Designing Money for a Natural Interest Rate of Zero—An Exergy‐Based Monetary System

ABSTRACT This paper proposes a new design for a monetary system grounded in the laws of physics and in which the rate of interest would converge to zero as envisioned by Silvio Gesell. Drawing on the first and second laws of thermodynamics, the concept of exergy is introduced as a biophysical numeraire that directly links monetary circulation to real productive activity. The proposed framework replaces the exponential growth logic inherent in interest‐bearing money with a logistic growth model reflecting the finite carrying capacity of ecological systems. Money creation is strictly limited by the annually harvested exergy used in economic production and implemented through a transparent institutional procedure. Since exergy cannot reproduce itself, interest‐bearing money creation becomes physically infeasible, leading endogenously to a natural interest rate of zero. The paper discusses implications for economic stability, banking, investment behavior, and sustainability, arguing that an exergy‐based monetary architecture would enable a stationary flow equilibrium without a systemic growth imperative.