Prognosticating the future world population has always been a difficult endeavor due to the inability to foresee the possible cataclysmic pandemic or the paradigm shifting new therapy that cures disease x, but attempts need to be made in order to properly design strategies for the present that will accommodate those in the future. Current predictions put the world population at approximately 9 billion (and 9 billion is a conservative estimate based on current dropping fertility trends) by 2050.1 If such an estimate is correct then a net of approximately 2.3 billion humans will come into existence over the next 40 years. Already anywhere from 900 million to 1.1 billion humans that currently exist are chronically malnourished or starving.2 If global society wants to avoid adding the additional 2.3 billion to that starving roster then more food will need to be produced.
Some argue that supply is not the problem; the absolute amount of food that could be produced globally is sufficient to meet the caloric requirements of all humans currently living. Instead the problem is socio-economical in that those that are starving cannot breach the financial barriers that prevent the acquisition of food whereas other individuals eat too much. Part of the rationality for this thought-process is that in a number of developed countries significant amounts of farmland are left unplanted in order to collect government based subsidies designed to maintain a certain price on cereals and other food items. Proponents of this policy claim that profit margins for farmers are already razor thin and increasing supply would ruin the smaller rural farmer due to a drop in price which would pull more food from the market than the subsidies do. Although a potential socio-economical barrier is an important issue, if 2.3 billion new humans come into existence more food will need to be grown regardless of whether or not enough food is available now.
However, there in lies the problem. Some estimate that eventually up to 900 million additional hectares of land will be required to meet the needs of those new arrivals, but no one believes that there is enough land left to cultivate to reach even 20% of this goal, let alone the entire 100%.3,4 Therefore, unless new growing strategies are developed (as it is unrealistic to expect the breadth of dietary changes needed to influence food production from that avenue), a much larger percentage of future generations can expect to have limited to no food options, a situation that is completely and utterly unacceptable. Note these estimates are independent of any negative influences of climate change, which will only complicate matters.
The prospect of food shortage is not a new potential consequence as agricultural (green) revolutions in both the 1960s and the 1970s were driven by the introduction of high yield seed supported by fertilizer and dwarf wheat saving millions from starvation. What is new is the prospect of food shortage with few viable options for increasing yield. Genetically engineered crops no longer appear to be the bulletproof solution they once were, use of large quantities of highly industrialized fertilizer cannot go on much longer and organic farming techniques do not appear to have the ability to scale-up beyond mid-sized farms that can serve a small city.5,6,7,8 One of the big new ideas that has been floated to accommodate these future food requirements is the advancement of vertical farms.
A vertical farm can be viewed in the context of using pre-existing urban infrastructure, such as a skyscraper, to support the growth of large-scale agriculture.4,9 Although some have proposed constructing new specialized building to act as vertical farms, such a strategy has capital expenditure concerns. A primary reason for the interest in vertical farming is that potential available land space is almost infinite as expansion proceeds vertically instead of horizontally. Unfortunately vertical farms have a lot of concerns that need to be addressed before mass deployment. These concerns stem from the fact that very little actual analysis has gone into judging the pros and cons of vertical farming. As is typical proponents have concluded that there are a number of additional advantages besides land management and that vertical farms will instantly succeed once the public signs on with their checkbooks open whereas opponents have concluded that it is a cute idea with no level of viability.
One of the champions of vertical farming is Dickson Despommier. In his two major essays on the topic he identifies a myriad of benefits to vertical farming.4,9
1. Year-round crop production;
2. Eliminates agricultural runoff;
3. Significantly reduces use of fossil fuels (farm machines and transport of crops);
4. Makes use of abandoned or unused properties;
5. No weather related crop failures;
6. Offers the possibility of sustainability for urban centers;
7. Converts black and gray water to drinking water;
8. Adds energy back to the grid via methane generation;
9. Creates new urban employment opportunities;
10. Reduces the risk of infection from agents transmitted at the agricultural interface;
11. Returns farmland to nature, helping to restore ecosystem functions and services;
12. Controls vermin by using restaurant waste for methane generation;
Although all of those additional advantages initially appear to make vertical farming a no-brainer there is a hidden problem in that not all of these advantages are mutually exclusive. For example advantages 1 and 3 are contradictory to one another because year-round crop production would require additional application of electricity and other energy sources which would reduce the significance, if not completely reverse, any reduction in fossil fuels compared to traditional farming. Also some of the advantages are somewhat fantastical, especially those that focus on generating significant levels of energy from methane gas derived from waste products. Of the 12 potential advantages listed above only 4 can be thought of as useful and with no tradeoff: elimination of agriculture runoff, utilizes abandoned/unused properties, no weather related crop failures and reduction in infection risk (due to hydroponic growth). It must be noted that the chief strategy for crop growth in a vertical farm is the application of hydroponic techniques.
