Consumers are increasingly interested in food that is locally grown, traceable, healthful and fresh tasting, price competitive, conveniently available, and environmentally responsible. Urban greenhouses may be a source for food that meets most or all these demands.
Greenhouse technology depends on a transparent structure, usually glass or plastic, which provides plants with a more controlled and favorable environment to grow. Greenhouse plants still use natural sunlight but are better protected from temperature variations, high winds, excess precipitation, and wildlife.
Gotham Greens, which operates several urban farm operations in the U.S., is one company pursuing this idea. In 2015, the company opened a 75,000 square feet greenhouse in Chicago—built on a factory roof. Gotham Greens distributes its produce via nearby grocery stores and local deliveries.
According to a USDA census, there were 1,745 U.S. greenhouse farms of 10,000 square feet or more growing vegetables, fresh-cut herbs, and/or tomatoes in 2017. Altogether, those greenhouses totaled 141.5 million square feet, up 14 percent from 2012 figures.
Greenhouse technologies are also used extensively in other countries. Almeria, Spain is home to over 1 billion square feet of greenhouse growing space. The numerous structures there cover over 75,000 acres and are distinctly visible from outer space. While greenhouses and outdoor urban farms offer fresh locally grown produce to nearby consumers, they often depend exclusively on sunlight, which, depending on the area, can overheat outdoor and greenhouse cropland.
Vertical farming could solve this issue. As with greenhouse farming, vertical farming requires fewer or even no pesticides or herbicides, which are a concern for many consumers. Vertical farming utilizes shelves to vertically stack trays of plants and does rely directly on sunlight, instead using LED grow lights for photosynthesis. The extra cost of grow lights can be lowered and even eliminated if enough solar energy is available—reducing the operation’s carbon footprint. This is particularly attractive in places like the Middle East, where several vertical farming projects are under way.
While recent research has found urban, greenhouse, and vertical farming produce to be more costly than conventional produce, this gap is likely to close with advancement in technology and expansions in scale. Cost advantages can also come from reduced use of chemical inputs and, particularly in the case of vertical farming, more efficient use of available land.
Aside from costs, current alternative farm products cater well to consumer demands which could drive the rapid growth of more alternative farming operations. In the spring of 2020, France-based Agropolis plans to formally open the world’s largest urban farm atop a convention center in southwest Paris. The farm will be span across 150,000 square feet of uncovered soil and rely on natural sunlight.