The Vertical Farm: Are We There Yet?
This study stems from a larger research project that examined vertical-density applications to the Twenty-First Century City [2.3]. As cities try to cope with rapid population growth—adding 2.5 billion dwellers by 2050—and grapple with destructive sprawl, politicians, planners, and architects have become increasingly interested in the vertical-city paradigm. Unfortunately, cities all over the world are grossly unprepared for embracing vertical density because it may aggravate multidimensional sustainability challenges resulting in a “vertical sprawl” that could have worse consequences than “horizontal sprawl.” Because of their enormous scale, tall buildings exert significant demand on infrastructure and transportation systems, resulting in unbearable traffic congestions. They also influence the microenvironment by casting shadows and blocking views and sunlight. Tall buildings are expensive to building, operate, and maintain. They also intrude on the existing built environment that matches the human scale. Consequently, they may reduce the overall quality of urban life. One key problem of future cities will be transporting large amount of food to serve dense population, and the vertical farm model offers a potential solution to this problem [1—5].
Goals and Scope of the Study
As urban population continues to grow and as arable land is diminishing rapidly across the globe, a fundamental change in food production is needed [4-7]. In particular, building-based urban agriculture is increasingly needed in dense urban environments and a review of current cultivation techniques and projects would likely to contribute positively to academic discussions [6-10]. This is particularly important because vertical farming engages multiple disciplines of natural sciences, architecture, and engineering and affects both people and the environment [9-11]. This chapter attempts to answer the following questions:
- • What is a vertical farm?
- • What are the driving forces for building it?
- • What are the involved high-tech farming methods?
- • What are the salient project examples of vertical farming?
- • What are the implications for the vertical city?
What Is a Vertical Farm?
In principle, the vertical farm is a simple concept; farm up rather than out [8-10]. The body of literature on the subject distinguishes between three types of vertical farming [9-11 ]. The first type refers to the construction of tall structures with several levels of growing beds, often lined with artificial lights. This often modestly sized urban farm has been springing up around the world. Many cities have implemented this model in new and old buildings, including warehouses that owners repurposed for agricultural activities . The second type of vertical farming takes place on the rooftops of old and new buildings, atop commercial and residential structures as well as on restaurants and grocery stores [9,10]. The third type of vertical farm is that of the visionary, multistory building. In the past decade, we have seen an increasing number of serious visionary proposals of this type. However, none has been built. It is important, nevertheless, to note the connection between these three types: the success of modestly sized vertical farm projects, and the maturation of their technologies will likely pave the way for the skyscraper farm .
Why Vertical Farms?
Food security has become an increasingly important issue. Demographers anticipate that urban population will dramatically increase in the coming decades. At the same time, land specialists (e.g., agronomists, ecologists, and geographers) warn of rising shortages of farmland [4-6]. For these reasons, food demand could exponentially surpass supply, leading to global famine. The United Nation (UN) estimates that the world’s population will increase by 40%, exceeding 9 billion people by the year 2050 . The UN also projects that 80% of the world’s population will reside in cities by this time. Further, it predicts that by 2050 we will need 70% more food to meet the demands of 3 billion more inhabitants worldwide . Food prices have already skyrocketed in the past decades, and farmers predict that prices will increase further as oil costs increase and water, energy, and agricultural resources diminish [7-10]. The sprawling fringes of suburban development continue to eat up more and more farmland. On the other hand, urban agriculture has been facing problems as a result of land scarcity and high costs. We desperately need transformative solutions to combat this immense global challenge [8-11].
Climate change has contributed to the decrease of arable land. Through flooding, hurricane, storms, and drought, valuable agricultural land has been decreased drastically, thereby damaging the world economy [7,11,12,13,14,18]. For example, as a result of an extended drought in 2011, the United States lost a grain crop assessed at $110 billion [11,19,20]. Scientists predict that climate change and the adverse weather conditions it brings will continue to happen at an increasing rate. These events will lead to the despoliation of large tracts of arable land, rendering them useless for farming. It is common for governments to subsidize traditional farming heavily through mechanisms such as crop insurance from natural causes [6,21,22]. Furthermore, traditional farming requires substantial quantities of fossil fuels to carry out agricultural activities (e.g., plowing, applying fertilizers, seeding, weeding, and harvesting), which amounts to over 20% of all gasoline and diesel fuel consumption in the United States. We need to understand that “food miles” refers to the distance crops travel to reach centralized urban populations. On average, food travels 1500 miles from the farm field to the dinner table [8,15]. In special circumstances—cold weather, for example—food miles can rise drastically as stores, restaurants, and hospitals fly produce in from overseas to meet demands. On a regular basis, more than 90% of the food in major US cities is shipped from outside. A 2008 study at Carnegie Mellon concluded that food delivery is responsible for 0.4 tons of carbon dioxide emissions per household per year [23,24]. This is especially important given the increasing distance between farms and cities from global urbanization. Sadly, the resulting greenhouse gas emissions from food transport and agricultural activities have contributed to climate change (Figure 4.1).
