Coupled reaction free energy and energy "stored" in selfassembled structures. The focus on molecules as "fuel" has also led to the idea of energy from the fuel being stored in selfassembled structures at non-equilibrium steady state. However, given that such networks are driven by the free energy change associated with mass action in the system rather than a specific energetic property of the coupled reaction, this is potentially misleading. This is not to say that such a reaction network cannot result in an "unstable" distribution between monomers and the self-assembled state that would spontaneously disassemble were the coupled reaction "switched off" (i.e., if all reaction components were rapidly removed). However, the distribution obtained is a consequence of kinetic asymmetry, as well as the free energy change associated with mass action, and is not a simple function of the free energy of a "fuel" to "waste" reaction. The same applies to molecular switches and motors operating at a non-equilibrium steady state.