How Different Types of Agriculture Impact CO2 Emissions

An overview of how different agricultural practices such as field farming, greenhouse farming and vertical farming impact on CO2 emissions.

In today’s landscape of environmental emergency, agriculture, among many other industries, needs to step up and evolve in a way that is both scalable and sustainable. Traditional, open-air industrial farming has been vastly criticized for the damage it does to our environment, but is it really that bad compared to current alternatives?

Mean CO2 emissions per kg of lettuce for Green Vertical Farming, Conventional Vertical Farming, AdvancedGreenhouse, Conventional Greenhouse and Open Field Agriculture. Source: OneFarm CO2 report.
Mean CO2 emissions per kg of lettuce for Green Vertical Farming, Conventional Vertical Farming, AdvancedGreenhouse, Conventional Greenhouse and Open Field Agriculture. Source: OneFarm CO2 report.


A study conducted in 2018 by OneFarm, a dutch vertical farming company, tried to answer this question by comparing the CO2 emissions of the major agricultural techniques available today. The report takes as unit of measure kilograms of CO2 emitted per ton of lettuce harvested.

The key takeaway is that vertical farming can be the practice with the lowest emissions, if powered by renewable energies. Otherwise, it would generate by far the highest amount of CO2 emissions.

Here is an overview of the different agricultural techniques studied and the variables taken into consideration.

Variables considered in this study for Green Vertical Farm, Conventional Vertical Farm, Advanced Greenhouse,Conventional Greenhouse and Open Field Agriculture. Source: OneFarm CO2 report
Variables considered in this study for Green Vertical Farm, Conventional Vertical Farm, Advanced Greenhouse,Conventional Greenhouse and Open Field Agriculture. Source: OneFarm CO2 report

Let’s have a look at the different techniques:

Open Field Agriculture

A large agricultural field.
A large agricultural field.

Open field agriculture includes industrial farming and other subcategories of traditional farming.  It accounts for most our food production output  and is bound to change its dynamics to face the sustainability challenge.

The majority of the emissions linked to open field agriculture is caused by transportation, averaging 62% of total emissions. We have to consider, though, the high variability of this factor. Emissions can go from as low as 11kg to 666kg, depending on the distance the food has to travel to reach its consumers.

Food waste is another important factor in this equation, accounting on average for 25% of total emissions.  On average, global food losses account for 30% of total production. It is estimated that the amount of food wasted could feed up to 800 million people. These losses correspond to on-farm losses, non-marketable crops and transportation losses, putting the high inefficiency of the current food production system under the spotlight.

CO2 emissions per ton of harvested lettuce - 540kg

Greenhouses

Tomato plants inside of a greenhouse.
Tomato plants inside of a greenhouse.

The Netherlands are a perfect example of exploiting greenhouse farming at full potential. Controlled-environment greenhouses have been the fuel pushing this tiny country to become the world’s second largest exporter of food as measured by value, second only to the United States.  The one constraint of greenhouses is obviously space.  Half of the territory of the Netherlands is used for agriculture,  with seas of greenhouses extending to the horizon in many areas of the country.

Conventional greenhouses

This report divides greenhouses into two subcategories. Conventional greenhouses include those practices that employ non-renewable sources of energy.  Although the variability is pretty high, they are usually located outside urban areas, making food transportation a bigger factor into their equation.

CO2 emissions per ton of harvested lettuce - 575kg

Advanced greenhouses

Advanced greenhouses were assumed to be located in peripheral areas of major cities. The use of renewable  energies along with a closed-loop system for water irrigation make them less pollutant compared to conventional greenhouses.

CO2 emissions per ton of harvested lettuce - 352kg

Vertical Farming

Indoor hyrdroponics of Morus, Japan.Photo by Satoshi KINOKUNI
Indoor hyrdroponics of Morus, Japan.Photo by Satoshi KINOKUNI

Vertical farming refers to practice of growing food indoors in vertically stacked layers. In this study, conventional vertical farming is distinguished from green vertical farming based on one variable: whether or not it employs sources of renewable energy.

Conventional vertical farming

Conventional vertical farming is by far the practice associated with the most emissions. The reason is very simple: energy.  The use of perishable sources of energy to power vertical farming is clearly inefficient and not sustainable.

“Energy inputs account for the highest source of CO2 emissions in current vertical farming. This represents 90% of the total emissions. Estimated energy emissions are 5,000kg CO2eq for vertical farms if green energy is not used.”  

In conventional vertical farming, the emissions linked to energy use alone are ten times higher than the total emissions generated by open field agriculture.

CO2 emissions per ton of harvested lettuce - 5,744kg

Green vertical farming

“The emission reduction from energy use improvements, renewable energy sources and full recycling of waste energy is at the core of the sustainable development solution in vertical farming. This represents up to 98% of total emission reductions to around 160 kg CO2eq for each ton of harvested lettuce.”

Based on the results from this study, green vertical farming can potentially emit 70% less CO2 compared to open field agriculture, with additional benefits of 95% less land used and 80 to 90% less water use.

Moreover, green vertical farming can substantially reduce the amount of food waste. The enclosed nature of the growing setup, making contamination related to crop failure extremely unlikely,  and the proximity to the consumers, reducing transportation emissions to a minimum,  could reduce food losses by up to 99% and emissions associated with it by up to 70%.

CO2 emissions per ton of harvested lettuce - 158kg

Conclusion

The most efficient solution seems to be a combination of the existing alternatives, maximizing on their strengths and trying to minimize their shortcomings.

Vertical farming can be a major player in the transition to a green, circular economy in urban environments, but it does have its own challenges. The main ones are assessing which crops are best grown in a vertical farming setup in terms of resource efficiency and sustainability along with assuring a renewable source of energy to power its technology.

But as you can see, if done properly, the expansion of vertical farming can reduce the overall C02 emissions generated by food production.

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