February 2008

Science Barge: A Sustainable Urban Farm
Designed by New York Sun Works, An Environmental Nonprofit Organization

STORY BY EMILY ANDREN

"Half of the world's population lives in cities, and our urban environment is a black hole for vital resources," says Zak Adams, director of Ecological Systems at New York Sun Works. "Food, clean water and power flow into a city. Garbage, wastewater and heat come out. Our built-up environment is increasingly isolated from the ecological world. A sustainable city must meet as many of its own needs as possible with its own resources, making less impact on the planet."

Founded in 2004 by Ted Caplow, an environmental engineer, New York Sun Works is a not-for-profit organization that promotes sustainability by designing ecologically responsible systems to produce energy, clean water and food. It provides technical services in support of rooftop greenhouses in educational and commercial settings worldwide.

Its first project, the Science Barge, is a sustainable floating urban farm powered by solar, wind and biofuels, irrigated by rainwater and purified Hudson River water. The barge has no carbon emissions, no net water consumption and minimal waste. The vegetables grown on the Science Barge require seven times less land and four times less water than field crops.

Why a barge? It's mobile, accessible and visible to the public and more affordable than alternatives. "It's an isolated, self-sufficient platform, a metaphor for the earth as a closed ecosystem; it's truly off-grid," Adams says. Using proven existing technology, food could also be grown on rooftops. "New York City has enough unshaded rooftops to produce all the food needed by its population," he adds.

Hydroponic-controlled environmental agriculture, a technically sophisticated practice used in many regions of the world, is used in the greenhouse. The vegetables are grown in water containing the essential nutrients, without the need for soil.

Separate greenhouses for vine and leaf crops produce tomatoes, cucumbers, bell peppers, hot peppers, lettuce, herbs and edible flowers. Red worms convert school lunches and greenhouse waste into fertilizer. The worms can double their population in two months and are fed to tilapia, a gourmet fish variety grown on the barge. Tilapia waste water is converted by a biofilter to fertilize salad greens.

Computer controls regulate temperature to increase production and optimize energy consumed by exhaust fans, a heater, pumps, and vent motors. The daily average load is 25 kilowatt hours, comparable to a small house.

An integrated energy system supplies power from several renewable sources: solar panels for warm months; biodiesel fuel, a derivative of waste vegetable oil, for cooler seasons and battery backup that will keep everything running for two days. An inverter converts battery-generated DC into AC, compatible with the other power sources.

The barge consumes 150 to 200 gallons of water a day, depending on cooling needs. A 300-gallon tank stores purified rainwater, usually collecting less than needed. The rest is obtained from up to 330 gallons a day of purified river water which a high-pressure, dense filtration process called reverse osmosis renders even cleaner than drinking water.

Barge construction maximized use of recycled materials. The office is a modified and refurbished shipping container, aptly painted vibrant green. Reclaimed building materials, recycled plastic, and reused steel and aluminum were also used. Compromises were sometimes necessary in selecting such materials as sealant, paint, and glue. Adams' advice is: "Aim for perfection, but build in reality."

The Science Barge has an active public education program, with school groups from all five boroughs of New York City visiting during the week and the public on weekends. Children can see and understand the ecological life cycle and take home vegetable samples.

For future projects, New York Sunworks is looking at building greenhouses on rooftops that will improve the energy efficiency of buildings and also count toward points in the LEED classification system.

"The Science Barge is helping New Yorkers understand the choices we all need to make to ensure that New York is not only the greatest city on Earth, but also the most livable. It's a fantastic addition to our waterfront," states Manhattan Borough President Scott Stringer.