FIGURE 4.1 Food travels great distances from farm fields to dinner tables. The map illustrates the case of the travel of basic ingredients of a strawberry yogurt can. (Adapted from Despommier, D., Trends Biotechnol., 31, 388-389, 2013.)
Vertical farming offers advantages over “horizontal” urban farming because the former frees land for incorporating more urban activities (i.e., housing more people, services, and amenities) . Research has revealed that designating urban land to farming results in decreased population density, which leads to longer commutes. “If America replaced just 7.9% of its whopping one billion acres of crop and pastureland with urban farms, then metropolitan area densities would be cut in half” [4, p. 71]. Lower density living incurs higher energy use and generates more air and water pollution. The National Highway Travel Survey (NHTS) indicates, “If we decrease urban density by 50%, households will purchase an additional 100 gallons of gas per year. The increased gas consumption resulting from moving a relatively small percentage of farmland into cities would generate an extra 1.77 tons of carbon dioxide per household per year” . Dickson Despommier details space efficiency of vertical farms. He suggested that a 30-story building (about 100 m high) with a basal area of 2.02 ha (5 ac) would be able to produce a crop yield equivalent to 971.2 ha (2400 ac) of conventional horizontal farming. This means that the production of 1 high-rise farm would be equivalent to 480 conventional horizontal farms [24,25].
Conventional farming practices often stress profit and commercial gain while paying inadequate attention to inflicted harm on the health of both human and the natural environment [7,8,10]. These practices repeatedly cause erosion, contaminate soil, and generate excessive water waste. Regarding human well-being, the World Health Organization (WHO) has determined that more than half of the world’s farms still use raw animal waste as fertilizer, which may attract flies and may contain weed seeds or disease that can be transmitted to plants . Consequently, people’s health is adversely affected when they consume such produce. Further, growing crops in a controlled indoor environment would provide the benefit of reducing the excessive use of pesticide and herbicide, which create polluting agricultural runoff . According to Renee Cho, “In a contained environment, pests, pathogens, and weeds have a much harder time infiltrating and destroying crops” . When excess fertilizer washes into water bodies (e.g., rivers, streams, and oceans), a high concentration of nutrients is created (called eutrophication), which could disturb the ecological equilibrium. For example, eutrophication may accelerate the proliferation of algae. However, when it dies, microbes consume algae and suck all the oxygen in water, resulting in dead aquatic zones . “As of 2008, there were 405 dead zones around the world” . Further, indoor vertical farming employs high-tech growing methods that use little water (about one-tenth of that used in traditional farming) by offering precision irrigation and efficient scheduling [25,26]. This can have a significant ameliorative effect because demands on water will increase as the urban population grows. Agricultural activities use more than two-thirds of the world’s fresh water, and farmers are losing the battle for crop water because urban areas are expanding and consuming more water. The water crisis is likely to become severer as climate change causes warmer temperatures and proliferates more droughts .
Another argument that the vertical farm proponents use is that traditional agriculture has been encroaching on natural ecosystems for millennia. For example, according to Despommier, “Farming has upset more ecological processes than anything else—it is the most destructive process on earth” [4, p. 7]. In the past half-century or so, the Brazilian rainforest has been severely impacted by agricultural encroachment, with some 1,812,992 km2 (700.000 mi2) of hardwood forest being cleared for farmland . Despommier suggested that encroachment on these ancient ecosystems is furthering climate change. In this way, indoor vertical farming can reduce the agricultural impact on the world’s ecosystems by restoring biodiversity and reducing the negative influences of climate change. If cities employed vertical farms to produce merely 10% of the ground area they consume, this might help to reduce carbon dioxide (C02) emissions enough to develop better technological innovations for improving the condition of the biosphere long-term. By eliminating fertilizer runoff, coastal and river water could be restored, and fish stock of wild fish could increase. Wood et al. summarize this point by stating “The best reason to consider converting most food production to vertical farming is the promise of restoring [the] services and functions [of ecosystems]” [26, p. 110].
Proponents of the vertical farm also argue that it will supply competitive food prices . The rising expense of traditional farming is quickly narrowing the cost gap. For example, when vertical farms are located strategically in urban areas, it would be possible to sell produce directly to the consumer, reducing transportation costs by removing the intermediary, which can constitute up to 60% of costs . Vertical farms also use advanced technologies and intensive farming methods that can exponentially increase production. Researchers have been optimizing indoor farming by calibrating, tuning, and adjusting a wide range of variables, including light intensity, light color, space temperature, crop and root, C02 contents, soil, water, and air humidity [27-29]. In addition, vertical farming provides an opportunity to support the local economy. Abandoned urban buildings can be converted into vertical farms to provide healthy food in neighborhoods where fresh produce is scarce. Additionally, the high-tech environment of indoor farming can make it fun to farm. Hence, a technology-savvy younger generation has been enticed by the practice, grooming a new breed of farmers. Further, vertical farming provides impetus in the development of innovative agricultural technologies. Finally, it could reconnect city dwellers with nature through the activity of farming .