Agoada walked me through the basics. “We come in on the rooftop as a tenant of the building. We rent the rooftop space. We pay for the upgrade, the insurance costs, the fixed costs for planning and development and the soft costs of architects, etc. We take all of that on. We outsource the equipment. We don’t invent technologies. We’re taking existing proven technologies and applying them to this rooftop. Then we make our money off the sale of the produce. The technology is controlled-environment greenhouses, year-around systems keeping constant temperatures and controlling the environment there. No pesticides, no herbicides, all integrative pest management systems and composting and trying to use paper and food waste from the building as the nutrient stream for our plants.“
A typical project covers about 20,000 square feet — about half an acre — and fairly efficient, says Agoada. “Our growing techniques use somewhere between 5% and 10% of the water that they’re using to grow lettuce out in Salinas Valley,” in California’s Central Valley, considered the nation’s breadbasket. Given that around 80% of water use in the state goes toward agriculture — and about a fifth of the state’s total energy use goes to move and treat water — such efforts could create significant water-efficiency and greenhouse gas benefits, should the Sky Vegetables model catch on.
More here – Joel Makower at GreenBiz.com
We need more details on energy costs etc. They may be able to use less water but it is incredible if they are more efficient on greenhouse rooftops than normal farming.