Is the Science Barge Sustainable?
The Science Barge is supposed to demonstrate sustainable urban farming using technology that could grow vegetables on New York City rooftops. It was designed by engineering firm New York Sun Works, whose website describes the project with an audacious claim:
The Science Barge is a prototype, sustainable urban farm and environmental education center. It is the only fully functioning demonstration of renewable energy supporting sustainable food production in New York City. The Science Barge grows tomatoes, cucumbers, and lettuce with zero net carbon emissions, zero chemical pesticides, and zero runoff.
There are much better examples of renewable energy supporting food production in urban environments. Compared to them — or even to conventional means of feeding New Yorkers — the Science Barge is an energy hog with a gigantic ecological footprint.
The Science Barge technical specs (pdf) show that this is not a sustainable operation. Powering the 1,300 sq. ft. growing space requires about 25 kWh per day, or about 25 megajoules per square foot per year (do the math). In comparison, US farmland uses about 0.018 megajoules per square foot per year (1.8 exajoules over 2.26 billion acres, do the math). Each square foot of growing space on the Science Barge consumes as much energy as 1,400 square feet of typical US farmland.
Admittedly, small-scale vegetable production can be more energy intensive than the land-extensive field-crop and pasture production systems that occupy the bulk of US farmland. Last year we used 0.07 megajoules per square foot to grow vegetables and grain in a tractor-based production system, but only 0.01 megajoules per square foot to grow the same crops using hand tools (preliminary results of ongoing study). The Science Barge used about 350 times more energy per square foot of growing space than our tractor-based system, and 2,500 times more energy per square foot than our human-powered system.
A well-managed hydroponic greenhouse — like the Science Barge — can produce 10-20 times more food per square foot than a typical field vegetable operation. Even so, the greenhouse is orders of magnitude less energy efficient than the field.
Less than 30% of the Science Barge surface can actually grow food. The remainder is dedicated to the 12 solar panels and five wind turbines capable of generating 4.5 kW of electricity when the sun is shining and the wind is strong. Their capacity pales in comparison to the 400-pound furnace that can burn through 29 gallons of oil each day to warm the growing space in the cool season. Every week the furnace operates at capacity it burns enough to coat the entire growing space in a quarter-inch of oil. Then there’s the generator — which also burns oil — needed to supply the electricity demand that the solar panels and wind turbines can’t.
Such obscene energy consumption to grow food is sustainable, say Science Barge promoters, because the fuel oil is a waste product. The Science Barge burns vegetable oil from New York’s deep fryers.
But the oil that fuels the Science Barge wouldn’t necessarily go to waste otherwise. New York City deep fryer oil can be recycled into biodiesel for use in any diesel engine. The energy needed to keep the Science Barge’s furnace operating at capacity for a single day is enough to bring 1.3 tons of vegetables from California to New York by truck, or 4.2 tons by train (source, truck math, train math). New Yorkers could save energy by eating field-grown vegetables from anywhere in the country, instead of greenhouse-grown vegetables from the Science Barge in Yonkers.
The claim of “zero net carbon emissions” is suspect, too. The fuel sources may be renewable, but carbon was emitted to manufacture the aluminum greenhouse frame; the glass and polycarbonate cladding; the furnaces, fans, and computers; the solar cells and windmills; the PVC hydroponic troughs; the fertilizer in the hydroponic solution; the pumps and water purifiers; and all of the other components of this complex system. The only way to arrive at the “zero net carbon” figure is to omit these factors.
Even if the Science Barge were carbon neutral, aiming for zero net emissions is setting the bar low for a model sustainable agriculture system. A good soil-based vegetable farmer aims to sequester carbon by building soil organic matter levels. Farmers should strive to be carbon negative, not carbon neutral.
Below are a few links to stories and websites about New Yorkers who know how to grow food using soil, sun, rain, and urban waste, without relying on furnaces, generators, hydroponic systems, and other high-tech, resource-intensive gadgets. Each of these is a “fully functioning demonstration of renewable energy supporting sustainable food production in New York City.” The Science Barge is not.
- Winners of New York City Housing Authority’s annual Garden Contest (Staten Island Advance)
- Market Gardeners Use Brooklyn’s Vacant Lots (New York Times)
- Urban Permaculture in Brooklyn (Wild Green Yonder)
- The City Farms (Just Food)
- New York City Sharecroppers (City Dirt)