Solar radiation is one of the most important energy resources of our planet. The interest in its use as a renewable and clean energy to mitigate the greenhouse gases (GHG) effects has increased significantly. This paper evaluates the measurements of global solar radiation and its energy potential and presents a comparison between both of them, as an example of the effort to reduce GHG emissions. The measurements were made with pyranometers installed in the city of Mexicali, Baja California, located in northwestern Mexico, and the city of Yuma, Arizona, located in the southwestern United States. Separated by a distance of 96 km, both cities have a sustained development and are climatically similar, since they present numerous sunny days, extreme hot temperatures and little precipitation. The results presented show differences in their behavior and in the solar radiation measurement values, especially for the critical spring and summer seasons, with values 15.73% (0.042 kW/m²) higher in Mexicali with respect to Yuma. Energy power is estimated, and it is discussed with some variables as global solar radiation, rainfall, air temperature, relative humidity and climatology of clear, partly cloudy, and cloudy days. With this estimation, the solar energy used and GHG avoided is projected for Mexicali. It is assessed that 291 tons of GHG are prevented. The Mexicali values of potential energy are higher than those of Yuma; therefore, this solar and energy comparative study provides reasons to develop these technologies in Mexico, but solar technologies should be deployed also in Yuma. The measured data at the regional level demonstrate their importance, and the relevance of the proposed mitigation strategy for climate change.

La radiación solar es una de las fuentes de energía más importantes de nuestro planeta. El interés por su uso como energía renovable y limpia para mitigar los efectos de los gases de efecto invernadero (GEI) se ha incrementado de manera significativa. Este artículo presenta una evaluación de las mediciones de radiación solar y la estimación del potencial energético, así como una comparación de ambas, como ejemplo del esfuerzo para reducir los GEI. Las mediciones fueron realizadas con piranómetros instalados en la ciudad de Mexicali, Baja California, localizada en el noroeste de México, y en la ciudad de Yuma, Arizona, en el suroeste de EUA, que están separadas por una distancia de 96 km. Ambas ciudades muestran un desarrollo sostenido y características climáticas similares con numerosos días soleados, elevadas temperaturas extremas y escasa precipitación. Los resultados muestran diferencias tanto en su comportamiento como en las mediciones de radiación solar global, especialmente durante las estaciones críticas primavera y verano, con valores 15.73% (0.042 KW/m²) superiores en Mexicali con respecto a Yuma a pesar a pesar de su cercanía. Esto indica que los flujos de mesoescala parecen dominar los sistemas sinópticos prevalentes en la región. Se estima el potencial energético, y se analiza con algunas variables como radiación solar global, precipitación, temperatura del aire, humedad relativa y climatología de los días claros, parcialmente nublados y nublados. Con esto se estima la energía proyectada para Mexicali en caso de que se utilizara el recurso solar, y se calcula que se evitarían 291 ton de GEI. Los valores de energía potencial obtenidos en Mexicali son mayores que los registrados en Yuma, por lo que este estudio comparativo de radiación solar y energía contribuye al desarrollo de estas tecnologías en México. Los resultados de las mediciones en la región demuestran la importancia de la estrategia propuesta para mitigar el cambio climático.

In recent years a new group of ferritic-martensitic chromium steels for the use in fossil power stations has been developed with chromium contents between 9 and 12%. Typical representatives of these steels are P91, E911 and Nf616, which are nowadays widely used in the more advanced power plants. In the development phase the focus was on the mechanical properties of these steels but when taking them to practical operation conditions it turned out that much of the life-time of the materials and components is determined by their oxidation properties. Oxidation resistance is first of all a function of alloy composition. For the steels of this group it is chromium, silicon, manganese and molybdenum that decide their oxidation performance and since the contents especially of the four elements can be significantly different for the different steels there can be clear differences in oxidation behaviour. One of the most important issues from this point of view is how the concentrations of these elements change in the metal subsurface zone during operation/oxidation since if their level drops below a critical level oxidation resistance of the steels will be lost. In the work to be reported the influence of alloy composition and metal subsurface zone concentration as a function of oxidation time up to 10000 h was investigated in dry air and air up to 10% water vapour at 650 °C. The investigations comprised several of the advanced commercial 9% Cr steels including P91, E911, Nf616 and six laboratory melts of Nf616 with different amounts of silicon. As the results of the investigations show humidity, which is omnipresent in combustion environments, can dramatically accelerate oxidation. Silicon as an alloying element reduces the detrimental effect of water vapour significantly while molybdenum has a negative effect. The effects of the key alloying elements in these steels was quantified for conditions with and without water vapour in the environment including the role of mechanical load and recommendations were developed on how to guarantee the optimum oxidation resistance of these steels.