Raising on the Roof

MATTHEW ENIS

Rising energy and transportation costs are one reason there's been upward pressure on food prices. And increasing concern over “food miles” — a measure of a product's impact on the environment, taking into account how far it must travel from production to retail — is helping to drive the growth of the local foods movement.

So, why not grow fruits and vegetables as close to the supermarket as possible — say, on the roof? That was the question asked and answered by Keith Agoada and Troy Vosseller, a senior and an MBA student, respectively, at the University of Wisconsin, Madison, who last month won their university's G. Steven Burrill Business Plan Competition for “Sky Vegetables,” a venture they hope will soon lead to their building hydroponic greenhouses on top of supermarkets around the country.

“One of my inspirations for this project was a hospital in Singapore that uses hydroponics on its roof to grow food for patients inside,” Agoada told SN. “I was amazed by it, and the more I thought about it, I thought maybe the idea could apply commercially.”

Obviously, structural considerations and lease contracts will rule out the idea at many stores, but similar concepts have worked before. For example, Eli's Vinegar Factory, a market and restaurant concept developed by Manhattan grocer and restaurateur Eli Zabar, has a rooftop greenhouse that grows produce that's sold downstairs and used by chefs in the store's cafe. Several other groups are on the case as well, including Green Roofs for Healthy Cities, a Toronto-based trade association, which last week hosted its sixth annual Greening Rooftops for Sustainable Communities conference in Baltimore.

Sky Vegetables estimates that the fixed costs to develop one of these supermarket rooftop greenhouses would typically run around $350,000 to $425,000, but Agoada said that since the concept is designed to use solar panels for energy and recycled rainwater for irrigation, they're inexpensive to maintain going forward. A return on investment would be realized after 19 to 20 months at most stores, he estimates, based on factors ranging from sales of the produce to reduced warehousing and distribution costs. And, Sky Vegetables would manage its greenhouses as a third-party entity, insulating the stores below from risk and liability.

Currently, Agoada and Vosseller are looking for a store that will work with them on a prototype.

“We're not rushing into it,” Agoada said. “We want to find someone that's as committed environmentally and socially as they are economically.”