《Comparative analysis of effect of methanol and ethanol on Karanja biodiesel production and its optimisation》
Extensive use of fossil fuel resources especially petroleum has resulted in situation to look for alternative fuel sources. Biodiesel offers a good choice due to its renewable nature. In recent times, mainly methanol has been used in transesterification reaction for biodiesel production as it is derived from fossil sources, and biodiesel produced cannot be termed as completely renewable while other alcohols such as ethanol, being obtained from renewable sources such as potatoes, sugarcane, grains, corn and sorghum can be used for transesterification reaction. The aim of this work was to investigate the impact of ethanol on biodiesel production from Karanja oil and then optimise process variables for transesterification process. Further a comparison was done in optimised reaction parameters for methanolysis and ethanolysis. The result of experimental investigation shows that Karanja biodiesel yield of 91.05% was achieved with molar ratio of 10.44:1 for methanol using 1.22% w/w KOH as catalyst for 90.78 min at the temperature of 66.8 °C. On the other hand for, ethanolysis, optimised reaction conditions were, 8.42:1 molar ratio, 61.3 °C reaction temperature with 1.21% of catalyst and 120 min of reaction time to obtain yield of 77.4%.
Like ester type biodiesel fuel, green diesel is a next generation transportation fuel emerging due to the need for a renewable replacement of internal combustion engine fuel, which is also fully compatible with existing automotive powertrain systems. Besides other limitations, the main obstacle for wider application of such renewable fuels is their relatively high production cost, depending mainly on the raw material cost and the application of more efficient processing technology. Green diesel and ester type biodiesel can be produced from waste vegetable oil by catalytic hydrogenation, homogeneous alkali catalysed transesterification and supercritical non-catalytic transesterification. Techno-economic analysis and the sensitivity analysis reveal that economics of these production technologies strongly depend on the process unit capacity and the cost of feedstock. Green diesel production by catalytic hydroprocessing located in a petroleum refinery appears to be the most cost effective option for unit capacity close to and above 200,000 tonnes/year. Conventional ester biodiesel process and non-catalytic ester biodiesel process under supercritical conditions are less profitable at specified capacity. Unit capacities of the investigated processes which are below 100,000 tonnes/year are likely to result in negative net present values after 10 years of project lifetime.
We study changes in the aggregate carbon intensity (ACI) for electricity at the global and country levels. The ACI is defined as the energy-related CO2 emissions in electricity production divided by the electricity produced. It is a performance indicator since a decrease in its value is a desirable outcome from the environmental and climate change viewpoints. From 1990 to 2013, the ACI computed at the global level decreased only marginally. However, fairly substantial decreases were observed in many countries. This apparent anomaly arises from a geographical shift in global electricity production with countries having a high ACI increasingly taking up a larger electricity production share. It is found that globally and in most major electricity producing countries, reduction in their ACI was due mainly to improvements in the thermal efficiency of electricity generation rather than to fuel switching. Estimates of the above-mentioned effects are made using LMDI decomposition analysis. Our study reveals several challenges in reducing global CO2 emissions from the electricity production sector although technically the reduction potential for the sector is known to be great.