An alternative form of the Second Law of Thermodynamics for systems experiencing volume-change work transfer interactions has been presented in a companion paper, from which the volume generation concept emerges in a similar way with what happens with entropy generation in the well established thermodynamics. The volume balance equation and the new concept of volume generation are introduced into the framework of thermodynamics in the present work. A volume balance equation is developed to apply to closed or open systems. Thermomechanical availability is evaluated taking into account these new developments and emphasis is given to the physical meaning of volume generation, which is closely related with the lost available work associated with irreversibilities of volume-change work transfer interactions. Special attention is given to the fundamental relation of thermodynamics, the volume generation concept being of crucial importance to set the conditions under which this relation applies to reversible or/and to irreversible processes. (c) 2007 Elsevier Ltd. All rights reserved.