scholarly journals Assessing life's effects on the interior dynamics of planet Earth using non-equilibrium thermodynamics

2010 ◽  
Vol 1 (1) ◽  
pp. 191-246 ◽  
Author(s):  
J. G. Dyke ◽  
F. Gans ◽  
A. Kleidon
Keyword(s):  
Free Energy ◽  
Boundary Conditions ◽  
Continental Crust ◽  
Oceanic Crust ◽  
Mantle Convection ◽  
Maximum Power ◽  
Earth System ◽  
Equilibrium Thermodynamics ◽  
Non Equilibrium ◽  
Whole Earth

Abstract. Vernadsky described life as the geologic force, while Lovelock noted the role of life in driving the Earth's atmospheric composition to a unique state of thermodynamic disequilibrium. Here, we use these notions in conjunction with thermodynamics to quantify biotic activity as a driving force for geologic processes. Specifically, we explore the hypothesis that biologically-mediated processes operating on the surface of the Earth, such as the biotic enhancement of weathering of continental crust, affect interior processes such as mantle convection and have therefore shaped the evolution of the whole Earth system beyond its surface and atmosphere. We set up three simple models of mantle convection, oceanic crust recycling and continental crust recycling. We describe these models in terms of non-equilibrium thermodynamics in which the generation and dissipation of gradients is central to driving their dynamics and that such dynamics can be affected by their boundary conditions. We use these models to quantify the maximum power that is involved in these processes. The assumption that these processes, given a set of boundary conditions, operate at maximum levels of generation and dissipation of free energy lead to reasonable predictions of core temperature, seafloor spreading rates, and continental crust thickness. With a set of sensitivity simulations we then show how these models interact through the boundary conditions at the mantle-crust and oceanic-continental crust interfaces. These simulations hence support our hypothesis that the depletion of continental crust at the land surface can affect rates of oceanic crust recycling and mantle convection deep within the Earth's interior. We situate this hypothesis within a broader assessment of surface-interior interactions by setting up a work budget of the Earth's interior to compare the maximum power estimates that drive interior processes to the power that is associated with biotic activity. We estimate that the maximum power involved in mantle convection is 12 TW, oceanic crust cycling is 28 TW, and continental uplift is less than 1 TW. By directly utilizing the low entropy nature of solar radiation, photosynthesis generates 215 TW of chemical free energy. This high power associated with life results from the fact that photochemistry is not limited by the low energy that is available from the heating gradients that drive geophysical processes in the interior. We conclude that by utilizing only a small fraction of the generated free chemical energy for geochemical transformations at the surface, life has the potential to substantially affect interior processes, and so the whole Earth system. Consequently, when understanding Earth system processes we may need to adopt a dynamical model schema in which previously fixed boundary conditions become components of a co-evolutionary system.

scholarly journals Towards understanding how surface life can affect interior geological processes: a non-equilibrium thermodynamics approach

2011 ◽  
Vol 2 (1) ◽  
pp. 139-160 ◽  
Author(s):  
J. G. Dyke ◽  
F. Gans ◽  
A. Kleidon
Keyword(s):  
Continental Crust ◽  
Oceanic Crust ◽  
Mantle Convection ◽  
Dynamical Models ◽  
Geological Processes ◽  
The Earth ◽  
Uplift And Erosion ◽  
Life On Earth ◽  
Mantle Temperature ◽  
Non Equilibrium

Abstract. Life has significantly altered the Earth's atmosphere, oceans and crust. To what extent has it also affected interior geological processes? To address this question, three models of geological processes are formulated: mantle convection, continental crust uplift and erosion and oceanic crust recycling. These processes are characterised as non-equilibrium thermodynamic systems. Their states of disequilibrium are maintained by the power generated from the dissipation of energy from the interior of the Earth. Altering the thickness of continental crust via weathering and erosion affects the upper mantle temperature which leads to changes in rates of oceanic crust recycling and consequently rates of outgassing of carbon dioxide into the atmosphere. Estimates for the power generated by various elements in the Earth system are shown. This includes, inter alia, surface life generation of 264 TW of power, much greater than those of geological processes such as mantle convection at 12 TW. This high power results from life's ability to harvest energy directly from the sun. Life need only utilise a small fraction of the generated free chemical energy for geochemical transformations at the surface, such as affecting rates of weathering and erosion of continental rocks, in order to affect interior, geological processes. Consequently when assessing the effects of life on Earth, and potentially any planet with a significant biosphere, dynamical models may be required that better capture the coupled nature of biologically-mediated surface and interior processes.

scholarly journals Analysis of Existing Thermodynamic Models of the Liquid Drop Deposited on the Substrate—A Sufficient Condition of the Minimum Free Energy of the System

