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Indoor Farming

Indoor farming techniques--greenhouses, hydroponics, and vertical farming--tend to greatly decrease land and water use, relative to conventional farming, while also greatly increasing energy use.

Greenhouses

Greenhouses are an increasingly widely used tool for producing vegetables 1. Greenhouses are estimated to have the following environmental impacts relative to outdoor farming, often spending more energy to save land and water.

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The above figures are the range of estimates sources as follows: land use 2, 3, energy 4, 2, 5, 6, greenhouse gases 4, 2, eutrophication 4, 2, acidification 4, 2.

Following is an illustration of the energy required to produce all world tomatoes from greenhouses.

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Energy requirements are the 25th and 75th percentiles figures for greenhouse tomato production as reported by Clark and Tilman 2. The wide range of estimates account for widely varying climates, types of greenhouses, and study methodologies. Overall tomato and food production is determined from FAOSTAT 7. Due to the wide variation in life cycle analysis results, precise figures are not available.

Greenhouses can be used to grains, such as barley 4, but the environmental case for doing so may be weaker than it is for vegetables.

The Netherlands is the world leader in effective use of greenhouses. They have drastically cut water and pesticide usage, and the Netherlands, a country that is not naturally well-suited for agriculture, is the number two food exporter by monetary value.

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A tomato greenhouse in The Netherlands. (Source: Wikipedia. CC BY-SA 3.0)

Problem:
Land Use in Agriculture
Solution:
Expand Use of Greenhouses

Hydroponics

Hydroponics--the practice of growing plants with a nutrient solution instead of soil--may also save land and water at the cost of greater energy consumption. The following impacts, relative to open field farming, have been estimated.

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Numbers are highly uncertain due to limited data and wide variance in both hydroponic and open field practices. Sources: 8, 9, 10, 11, 12, 13.

Over 80% of the energy consumption identified by Barbosa et al. 9 is for heating and cooling, an area for which a clean source of low-temperature industrial heat would be valuable. Passive ventilation 9 and efficient LED lighting 14 would also save energy.

Related growing techniques are aquaponics, which is a symbiotic combination of an aquaculture and hydroponic system, and aeroponics, which does not use a growing medium. Their water, fertilizer, and land use impacts have been estimated as follows.

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Source: AlShrouf [1].

An aquaponics system can save fertilizer consumption by using excretion from the fish 15. An aquaponics system designed specifically for Martian astronauts has been estimated to require 10 square meters per person without stacking 16.

Labor intensity is a barrier to expansion of hydroponics 17 and aquaponics 18, which can be addressed through greater automation.

Vertical Farming

Vertical farming is the concept of growing food in layers. This may refer to the food-producing skyscrapers described by Dickson Despommier 19, or more commonly, any indoor growing that relies mostly on artificial lighting 20. Even more so than greenhouses, vertical farm conserves land and water at the cost of additional energy consumption.

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Source: Hallikainen 21.

Most of the energy cost of a vertical farm is for artificial lighting, and vertical farms also have higher labor costs per unit product than other forms of farming 22. Due to high energy and other costs, vertical farms for the foreseeable future will probably be confined to producing leafy greens, herbs, and berries, which together constitute 6% of global caloric intake 23.

References

  1. Farm Credit Canada. "Update on the North American Greenhouse Vegetable Industry". ↩

  2. Clark, M., Tilman, D. "Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice". Environmental Research Letters 12(6). June 2017. ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  3. Smith, G. "Issue 94: Field Vs Glasshouse Tomatoes". Practical Hydroponics & Greenhouses. May/June 2007. ↩

  4. Bartzas, G., Zaharaki, D., Komnitsas, K. "Life cycle assessment of open field and greenhouse cultivation of lettuce and barley". Information Processing in Agriculture 2(3-4), pp. 191-207. October-December 2015. ↩ ↩2 ↩3 ↩4 ↩5

