Keywords: General equilibrium modelling, Welfare programs, Non-convexities, Novel Protein Foods, Environmental life cycle assessment.Intensive animal production systems inEurope, particularly in theNetherlands, result in a series of environmental problems mainly due to manure surplus. This thesis aims to make contributions to identifying solutions to the problems related to protein production and consumption.The first contribution concerns the theoretical modelling of environmental problems. This includes how to represent environmental impacts in economic models considering the interactions between the economic system and the environmental system, and how to deal with the relevant non-convexities.We represent the environmental impacts theoretically by including the biophysical processes of environmental changes and feedbacks to the economy in welfareoptimisationand equilibrium models. This often brings non-convexities to the model, and thushas implications for policy recommendations, because a non-convex program usually has multiple local optima and has the difficulty of decentralisation. Particularly we illustrate how to solve a non-convex program using parameterisation for the interaction between pork and crop production and how to check decentralisability of the welfare optimum.The second contribution is a systematic analysis of protein chains, which provides information on their environmental pressures. We use the environmental life cycle assessment (LCA) to compare the environmental pressures of a Dutch pork chain and a pea-based chain for Novel Protein Foods (NPFs). We concluded that NPFs are environmentally more friendly than pork based on per unit of protein consumption in terms of environmental pressure indicators.The third contribution is the empirical application of Applied General Equilibrium (AGE) models to analyse the economic and environmental impacts of enhanced consumption of NPFs under different scenarios in a global context. Our model results show that an exogenous shift from animal protein ...