This third chapter concludes the first part of the book with a specific focus on the current mainstreamed conceptualisation of the bioeconomy, including expectations and criticisms about its potential societal contribution. Drawing from the green and circular economy – two ideas popularised during the past two decades in the academic, policy, and practitioner communities – the chapter discusses future avenues for the conceptual development and practical implementation of the bioeconomy.

A distinct branch of socio-environmental research, grounded in the physical principles of conservation of mass and energy, applies a systems modeling approach to society–environment interactions, emphasizing material and energy flows. Technology and technological advancement, alongside population and resources, feature prominently in determining the metabolisms linking society and nature. This approach mostly focuses on analyzing industrial systems (e.g. Ayers and Kneese, Meadows et al., Beck, Graedel et al.) but also offers insight on agrarian societies (Boserup) and hunter-gatherer communities (Fischer–Kowalski). Across these levels of social organization, technology is variously viewed as overcoming the limits nature places on society, as facilitating the resource exploitation and production of waste that lead to social collapse, or as the basis for internalizing externalities and building a circular economy. Key readings constituting this branch of socio-environmental research draw on tools from economics and engineering, such as input–output models, system models, feedback loops, environmental impact analysis, and material and energy flow accounting.

Energy usage by an exponentially increasing human population has created environmental problems that are stressing several ecosystems on earth. The concept of eco-exergy (which is not equivalent to mechanical work) has been used to explain the relationship between energy use and the formation of complex organisms in ecosystems. The harmonious co-existence in ecosystems has inspired the notion of industrial ecology as a paradigm for the improvement of exergetic efficiencies and complete utilization of resources. The exergy-environment nexus and the implications of exergy analyses on sustainable development are critically examined in this chapter. Environmental exergonomics, exergoenvironmental analysis that includes eco-indicators, life-cycle exergy analysis, and sustainability indices are theoretical tools that use exergy and other thermodynamic variables to define the state of the environment and to recommend industrial practices that would alleviate the detrimental effects of energy use and would promote global environmental stewardship and sustainability.