Fossil fuels hydrocarbons from

Prior to the discovery of plentihil suppHes of natural gas, and depending on the definition of the resources (1), there were plans to accommodate any shortfalls in gas supply from soHd fossil fuels and from gaseous resources by the conversion of hydrocarbon (petroleum) Hquids to lower molecular weight gaseous products. 

The atmosphere is an important conveyor belt for many pollutants. The atmosphere reacts most sensitively to anthropogenic disturbance because proportionally it represents a much smaller reservoir than land and water furthermore, the residence times of many constituents of the atmosphere are smaller than those that occur in the other exchange reservoirs. Water and atmosphere are interdependent systems. Many pollutants, especially precursors of acids and photooxidants, originate directiy or indirecdy from the combustion of fossil fuels. Hydrocarbons, carbon monoxide, and nitrogen oxides released by thermal power plants and, above all by automobile engines, can produce, under the influence of sunlight, ozone and other photooxidants. 

Better cleaning products have been developed using chemicals derived from hydrocarbons. These synthetic detergents are carefully tailored to provide excellent cleaning power without the formation of scum. In most applications hydrocarbons derived cleaners have largely replaced soaps made from animal and plant products. Today 80% to 90% of the cleaning compounds used, both in the home and by industries, are based on chemicals derived from fossil fuel hydrocarbons. 

The reaction products from the fuel must be gaseous so that they can be directly vented to the air. This eliminates the requirement for hardware to collect, store and return the spent solid or liquid reaction products. The product of the reaction of hydrogen with oxygen, from the air, is water. There is no carbon so no un-bumed hydrocarbons or toxic carbon monoxide is produced. All fossil fuels contain some amount of sulfur compounds. These are converted to sulfur dioxide when the fuel is burned. Most processes under consideration for the production of hydrogen are free from sulfur or any other harmful contaminants. Thus, unlike fossil fuel hydrocarbons, hydrogen combustion products will not be contaminated with sulfur compounds. 

The analytical methodology currently available for fossil fuel hydrocarbon analyses is sensitive and selective to the point that individual aromatic hydrocarbons can be measured in sediment and tissue samples at 10 9 g/g dry weight concentration levels. We should all be concerned that intercalibration exercises reveal wide differences, often a factor of 10 or more in values reported by different laboratories. We cannot ignore this and we should strive to calibrate and refine the methodology to the point where we and others can be more confident of the data comparisons from area to area and from one laboratory study to another. A factor of 10 in concentration of toxic compounds can easily be the difference between a healthy and a severely impacted ecosystem. 

Pollutants derived from burning of fossil fuels, radionuclides from fallout, or emissions from industrial processing (toxic trace elements, radionuclides, polycyclic aromatic hydrocarbons, dioxins). 

The increasing number of atomic reactors used for power generation has been questioned from several environmental points of view. A modern atomic plant, as shown in Fig. 28-3, appears to be relatively pollution free compared to the more familiar fossil fuel-fired plant, which emits carbon monoxide and carbon dioxide, oxides of nitrogen and sulfur, hydrocarbons, and fly ash. However, waste and spent-fuel disposal problems may offset the apparent advantages. These problems (along with steam generator leaks) caused the plant shown in Fig. 28-3 to close permanently in 199T. 

Hydrogen is the most abundant element in the universe and is found in a variety of compounds, including hydrocarbons (e.g., fossil fuels or biomass) and water. Since free hydrogen does not occur naturally on earth in large quantities, it must be produced from hydrogen-containing compounds. 

As we have seen, the primary sources of hydrocarbons are the fossil fuels petroleum and coal. Aliphatic hydrocarbons are obtained primarily from petroleum, which is a mixture of aliphatic and aromatic hydrocarbons, together with some organic compounds containing sulfur and nitrogen (Fig. 18.15). Coal is another major source of aromatic hydrocarbons. 

CRMs for Contaminants in Environmental Matrices For nearly two decades NIST has been involved in the development of SRMs for the determination of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and chlorinated pesticides in natural environmental matrices such as fossil fuels (Hertz et al.1980 Kline et al. 1985), air and diesel particulate material (May and Wise 1984 Wise et al. 2000), coal tar (Wise et al. 1988a), sediment (Schantz et al. 1990, 1995a Wise et al. 1995), mussel tissue (Wise et al. 1991 Schantz et al. 1997a), fish oil, and whale blubber (Schantz et al. 1995b). Several papers have reviewed and summarized the development of these environmental matrix SRMs (Wise et al. 1988b Wise 1993 Wise and Schantz 1997 Wise et al. 2000). Seventeen natural matrix SRMs for the determination of organic contaminants are currently available from NIST with certified and reference concentrations primarily for PAHs, PCBs, chlorinated pesticides, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofiirans (PCDFs) see Table 3.11. 

For each ton of hydrogen produced from hydrocarbons, approximately 2.5 t of carbon is vented to the atmosphere [44-47], However, for each ton of hydrogen produced from current coal technology, approximately 5 t of carbon is emitted to the atmosphere. Principally, C02 capture and sequestration is a precondition for use of these fossil fuels. However, the sequestration necessity varies, because the relative atomic hydrogen-to-carbon ratios are 1 2 4 for coal oil natural gas. There are two basic approaches to C02 sequestration either at the point of emission (in situ capture) or from the air (direct capture). In either case, C02 must be disposed off safely and permanently. With the capture and sequestration of C02, hydrogen is one path for coal, oil, and natural gas to remain viable energy resources [46]. Carbon sequestration technologies are discussed in detail in Chapter 17. 

The two most important environmental hazards faced by humankind today are air pollution and global warming. Both have a direct link with our current overdependence on fossil fuels. Pollutants produced from combustion of hydrocarbons now cause even more health problems due to the urbanization of world population. The net increase in environmental carbon dioxide from combustion is a suspect cause for global warming, which is endangering the Earth—the only known place to support human life. In addition, the import of expensive hydrocarbon fuel has become a heavy burden on many countries, causing political and economic unrest. 

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