  5. Kuswardhani, N., Soni, P., Shivakoti, G. "Comparative energy input–output and financial analyses of greenhouse and open field vegetables production in West Java, Indonesia". Energy 53(1), pp. 83-92. May 2013. ↩

  6. Ozkan, B., Fert, C., Karadeniz, F. "Energy and cost analysis for greenhouse and open-field grape production". Energy 32(8), pp. 1500-1504. August 2007. ↩

  7. Food and Agriculture Organization of the United Nations. "FAOSTAT". ↩

  8. AlShrouf, A. "Hydroponics, Aeroponic and Aquaponic as Compared with Conventional Farming". American Scientific Research Journal for Engineering, Technology, and Sciences 27(1). January 2017. ↩

  9. Barbosa, G., Gadelha, F., Kublik, N., Proctor, A., Reichelm, L., Weissinger, E., Wohlleb, G., Halden, R. "Comparison of Land, Water, and Energy Requirements of Lettuce Grown Using Hydroponic vs. Conventional Agricultural Methods". Int J Environ Res Public Health 12(6), pp. 6879-6891. June 2015. ↩ ↩2 ↩3

  10. Biksa, E. "Hydroponics Yields Versus Field Grown Harvest Weights". Grozine. March 2014. ↩

  11. Khandelwal, G. "Growing Compact and Going Compact". UWSpace, Masters Thesis. January 2020. ↩

  12. Martinez-Mate, M., Martin-Gorriz, B., Martínez-Alvarez, B., Soto-García, M., Maestre-Valero, J. "Hydroponic system and desalinated seawater as an alternative farm-productive proposal in water scarcity areas: Energy and greenhouse gas emissions analysis of lettuce production in southeast Spain". Journal of Cleaner Production 172, pp. 1298-1310. January 2018. ↩

  13. Romeo, D., Vea, E., Thomsen, M. "Environmental Impacts of Urban Hydroponics in Europe: A Case Study in Lyon". Procedia CIRP 69, pp. 540-545. 2018. ↩

  14. Singh, D., Basu, C., Meinhardt-Wollweberm, M., Roth, B. "LEDs for energy efficient greenhouse lighting". Renewable and Sustainable Energy Reviews 49. September 2015. ↩

  15. Monsees, H., Suhl, J., Paul, M., Kloas, W., Dannehl, D., Würtz, S. "Lettuce (Lactuca sativa, variety Salanova) production in decoupled aquaponic systems: Same yield and similar quality as in conventional hydroponic systems but drastically reduced greenhouse gas emissions by saving inorganic fertilizer". PLoS ONE 14(6): e0218368. June 2019. ↩

  16. Greenbaum, C. "MEALS: Mars Experimental Aquaponics Long-Duration System". The Mars Society. 2021. ↩

  17. Daly, W., Fink, J., Shamshak, G. "Economic Assessment of Hydroponic Lettuce Production". Groucher College. ↩

  18. Heidemann, K., Bailey, D., Shultz, C. (ed.). "Commercial Aquaponics Case Study #3: Economic Analysis of the University of the Virgin Islands Commercial Aquaponics System". Funded by Southern Sustainable Agriculture Research & Education (SARE) through a Graduate Student Grant under the award number 3048110880. 2015. ↩

  19. Despommier, D. The Vertical Farm. Picador; Reprint edition. October 2011. ↩

  20. Crowley, A. "The Economic and Financial Feasibility of Food Innovation Centers". Thesis - Master in City Planning and Master in Science in Real Estate Development, Massachusetts Institute of Technology. June 2015. ↩

  21. Hallikainen, E. "Life cycle assessment on vertical farming". Aalto University, Masters Thesis. January 2019. ↩

  22. Banerjee, C., Adenaeuer, L. "Up, Up and Away! The Economics of Vertical Farming". Journal of Agricultural Studies 2(1). 2014. ↩

  23. Tuomisto, H. "Vertical Farming and Cultured Meat: Immature Technologies for Urgent Problems". One Earth 1(3), pp. 275-277. November 2019. ↩