3.1. Biomass: an inexhaustible and underused resource for the bioeconomy?
Institutions view the bioeconomy as inexhaustible because it is based on biomass, which is renewable by definition, but renewable does not mean sustainable or unlimited.
a. Renewable does not mean sustainable
Institutional descriptions of the potential of the bioeconomy avoid the issue of sustainability (Vivien et al., 2019), particularly for biomass production. Pfau et al. (2014) highlight this conflation of 'renewable' and 'sustainable'. Because the bioeconomy uses renewable resources, it is assumed to be intrinsically sustainable. Sustainability is equated with replacing fossil resources with renewable resources and optimising their use, but using renewable resources does not mean that producing them is sustainable. Cidón et al. (2021) show that little of the scientific literature has focused on the relation between organic farming and the development of the bioeconomy. The focus on biomass can mask the issues of dependence on and use of other resources, particularly natural resources (e.g. water, soil; Staffas et al., 2013), the sustainability of biomass use (e.g. deforestation, soil erosion), and interactions between sectors and diversions of flows (Marty et al., 2021), which is why it is worth taking specific interest in this area (Allain et al., 2022).
Another criticism is the lack of considering social dimensions, which is another component of sustainability. Corvellec et al. (2021) explain the controversies surrounding these policies and strategies, which are presented as 'win-win', but ignore implementation problems, constraints, socio-technical obstacles, losers/winners, and conflicts arising from reorganisation and reorientation of flows and destructurings/restructurings.
Bioeconomic strategies also do not specify the scales at which they will be implemented. They highlight the territorial scale (CGAAER, 2019) without raising questions about the place of territories in industrial rationales. Bahers et al. (2017) discuss the risk that resource-use efficiency will override the territorial dimension. Investment in infrastructure and the need to make it profitable can lead to intensification of production, resulting in the agronomic dead-end of monocultures, an increase in the use of inputs or natural resources (water), diversions of flows that undermine the existing system, or an increase in the disconnect between crops and livestock, as illustrated next.
Illustrations of tensions among territorial, environmental, and industrial considerations
Marty et al. (2021) describe how the use of anaerobic digestion in the north of the Aube department changes crop rotations, irrigation, the return of intermediate crops to the soil, and existing infrastructure and sectors. Beet pulp is increasingly fed into digesters, diverting it from dehydrators, which could cause the latter to close. This would impact the livestock sector, as 350,000-400,000 t of beet pulp and 100,000 t of lucerne are dehydrated in northern Aube and exported as animal feed. The few remaining livestock farms in the region could also disappear. Competition for beet pulp is developing along with anaerobic digestion, which is particularly attractive economically for beet growers. There is also a risk that lucerne will disappear from crop rotations in this crop-oriented department, which would negatively impact the renewal of soil fertility.
At the same time, intermediate crops, including catch crops (not only those used for energy), are increasingly harvested to supply digesters, and less is returned directly to the soil. As intermediate crops become more profitable than main crops, the time spent growing cereals (main crops) has decreased in favour of maize, which requires more irrigation, is now considered an intermediate crop, and is fed whole into digesters. The development of anaerobic digestion has raised several concerns, including the effects on water resources and soil biodiversity of spreading digestate (Madelrieux et al., 2020) and the social acceptability of anaerobic digestion itself (Bourdin and Nadou, 2020).
However, collective-management approaches are developing in response to environmental problems, using an industrial approach that is more firmly rooted in the local area. The Ferti'Eveil composting platforms in the Vendée department are one example. Faced with more stringent environmental regulations (e.g., the EU Nitrates Directive), 15 poultry farmers joined forces in 2006 to pool the management of their poultry manure, in particular by exporting surplus fertilising nutrients outside their production area viacomposting (Le Houerou and Blazy, 2021). The approach was extended to other types of livestock (i.e. cattle, sheep, goats, and pigs) and in 2021 included 140 farms within 50 km of the two composting platforms. The compost is sold within a 150 km radius to crop farmers, wine growers, market gardeners, and arboriculturists. In return, livestock farmers are supplied with bedding via the cooperative. One key to the success of this long-term approach was the construction of a multi-stakeholder, multi-sector, and multi-scale project. Impacts of the increase in road transport and the energy dimension of the system remain to be determined.
b. Underused does not mean unlimited
The assumption that renewable resources can replace fossil fuels is misleading (Allain et al., 2022) because it does not consider that the current energy transition involves adding renewable resources to fossil fuels (rather than replacing them) and that not all materials have the same properties. For example, biomass has a much lower energy density than fossil fuels (Harchaoui and Chatzimpiros, 2018).
