Is hydroponic farming environmentally sustainable?

What is hydroponic farming? 

Hydroponic farming, commonly referred to as hydroponics or hydroponic cultivation, is a farming method that has a lot of promise in terms of reducing the overall environmental impact of global food production. In short, hydroponic farming is a type of horticulture in which plants are grown without soil, and instead, hydroponics grows plants by exposing their roots directly to a nutrient-rich water solution, which is then recycled in a closed-loop system. Hydroponics allows the farming of fresh leafy vegetables, herbs and berries in a controlled environment, offering an alternative solution to the rapidly growing demand of food around the globe.

Is hydroponics more sustainable than conventional agriculture? 

The global hydroponics market has seen a rapid growth with the first large scale commercial farms being already used in the US, Europe and Asia. However, with the growing interest towards hydroponics among investors, consumers as well as public institutions, many of these stakeholders are now asking important questions like is hydroponic farming sustainable and how does hydroponics compare to conventional agriculture in terms of the environment? Well, according to an exhaustive life cycle assessment (LCA) by the World Wildlife Fund (WWF), the answer to these questions depends on the energy sources being used [1].

The assessment compared the environmental impacts of different greenhouse and vertical hydroponic systems with conventional agriculture using a functional unit of one kilogram (2.205 pounds) of lettuce that was packaged and transported from its point-of-origin to a grocery store in the St. Louis region. The analysis assumed that a vertical system would use LED technology as its primary source of lighting while a greenhouse would be able to utilise sun as a light source. In addition, the following variables were considered in the life cycle inventory: 

• Nutrients 

• Land use 

• Energy 

• Water 

• Pesticides 

• Emissions (including food spoilage) 

• Packaging 

• Distribution 

Using the variables listed above and considering a standard electricity mix in the California and St. Louis regions, the results show that hydroponic farming had a higher environmental impact compared to conventional farming due to the significantly higher energy consumption and the subsequent GHG emissions. While greenhouse hydroponics consumes most of its energy for climate control, the energy consumption in vertical hydroponics comes mostly from the need for LED lighting.  

It is fair to say that results like these are not new. For example, Louis Albright, an emeritus professor of biology and environmental technology at Cornell University, published similar results  already in 2012. He argued that the biggest challenge facing indoor hydroponic farming in the future would be the considerable amount of electricity needed. [2]

Vertical hydroponics vs greenhouse hydroponics 

Now that we know that conventional agriculture has an advantage over hydroponics in terms of environmental issues, the next question is, how do greenhouse and vertical hydroponics compare to each other? Again, the results from the LCA are rather clear. They show that greenhouse-based hydroponic systems have a lower impact of the two, and that the disparity is once again explained to the most part by the higher energy usage in vertical farms.

Even when looking at a hypothetical future scenario where vertical hydroponics could reduce its overall electricity footprint by 20% (assuming an improvement in LED technology), greenhouse hydroponics still scored better in its environmental impact.  

How to make hydroponics more environmentally sustainable?

So, as we can see in the results above, the extensive use of LED technology, and the resulting high energy consumption can still be considered as one of the biggest hurdles faced by vertical farming companies. Thus, the question still stands, can hydroponic farming be more environmentally sustainable than conventional farming? Again, the simple answer is yes, hydroponic farming can have a lower more environmentally impact than conventional farming if the correct energy mix is used. 

This argument by WWF is based on a hypothetical LCA analysis where both the hydroponic systems as well as the conventional farms would be fully powered by renewable energy. According to the results, hydroponic farming can actually make for a more environmentally friendly solution if the electricity is sourced directly from renewable sources, for example solar or wind. In such a case, hydroponic was not only the better option in terms of emissions but it also had a lower impact on both the overall human and ecosystem health. 

While these results are exciting and provide some insight into the potential future where a larger portion of the global energy grid is based on renewables, it should be noted that with the current grid mixes around the world, being able to directly source renewable energy is not always an option. Regardless, hydroponic farming can offer interesting opportunities in regions where local food production is not necessarily possible, where water is a scarce resource and where the access to renewable energy is more abundant.

Future sustainability opportunities

Reflecting on the results from the LCA presented above, hydroponic farming has still a long way to go in order to compete with conventional agriculture without having to rely 100% on renewable energy. However, one should also keep in mind that this field of research is still rather new, and there are many gaps to fill. In fact, we suggest that future research should  focus on hydroponic farming as a solution for the urban environments. In fact, many of the benefits brought by vertical farms are better achieved when production is brought into an urban environment and closer to the consumers.  Some of the benefits from vertical farming include the 

• reduced energy, packaging and fuel requirements for transportation, 

• significant decreases in food waste, 

• the reduced emissions from the lack of agricultural machinery and fertilisers, as well as 

• the opportunity to transform some of the current agricultural lands into carbon sinks through afforestation. 

These, and many of the other benefits promise to make vertical hydroponics into a viable, and more sustainable substitute to conventional agriculture. As with any emerging technology, it is reasonable to expect significant increases in efficiency as well as decreases in costs as the technology matures over time. In fact, there are already signs of great leaps in many of the critical technologies as in the development of more efficient LEDs [3, 4]. In addition, some of the pioneers of vertical farming, including Dr. Nate Storey from Plenty, argue that many of the relevant technologies are already coming down the cost curve, making large scale vertical farming even more attractive in the future.

In summation, hydroponic farming is still suffering from the high energy consumption that has plagued the market for the past few decades. While the technology is improving, it is not yet quite as environmentally sustainable as conventional farming. However, some of the recent technological improvements have made it possible for hydroponics to achieve lower overall environmental impact when compared to conventional farming when the electricity needed is sourced directly from renewable sources. While this does not make hydroponics the sustainable breakthrough that some would have expected, it is still a big leap forward, and we are excited to see ever more investments go into improving these technologies during the next few years.

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With a growing interest in hydroponic farming by investors, consumers and public institutions, there is a need for more sustainable technologies to improve the overall market. If you are interested in learning more about hydroponic farming and how we approach the technology, please contact us using the form below.

Sources: 

[1] World Wildlife Fund (2020). Indoor soilless farming: Phase I: Examining the industry and impacts of controlled environment agriculture. 

[2] Albright, L. (2012). UK International Greenhouse Conference. CEA: Controlled Environment Agriculture. Cornell University, New York. 

[3] Hughes, S. (2018). Vertical farming: does the economic model work? The Nuffield Farming Scholarship Trust: July 2018. 

[4] Al-Kodmany, K. (2018). The Vertical Farm: A Review of Developments and Implications for the Vertical City. Department of Urban Planning and Policy, College of Urban Planning and Public Affairs, University of Illinois at Chicago: February 5, 2018.