Electrochemical energy conservation

An HEM is a membrane-form polymer electrolyte capable of conducting hydroxide anions (OH ), and an HEI is a binder-form polymer electrolyte capable of not only conducting hydroxide anions but also creating triple-phase boundary in the electrode catalyst layer. HEMs and HEIs are already used in hydroxide exchange membrane fuel cells (HEMFCs) and can also be used in many other electrochemical energy conservation and storage devices. 

Symposium-Conducting organic polymers in energy conservation and storage. The Electrochemical Society Meeting, San Franda o, May 1983... 

The quantum efficiency for solid-state devices, e.g. solar cells, is always below unity. For n-type silicon electrodes anodized in aqueous or non-aqueous HF electrolytes, quantum efficiencies above unity are observed because one or more electrons are injected into the electrode when a photogenerated hole enters the electrolyte. Note that energy conservation is not violated, due to the enthalpy of the electrochemical dissolution reaction of the electrode. 

Fig. 7. Proposed function of electrochemical H and Na" potentials in energy conservation coupled to CH4 formation from CO2/H2. The Na+/H antiporter is involved in the generation of from A/iNa ". CHO-MFR, formyl-methanofuran CH2=H4MPT, methylene-tetrahydromethanopterin CH3-H4MPT, methyl-tetrahydromethanopterin CH3-S-C0M, methyl-coenzyme M. The hatched boxes indicate membrane-bound electron transport chains or membrane-bound methyltransferase catalyzing either Na or translocation (see Figs. 5, 6 and 12). ATP is synthesized via membrane-bound H -translocating ATP synthase. The stoichiometries of Na" and translocation were taken from refs. [105,107,167]. x, y and z are unknown stoichiometric factors.

The proposed functions of electrochemical potentials of H and Na in energy conservation coupled to acetate fermentation to CH4 and CO2 are summarized in Fig. 11 CH3-S-C0M reduction, including heterodisulfide reduction, and the oxidation of enzyme-bound CO are coupled with the primary translocation of generating AfiFl, which drives the synthesis of ATP via Fl -translocating ATPase. Methyltransferase is coupled with the primary translocation of Na ions across the membrane. The A/iNa generated can be converted by the Na /H antiporter into a Ap,U which then drives ATP synthesis. 

This chapter is concerned with the proton circuit which in the chemiosmotic scheme links the generators and utilizers of proton electrochemical potential (A/if ) [1,2]. Since the topic has been covered extensively in a recent monograph [3], this chapter will attempt to avoid repetition by concentrating on the ionic circuitry found in association with energy conserving organelles, and no attempt will be made to discuss the structures of the black boxes of the membrane. 

Fig. 10.1. The thermogenin concept. In the model for mitochondrial thermogenesis presented here, the thermogenesis is assumed to originate from the action of the brown fat-specific protein, thermogenin. Thermogenin acts as an OH conductor, regulated by cytosolic nucleotides (here shown as ATP) and by the so-called mediator (see Section 5). The OH neutralizes the H electrochemical gradient created by respiration, and substrate oxidation occurs unhampered by this gradient and without energy conservation. (Adapted from Ref. 6.)...

Report of the Committee on Electrochemical Aspects of Energy Conservation... 

The committee recognized that the electrochemical science base relevant to energy conservation is also relevant to many other... 

D.Ohms, K.Wiesener UNESCO Expert Workshop "Contrib. of Electrochem. to Energy Conserv. and Saving and Environm.Protect.", Gaussig Castle, Oct 30-Nov 3, 1989, Dresden University of Technology, Proceed., TU Dresden (1990) 153-164.. 

A.B. LaConti, A.R. Fragale, andJ.R. Boyack, Solid Polymer Electrolyte Electrochemical Cells Electrode and Other Materials Considerations, In J.D.E. McIntyre, S. Srinivasan, and F.G. Will (eds). Electrode Materials and Processes for Energy Conservation, PV 77-6, The Electrochemical Society, Pennington, NJ (1977), p. 354. 

E. Vieil, Simple and direct interpretation of phase angles or derivation degrees in term of energy conservation vs. dissipation with Formal Graphs, J. Solid State Electrochem., 15, 2011, 955-969, doi 10.1007/ S10008-011-1308-9. 

The multi-physics of SOFCs are governed by the mass, momentum, and energy conservation equations, and the chemistry and electrochemistry. The governing equations of SOFCs are tightly coupled and changes to one aspect of the fuel cell can drastically affect another. For example, the rate and composition of the fuel flow in the anode will affect the temperature distributions in the cell, which can induce stresses due to mismatches between the coeSicients of thermal expansion of the various layers in the SOFC. The fuel flow wiU also affect the overall performance of the fuel cell based on the distribution of species in the anode and the electrochemical reactions. 

To study the stresses in the system, it is first necessary to calculate the temperature distributions of the SOFC stack. Owing to the coupled nature of the SOFC multi-physics, the temperatures in the stack wiU affect both the electrochemical performance and the mechanical stresses of the stack [49]. The electrochemical performance of the SOFC is coupled to the temperature through the Nernst equation [Eq. (26.11)]. Stack-level models are often used to consider the temperature distributions and how the operating conditions and design of the stack affect the temperatures [1, 48, 49]. In these models, the energy conservation equation [Eq. (26.7)] is solved in the gas and sohd phases, and includes the effects of convection in the fuel and air charmels, radiation between the soHd tri-layer and the gas, radiation between the stack and its surroundings, conduction through the tri-layer, and heat sources due to chemical and electrochemical reactions [1, 50]. The balance... 

Gupta SL, Tryk D, Daroux M, Aldred W, Yeager E. In Chin D, editor. Proceedings of the Symposium on Load Leveling and Energy Conservation in Industrial Processes. Pennington, NJ The Electrochemical Society, 1986 207. 

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