New York Sun Works Science Barge on the Hudson with the Manhattan skyline behind it

An urban farm may seem out of place on a pier in the Hudson River, with the Manhattan skyline towering a mere half-kilometer to the east. But environmental engineer Ted Caplow looks quite at home standing on the deck of the science barge he designed, then built, with a small group of plant scientists, energy specialists and fellow environmentalists.

Part high-tech farm, part laboratory, and part floating classroom, the New York Sun Works Science Barge sports solar panels, wind turbines, a couple of greenhouses and other gear aimed at demonstrating sustainable agriculture in one of the world's most densely-packed cities.

The Science Barge's two greenhouses, solar array panels against a neon green refurbished shipping container and recycled plastic deck are visible as it floats along Pier 92

The Science Barge project, which is set to launch next month, aims to show how urban areas like New York can support agriculture using recycled water and renewable energy, and that doing so is good for the environment in a number of ways.

"When we grow food out in the country," says Caplow "we use a tremendous amount of water and land and fertilizers that have a large impact on the environment in the countryside. By moving food production into the city, we save a lot of land, and at the same time, we bring the food closer to the consumer."

City-grown food also avoids the environmental and financial costs of trucking food, often over thousands of kilometers, from the field to the dinner plate.

There is not a lot of vacant land in Manhattan that would be suitable for farming. But Caplow says farms don't have to be on ground level. They can be on roofs.

"In New York City for example, we have approximately 5000 hectares of available space just on existing rooftops. That is space that is open to the sky so there is plenty of sunlight where we can grow vegetables," he beams.

New York Sun Works Science Barge greenhouse director Jenn Nelkin displays stackable plant containers

On traditional farms, there is just one horizontal surface where plants are grown. It's the surface of the Earth itself. The broader the field, the greater the yield. But the Science Barge folks say many crops can be grown in containers stacked one atop the other, somewhat like a high-rise apartment building.

"So instead of having just a horizontal row of plants, here I have 40 plants that might take up that same square footage of space if we were growing everything horizontally," says Sun Works' greenhouse director Jenn Nelkin. "That's how we get some vertical space out of short crops," she adds, pointing to the vibrant basil, parsley and edible flowers nearly bursting from their containers.

Crops aboard the Science Barge are grown without soil, using hydroponic technology

An abundance of other crops, including tomatoes, lettuce, cucumbers, and other vegetables are flourishing in the New York Sun Works greenhouses. They're grown using hydroponics technology where the roots are immersed in trays of nutrient rich water, not soil.

The water itself comes either from rainwater stored in an onboard tank, or from the Hudson River itself. Sun Works staff member Viraj Puri explains that the river water is purified and desalinated by a "reverse osmosis" machine.

"You pump water up, a lot of pressure builds up and it is passed through a membrane," says Sun Works program coordinator Viraj Puri. "It separates the salt from the water and the brine goes back into the water."

This machinery along with sophisticated environmental control devices and computers, are powered by wind turbines, solar power, and bio-diesel fuel made from used cooking oil from city restaurants.

Environmentalists Ted Caplow, Jenn Nelkin and Viraj Puri on the deck of the New York Sun Works Science Barge in front of the solar array

But high productivity and new technology are only part of the project's mission. Ted Caplow says the barge is also a floating classroom that will educate Big Apple youngsters about how food is actually produced.

"The joke about New York City kids is that they think that tomatoes grow in the supermarket and all the food just comes from the shelf somewhere," Caplow says. "This is a wonderful way for kids to understand where food comes from and what a plant needs to grow."