Hydroponic fodder and greenhouse gas emissions: a potential avenue for climate mitigation strategy and policy development

Great potential exists for reducing greenhouse gas (GHG) emissions in the animal agriculture industry. The imminent pressures on our food systems through demand for consumption of animal products are becoming more apparent as our global population increases, with estimates suggesting a global population of almost 10 billion by 2050 (Sun et al. 2020). As pressures on our global food system grow to meet the demand for animal products (McGregor and Houston 2018), so do the apparent effects of livestock production on climate change. Approximately 70% of all agricultural land is used for some aspect of livestock production (Bonny et al. 2015), and it represents 14.5% of human-induced GHG emissions, with feed production and enteric fermentation from ruminants representing the two main sources, 45% and 39% of sector GHG emissions (Opio et al. 2013). Accordingly, targeting the feed chain of animal agriculture can potentially reap near-term gains toward climate change objectives.

There are promising advances in the structure and technologies of our food systems. For example, cellular agriculture has been shown to emit fewer GHG emissions than conventionally produced meat, requiring only a fraction of land and water (Tuomisto and de Mattos 2011). In addition, consumers are increasingly transitioning to plant-based or vegan diets, minimizing or abstaining from the use of animal products with environmental issues and animal welfare associated with the cost of industrial meat production being the primary concerns (Angus and Westbrook 2019). However, in the near-term, both technology and dietary trends do not comprise viable climate strategies for animal agriculture. Meat products cultured and manufactured through cellular agriculture are not yet widely commercially available; thus, these products discuss more in terms of their “promise”, without a complete understanding of their actual potential to contribute to environmental sustainability (Mouat and Prince 2018). In terms of dietary trends, although plant-based eating is rising, demand for meat is also rising (Lee 2019), particularly with the rise of a middle class with dietary transitions trending towards higher consumptions of meat, dairy products, and other more resource-intensive foods (FAO 2017). It is impractical to regard a complete transition away from animal agriculture as a viable strategy for meeting the critical and immediate challenge of climate change. How, then, can near-term climate goals be achieved?

Meeting the demands for animal products with conventional meat production practices is reaching its limits (Bonny et al. 2015), and innovative approaches with new technology applications are becoming imperative for reducing the current and future carbon footprint of livestock production. One such approach is to focus on addressing a major source of emissions in livestock agriculture, that is, feed production (Opio et al. 2013). Conventionally grown crops are associated with heavy external inputs of nutrients, fossil fuels, water, and land consumption, and as more people consume animal products on a global scale, the environmental impacts of feed crop farming become substantial (McAlpine et al. 2009). Fortunately, the development of agricultural technologies for the advancement of feed production is currently in use. These technologies have the potential to address climate change and other environmental issues by focusing on indoor production facilities, where the environment can be manipulated and adapted to be crop specific (Gnauer et al. 2019). Space can be used much more efficiently resulting in higher yields with much smaller footprints and lower water and nutrient consumption (Marchant and Tosunoglu 2017).

Advancements in agricultural technologies can potentially lead to the production of nutritious foods without requiring extensive land clearing for pasture and feed; thus, these technologies may be able to serve as strategies for achieving both agricultural and land efficiency objectives. Applying this perspective to hydroponic farming positions the technology within the “land sparing” versus “land sharing” framework, in which land sparing practices increase agricultural intensity and yield in smaller areas to reserve space for habitat, and land sharing consists of ecologically sound practices that reduce impacts and incorporate biodiversity in farmland (Green et al. 2005; Fischer et al. 2014). Hydroponic technologies, in this sense, would be considered land sparing due to their potential to reduce or limit expansion of forage and fodder agricultural lands. The land sparing versus sharing framework generally refers to the benefits of sparing strategies as biodiversity enhancement, as more space is (theoretically) available for ecological reserves (Von Wehrden 2014; Jiren et al. 2017), but this could also be considered a contribution to climate action objectives due to the carbon sequestration and storage benefits associated with habitat conservation (Sollmann et al. 2017; Spencer et al. 2017).

Although promising, hydroponic technologies are emerging and evolving, and their potential contribution to climate objectives are still uncertain. Many indoor farms require inputs that are produced through conventional farming methods; for example, seeds for hydroponic systems may be obtained through outdoor farms. In addition, indoor hydroponic farming involves highly automated systems that control aspects of crop growing, such as temperature, lighting, humidity, etc. (Marchant and Tosunoglu 2017; Gnauer et al. 2019), and although this makes for an efficient farming system, it requires energy and thus has associated GHG emissions. Therefore, to truly assess their potential for climate mitigation, it is important to examine the contributions that value-added hydroponic operations provide to agricultural systems and to ensure that the GHG production from incorporating these technologies into agriculture does not exceed mitigation benefits. In addition, development and use of technology alone are insufficient to drive change toward sustainable development (Huesemann 2003); these are highly dependent on the conditions in which said technology operates, such as the carbon intensity of electrical grids and willingness of farmers to allocate “land spared” for habitat and carbon sequestration purposes. It is important to both understand the potential of agricultural technologies and identify the best complementary policy options to optimize climate mitigation benefits.

