Earlier this week, I posted a story about a net-zero greenhouse that grows food, fish and renewable energy – all in a small backyard space.
The greenhouse, invented by German physicist Franz Schreier, adds solar power to the super- efficient plant- and fish-growing system called aquaponics.
And while his invention is quite advanced, the basics of aquaponics isn't. Aquaponics combines aquaculture and hydroponic techniques to create way of growing large quantities of organic food year-round in small urban spaces – without soil and with 90 percent less water than conventional growing. (Here's a helpful explanatory video.)
How much food are we talking? Will Allen of Growing Power in Milwaukee, Wisc., has turned heads by using aquaponics to produce 1 million pounds of food a year on a mere 3 acres as cars whiz by on city streets and frigid Midwest winter temperatures drop to below zero.
Ann Forthoefel, a former director of the Portland Farmers Market, said Allen's success in Wisconsin means Portland's urban farmers could easily be using aquaponics to produce more local food. She's been promoting the idea to city officials as a way to make Portland's ecodistricts self-sufficient in food production.
"My goal is to make aquaponics part of our new vocabulary," she said. "A lot of the ecodistricts own't have land available. With aquaponics, you can grow in a warehouse. You can grow vertically."
One of the aquaponics systems Portland Purple Water is testing at its storefront in Beaverton.
The basic genius of aquaponics is tapping the natural synergy between fish, water and plants. Fish excrete ammonia, and naturally occurring bacteria turn that ammonia into nitrites and nitrates that fertilize plants.
Aquaponics create a contained growing system that circulates "dirty" fish water into a clay and/or rock-lined planting bed. The plants clean the water and gather nutrients for growth before the water is circulated back into the fish tank.
Getting started
It's not a system you can start up overnight, said James Ragsdale of North Portland Farm.
His farm has spent a year and a half building an aquaponics system that will grow herbs and tilapia in a 10-square-foot insulated room outside. And the system isn't up and running yet.
"It's not something you can just put in in a weekend and expect to run as a turnkey system," he said. "You can't just put water in it and expect it to be running. People are obviously getting interested in it, but it really takes a lot of energy and resources to get it started."
His farm was built on abandoned and contaminated land – not exactly prime growing turf. One of the benefits of aquaponics is it allows for farming in marginal urban spaces such as abandoned warehouses, Superfund sites or just the extra bits of space in and around people's homes.
"People are obviously getting interested in it, but it really takes a lot of energy and resources to get it started." --James Ragsdale, North Portland FarmBut Ragsdale said one of the main reasons he's gotten into aquaponics is for the promise of protein.
"Fish just sound really cool," he said. "We just kind of got excited about it. It seemed like a fun machine to build. We're always looking at ways we can create our own protein source."
Ragsdale said he's found out the hard way – through lots of homework and fund-raising – that aquaponics isn't easily accessible to everyone.
