The influence of thermodynamics on the emerging transdisciplinary field of 'ecological economics‘ is critically reviewed from an interdisciplinary perspective. It is viewed through the lens provided by the 'bioeconomist' Nicholas Georgescu-Roegen (1906–1994) and his advocacy of 'the Entropy Law' as a determinant of economic scarcity. It is argued that exergy is a more easily understood thermodynamic property than is entropy to represent irreversibilities in complex systems, and that the behaviour of energy and matter are not equally mirrored by thermodynamic laws. Thermodynamic insights as typically employed in ecological economics are simply analogues or metaphors of reality. They should therefore be empirically tested against the real world.