Vertical Farming

As the world population grows, and we continue to damage our environment, there is natural concern over our ability to produce enough food to feed the world. This is a real problem, but unfortunately some of the suggestions on how to deal with it are rather fantastical and completely unrealistic. One example is the idea of "vertical farming" and involves the building of large skyscrapers (dubbed "farmscrapers") dedicated to growing food within cities. The economic and energy costs simply make such proposals completely counter productive.

One of the claims about vertical farming is that by reducing the distance food has to travel, vertical farms could help to reduce carbon emissions and help with global warming. This claim seems fairly ludicrous. The construction of a large skyscraper generates a massive amount of carbon emissions. The amount of concrete needed in such a project is very large and the production of concrete is one of the most carbon intensive processes. There are also all the other building resources required such as steel, glass and other materials. The total energy involved, from extraction of the raw resources, to their transportation and the construction process itself, is quite significant.

It is obvious that the amount of energy saved from shipping food a shorter distance is outweighed, by several orders of magnitude, by the energy used in building a vertical farm. However, we must also consider the ongoing energy use of such a building. The energy (and resources) required for ongoing maintenance and simple daily use is substantial and, by itself, would negate any energy savings from shorter food transportation. Far from producing carbon savings, a vertical farm would be a carbon factory, greatly contributing to global warming and climate change.

One of the main proponents of this idea, Dickson Despommier, claims that a 30-story vertical farm, occupying an entire city block, could feed 10,000 people. That is a scandalously low return for such a massive investment. In a city of millions, this would represent a fraction of one percent of the total food requirement. Vertical farms are also very complex systems, prone to failure. Despommier describes their functioning:

Each floor will have its own watering and nutrient monitoring systems. There'll be sensors for every single plant that tracks how much and what kinds of nutrients the plant has absorbed. You'll even have systems to monitor plant diseases by employing DNA chip technologies that detect the presence of plant pathogens by simply sampling the air and using snippets from various viral and bacterial infections. It's very easy to do.

The industry required for this level of automation and computerization is extensive, and involves another chain of energy and resource intensive production. It also makes vertical farms extremely non-resilient in the face of energy shortages or peak oil. Entire crops could be lost in the case of power outages, assuming generators (burning oil) are not used as a backup system.

The idea of growing food within cities, however, is still a good idea. Contrast the idea of vertical farms with the approach taken by Cuba after the fall of the Soviet Union. They lost most of their oil imports and had to transition quickly to low-energy farming methods. They switched to organic methods to reclaim soil, and setup urban gardens on every plot available. Many people even setup gardens on balconies or roofs. They managed to increase food output using very little energy, or in some cases, none at all.

This is an approach many people have already started to take in the US and other western countries. Instead of grass, many people have started growing food on their front or back yards. In some areas old parking lots are being ripped up and replaced with community gardens. Were this expanded on a larger scale, this would provide food to feed a great number of people, far more than 10,000. Of course, even with such methods, a city can never be self-sufficient in food, but it can significantly reduce the amount of food that has to be imported. None of this requires much energy, and has the benefit of being resilient to power outages and peak oil.

In the countryside, more acreage may be required for food than in a theoretical vertical farm, but the primary energy input is from the sun, essentially free energy. A vertical farm, however, while more dense, would not have enough light for crops to survive. Artificial light and heat would be needed year round, requiring a lot of energy. Of course, most farms today use industrial methods that are very energy intensive, but these methods are damaging the soil and are unsustainable. A transition to organic methods can provide that sustainability, while also requiring much less energy.

Food supply and global warming are both serious issues that demand serious action. Vertical farms are not a solution to these problems in any possible sense. They waste resources and energy, produce a great deal of carbon, and feed very few for their trouble. We need to focus our efforts on practical solutions that can make a real difference, and not get lost in fantasy land.