With industrial development growing rapidly, there is a need for environmentally sustainable energy sources. Bioethanol (ethanol from biomass) is an attractive, sustainable energy source to fuel transportation. Based on the premise that fuel bioethanol can contribute to a cleaner environment and with the implementation of environmental protection laws in many countries, demand for this fuel is increasing. Efficient ethanol production processes and cheap substrates are needed. Current ethanol production processes using crops such as sugar cane and corn are well-established; however, utilization of a cheaper substrate such as lignocellulose could make bioethanol more competitive with fossil fuel. The processing and utilization of this substrate is complex, differing in many aspects from crop-based ethanol production. One important requirement is an efficient microorganism able to ferment a variety of sugars (pentoses, and hexoses) as well as to tolerate stress conditions. Through metabolic engineering, bacterial and yeast strains have been constructed which feature traits that are advantageous for ethanol production using lignocellulose sugars. After several rounds of modification/evaluation/modification, three main microbial platforms, Saccharomyces cerevisiae, Zymomonas mobilis, and Escherichia coli, have emerged and they have performed well in pilot studies. While there are ongoing efforts to further enhance their properties, improvement of the fermentation process is just one of several factors-that needs to be fully optimized and integrated to generate a competitive lignocellulose ethanol plant.

Fuel ethanol production from lignocellulose: a challenge for metabolic engineering and process integration.

Engine performance and exhaust gas emissions of methanol and ethanol–diesel blends

The effects of ethanol―unleaded gasoline blends on engine performance and exhaust emissions in a spark-ignition engine

http://maghaleh2012.persiangig.com/document/yasaman/ls2.pdf

Experimental and theoretical investigation of using gasoline–ethanol blends in spark-ignition engines

Fossil fuels are the most imperative parameters to flourish the every sphere of modern civilization including industrial development, transportation, power generation and easing the accomplishment of works. The rapid increase in usage of fossil fuel has unavoidable deleterious effect on environment. The international consciousness for environment protection is growing and ever more strict emission legislations are being enacted. Simultaneously the storage of fossil fuel is depleting. Hence, the above situations promote the scientists to find alternative sustainable fuels along with their suitable using technique which will reduce the pollutant emission and will be applicable for gaining satisfactory engine performance. In these perspectives, alcohol fumigation is getting high demand as an effective measure to reduce pollutant emission from diesel engine vehicles. Alcohol fumigation is a dual fuel engine operation technique in which alcohol fuels are premixed with intake air. The aim of this paper is to identify the potential use of alcohols in fumigation mode on diesel engine. In this literature review, the effect of ethanol and methanol fumigation on engine performance and emission of diesel engine has been critically analyzed. A variety of fumigation ratios from 5% to 40% have been applied in different types of engines with various types of operational mode. It has been found that the application of alcohol fumigation technique leads to a significant reduction in the more environment concerning emissions of carbon dioxide (CO₂) up to 7.2%, oxides of nitrogen (NO x ) up to 20% and particulate matter (PM) up to 57%. However, increase in carbon monoxide (CO) and hydrocarbon (HC) emission have been found after use of alcohol fumigation. Alcohol fumigation also increases the BSFC due to having higher heat of vaporization. Brake thermal efficiency decreases at low engine load and increases at higher engine load.

Review on alcohol fumigation on diesel engine: A viable alternative dual fuel technology for satisfactory engine performance and reduction of environment concerning emission

An economical and abundant feedstock for methanol manufacture is North Dakota lignite. In a plant consuming lignite and self-sufficient in utilities, energy in the methanol would represent about 45% of the energy in the feedstock. The cost of energy from the methanol produced would be about twice that from gasoline at 1979 prices. Liquefaction of lignite or coal to a synthetic crude with subsequent refining by conventional processes would provide motor fuel at somewhat higher energy efficiency and lower cost than by methanol synthesis. Municipal solid wastes could also be used as feedstock for methanol manufacture, but the cost would be even higher than with lignite as feedstock. The lowest cost and most abundant feedstock for ethanol manufacture is corn. With current farming and ethanol manufacturing practices, energy in the ethanol plus that in the byproducts is only about 55% of the energy in the petroleum fuels consumed. If the ethanol plant used only nonpetroleum fuels, the efficiency based on just the petroleum fuels used in farming and collection of wastes would range from 130 to 160%; overall efficiency would remain at 55% or less. Energy in the byproducts represents about 40% of the energy output. The cost of energymore » from the ethanol produced would be at least four times that from gasoline. While both methanol and ethanol have characteristics that complicate distribution and detract from product quality, poor energy yield and high cost are the most serious deterrents to commercialization of either alcohol. Methanol is definitely preferred, but neither represents a practical alternative unless the price of petroleum-based fuels rises markedly relative to that of the alcohols.« less

B.Y. Zarah

Papers

Practicality of Alcohols as Motor Fuel