The spherical Plantagon greenhouse is designed for construction on urban rooftops.

The spherical Plantagon greenhouse is designed for construction on urban rooftops.

Plantagon wants to bring food production to a roof near you. The Swedish start-up aims to commercialize a vertical greenhouse designed to maximize crop yields while bringing harvests closer to the consumer.

By some estimates, as much as 80 percent of the world’s arable land has already been claimed for agriculture. And as population growth continues unabated, more and more people move to ever-expanding cities, pushing farms further away from population centers. The inevitable result, says Plantagon CEO Hans Hassle, is longer transportation routes, increased reliance on petroleum-based fertilizers, and more high-intensity monoculture farming on the remaining agricultural land. “It’s simply not sustainable,” Hassle proclaims. “We have to find alternative ways to grow food.”

Hans Hassle, Plantagon CEO.

Hans Hassle, Plantagon CEO.

The basic concept behind the vertical greenhouse—growing plants on racks to take advantage of the entire volume enclosed by glass—is not a new one. The novelty introduced by Plantagon is the solution created by Hassle’s partner, Åke Olsson, a dedicated organic farmer with a bent for technically simple but effective innovations. Olsson has designed a rack transport system that slowly moves planting boxes from the floor to the ceiling of the greenhouse, eliminating the need for artificial light.

“One problem with traditional rack systems for greenhouses is getting enough light to the plants in the middle,” Hassle says. “By keeping the boxes in motion, we make sure that the available light is evenly distributed to all the plants.”

Another challenge faced by growers is finding a way to efficiently harvest crops grown high over the heads of greenhouse workers. The Plantagon greenhouse includes a platform for roof access, so the boxes can be easily reached just as the plants mature.

The core of the vertical greenhouse is a spiral-shaped transport mechanism that slowly moves hundreds or even thousands of soil-filled planting boxes upward as the plants grow. With the boxes resting on a pair of rails that corkscrew through the entire volume of the structure, a third rail carries a device that continuously cycles from the bottom of the spiral to the top, nudging each box a few centimeters upward. When they reach the top, the mature plants are pushed out onto the harvest platform and new boxes of soil and seed are pulled in at the bottom.

Åke Olsson, organic grower and innovator.

Åke Olsson, organic grower and innovator.

The soil boxes are heavy, but the design of the transport device invented by Olsson keeps energy costs to a minimum. “We can move these 300-kg boxes with a motor that generates just 1 horsepower,” Hassle says. “A band-driven transport system would consume much more electricity, and would require complex mechanics that would be vulnerable to breakdowns. The genius in Åke’s invention is that this device is incredibly simple.”

The spherical shape of the Plantagon greenhouse is designed to maximize the amount of light available for plant growth. The unusual form adds to construction expenses, but the company says that the doubling or even tripling of yields makes the structure more than competitive with traditional greenhouses or surface agriculture. “With a ground footprint of 10,000 square meters, a vertical greenhouse represents the equivalent of 100,000 square meters of cultivated land,” Hassle says.

Hassle expects the real savings to come from eliminating layers of middlemen in the food supply chain, which can account for the lion’s share of the price paid by consumers. Plantagon estimates that about 70 percent of an urban consumer’s food budget goes to pay for transportation and storage. “We can deliver fresh, healthful organic produce directly to the consumer at a lower price,” Hassle says.

Soil-filled boxes move slowly through the Plantagon greenhouse as crops mature.

Soil-filled boxes move slowly through the Plantagon greenhouse as crops mature.

Plantagon was awarded the prestigious “Innovator Idol” prize at the Globe Forum in Stockholm in June of 2009. Globe Forum describes itself as a matchmaker between innovators, entrepreneurs and investors with a focus on business innovation, sustainability and high-growth markets. At its annual conference, ten finalist projects are given the opportunity to present their ideas to about 1,000 participants, with the winning entry chosen by popular acclaim.

“Winning the Innovator Idol award helps us get our message out,” says Hassle. “Our plans call for us to have a first full-scale project built and operating by 2012, and we’ve received expressions of interest from 15 cities on four continents. We’re grateful for the recognition that entrepreneurial activity has a central role to play in determining our common future.”

Article published in June 2009