This combination of cool technologies and common sense has me feeling pretty good about how we can feed ourselves as more and more of us become city dwellers — in the U.S. and in other countries too.
Vanessa Rae: We've all heard of community gardens, but in a city like New York, there's so little space for serious farmers. That a sustainable urban food system seems next to impossible. The Science Barge, now located on the Hudson River near Midtown Manhattan is taking urban farming seriously. This barge is a demonstration station. Showing the public that taking hydroponics to the roof top is a viable way to become a sustainable city.
Benjamin Linsley: Roughly speaking, there's something like 5,000 hectares of unshaded flat rooftop space in New York City. If we were to grow vegetables using the technology that we are demonstrating here, on all 5,000 of those hectares, we could grow enough vegetables to feed something like 15 million people. The unique thing about the Science Barge is that we're powering our greenhouse with renewable energy.
We have two large solar arrays that produce like 70 or 80 % of our power. We do also have the wind turbines, and then our third source of power is our diesel generator. We run our diesel generator off of waste vegetable oil, or biodiesel. You imagine in a city like New York, with a huge catering industry, is really, really good to be able to use waste vegetable oil.
Vanessa Rae: The secret to this ultra modern urban farming, is the technology that runs the greenhouse and nourishes the plants. Jennifer Nelkin, the greenhouse director and a hydroponics expert, told us how this high tech system grows food without wasting any resources.
Jennifer Nelkin: This weather station has wind speed, wind direction, temperature, solar radiation, precipitation, and so that feeds into our climate controller which then makes decisions about what to do with the equipment. The computer knows whether to turn on an exhaust fan, or to open a roof, and it knows if it is raining, it needs to close the roof vent so we can conserve a lot of energy and really manage the climate the way it should be for the plants and for what the plants want, not what it feels like when you walk in for human comfort. We are using a lot of different kinds of hydroponic systems here. This system right here, produces about 75 heads of lettuce a week. That one's more lettuce, this one's all different greens. We have bok choi and swiss chard and some broccoli rabe.
This one's called NFT which stands for nutrient film technique, where you just have a thin film of water that's traveling along the bottom of these trays, and because we capture the water and reuse it, we use a fraction of fertilizers and about five to ten times less water than conventional field agriculture. Also, we use less space and produce about five to ten times more per square foot, with these kind of techniques.
This is our test bed right now for aquaponics, which uses aquaculture, the production of fish, with hydroponics so it's seaming all these systems. When you put them together you can have an organic fertilizer that you can produce crops off of, because ideally we'd like to be using fish waste to feed our leaf and herb crops. So, in here we're growing tilapia. You can see some of these fish right here. These fish, then produce waste that then feed these plants, but based on what we've learned here will increase the number of fish and then eventually connect this fish tank to one of our larger NFT systems so that they can be one closed cycle.
Any material we have left over from the plants we compost all of that and then harvest the worms out of that, and feed the worms to the fish, which is actually kind of fun. We have this little worm raft that we do it with, so we just put a little pile of the compost with the worms on here and then the worms are looking for water, and so they'll go through these holes and dangle themselves underneath, and it's pretty exciting. The fish just come out and snatch them really quickly. They're probably excited just seeing this worm raft get picked up.
We have other kinds of hydroponic systems. One of which is a dutch bucket system, and we can see the tomatoes growing in that. So, what we have is a reservoir, like all of ours. They're all recirculating hydroponics systems. We capture all the water. It drains back into here and we reuse it. We're on our third cucumber crop here, and you can see these are just starting to set their first fruits.
Now the high productivity we see and our plants being so healthy, are because of how we can manage the nutrition and that's the real advantage of using hydroponics is being able to control exactly how much nitrogen, and calcium, and magnesium. How much you have of all these elements that the plant needs to grow.
Why we are so productive per square foot is the use of vertical space. A lot of times you see vine crops like this sprawling all over the ground. So these plants, you can see, have been growing for about five months now and they just keep wrapping around this system. This is actually 24 basil plants right here.
These shorter crops that we can't use our high wire production techniques with, like what we saw with the tomatoes and the cucumbers, we still want to be able to use more vertical space. So, this is a demonstration of how you can grow short crops vertically. Collectively, what we're doing is controlled environment agriculture. That's why these systems are so highly productive.
Benjamin Linsley: As more people move into cities, and we are increasingly concerned at reducing CO2 emissions it is simply unsustainable to consume food that is produced thousands of miles away.
Vanessa Rae: To find out more about urban farming go to riverwired.com.