Showing papers on "Substitute natural gas published in 1993"

Role of fossil fuels in electricity generation and their environmental impact

Abstract: Approximately 46% of the world's electricity is generated by the combustion of fossil fuels and there is consequential environmental impact due to the production of the fossil fuels and their transportation as well as from their combustion. At present, the solid fossil fuels are the major fuel for electricity generation and are responsible for 58% of the electricity generated from fossil fuels; natural gas accounts for about 23% and fuel oils for 19%. The scene however is apparently shifting towards a greater use of natural gas and by the year 2000 it could provide 25–30% of the world electricity output, while the amount of fuel burned will have decreased. The reason for this scenario is simply that the combustion of coal can cause a considerable amount of pollution compared to natural gas. The environmental impact of these fossil fuels in relation to electricity are considered together with the available methods of emission control. Cleaner coal technologies to reduce the emission of NOx, SO2 and CO2 are described and include fluidised bed combustion and an integrated gasification combined cycle. There is no SOx problem with natural gas and NOx is controlled by injecting steam or water into the gas turbine inlet.

The Impact of Natural Gas Imports on Air Pollutant Emissions in Mexico

Abstract: This paper analyzes the impact that natural gas imports could have on fuel emissions in northern Mexico. The authors discuss the problem created in the 1980s when a shift from natural gas to residual oil in industrial processes increased emissions of air pollutants significantly. The benefits of substituting leaded for unleaded gasoline in the 1990s are discussed also. In July 1992 the Mexican government announced for the first time since oil nationalization that private companies in Mexico are allowed to directly import natural gas. The transportation of natural gas, however, remains reserved only for Pemex, the national oil company. This opens the possibility of reducing the burning of high-sulfur residual oil in both the industrial and the energy production sectors in Mexico, particularly in the northern region where only 6.7% of the of the country`s natural gas is produced. Natural gas imports have also opened the possibility of using compressed natural gas (CNG) in vehicles in northern Mexico. 15 refs., 13 figs., 3 tabs.

Fueling up with natural gas

Abstract: A careful analysis is needed of the energy efficiency of the fuel cycle (the efficiency of the conversion from resource extraction to final use by consumers) and the environmental impact of natural gas fuels. This information can help policy makers decide which fuels could be used to displace imported oil, maintain air quality, and be the basis of a new transportation fuels infrastructure. The authors compare the impact of natural gas fuels and additives derived from natural gas and blended with gasoline with that of gasoline alone by examining the energy efficiency of the fuel cycle as well as greenhouse gas emissions. Although this subject has been studied before, they add to those earlier studied by looking at MTBE, alkylate, and gasoline (from natural gas). The authors also reexamine CNG, LPG, and methanol on the basis of a vehicle's efficiency potential. Although LNG vehicles were included in an earlier study, they are not included here because lifecycle greenhouse gas emissions were found to be comparable to those from CNG vehicles. They compare natural gas fuels against a baseline fuel--nonoxygenated gasoline (hereafter referred to simply as baseline gasoline).

Hydrogen: Its comparison with fossil fuels and its potential as a universal fuel

Abstract: The fuels most often considered for the post-petroleum and natural-gas era are hydrogen (both gas and liquid forms), coal, and coal-derived synthetic fossil fuels. These fuels can be compared in terms of production cost, external cost, and end-use efficiency. The results show that hydrogen is a much more cost effective energy carrier than coal or synthetic fossil fuels, as well as being the most environmentally compatible fuel. 21 refs., 4 figs., 12 tabs.

Production of substitute natural gas

Abstract: PURPOSE:To provide a process for producing a substitute natural gas which is easily adapted for the production in a city gas plant in a local small or middle town and is easy in operation, maintenance and administration. CONSTITUTION:A process for producing a substitute natural gas comprising treating a reformed gas obtained from lowtemperature steam reforming, using a methane-based gas on the side of unpassed gases as a starting gas for the substitute natural gas and using a gas based on hydrogen and carbon monoxide on the side of diffused gases as a recycle gas for hydrodesulfurization.

Bioconversion of synthesis gas into fuels

Abstract: Synthesis gas, a mixture of primarily CO, H{sub 2}, and CO{sub 2}, is a major building block of fuels and chemicals. The gas may be produced from several sources including coal, oil shale, tar sands, heavy residues, biomass, or natural gas. Only a small percentage of synthesis gas is currently produced by solid fuel, however, because of large coal reserves in the United States, synthesis gas production from coal will become an important technology in the future. Catalytic processes may be used to convert the synthesis gas into a variety of fuels and chemicals, such as alcohols, organic acids, paraffins, etc. Microorganisms may also be used to convert synthesis gas components into fuels and chemicals. Biological processes, although slower, have several advantages over catalytic processes, such as a higher specificity, higher yields, lower energy costs and generally greater resistance to poisoning. This paper presents data for the production of ethanol, hydrogen, and methane from synthesis gas. Various bioreactor schemes are investigated and models are developed.

Method for separating carbon dioxide gas and water content in gas in city gas purification process

Abstract: PURPOSE:To separate water content from carbonic acid gas in high economic efficiency and obtain high-purity city gas in high yield by passing a raw material gas generated in production of substitute natural gas through an adsorbing tower, continuously treating the gas by cyclic operation of adsorption, peradsorption, desorption and pressurization CONSTITUTION:When a raw material gas produced in production of substitute natural gas is purified using four adsorbing towers in which a molecular sieving carbon is packed as an adsorbent, in an adsorption process (I), temperature behavior is detected and adsorption time is automatically controlled and high-purity combustible gas is stationarily taken out and in a peradsorption process (II), CO2 having high concentration in a recovery gas of a desorption tower (B) is excessively adsorbed in the adsorbent in which CO2 was adsorbed once in an adsorption process and a combustible gas having high concentration is taken out and in a desorption process (III), all of the combustible gas in a desorption tower is allowed to flow and then water content and CO2 are sucked and desorbed and in a pressurizing process (IV), pressure of the gas in the process (IV) is raised to adsorption pressure by a primary pressurizing operation for adsorbing CO2 in pressure-uniformed gas in the process (III) into only lower part of a pressurizing tower and secondary pressurizing operation for feeding high-purity combustible gas at a definite flow rate from the upper part of tower Thereby CO2 and water content in city gas are separated in high economic efficiency