Journal article: Economic analysis is increasingly addressing long-term issues (such as global warming) that require a dynamic baseline for the world economy. In this article, we develop a three-factor (capital, energy, labour) macroeconometric (MaGE – Macroeconometrics of the Global Economy) model, and project growth for 147 countries to 2050. We improve on the literature by the following: (i) accounting for the energy constraint through dynamic modelling of energy productivity, (ii) modelling female participation rates consistent with education catch-up, (iii) departing from the assumptions of either a closed economy or full capital mobility (by applying a Feldstein-Horioka type relationship between saving and investment rates), and (iv) offering a fully consistent treatment of the Balassa-Samuelson effect. These innovative features have a sizeable impact on projected GDP.