This paper examines the use of a fully automated vertical indoor hydroponic system for sprouting fodder and will look at its potential for reducing GHGs in livestock agriculture. Using the western provinces of Canada and the HydroGreen system as a case study, the paper estimates GHG emissions associated with hydroponic and conventional barley fodder production with specific attention to energy consumption, transportation, land use, and farming practices. The paper reports on the results and discusses how the implementation of hydroponic fodder farming practices could be complemented with different policies to enhance climate mitigation (and broader environmental) benefits.

This study demonstrated that the incorporation of hydroponic systems into fodder production can provide added value in terms of climate mitigation benefits. In the case of feeding BC livestock, hydroponic systems could be a particularly valuable strategy, as they have the potential to offset GHG emissions produced through the transportation of fodder products. A major challenge for climate mitigation in agriculture is that localization of production does not necessarily lead to emissions reductions because, in many cases, certain crops can be produced more efficiently elsewhere (Avetisyan et al. 2014). Ultimately, this can lead to difficult decisions around how to balance trade-offs between production- and transportation-related emissions. However, when using technologies that augment crop output such as the HydroGreen hydroponic system, transportation requirements for crops decrease as only a fraction of the total product mass (i.e., seeds) is being moved inter-regionally, thereby harnessing the benefits of both superior growing conditions in distant regions and (some) local production.

It is important to note that indoor, hydroponic farming is an evolving technology (Marchant and Tosunoglu 2017; Gnauer et al. 2019), and its ability to augment and semi-localize production will improve with technological advancements. The results of this study represent mitigation benefits of implementing agricultural technologies currently, and it is expected that these will increase as the technologies improve over time. Similarly, it is also important to recognize that these systems can range in their performance, as evidenced by studies that report on differing seed-to-fodder output for barley (Dung et al. 2010; Al-Karaki 2011; Saidi and Omar 2015) and as found in the data provided by the HydroGreen demonstration farm. The sensitivity analyses done in this study demonstrated how hydroponic farming systems can no longer provide GHG reduction benefits when they cross certain seed-to-fodder and energy consumption thresholds. Such findings highlight the importance of implementing these systems with monitoring and continual optimization programs for them to effectively serve as climate mitigation strategies.

Interestingly, the sensitivity analysis also revealed that more significant changes in seed-to-fodder and energy consumption levels need to occur before crossing thresholds in situations that involve longer supply chains and product transportation distances. For example, seed-to-fodder output could be lower in BC scenarios than in Alberta scenarios before a hydroponic system’s climate mitigation potential is lost. Furthermore, the energy consumption threshold was not reached in the BC scenario, but these thresholds were crossed in both Alberta scenarios. Such findings reinforce the idea that hydroponic systems can be particularly valuable for the semi-localization of fodder agriculture (i.e., sprouting fodder locally, while obtaining seeds from places where these are better produced), in terms of supporting climate mitigation objectives.

This research considers the policy implications for strategically implementing hydroponic fodder systems, and a particularly salient observation in this study was the energy implications around employing these systems. GHG emissions for hydroponic fodder in Alberta were significantly higher than those of conventional barley and the BC scenarios. The differences between the BC and Alberta context reflect the energy sources used to power the electrical grids of each province. Hydropower is the primary source of electricity in BC, whereas coal and natural gas are dominant in the Albertan electrical grid (Environment and Climate Change Canada 2019; Canada Energy Regulator n.d.). The study found that the GHG emissions produced by a hydroponic fodder farming system within a fossil fuel-based grid exceed those of a system that has longer supply chains (i.e., interprovincial transportation of seeds) but a low-carbon grid. When examining scenarios involving the implementation of renewable energy in Alberta, the lowest carbon option for fodder production was realized. Such observations elucidate the importance of strategically implementing low-carbon energy policies along with agricultural technologies. Ideally, this would occur on a provincial scale; however, a complete “greening” of a provincial grid is a significant and lengthy undertaking. Energy policies and strategies could instead target agriculture on local and farm levels in the near-term. For example, governments can develop policies such as those that provide incentives for farmers to implement low-carbon and renewable energy systems to power their operations (Bangalore et al. 2016), which can be coupled with further incentives for developing and using hydroponic systems. Such a suite of policies and strategies carry the potential for maximizing GHG reductions in fodder production systems.

