Direct energy conversion of heat to electricity using AMTEC
Former renewable technologies, which did not prosper at that time due to engineering and material limitations, emerge once again, as in the case of the Alkali Metal Thermal to Electric Converter (AMTEC). This energy converter transforms heat to electricity through an electrochemical process at high temperature (700 - 1000 °C). At Karlsruhe Institute of Technology (KIT) an AMTEC test cell and an AMTEC TEst FAcility (ATEFA) have been designed and are under construction. The paper gives an overview of the history of AMTEC converter and its development; and presents the ATEFA facility included its latest progress in design and construction. In addition, a scoping study on the stability of PEEK polymer compound in liquid sodium environment was started and is reported.
Slow degradation and electron conduction in sodium/beta-aluminas
Slow degradation was observed in sodium/beta-alumina electrolytes subjected to long term in cycling Na/S cells. The degradation propagated as a layer from the sodium side. It involves the internal deposition of sodium metal during current passage. This Mode II degradation was distinct from chemical colouration and from the Mode I failure (Poiseuille pressure due to cathodic deposition driving isolated cracks). Degradation was also observed on the sulfur side of the electrolyte and was associated with the graphite felt “imprinting effect.” It is thought that the Mode II degradation resulted from electron conduction into the solid electrolyte from the beta-alumina/sodium metal interface during the charging cycle.
Sur l'Utilisation d'une electrode ponctuelle dans les cellules à oxyde electrolyte solide. II. Application a la détermination des tensions d'oxydoreduction des defauts ponctuels dans l'electrolyte
Resume Une methode de mesure directe des tensions d'oxydoreduction des defauts ponctuels dans les electrolytes solides est decrite. Des mesures ont ete effectuees sur plusieurs electrolytes solides a base de dioxyde de zirconium ZrO2 ou de dioxyde de hafnium HfO2. Les resultats obtenus nous ont permis de preciser le domaine d'application de ces electrolytes en particulier en ce qui concerne la variation de leur conductivite electronique. Ils nous ont permis egalement de determiner les reactions qui interviennent lors de la reduction electrochimique de la zircone.