Singapore’s 100-foot concrete supertrees tower over Gardens by the Bay, part of the government’s attempt to create “a city in a garden.” These mammoth steel and concrete structures serve as cooling ducts for conservatories, generate solar power, and collect rainwater. But supertrees are just one example of Singapore’s horticultural innovations. Singapore’s strides in modern agriculture herald the beginnings of a green revolution—including the Hort Park rooftop gardensand Sky Greens, one of the world’s first commercial vertical farms.
Singapore’s population density is the highest in the world and has little arable land at its disposal. As a result, only seven percent of Singapore’s food supply is homegrown. Though an extreme case, Singapore serves as an important example of the future challenges of urbanization, population growth, and food production. Feeding the world’s population has been tricky, due to the unequal distribution of arable land, as well as the additional challenges of desertification, deforestation, drought, and increasing transportation costs. Analysts predict that the world’s population will reach 9.6 billion by 2050. Consequently, many experts are looking to Singapore as the forefront of urban agriculture experimentation in the developed world.
Of particular interest is vertical farming, championed by Dickson Despomier, a professor of public and environmental health at Columbia University. The idea involves equipping specially built skyscrapers to produce crops year round using components of a traditional greenhouse. Large scale implementation of vertical farming in developed countries not only would reduce transportation costs, but also would allow for a more efficient use of space (one of the most pressing problems for an increasingly urbanized world of 9.6 billion people). Other benefits of a self-contained design include the limitation of pesticide use, soil erosion, run-off, and water waste.
Numerous structural designs exist, each with its specific purpose and niche. For example, one structure was designed to fit within the road junctions (“cloverleafs”) of urban highways. Another design is Gordon Graff’s Sky Garden project, which envisioned an agricultural high rise in downtown Toronto. The greatest limiting factor to vertical farming, apart from start-up costs and setting aside space, is energy consumption; however, researchers and entrepreneurs have been chipping away at this problem. The glasshouse industry already has decades of experience in growing crops indoors, while the modern conception of hydroponics (growing plants without soil) has been around since the eighteenth century. Furthermore, LED lighting serves as a likely candidate for a low-energy solution and already has received attention from researchers and engineers alike.
One standout example of sustainable vertical farming is Sky Greens, Singapore’s first commercial vertical farm. Founded by engineer Jack Ng, Sky Greens grows organic bok choy and Chinese cabbage inside 120 A-shaped waterwheel towers, four stories each. This tower design makes efficient use of gravity in its closed loop hydraulic system—called “A-Go-Go Vertical Farming ”—as the trays of plants travel up and down like a Ferris wheel. Ng spends only $360/month ($3/tower) on electricity costs to power his innovative towers. With such a low variable cost and superior freshness, Ng’s product has earned a higher price point than imported equivalents. According to a local news source, Sky Greens vegetables cost about five to ten percent more than imported greens. Sky Greens is supported by Singapore’s government and Ng is looking to expand by building at least 2,000 more towers in the coming years.
Ng’s A-frame system takes up only 60 square feet, about the size of a bathroom; however, these systems are ten times more efficient when compared to conventional farming. Though Ng’s waterwheel towers are small in stature, Sky Greens’ success represents an important step in establishing vertical farming merits to potential investors. Ng’s experience thus far has proved that vertical farming can be commercially viable, so long as energy concerns are taken into consideration. The feasibility of large scale vertical farms (“farmscrapers”) is still in question, especially due to the limiting factor of light. Greenhouse buildings like those housing Ng’s waterwheel towers have the advantage in this regard. In addition to mid-size greenhouses, other options include rooftop gardens atop restaurants and grocery stores; for a country with a lower population density, each of these options is a potential solution to the looming threat of global food insecurity.