Pahun et al. (2018) showed how institutions have moved from a vision of overexploited resources (through the mining/industrial regime) to underexploited resources (i.e. new uses made possible by technology, agricultural abandonment/fallow land, waste), without changing the regime. There is even a high risk of following a mining approach to the use of biomass, which exacerbates environmental problems and social inequalities. Daviron (2019) considers that biomass is limited, and that the institutional view that it is abundant and underused is due simply to the massive use of fossil fuels in all sectors of human activity. Net primary agricultural production is the product of agricultural yields and available agricultural land, each of which is limited (the former by the conversion efficiency of photosynthesis and the potential yield as a function of farming practices (Mueller et al., 2012), the latter by global boundaries (Steffen et al., 2015)). At the scale of France, the degree to which crop yields and nutrient-use efficiency can be increased is small (Harchaoui and Chatzimpiros, 2019).
At the European scale, Renner et al. (2020) show imbalances between internalisation and externalisation of pressures on agricultural resources and emissions, Europe's dependence on 'virtual' flows of land and water, and the impossibility of extending this model to other parts of the world. With the deployment of the bioeconomy and the increase in demand for biomass, Bruckner et al. (2019) show that an increasing proportion of the world's agricultural land is used to produce biomass for non-food purposes. However, they also show that two-thirds of the agricultural land needed to meet non-food biomass consumption in Europe is located in other countries (i.e. China, United States, and Indonesia), which impacts their ecosystems. This consumption includes oilseeds to produce biofuels, detergents, and polymers, but also more traditional products, such as fibre for textiles and animal hides. In addition, fluctuations in the spatial footprint of consumption highlight the connection to fluctuations in agricultural yields due to drought, which will likely intensify in response to climate change (Harchaoui, 2019).
Competing uses will require more land or more intensive biomass production, whose environmental impacts will depend on the location (Lewandowski, 2015). This competition among uses is rarely studied in a systemic way by the bioeconomy, even though the issue of prioritising biomass uses is unavoidable (Muscat et al., 2021).
Illustrations of tensions among food, feed, and energy
The challenge for agriculture is to produce enough to meet the needs of human and animal consumption, as well as society's bioenergy, without increasing the agricultural area (Harchaoui and Chatzimpiros, 2018). Increasing the area could impact other ecosystems and lead to a loss of biodiversity, another planetary boundary (i.e. ‘biosphere integrity'; Steffen et al., 2015). Many studies ignore that agriculture depends on fossil fuels to produce biomass.
Harchaoui and Chatzimpiros (2018) applied the concept of energy neutrality to describe agriculture's capacity to be a source of energy for itself and society that could replace fossil fuels. Agriculture is energy neutral if the energy potential of its resources (i.e. essentially crop residues and livestock waste) exceeds the biomass equivalent of the fossil fuels invested in it. The study considered several scenarios for mainland France that combined reducing the proportion of cereals and annual fodder in animal feed with different rates of energy recovery from agricultural residues. It found that energy neutrality is difficult to achieve, being possible only if cereals and annual fodder are excluded from animal feed and all agricultural residues have an energy recovery rate of 30-70%. This scenario would decrease the proportion of monogastric animal products in the human diet and run counter to minimum rates of returning crop residues to the soil to meet soil-conservation and carbon-enrichment objectives, leading to dilemmas and compromises between energy and climate objectives (Harchaoui and Chatzimpiros, 2018). This study considered boundary conditions of impacts of competition among food, feed, and energy on agriculture's energy balance, but it did not consider the important practice of reducing food loss and waste to improve the energy balance.
Research is beginning to highlight the role of livestock farming in the recovery of agricultural and agro-industrial co-products (Chapoutot et al., 2018; Van Selm et al. 2022), and more generally of plant biomass that humans cannot consume (Laisse et al., 2018; Van Zanten et al., 2019), in reducing competition between animal feed and human food. Estimates of the co-products available still need to be improved by considering i) their potential use in other sectors (Laisse et al., 2018), such as beet pulp for anaerobic digestion; ii) the energy cost of using them, in particular for dehydration (Lindberg et al., 2021); and iii) the resources needed to change the current economic rationale, develop knowledge and health regulations, and build new value chains and farming practices to create animal feed that contains large proportions of co-products (Laisse et al., 2018), while decreasing health risks for animals (Chapoutot et al., 2018).