A big problem that faces vertical farm deployment is profitability largely due to questions regarding the total capacity of food generation because of the high initial starting capital costs of establishing the first portion of the vertical farm through new construction and/or retrofitting. For instance one of the more significant problems opponents have with vertical farming is the lack of sunlight available to the crops, a free energy source for traditional farms. Typically due to the structure of a vertical farm situated in an already constructed skyscraper, sunlight will only be available for about 4-6 hours and that sunlight will provide less energy than average. The angle in incline of the penetrating rays relative to the building eliminates most of the more energetic rays during the noon hours. Also the principle amount of sunlight received by the farm will be located around the edges of the given floor with almost none reaching the center.
Due to the lack of sunlight artificial light will be required to augment growth conditions, but artificial light is much less efficient at fostering photosynthesis in most plants due to a large percentage of the resultant light existing in the infrared spectrum, which typically falls out of the desired range for photosynthesis. Due to this large inefficiency both in intensity and frequency a much larger amount of artificial light is required to stimulate growth (this problem is significant regardless of the type of light). All this additional light will require much more electricity and more carbon dioxide and other greenhouse gases making the cost of vertical farming heavily outweigh it benefits, both financially and environmentally.
This problem is not a game-breaker because solar cells or other trace/zero emission energy sources can be used to provide the requisite energy, which would eliminate the problems of electricity demand and carbon emissions. The problem with using solar cells though is that it is unlikely that the cells would be able to provide enough excess electricity for an expansion of the growing season beyond that of the traditional season, eliminating the dream for 365/24/7 growth. Also the price of installing enough solar cells to provide an appropriate level of electricity will create another barrier to profitability.
Proponents of the vertical farm believe that generating methane from organic waste discarded by the restaurant industry can alleviate energy concerns.4,9 Unfortunately such a strategy appears to be complimentary at best due to the energy requirements to compensate for the lack of sunlight as well as the other operational procedures. Overall a better strategy for these organic waste sources may be to use them as a feedstock in pyrolysis to create bio-char which can then be transported to a traditional farm and increase the nutrient content of the soil.
Unfortunately there are further problems with yield expansion and increasing the overall growth capacity and efficiency of a vertical farm. Ironically the problem is largely due to the chief verticality advantage of vertical farms. Although most proponents like to point out the reduction in fossil fuel expenditure and carbon emission due to the lack of farm equipment, they ‘conveniently’ forget to consider the fact that mechanization was a critical element to increasing farm productivity and efficiency. The reason farm equipment is excluded in vertical farm designs is that it would be quite difficult to operate heavy machinery in the enclosed environment of a vertical farm as the total area is more vertical than horizontal. The hydroponic growing conditions also reduce the probability of successfully utilizing traditional farm equipment.
Therefore, the farm will either provide very little food efficiency or crop collection will become extremely labor intensive similar to the picking of cotton back before mechanization. The problem with reverting back to a labor intensive farm structure is that farm profits are already small, thus increasing the amount of hands by removing mechanization would more than likely add a greater cost to vertical farming vs. traditional farming from the standpoint of a profit per yield ratio. Such additional costs will eat into the savings produced from other aspects of vertical farming like the lack of transportation expenses due to proximity.
It also appears that vertical farm proponents believe that vertical farms can both accommodate the new population additions as well as cover any losses from the abandonment of traditional fields to allow ecosystem remediation. This belief is largely derived from the hope that vertical farming can generate longer growing seasons than traditional farming (2-4 times as many crops during a single year on the same land area). The huge rationality flaw with this mindset is that the total landmass that would comprise vertical farms is far smaller than that which would be lost from traditional farms, in addition to the energy and profitability problems already discussed. For example the typical office space per floor ranges from 5,000 to 10,000 sq ft. or 0.115-0.230 acres. Next assume that the building consists of 40 floors. The total area of potential ‘farmland’ would be 200,000 to 400,000 sq ft or 4.6-9.2 acres, which is smaller than the average farm, which averages about 450 acres.10
Basically vertical farms not only have to accommodate the 900 million additional hectares projected for 2050, but also cover the 800 million hectares currently under agricultural development. To accomplish such a goal would require 183 trillion sq ft or 456,607,771 to 913,215,541 buildings of the above example dimensions. Of course such a declaration is only contingent on those buildings providing the same yield level as existing and future farmland. However, whether or not multiple growing cycles can be generated in vertical farms has yet to be demonstrated on any consistent level, so it would be premature at this point to assume multiple yields in a single year. Even if a greater total yield could be achieved due to extension of the growing season it is difficult to rationally conclude that a vertical farm could cover the additional need as well as the losses from environmental remediation. Therefore, it is irrational at this time to suggest that vertical farms would somehow aid in environmental remediation of traditional farmland while maintaining the ability to feed the current and future global population.
