Water vapor from fossil fuels

Fiydrothermal plants produce electric power at a cost competitive with the cost of power from fossil fuels. Besides generating electricity, hydrothermal energy is used directly to heat buildings. Across the United States, geothermal hot-water reservoirs are much more common than geothermal steam reservoirs. Most of the untapped hot-water reservoirs are in California, Nevada, Utah, and New Mexico. The temperatures of these reservoirs are not hot enough to drive steam turbines efficiently, but the water is used to boil a secondary fluid, such as butane, whose vapors then drive gas turbines. 

Mercury in its elemental form is a liquid that is vaporized upon heating. It is a component of fossil fuel and is found in airborne emissions from fossil fuel burning plants. It travels through the environment via several pathways, including air, water, and bioaccumulation routes. 12 ... 

Acid rain is caused primarily by sulfur dioxide emissions from burning fossil fuels such as coal, oil, and natural gas. Sulfur is an impurity in these fuels for example, coal typically contains 2-3% by weight sulfur.1M Other sources of sulfur include the industrial smelting of metal sulfide ores to produce the elemental metal and, in some parts of the world, volcanic eruptions. When fossils fuels are burned, sulfur is oxidized to sulfur dioxide (SO2) and trace amounts of sulfur trioxide (SC>3)J21 The release of sulfur dioxide and sulfur trioxide emissions to the atmosphere is the major source of acid rain. These gases combine with oxygen and water vapor to form a fine mist of sulfuric acid that settles on land, on vegetation, and in the ocean. 

Acid Dew Point For fossil fuels, the acid dew point temperature is that temperature at which the actual mixed acid vapor pressure equals the mixed acid vapor saturation pressure. The mixed acid dew point can be approximated by the sulfuric acid dew point (Fig. 24-56). It can be described as a function of the SO3 and water content of the flue gas (Huijbregts). These concentrations result from the sulfur, hydrogen, and free water content of the fuel the relative humidity of the air and the amount of excess air used. Using the equation of Ver-hoff, where T is degrees K and P is mm Hg (see OUces, A.G.) ... 

The burning of fossil fuel is a chemical reaction, which, as you recall from Section 2.1, is a reaction that involves changes in the way atoms are bonded and results in the formation of new materials. For fossil fuels, these new materials are mostly carbon dioxide and water vapor. As we explore in future chapters, the only thing that determines the ability of atoms to form new materials in a chemical reaction is the atoms ability to share or exchange electrons—the atomic nuclei are not directly involved. The chemistry of an atom is therefore more a function of its electrons than of its nucleus. Nuclear fission, by contrast, involves nuclear reactions, which, as shown in the chapter-opening photograph, involve the atomic nucleus. In this sense, the study of the atomic nucleus is not a primary focus of chemistry. 

Today, the United States is using some 9 billion cubic feet of H2 a day in the petrochemical, food, and rocket propulsion industries. Around 98% of the bulk H2 is produced by steam reformation of natural gas (e.g., methane). Methane is reacted with water vapor over a catalyst to form carbon monoxide (CO) and H2. H2 can also be made from ethanol (alcohol), biomass, fossil fuels, or organic waste by the process of "reforming." Most of the currently operating H2 production plants depend on reforming natural gas. This is a process that emits C02 while consuming a nonrenewable fossil... 

Many greenhouse gases such as water vapor occur naturally and are important for life to exist on Earth. Human production of carbon dioxide from combustion of fossil fuels has increased the concentration of this important greenhouse gas to its highest value since millions of years ago. The precise impact of these changes in the atmosphere is difficult to predict and is a topic of international concern and political debate. 

Other Gases The most extensive available data for gas emissivity are those for carbon dioxide and water vapor because of their importance in the radiation from the products of fossil fuel combustion. Selected data for other species present in combustion gases are provided in Table 5-6. 

Appreciable interest has been generated in the use of activated carbons for flue gas cleanup, especially for the removal of SOx and NO the adsorption of mercury from flue gases was discussed earlier. From the environmental point of view, emissions from the combustion of fossil fuels in power plants and similar industrial processes are major contributors to a lowering of air quality. The flue ga.ses carry traces of SOi and NO, which can be oxidized and converted to their acid forms in the presence of atmospheric water vapor, and they may also combine with other volatile organics to form ozone and smog. Similarly, low level SOj and NOx emissions from automobiles, while insignificant for individual vehicles, become a large source of pollution when multiplied by the millions of vehicles that are on the roads. 

Identify the limiting and excess reactants in the production of nitric acid when nitrogen dioxide from combustion of fossil fuels reacts with water vapor in the air. 

Sulfates are discharged into water from mines and smelters, and from kraft pulp and paper mills, textile mills, and tanneries. Atmospheric sulfur dioxide, formed by the combustion of fossil fuels and by metallurgical roasting processes, may contribute to the sulfate content of surface waters. Sulfur trioxide, produced by the photolytic or catalytic oxidation of sulfur dioxide, combines with water vapor to form dilute sulfuric acid, which falls as acid rain . The environmental fate and transport of sulfate are inextricably linked to the physical and chemical processes active in the earth s sulfur cycle. 

It is possible for you to be exposed to metallic mercury vapors from breathing contaminated air around hazardous waste sites, waste incinerators, or power plants that bum mercury-containing fuels (such as coal or other fossil fuels), but most outdoor air is not likely to contain levels that would be harmful. Exposure to mercury compounds at hazardous waste sites is much more likely to occur from handling contaminated soil (i.e., children playing in or eating contaminated surface soil), drinking well-water, or eating fish from contaminated waters near those sites. Not all hazardous sites contain mercury, and not all waste sites that do contain mercury have releases of mercury to the air, water, or surface soils. 

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