Author(s):  
Mayke Feitosa Progênio ◽  
Claudio José Cavalcante Blanco ◽  
Josias da Silva Cruz ◽  
Felipe Antônio Melo da Costa Filho ◽  
André Luiz Amarante Mesquita

2021 ◽  
Author(s):  
Mehmet Ozcelik

Abstract The use of renewable energy is critical to the long-term development of global energy. Geothermal Power Plants (GPP) differ in the technology they use to convert the source to electricity (dual, single flash, double flash, back pressure, and dry steam) as well as the cooling technology they use (water-cooled and air-cooled). The environmental consequences vary depending on the conversion and cooling technology used. Environmental consequences of geothermal exploration, development, and energy generation includes land use and visual impacts, microclimatic impacts, impacts on flora-fauna and biodiversity, air emissions, water quality, soil pollution, noise, micro-earthquakes, induced seismicity, and subsidence. It can also have an impact on social and economic communities. As geothermal activity progresses from exploration to development and production, these effects become more significant. Before beginning geothermal energy activity, the positive and negative aspects of these effects should be considered. The number of GPPs in the Büyük Menderes Graben (BMG) geothermal area is increasing rapidly. According to the findings, in order to reduce the environmental and social impacts of the GPPs in the BMG, resource conservation and development, production sustainability, and operational problems should be continuously monitored.


Author(s):  
Steven D. Toteda

Zirconia oxygen sensors, in such applications as power plants and automobiles, generally utilize platinum electrodes for the catalytic reaction of dissociating O2 at the surface. The microstructure of the platinum electrode defines the resulting electrical response. The electrode must be porous enough to allow the oxygen to reach the zirconia surface while still remaining electrically continuous. At low sintering temperatures, the platinum is highly porous and fine grained. The platinum particles sinter together as the firing temperatures are increased. As the sintering temperatures are raised even further, the surface of the platinum begins to facet with lower energy surfaces. These microstructural changes can be seen in Figures 1 and 2, but the goal of the work is to characterize the microstructure by its fractal dimension and then relate the fractal dimension to the electrical response. The sensors were fabricated from zirconia powder stabilized in the cubic phase with 8 mol% percent yttria. Each substrate was sintered for 14 hours at 1200°C. The resulting zirconia pellets, 13mm in diameter and 2mm in thickness, were roughly 97 to 98 percent of theoretical density. The Engelhard #6082 platinum paste was applied to the zirconia disks after they were mechanically polished ( diamond). The electrodes were then sintered at temperatures ranging from 600°C to 1000°C. Each sensor was tested to determine the impedance response from 1Hz to 5,000Hz. These frequencies correspond to the electrode at the test temperature of 600°C.


Author(s):  
John D. Rubio

The degradation of steam generator tubing at nuclear power plants has become an important problem for the electric utilities generating nuclear power. The material used for the tubing, Inconel 600, has been found to be succeptible to intergranular attack (IGA). IGA is the selective dissolution of material along its grain boundaries. The author believes that the sensitivity of Inconel 600 to IGA can be minimized by homogenizing the near-surface region using ion implantation. The collisions between the implanted ions and the atoms in the grain boundary region would displace the atoms and thus effectively smear the grain boundary.To determine the validity of this hypothesis, an Inconel 600 sample was implanted with 100kV N2+ ions to a dose of 1x1016 ions/cm2 and electrolytically etched in a 5% Nital solution at 5V for 20 seconds. The etched sample was then examined using a JEOL JSM25S scanning electron microscope.


Author(s):  
Marjorie B. Bauman ◽  
Richard F. Pain ◽  
Harold P. Van Cott ◽  
Margery K. Davidson

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