Another important policy area illuminated through this study involves harnessing the land sparing and (related) carbon sequestration potential associated with implementing hydroponic agriculture systems. The study found that covering the land spared from transitioning to hydroponic farming systems with permanent vegetation produced greater climate mitigation benefits than were found with shifting from intensive tillage to no-tillage farming practices. In addition, this research examined carbon sequestration potential based on calculations for vegetation such as perennial grasses (Kosinski 2012), and it is possible that further (and enhanced) potential for sequestration exists when exploring agroforestry strategies (Bustamante et al. 2014). However, it is important to recognize that the results of this research simply communicate “potential”, and although agricultural technologies provided valuable opportunities for land sparing (Ausubel et al. 2013), increased efficiencies can also result in disproportionately higher production, consumption, and (consequently) resource consumption (Jiren et al. 2017). In addition, the land-sparing potential could be counteracted if the widespread implementation of hydroponic farming systems extends beyond adding to (and ideally improving) current annual crop supply chains and instead results in economic pressures that lead farmers to shift from perennial (i.e., permanent vegetation cover) to annual crops that fit within new (and profitable) hydroponic supply chains. It is critical to complement the implementation of land sparing technologies with policies that incentivize the conversion of cropland to permanent vegetation and (or) easements. Furthermore, these policies must be supported with structures or strategies that ensure certain farmers do not bear the full economic burden of setting aside land for sequestration purposes, such as cooperative systems that allow barley seed and hydroponic farmers to share in the financial benefits of increased efficiencies in and volumes of fodder production.

This research holds implications for agricultural planning, as it demonstrated that hydroponic technologies result in greater benefits depending on how they are integrated into regional and local agricultural systems. In particular, differences were observed between the distributed and centralized hydroponic system scenarios in Alberta, and the analysis indicates that distributing the hydroponic systems so that these operations are nearby grain storage facilities would result in GHG reductions. The distributed system, coupled with renewable energy sources, exhibited the greatest reductions in GHG emissions among all scenarios. Such observations indicate that localization of hydroponic operations (i.e., positioned next to local grain storage facilities) can enhance the technology’s ability to contribute to climate mitigation objectives. The reductions in GHGs resulting from distributing these systems observed in this study may appear minor (e.g., 4.2% for the renewable energy in Alberta scenarios); however, it is important to recognize that the study focuses on units of GHG emissions per TDN of fodder produced rather than total emissions produced. The gross amount of GHG reductions could be relatively large when accounting for the total volume of fodder produced in a year. In addition, localization in food and farm systems reduces supply chain distances and thusly can potentially increase local resilience (Rotz and Fraser 2015); in this case, distributed hydroponic systems may decrease potential problems associated with poor access to and (or) systems failures in fewer, centralized operations. However, it is also important to recognize that this research does not include GHG emissions produced through the construction of hydroponic facilities, and building numerous, smaller operations may be more impactful than building fewer, larger operations that are centralized in (for example) the industrial zones of the Census Districts. A more comprehensive analysis may elucidate such trade-offs between distributed and centralized systems.

This study considered a number of variables related to GHG emissions, incorporating considerations around energy consumption, fertilizer use (Kulshreshtha et al. 2011), transportation, land use, and agricultural practices. However, albeit inclusive of multiple factors, the research did not examine every aspect of feed crop and livestock agriculture’s contributions to GHG emissions. Because of this, the study does not perform a complete lifecycle analysis for the product of livestock products, thereby obscuring the full picture of hydroponic fodder’s potential to contribute to climate mitigation objectives. For example, enteric fermentation is a major contributor to emissions (Nguyen et al. 2013; McGregor and Houston 2018), but it was out the scope of this study. This being said, evidence exists for positing that hydroponically grown sprouted fodder has potential mitigation benefits related to enteric fermentation. In an in vitro study that used ruminal fluid, Hafla et al. (2014) observed that treatments of sprouted barley resulted in lower methane production than that of barley grain. Therefore, for this aspect of livestock farming, the value that hydroponic systems add in terms of climate mitigation objectives could potentially extend beyond energy and land considerations and perhaps may also relate to its ability to produce more digestible feed. In addition, it is important to recognize that livestock feed consists of a variety of different fodder types, and it is not the intention of this research to propose a complete shift to a purely hydroponically sprouted diet. The study focuses entirely on barley to provide a clear comparison between hydroponic and conventional barley, but future work that builds on this research could include mixed feeds (Hafla et al. 2014) and perform a similar investigation that examines climate mitigation potential related to on-farm activities, product transportation, and carbon sequestration opportunities.

