On the estimate of the mechanical power that can be processed by the earth

The Earth is a finite system closed with respect to mass and open with respect to energy, the in and out radiation fluxes. Due to the symmetry of the body and the periodicity of the incoming-energy driving term it is presumable that the circulation of mass and heat is a very complex but steady state. This is a nonuniform state or a far from thermodynamic equilibrium state; as such the question arises of what is the availabilityor maximum mechanical work that can be extracted from this system. The concept of efficiency for a complex non-equilibrium system is formulated and approximate evaluations from two simplified models in which the wind circulation is neglected are driven