Van Reststof tot Grondstof: Circulaire Verdienmodellen voor Biogebaseerde Meststoffen

As our global food system faces increasing pressure to operate within the planet's ecological limits, the shift from a linear to a circular economy offers a promising solution. The circular model emphasizes the continual and sequential use of resources to maximize their value. Within the food system, this approach can be achieved by minimizing waste and recycling nutrients, ensuring that resources like food waste and agricultural residues are reused in a way that maximizes their economic and ecological value. Bio-based fertilizers, derived from organic residue streams, are a key component in closing nutrient loops to reduce reliance on mineral fertilizers and mitigate environmental impacts related to their production and use. However, successful implementation of bio-based fertilizers requires robust business models that account for value creation, value delivery and value capture, balancing economic and environmental viability. Despite technological advancements, there is a need for comprehensive business models that guarantee technical feasibility, economic and environmental sustainability, and market desirability of these products, particularly in the context of regional nutrient cycles and the adoption of circular practices in agriculture. By focusing on bio-based fertilizers closing regional nutrient loops, this dissertation aims to develop and validate innovative business models that encompass a holistic view on sustainability and circularity in the food system. The dissertation is structured to achieve three core objectives: (1) to develop a typology of sustainable circular business models (2) to explore the viability of bio-based fertilizers and their associated business models in terms of costs and sustainability, and (3) to identify factors that enhance the desirability of bio-based fertilizers among farmers. Chapter 1 sets the scene by introducing circular food systems, bio-based fertilizers and business models. Using an overarching business model development and validation framework, this chapter outlines the objectives of this dissertation and how these are addressed throughout the successive chapters. Following this, chapter 2 introduces a comprehensive typology of sustainable circular business modes through an in-depth analysis of business model components based on existing archetypes. To illustrate its applicability to the valorization of organic waste streams, this analysis is supported by a literature review. This typology serves as a foundation for the subsequent analysis and model development in the dissertation. The business models identified in chapter 2 are incorporated into chapter 3, where they are applied to optimize the fertilizer mix for a Flemish horticultural farmer, focusing on minimizing private fertilizer costs. The goal of the model is to minimize fertilizer cost for a representative farmer while ensuring nutrient uptake, adhering to nutrient standards, and using crop residues. The model incorporates bio-based fertilizer production from crop residues through composting, anaerobic digestion or leaving crop residues on the field. These bio-based fertilizers are compared against purchasing mineral fertilizer, commercial compost or pig slurry. Additionally, scenario analyses on changing cost or policy parameters assess the robustness of the results. The results point out that the cost-optimal fertilizer mix involves both mineral fertilizers and BBF, including pig slurry and certified compost. In addition, it is cost optimal to leave the crop residues on the field after harvest. Chapter 4 expands the model used in chapter 3 to include not only the private costs of fertilizer application but also the social costs, integrating environmental externalities into a multi-objective optimization model to assess the broader societal impacts of fertilizer choices. To do so, life cycle assessments are carried out for the fertilizers under study. The resulting environmental impacts are translated into external costs using monetary valuation of the environmental impacts. These environmental costs are added to the private cost minimization model to represent a multi-objective social cost minimization. The results show that external costs of fertilization are a multiple of the private farmer costs. Additionally, they show that a business model relying on cooperation between farmers and waste treatment companies for the treatment of part of the farmer's crop residues with anaerobic digestion and composting could be an effective strategy to replace the certified compost in the private optimum. Nevertheless, the results also show that the optimal application rates depend on the environmental impact, with ammonia emissions contributing heavily to the external costs. Thus, alternative optima with higher application rates of compost from crop residues are also possible. In chapter 5, in order to assess bio-based fertilizer desirability, the rational cost optimization reasoning developed in chapter 3 is combined with behavioral parameters to explore factors influencing the adoption of bio-based fertilizers among farmers in Flemish horticulture. This chapter employs a spatially explicit agent-based model coupled with a linear programming framework to incorporate rational and behavioral factors. The model examines the influence of several social variables and economic conditions. The results show how social networks influence BBF adoption, as do energy prices and waste treatment company profit margins. Having studied bio-based fertilizer viability and desirability for the case of Flanders, chapter 6 shifts focus to the Colombian context to broaden the geographical applicability of the research findings. In this chapter, preferences of Colombian farmers for bio-based fertilizers are investigated using a discrete choice experiment carried out with a sample of 270 farmers in the region of Valle del Cauca. Moreover, the impact of information provision on these preferences is assessed by means of an information video elaborating on the differences between bio-based fertilizers and mineral fertilizers. The results of this study indicate positive preferences for bio-based fertilizers with a low price, high organic matter, high nutrient content, available at close proximity to the farm and with a fast nutrient release. We find significant heterogeneity in preferences, allowing to group farmers into three classes with different preferences. Lastly, the results confirm that information provision increases the appreciation of organic matter and slow-release fertilizers. Finally, chapter 7 summarizes the findings from the preceding chapters, reflecting on the contributions to literature and limitations of the research and outlining opportunities for future research. The chapter concludes by reflecting on policy implications. The results of this dissertation are useful for policy makers to understand the adoption and acceptance of bio-based fertilizers. Additionally, they can contribute to the exploration of alternative management options for crop residues, for instance the establishment of biomass hubs, where organic residue streams are brought together to utilize them for different valorization technologies to maximize their value. These hubs, which can be established through value chain cooperation as shown in this dissertation, have the potential to be a key cornerstone for the development of circular food systems.