A Closer look at Vertical Farming

A novel concept called vertical farming, has been developed by the Medical Ecology department of Columbia University which aims to revolutionize farming and food production. Although proposals such as this have existed in the past, this one takes it to new heights (no pun intended).
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A recent trip to their website indicates this is still a project under conceptualization, with each year’s class filling in new details about the project and enhancing the calculations and research totals. It is a good thing, because this project is not ready for prime time. In fact its time may never come. Energy considerations are of course paramount to its eventual success (or failure) however other aspects such as economics are also important.
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This piece will not rehash the proposal itself, but rather key issues that stand out.
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Construction

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Any way you cut it, this is a significant sized building. It would take a large amount of concrete, glass, plastic, steel, and other metals to construct. Most of those materials require a significant amount of energy, not to mention the raw ore / chemical feedstock to produce. Within the building, significant climate control, water control and electrical devices would need to be purchased and installed. While this is obviously a one-time expense, it far outweighs the conventional approach: find level land with halfway decent soils and adequate water. At the moment this project is economically infeasable, but energetically possible to construct. Economics may change, but if you don't have the fossil fuels (or they are scarce), large scale construction will be difficult or impossible.
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An argument was made by a member of peakoil.com that an existing car park could be utilized for such a purpose. Perhaps a greatly stripped down version of a vertical farm could be established in unneeded car parks (which looks likely as the gasoline supply begins to decline). In this case the energy investment (the structure) had already been made, and with some relatively inexpensive retrofits (glass, mirrors, solar tubes) interior lighting could be brought in. However the size and scale would have to be greatly reduced in order to eliminate the need for artificial lighting. In all likelihood a car park of 4 stories or less might prove adaptable, with cultivation occurring only on the roof (fourth ) and third floors. The second floor could be used for small livestock, while the ground floor could hold processing and waste recovery operations. Granted, this is not the optimal way to farm, but adaptive reuse and necessity will go a long way in easing any future food crisis.
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Still, vertical farming remains hugely inefficient to all other forms of cultivation due to use of light.

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Light
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Light is vital to all growing plants. It is what drives photosynthesis. The light source for all previous forms of industrialized agriculture of course was the sun. It was free, did not ever fail to turn on when needed and never burnt out. Vertical farming on the other hand is totally dependent on artificial lighting. While in smaller structures, solar tubing may be able to light harder to reach interiors, this building is simply too massive to light this way. An estimate by the design team figured that the building would require approximately 26.5 million KW/yr. This is a significant amount of energy and only a partial estimate. The team did not consider all of the ancillary uses such as pumping, office space and other non-agricultural support services. In all likelihood the final total will be higher, though probably not by more than 10-15 million KW/yr in additional requirements.

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Water
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Vertical farming is a winner in this respect. A controlled environment such as this limits evaporation, permits more precise applications and creates no runoff. Many growth methods proposed would be hydroponic in nature, but even that is more efficient than conventional agricultural practices today. Additionally, rainwater could be captured and put to use.

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Nutrients
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This facility would almost certainly have to have chemical inputs. It may require less and have zero leakage but in the end, feedstock will still be required. It is likely hydroponics will play a large role here, necessitating precise measurements. Vertical farming will score better than conventional farming in this respect (less nutrients per yield) but there are organic and biointensive methods that require no chemically synthesized fertilizers at all. Unfortunately their application is limited in a closed environment such as the one proposed. Even with waste recovery methods on the remaining waste products, chemical fertilizers would still be a regular input to the vertical farm.

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Pesticides
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This application will almost certainly require fewer pesticides. Since the atmosphere is highly controlled, the chance of infestation is much lower. Any infestation can be quickly put under control and pesticides, if needed would be in far fewer quantities. On the other hand, growing methods do exist that require no pesticides and don't require a multimillion dollar skyscraper to implement. Never the less, a controlled atmosphere is not a guaranteed way to keep pests and diseases out. An infection, if introduced, could quickly spread out of control.

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Waste
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This one is significant, especially if there is livestock involved. This facility would produce a large amount of waste product, be it non edible portions of plants, contaminated water, urine, feces and odors. Some of this could be easily composted and reused but when it comes to livestock, this facility would essentially be a factory farm. Animal rights implications aside, that is a lot of excrement in a real small space. Methane production would reduce the totals (capturing energy) while additional amounts could be theoretically composted. But a significant amount of biosolids would remain. What would have to be done with those? Plus there is the inherent risk of disease when maintaining that number of animals in such a confined space. Finally, that place will stink to high heaven. Today's CAFOs stink and even if you could manage to keep the waste portion de-oderized, the stench from the pens, cages and stalls would be overpowering. Fresh air would have to be drawn in, but the exhaust would have to go somewhere. How will that be cleaned up?

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Energy Consumption

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This one is partially covered in the above categories but the vertical farm would still require significant amounts of energy to operate. As noted the design team calculated energy requirements just this past year and came up with the following (incomplete) assessment: The vertical farm will consume 26.5 million KW per year while generating 51.6 million KW of energy equivalent from biomass recovery. This assessment is incomplete overall calculations and flawed in reasoning.
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As noted by the researchers, energy consumption estimates only extended to the lighting and other processes directly needed for agriculture. Significant other expenditures for non-agricultural purposes will also be required. More importantly, the team estimated total energy production in Kilowatt hours, for which they arrived at their calculations by directly converting the energy equivalent of the Biogas from BTU to kilowatt-hours.
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This is a flawed argument. Natural gas is not converted into electricity by the utilities by calculating the energy equivalents. It is burned in a generator to produce heat that turns a turbine, creating electricity. In the process, there is an inevitable loss of efficiency (Second law of thermodynamics). The Columbia team neglected to consider any possible efficiency losses from biogas generation of electricity.
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Electricity would have to be used to run lights (discussed) as well as climate control (building would heat up in most climates during the summer), elevators, pumps (vertical transportation still has to fight gravity remember) and sophisticated monitoring equipment. Gas (biogas) would need to be used for heat for the building and various processes. Many modern CAFOs require natural gas to operate. In this county, dairies can use a significant amount of gas. In all cases where methane recovery is utilized, it still does not create more than is drawn in from the utility. None come close to needing to resell it back to the utility.
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Overall Conclusion

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Conventional modern farming is already a caloric loser. Vertical farming would in all likelihood be far worse, even though it solves the land and transportation arguments. (less embodied energy than those 3000 mile Caesar Salads) The stated necessity to feed an additional 2.3 billion people by 2050 and conserve land, is an argument of dubious worth. If these facilities increase yields and make food more wide spread, population will continue to grow, necessitating yet more vertical farms. As with most people, the Medical Ecology team believes in the argument that population drives the food supply. In actuality, it is the available food supply drives population growth (or decline).In the end there are two predictions for the future of vertical farms:

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Peak Energy Paradigm
Peaking energy supplies will make this proposal a stillborn dream. We won't have the energy to build, maintain or operate the facility. We will hit peak food and if we haven't reduced our populations by that point, many will starve.

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Limitless Energy Paradigm

If by some miracle we master fusion or zero point energy, vertical farms WILL BE THE FUTURE. We will have no choice. Continued growth (because we are genetic fools driven to grow) will force us to develop these structures to in order to feed our growing population. In the end, that will only encourage more growth (starvation is a great population limiting tool) and ever more food production. With limitless energy, we could still swing this though. Growth continues and all is right with the world until we hit another limiting factor.Though in the end, when you think about it, if we are that "smart" and "advanced" we will at some point figure out how to nano-convert inedible raw materials into food, bypassing the need for farming altogether.