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 791
Author(s):  
Torbus ◽  
Dolata ◽  
Jakiela ◽  
Michalski
Keyword(s):  
Free Energy ◽  
Liquid Droplet ◽  
Minimum Free Energy ◽  
Solid Substrate ◽  
Negative Energy ◽  
Contact Angles ◽  
Equilibrium Thermodynamics ◽  
Three Phase ◽  
The Moment ◽  
Non Equilibrium

On the basis of the principles of non-equilibrium thermodynamics, the following condition was determined: necessary and sufficient for the occurrence of a minimum free energy of a liquid droplet deposited on a solid substrate in a gaseous environment in an isothermal and isochoric system. Only for positive values of the energy of three-phase tension line (shrinking the wetting circumference) for small and large contact angles can the system not reach this minimum. Without exceeding a certain free energy limit, it is not possible for the drop to spontaneously spread over the surface. For zero and negative energy of three-phase tension line (stretching the wetting circumference), the system can always reach a minimum of free energy. The developed equations allow determining the change of free energy occurring between any two stationary states when the droplet volume and physicochemical parameters characterizing energies at the interfaces are known. For a known set of such parameters, the equations allow determining the trajectory of free energy changes in the system as a function of the contact angle from the moment the drop comes into contact with the substrate. The application of the principles of non-equilibrium thermodynamics makes it possible to treat a real system as one in which the drops do not evaporate. However, the system has to be isothermal.

scholarly journals Minimization of a free-energy-like potential for non-equilibrium flow systems at steady state

2010 ◽  
Vol 365 (1545) ◽  
pp. 1323-1331 ◽  
Author(s):  
Robert K. Niven
Keyword(s):  
Free Energy ◽  
Steady State ◽  
Entropy Production ◽  
Equilibrium Thermodynamics ◽  
Turbulent Fluid Flow ◽  
System A ◽  
Flow Heat ◽  
Observed Behaviour ◽  
New Formulation ◽  
Non Equilibrium

This study examines a new formulation of non-equilibrium thermodynamics, which gives a conditional derivation of the ‘maximum entropy production’ (MEP) principle for flow and/or chemical reaction systems at steady state. The analysis uses a dimensionless potential function ϕ st for non-equilibrium systems, analogous to the free energy concept of equilibrium thermodynamics. Spontaneous reductions in ϕ st arise from increases in the ‘flux entropy’ of the system—a measure of the variability of the fluxes—or in the local entropy production; conditionally, depending on the behaviour of the flux entropy, the formulation reduces to the MEP principle. The inferred steady state is also shown to exhibit high variability in its instantaneous fluxes and rates, consistent with the observed behaviour of turbulent fluid flow, heat convection and biological systems; one consequence is the coexistence of energy producers and consumers in ecological systems. The different paths for attaining steady state are also classified.

Non-Equilibrium Thermodynamics of Boundary Conditions

1967 ◽  
Vol 22 (8) ◽  
pp. 1269-1280 ◽  
Author(s):  
L. Waldmann
Keyword(s):  
Heat Flow ◽  
Boundary Conditions ◽  
Stokes Equations ◽  
Immiscible Fluids ◽  
Surface Heat ◽  
Thermal Slip ◽  
Equilibrium Thermodynamics ◽  
Surface Heat Flow ◽  
Mechanical Surface ◽  
Non Equilibrium

In part I a well-known pair of cross phenomena, thermo-osmosis and mechano-caloric effect, in a dense gas is treated by a “thermo-hydrodynamical” method: the FOURIER and NAVIER-STOKES equations are adopted for heat conduction and viscous motion whereas in the boundary conditions MAXWELL’S thermal slip (3.1) and a mechanical surface heat flow (3.7) appear. Both of them are connected by an ONSAGER relation (3.9). So far, the underlying geometry was a special one (circular cylindrical capillary). In part II the boundary conditions problem at the interface between two immiscible fluids is considered in the general case, by the method of continuum non-equilibrium thermodynamics. The fluids are in viscous motion and conducting heat, such that total mass, momentum, angular momentum and energy are conserved. It is assumed that none of these quantities is concentrated in the interface (vanishing densities per unit area). This leads to the global conditions (6.3) for the forces and (6.8) for the normal energy flows at the interface. After the general expression (7.8) for interfacial entropy production is at hand, the global conditions are replaced by stronger local ones in the vein of thermo-hydrodynamics. Two possibilities are considered in this context: the interface a) does not and b) does carry two-dimensional flows of momentum and energy. In case a) the ensuing local boundary conditions are merely mechanical slip for the velocity fields and temperature jump for the temperature fields. In addition to these, in case b) a pair of cross effects naturally comes out, namely thermal slip and mechanical surface heat flow, and a thermal surface heat flow as well. This reassures the results of part I which had been obtained in a somewhat indirect way.

Sign in / Sign up

Export Citation Format

Share Document