at a cost of 32,000 euros, plus some additional overhead for electricity and water, the project makes little business sense on a small scale.
So, Echternacht and his co-founder Nicolas Leschke have planned to build a 2,000-square-meter (21,500-square-feet) farm just on the other side of the brewery wall. At 24 metric tons of fish and 34 metric tons of vegetables in annual output, an ECF "CityFarm" could feed 350 families for a year -- making the business model viable for franchising, especially in large cities.
"In a city of 3.5 million inhabitants like Berlin, it's easy to find 350 people to buy your aquaponically grown produce," Echternacht said, adding that it runs at about the price of organic food.
Despite the absence of chemicals in the farming process, aquaponic food won't be allowed to carry either the German or the European Union's organic seal on supermarket shelves. Echternacht says regulations prohibit the label for any food not grown in soil -- though he doesn't view this as a problem.
"The purpose of the organic label has always been to introduce a kind of certification to food about how it was grown," Echternacht said. "But the aquaponic system is so transparent that you always know exactly where everything comes from."
After trying to introduce his ContainerFarm concept to Bavarians in the south of Germany, Echternacht said it became clear that Berlin is the ideal place in which to test a large-scale aquaponic model.
"A big city like Berlin understands why we're doing this and knows it's right," Echternacht said. "When you present this kind of thing to people in Bavaria, they tell you 'I have my tomatoes in my garden out back, and I get fish from the river, so why do we need this?'"
He says CityFarms can be built upon any flat and stable surface, including rooftops. Though it would take 10,000 such farms to feed all of Berlin -- including the grains needed for beer, grapes for wine and other products -- Echternacht said the point is not to replace traditional agriculture, but to bring more sustainability to consumption.
As for the small-scale ContainerFarm? The seasonal unit, which opened on April 1st, just closed down for the winter, as project sponsors were invited to enjoy the fruits -- and fish -- of their contributions at an EFC-hosted fish grill this past Friday.
PHOTOS: ECF | Efficient City Farming Berlin
This post was originally published on Smartplanet.com