While examining other factors that contribute to GHGs in the production of fodder, it is important to consider inputs used within a hydroponic system. Inputs for the HydroGreen are water and light, and it does not use fertilizers, instead relying on hydrolytic enzyme activity to release stored seed nutrients in the germination process (HydroGreen Global Technologies 2020). Thus, HydroGreen’s GHG production is primarily related to energy consumption. However, other hydroponic systems involve inputs that have associated GHG emissions, such as rockwool substrates used to grow tomatoes and N₂O (Hashida et al. 2014; Yoshihara et al. 2016). Ultimately, such emissions may be significantly lower when using hydroponic systems, rather than conventional, soil-based farming (Hashida et al. 2014); however, as hydroponic farming becomes more widespread, it is important to account for these GHG sources to fully understand the mitigation potential of these systems, similar to how Kulshreshtha et al. (2011) comprehensively modelled the emissions associated with a conventional farming.

The study specifically focuses on GHG emissions and the potential for carbon sequestration to examine the potential of implementing hydroponic fodder systems (and supporting policies) as a strategy for climate mitigation; however, the environmental implications of such systems and strategies are ultimately broader than climate change. Feed crop agriculture is associated with a number of environmental issues, including water consumption, pesticide use, water pollution, fertilizers, and habitat loss (Nguyen et al. 2013; McGregor and Houston 2018). In contrast, indoor farms such as the demonstration farm employing the HydroGreen system do not require pesticides, can reduce or eliminate fertilizer use, can reduce and reuse water, and can be developed in urban and industrial areas without expanding into wildlife habitat (Marchant and Tosunoglu 2017; Gnauer et al. 2019). In addition to contributing to climate objectives, incorporating hydroponic systems into fodder production could produce many co-benefits for addressing other critical environmental issues, such as those related to biodiversity, water conservation, pollution reduction, etc. In some cases, certain farming practices and opportunities may be lost due to changes associated with transitioning from conventional farming to indoor/hydroponic farming; for example, manure from livestock would not serve as a fertilizer inputs for hydroponic systems, which in the case of large-scale transitions to hydroponic farming, could create questions around what to do with manure waste. However, new systems present different opportunities; a livestock farm could integrate systems by establishing on-farm hydroponic and anerobic digester operations, which would reduce manure-related GHG emissions (Aguirre-Villegas and Larson 2017) while also providing a fuel source that is less GHG-intensive than, for example, coal (Yu et al. 2008). As hydroponic technologies advance and implementation increases, it is important to consider (and continually improve on) how these agricultural approaches integrate within broader food and farm systems.

The long-term future of animal agriculture is uncertain; as new alternatives to meat and dairy products are developed (Mattick 2018), consumer preferences shift toward these alternatives (Aydar et al. 2020), and global trends in vegetarianism rise (Angus and Westbrook 2019). The livestock industry is a major contributor to climate change and other critical environmental issues that challenge global sustainability (McGregor and Houston 2018), and perhaps a complete transition to sustainable food and farm systems involves decoupling these systems from animal-based industries. However, climate change is a critical imperative that requires immediate attention, and although vegetarianism and veganism have experience dramatic increases in recent years, so has meat consumption (Lee 2019). In addition, animal agriculture is socially, culturally, and economically significant to communities and societies across the globe, and it supports the livelihoods of numerous people. It is impractical and unwise to rely on dietary shifts toward vegetarianism and veganism as the sole strategy for transitioning toward sustainable agriculture, and immediate solutions are needed for reducing the impact of livestock industries.

As evidenced by this study, incorporating hydroponic systems such as the HydroGreen system into fodder agriculture has the potential for reducing the impact of livestock agriculture, as it can contribute to reductions in GHG emissions and climate mitigation objectives. The research estimated that the HydroGreen demonstration farm produced 7.4% fewer GHG emissions (per nutrient mass) than was found with conventional barley grain fodder farming, and greater reductions can be achieved with improved seed-to-fodder output, indicating that transitioning to such systems can result in GHG reductions and (ultimately) climate mitigation benefits. However, to maximize this potential, widespread implementation of agricultural technologies such as the HydroGreen system and (broadly) hydroponic farming must be supported with effective policies in areas such as energy and land use. Technological advancements alone do not comprise effective environmental strategies, and to realize the multiple (potential) benefits offered by hydroponic agriculture, these technologies must be strategically implemented with strong, supporting policies. It is through such strategic implementation of complementary technologies and policies that communities, regions, and countries will make significant progress toward sustainable futures.

Funding for this project was provided by the Food and Agriculture Institute (at the University of the Fraser Valley) and Nutriva Group. We gratefully acknowledge the Canada Research Chairs program for the funding that it has provided to the Food and Agriculture Institute.