3.2. A 100% circular economy?
a. Localised circularities vs. an increase in the size and environmental footprint of the entire system
One criticism of CE concerns its ‘relative' rather than ‘absolute' vision, because if the economy continues to increase in size, the environmental footprints of the flows into and out of it will exceed any gains made by a greater degree of circularity (Haas et al., 2020). Some studies refer to this as "circular washing" (Marrucci et al., 2022), a new way to justify the neoliberal economy. In addition, increasing circularity at one point can increase linearity in the rest of the system and the associated energy and environmental footprints. Indeed, CE is often implemented only in part of a system (Corvellec et al., 2021), as illustrated next.
Potential alliances for monogastric livestock farming in the circular economy
In the Drôme valley of France, a cooperative established a CE model between the crop and poultry sectors to use local cereals better and diversify the income of cereal farmers by developing poultry production, for which there is strong demand and markets for eggs and meat (Madelrieux et al., 2020). The sectors are connected mainly via the feed factory, which receives one-third of the cooperative's cereals, and the poultry manure is used to fertilise the crops. This ‘integrated' poultry sector generates much of the employment in the area. However, according to a life cycle assessment, the crop and poultry production also have the largest impacts on the environment in the territory (e.g. water and energy consumption, potential soil acidification). The poultry sector depends greatly on imports of soya bean and chicks and exports of offal. Poultry slaughterhouses and meat processors export 1,250 t/year of it to the pet-food sector, while the supply cooperative struggles to collect feathers, which are a primary ingredient in N fertilisers manufacturing. Farms' consumption of their own cereals keeps cereal prices higher and absorbs the price fluctuations in poultry production. This local CE model is a way to export poultry and eggs, which are sold through traditional distribution channels, and 50% and 60% of the farms' wheat and maize, respectively, mainly to Italy and North Africa (Madelrieux et al., 2020). This local CE for part of the system, which is strongly promoted by the cooperative, cannot however be isolated from the rest of the system to assess the sustainability of the entire system.
Monogastric animals can serve other functions in a CE by adding value to food waste of the people they help to feed. Uwizeye et al. (2019) investigates replacing cereals and soya bean with lost and wasted food in several pig sectors in Japan. A national incentive policy[12], accompanied by a system of health and economic regulation, enabled the industrial pig sector to establish a value chain for lost and wasted food, whereas many countries restrict such value chains due to the risk of infectious diseases and concerns about public health. In all cases, preventing and reducing loss and waste should always remain the priority (Papargyropoulou et al., 2014).
b. A 100% circular economy is not possible: determining which flows to circularise
Institutions promote ultimately obtaining a 100% CE. Corvellec et al. (2021) highlighted the recurring criticism that promoters of CE ignore established knowledge, in particular that of thermodynamics. The laws of thermodynamics indicate that matter cannot be created or destroyed; it can only change form. Because even cyclic systems consume resources and create waste and emissions (Korhonen et al., 2018), recovery can never be 100%. Thus, a CE future in which waste no longer exists, material cycles are closed, and products are recycled indefinitely is impossible.
Recycling also has time, material, and financial costs, as it involves internalising costs that previously fell on the environment through the accumulation of waste (Giampietro, 2019). The additional energy required to operate a CE thus requires switching to renewable energy (Haas et al., 2020), with the difficulties associated with replacing energy sources mentioned previously.
Another issue is which flows should be circularised (Giampietro, 2019). Dourmad et al. (2019) mention flows to and from livestock farming (e.g. animal feed, human food, livestock waste). Flows and transfers can compete (i.e. increasing the circularity of one flow can decrease the efficiency with which another flow is used) (Van der Wiel et al., 2020), which highlights the issue of the scale at which one should aim for 100% circularity, as illustrated next for areas with high livestock density.
