Developing non-food applications of biomass raises sustainability concerns because of its potential impacts on land-use changes, biodiversity or water resources and its interactions with food production. This chapter addresses these complex interactions at different scales to trace direct competition but also possible complementarities and synergies between green chemistry and the agri-food sector, from the point of view of biomass procurement and valorization. It provides agronomic background on cropping systems producing food and non-food products, reviews the methods available to assess biomass supply potentials at local to global scale, and illustrates their application in case-studies involving different organization levels. The chapter concludes by advocating inter-disciplinarity and inter-sectoral approaches when tackling the issue of sustainable biomass procurement and use.