This chapter presents a new field of research – termed exergy economics – which offers a new perspective on the contribution of energy to economic growth. The approach is based upon the thermodynamic concept of useful exergy and the associated measures of exergy efficiency. Contrary to orthodox economics, the chapter argues that improvements in exergy efficiency are a key driver of productivity improvements, and that useful exergy is a key driver of economic growth. The chapter summarises the theoretical arguments underpinning these claims, reviews the recent empirical work in this area and highlights some of the implications.