Flows that can be circularised in areas with high-density livestock farming
Rothwell et al. (2020) raise questions about the merits of a CE in areas with high livestock density. They investigate vulnerabilities of the agri-food system in Northern Ireland due to the supply of phosphorus (P) (i.e. risk of disrupted supplies and inflation of input prices) and its inefficient use (i.e. water pollution and impacts on biodiversity and human health). They show that the spatial and temporal distribution of P from manure is critical for the sustainability of agriculture in Northern Ireland. Its combination of locally intensive livestock production, limited availability of arable land, high cost of transporting manure, limited infrastructure for treating manure, and 57% of land classified as high risk for run-off poses significant challenges to farmers for balancing agronomic and environmental objectives. Increasing the circularity of P can improve the sustainability of P management and reduce losses, with the aim of a zero P balance. However, for regions with high livestock density, there is a trade-off between P circularity and surplus; in Northern Ireland, the P load of manure on the soil exceeds the P demand of crops by 20% (Rothwell et al., 2020). Recovering P from the waste-management sector to increase P circularity would only add to the P load already circulating in the system, thereby increasing the risk of surpluses and losses due to run-off.
Scenarios have been discussed to address this paradox, in which livestock farming can help reduce the vulnerability of crops to disruptions in the supply of synthetic fertilisers, but also has high environmental impacts (Martin-Ortega et al., 2022). They involve a variety of mechanisms and stakeholders: using economically viable technologies to treat livestock waste for easier export to areas with a deficit; relying more on the soil's past P heritage and existing reserves and meeting only the minimum crop requirements; aiming for an environmental target (1.5 kg/ha) and modifying P flows from fertilisers, animal feed, manure, and the waste-management sector accordingly; and reducing livestock populations, along with decreasing human consumption of animal products. Discussions with stakeholders will help identify socio-economic, logistical, and technological obstacles and needs.
3.3. Circular bioeconomy: can resource use and economic growth be decoupled?
Institutional visions of the bioeconomy/CE are based on the idea that resource use can be decoupled from economic growth, which is criticised as another misleading assumption (Allain et al., 2022). One argument against this idea is the rebound effect, or Jevons' paradox, which states that optimising the use of resources counter-intuitively leads to over-exploiting them (Alcott, 2005), as Jevons originally observed for coal[13].
Sorrell (2009) identifies different dimensions of the rebound effect: the interplay of supply and demand (i.e. technological innovation, improvement in the efficiency of a process, lower production cost, increased demand for the product, incentive to produce more, greater use of the initial resource) and the intention behind the increase in efficiency (e.g. decrease environmental impacts, lower costs). The rebound effect is often related to economic motivations (e.g. depletion of fossil fuels, price increases) rather than socio-ecological motivations, as we illustrate next for crop-livestock recoupling.
Rebound effect in crop-livestock recoupling
Recoupling crop and livestock production by exchanging materials within mixed farming systems is an effective way to close nutrient cycles. However, as farms are becoming increasingly specialised, one option is to recouple specialised farms at the territorial scale (Regan et al., 2017). In theory, this recoupling should result in using fewer synthetic fertilisers on crop farms and having less surplus N on livestock farms. However, this assumption is not always valid due to the rebound effect, as highlighted by Regan et al. (2017) for recoupling of crop and dairy production via cooperation between farms.
Based on four case studies of crop-livestock-recoupling strategies in Europe, Regan et al. (2017) found that the newly available resources in three of them facilitated adoption of more intensive farming practices on cooperating specialised dairy farms than on non-cooperating ones. In Spain, for example, material exchanges between crop and dairy farms and access to more land on which to spread surplus manure allowed the dairy farms to increase herd size and double the stocking rate, which decreased the benefits of cooperation (e.g. having less surplus N/ha). As the increase in the stocking rate was related to the ability to manage manure and not the ability to produce cattle feed, larger volumes of concentrated feed and fodder were imported to support the dairy farms. However, Regan et al. (2017) were unable to determine whether cooperation helped farmers to intensify their systems or was necessary to maintain systems that were already intensive.
In contrast, other studies of conventional and organic livestock farms (Martel et al., 2017) show that i) farms with a high degree of coupling have better environmental performance and economic efficiency, ii) organic farms have an above-average degree of coupling (to compensate for the lack of synthetic chemicals), and iii) effects of coupling and converting to organic farming are cumulative. Thus, the rebound effect does not always occur.
These results indicate the need to consider crop-livestock-recoupling strategies that replace purchased inputs, which impact the environment, with local resources (e.g. manure, feed) and to consider potential rebound effects. These effects will be even larger if crop-livestock recoupling is used to increase stocking rates and total livestock production rather than to reduce inputs to the entire system.