How does the earth system generate and maintain thermodynamic disequilibrium and what does it imply for the future of the planet?

TL;DR

This paper applies non-equilibrium thermodynamics to quantify Earth's chemical disequilibrium, highlighting life as the main energy source, and discusses sustainable human energy use and planetary engineering to maintain Earth's free energy generation.

Contribution

It introduces a thermodynamic framework to quantify Earth's disequilibrium and demonstrates that life significantly drives free energy generation, with implications for sustainable future energy strategies.

Findings

Life generates orders of magnitude more free energy than abiotic processes.

Earth's maximum thermodynamic efficiency is much less than Carnot limit.

Human activity consumes significant free energy, affecting Earth's energy budget.

Abstract

The chemical composition of the earths atmosphere far from equilibrium is unique in the solar system and has been attributed to the presence of widespread life. Here I show that this perspective can be quantified using non-equilibrium thermodynamics. Generating disequilibrium in a thermodynamic variable requires the extraction of power from another thermodynamic gradient, and the second law of thermodynamics imposes fundamental limits on how much power can be extracted. When applied to complex earth system processes, where several irreversible processes compete to deplete the same gradients, it is easily shown that the maximum thermodynamic efficiency is much less than the classic Carnot limit, so that the ability of the earth system to generate power and disequilibrium is limited. This approach is used to quantify how much free energy is generated by various earth system processes to generate chemical disequilibrium. It is shown that surface life generates orders of magnitude more chemical free energy than any abiotic surface process, therefore being the primary driving force for shaping the geochemical environment at the planetary scale. To apply this perspective to the possible future of the planet, we first note that the free energy consumption by human activity is a considerable term in the free energy budget of the planet, and that global changes are closely related to this consumption of free energy. Since human activity and demands for free energy is going to increase in the future, the central question is how human free energy demands can increase sustainably without negatively impacting the ability of the earth system to generate free energy. I illustrate the implications of this thermodynamic perspective by discussing the forms of renewable energy and planetary engineering that would enhance overall free energy generation and thereby "empower" the future of the planet.