One aspect of vertical farming that is rarely discussed is its potential to produce bio-fuels. One of the chief problems with the production of food-derived bio-fuels is that it eliminates food from the marketplace resulting in price spikes. If abandoned buildings were converted into vertical farms that are used for crop production that would eventually result in bio-fuels, it would reduce the probability of volatile price spikes in the food marketplace. However, although sufficient potential for the enhanced production of bio-fuels exists through the use of vertical farms, without the ability to predict the future market for bio-fuels it is difficult to identify whether or not such a strategy would be profitable or even environmentally beneficial.
Perhaps the end focus of vertical farming is misdirected. Deforestation is a serious problem in the context of both climate change and biodiversity. However, it must be remembered that individuals do not clear-cut forests just for the fun of it (that would be a rather labor intensive and expensive way to have fun), but typically to generate land that is suitable for agricultural purposes. One of the chief strategies for reducing deforestation in countries with plentiful forests, most notably Brazil and Indonesia, is to assign property rights and then pay those property owners a subsidy to ensure that the forest is not cut down. The subsidy is necessary otherwise the land owner would clear the forest for the purpose of growing some form of crop either for domestic sale, export or conversion to bio-fuel.
Unfortunately the subsidy program neglects to consider the fact that the populations of these forest heavy nations are not static. If more available land is not cleared for food growth then one of two situations occur. First, the country in question will have to import food, which will increase the total burden on trade and the national budget. Increased importation also places more influence on the global market and the environment in other regions. This increased dependency leaves the importing country more vulnerable to food shortages. Basically the subsidy to protect the forest imparts somewhat of a double-whammy against the country in question. Currently it is unclear whether or not the subsidies contributed by foreign nations, for such a condition has been demanded by forest heavy nations as a requirement for a forest protection program, will be large enough to neutralize these additional expenses. The second situation is that no increase in food stocks occurs through land clearance or importation and the new members of the country in question will have less food available, if any at all.
Vertical farming could play a critical role in neutralizing this issue. Establishing vertical farms in these forest heavy nations would provide a means that could both salvage the forests as well as increase food availability to both the current and future populations of the given country. The farm can either be government controlled or controlled by private industries which could receive low-interest loans from the government so that it has the necessary capital to establish the farm. Due to the fact that a vertical farm should be more labor intensive than a traditional farm (depending on the available mechanization) these newly established vertical farms could also compensate for potential job loss from the lack of clear cutting and traditional farm creation.
Overall vertical farms will probably never reach the stature that its proponents believe/wish it will/would. Despite it not being a silver bullet to the potential food shortage in the future, vertical farms can serve a useful purpose in growth niches for highly perishable, highly fragile and/or high profitable food crop freeing up the land on traditional farms that were once used for those types of crops for cereal and other grain production. Also vertical farms could play an important role in the deforestation prevention by augmenting the available food supply. Unfortunately due to profitability and efficiency concerns, it is unlikely that vertical farms will ever growth large quantities of staple crops. Perhaps at a later time this blog will perform a quantitative economic analysis of vertical farming.
1. Food and Agriculture Organization, World Health Organization. 2005 statistics on crop production. http://www.fao.org/economic/ess/publications-studies/statistical-yearbook/fao-statistical-yearbook-2005-2006/en/
2. “Feeding the World.” Economist.com. Oct 15th, 2009. http://www.economist.com/daily/chartgallery/displaystory.cfm?story_id=14636492
3. Biello, David. “Another Inconvenient Truth: The World's Growing Population Poses a Malthusian Dilemma Solving climate change, the Sixth Great Extinction and population growth... at the same time.” Scientific American Online. October 2, 2009.
4. Despommier, Dickson. “The Vertical Farm: Reducing the impact of agriculture on ecosystem functions and services: Part 1.” Unpublished Essay Mailman School of Public Health Columbia University. 2008.
5. Mancus, Philip. “Nitrogen fertilizer dependency and its contradictions: A theoretical exploration of social-ecological metabolism.” Rural sociology. 2007. 72(2): pp. 269-280.
6. Altieri, Miguel. “The Myth of Coexistence: Why Transgenic Crops Are Not Compatible With Agroecologically Based Systems of Production.” Bulletin of Science, Technology & Society, Vol. 25, No. 4, August 2005, 361-371.
7. Rosset, Peter. “Transgenic Crops to Address Third World Hunger? A Critical Analysis.” Bulletin of Science, Technology & Society, Vol. 25, No. 4, August 2005, 306-313.
8. “Evolution of Agriculture in Africa.” August 7, 2009. http://bastionofreason.blogspot.com/2009/08/evolution-of-agriculture-in-africa.html
9. Despommier, Dickson. “The Vertical Farm: Reducing the impact of agriculture on ecosystem functions and services: Part 2.” Unpublished Essay Mailman School of Public Health Columbia University. 2008.
10. U.S. Department of Agriculture. www.usda.gov.