Method’s new soap factory on the south side of Chicago has a wind turbine, photovoltaic panels, and a rooftop greenhouse bigger than an average city block.

Business Insider reports that the $30 million plant which opened in April will be able to produce as much as a million pounds of edible greens a year. The pesticide-free kale, arugula, bok choy, and butterhead lettuce will go to restaurants, stores and farmers’ markets in the area.

At 75,000 square feet, the garden is bigger than both an NFL football field and an average-sized city block in many parts of the U.S. When fully planted, it will be the largest rooftop greenhouse in the world.

The greenhouse is the work of a New York City-based company called Gotham Greens, which operates commercial-scale greenhouses in urban areas all over the country.

Dirt-free agriculture

In Chicago, the greens will be grown in a hydroponic system that requires no soil. Irrigation, heating and cooling, and other variables will be controlled by computers, Business Insider reports. Method says that farming practices used by Gotham require only 5% of the land and 10% of the water as conventional farming while eliminating fertilizer runoff.

Even without soil, the greenhouse is so heavy that Method had to re-engineer the factory roof for greater strength, but the garden will insulate the factory and keep heating and cooling costs down.

Method said that its new factory is the industry’s first LEED-platinum-certified facility. In addition to the 230-foot-fall wind turbine, which will supply an estimated 30% of the energy needed to run the plant, the factory is equipped with three 1,225-square-foot solar arrays that track the sun during the day. Each of them has a capacity of about 46 kW.

The building houses the company’s manufacturing and bottling operations and is a distribution center for both Method and its partner Ecover. The company says that putting all operations in a single building reduces the company’s carbon footprint, and its location in the Midwest helps it distribute products across North American efficiently.

Other features at the new factory include skylights for natural lighting, a solar hot water system, and delivery trucks that run on fuel with a minimum 20% biodiesel content, according to Method.