Synthetic fuels availability

Propylene has many commercial and potential uses. The actual utilisation of a particular propylene supply depends not only on the relative economics of the petrochemicals and the value of propylene in various uses, but also on the location of the supply and the form in which the propylene is available. Eor example, economics dictate that recovery of high purity propylene for polymerisation from a smaH-volume, dilute off-gas stream is not feasible, whereas polymer-grade propylene is routinely recovered from large refineries and olefins steam crackers. A synthetic fuels project located in the western United States might use propylene as fuel rather than recover it for petrochemical use a plant on the Gulf Coast would recover it (see Euels, synthetic). 

Reduction of exhaust emissions is being tackled in two ways by engineers, including precombustion and postcombustion technology. One of the most effective methods now being researched and adopted includes use of synthetic fuel made from natural gas. This fuel is crystal clear, and just like water, it has no aromatics, contains no sulfur or heavy metals, and when used with a postcombustion device such as a catalytic converter any remaining NO, or other emissions can be drastically reduced. Estimates currently place the cost of this fuel at 1.50 per gallon, with availability in 2004 to meet the next round of stiff EPA exhaust emission standards. 

Second-generation biofuel technologies make use of a much wider range of biomass feedstock (e.g., forest residues, biomass waste, wood, woodchips, grasses and short rotation crops, etc.) for the production of ethanol biofuels based on the fermentation of lignocellulosic material, while other routes include thermo-chemical processes such as biomass gasification followed by a transformation from gas to liquid (e.g., synthesis) to obtain synthetic fuels similar to diesel. The conversion processes for these routes have been available for decades, but none of them have yet reached a high scale commercial level. 

The alternative fuels and drive systems available only seem to be viable on the mass market, if the oil price stays above 60 to 70 /bbl for a sustained period. Oil prices peaked above 140 /bbl in summer 2008 and many experts believe that stable oil prices over 100 /bbl could be reached in the next one or two decades. The higher the market prices of fossil fuels, the more competitive low-carbon alternatives will become The principal choice here is between biofuels, electricity and hydrogen, provided that they are produced either from low/zero-carbon feedstock or that the C02 generated during their production is captured and stored. But higher priced conventional oil resources, on the other hand, can also be replaced by high-carbon alternatives such as oil sands, oil shale or synthetic fuels from coal and gas. 

The importance of sulfur as an industrial chemical is discussed and forecasts of projected sulfur demand in the U.S. are given. Three processes for conversion of coal and oil shale to synthetic fuels are examined in some detail to show how the sulfur in the original feedstock material is recovered as elemental by-product sulfur. Three synthetic fuel scenarios are examined and their potential impact on sulfur availability with current and projected markets to the year 2000 are examined. 

The projected synthetic fuels program involving conversion of coal and shale may have a profound effect on available supplies of sulfur and supply patterns. Desulfurization of intermediate process streams to hydrogen sulfide will be required to meet environmental standards. Conversion of intermediate hydrogen sulfide to elemental sulfur will be carried out as in the case of crude oil desulfurization. Elemental sulfur represents the preferred sulfur... 

We will examine three synthetic fuel scenarios and compare their implications regarding sulfur availability with the current and projected market for sulfur to the year 2000. The analysis will consider three production levels of synthetic fuels from coal and oil shale. A low sulfur Western coal will be utilized as a feedstock for indirect liquefaction producing both synthetic natural gas and refined liquid fuels. A high sulfur Eastern coal will be converted to naphtha and syncrude via the H-Coal direct liquefaction process. Standard retorting of a Colorado shale, followed by refining of the crude shale oil, will round out the analysis. Insights will be developed from the displacement of imported oil by synthetic liquid fuels from coal and shale. 

There are sufficient gas reserves presently proved, with the prospect of additional reserves to permit the utilization of as much as 2 trillion cubic feet of natural gas annually for the production of synthetic fuels. This quantity of gas is available in addition to that... 

The market penetration of synthetic fuels from biomass and wastes in the United States depends on several basic factors, eg, demand, price, performance, competitive feedstock uses, government incentives, whether established fuel is replaced by a chemically identical fuel or a different product, and cost and availability of other fuels such as oil and natural gas. Detailed analyses have been performed to predict the market penetration of biomass energy well into the twenty-first century. A range of from 3 to about 21 EJ seems to characterize the results of most of these studies. 

For example, the current policy in Washington to keep the energy demand tuned to a zero growth economy - 2% per year or less - means that conventional sources of fuels, particularly coal and natural gas, are currently available in excess and will in the future be available for a number of years longer than previously anticipated. The restraints on the economy will in turn mean that synthetic fuels from coal will not be produced commercially for many years to come. 

Coal ash is not always a deleterious material for a process. In coal liquefaction, it has been observed that the rate is increased in the presence of pyrite. In gasification, the rate is increased in the presence of alkalies. There is limited data available on the effects of materials on combustion. Although interest in synthetic fuels from coal is quite limited at present, there is an interest in developing the technical capability to permit the production of more premium fuel types from less desirable ones. The conversion of solid coal to liquid fuels has been a very demanding process in terms of the pressures and, to some extent, the temperatures that have been used. Catalysts have been required in all cases. The catalysts have been poisoned by the sulfur and other species in the mineral matter. As a result, catalyst costs and replacement rates can be quite high. A cheap, naturally occurring catalyst that came with the coal would be of significant interest. Pyrite seems to be such a material. 

Commercial adoption of the technologies to produce synthetic ultra-clean fuels has been minimal due to the historically low prices for and availability of traditional hydrocarbons. However, with the recent increases in world oil price, interest in synthetic fuels has also increased. Construction of commercial facilities has been limited to unique niche opportunities to leverage remote or stranded supplies of hydrocarbons, particularly natural gas. 

Studies estimate that there are various synthetic fuel production technologies and process schemes available that can be competitive with petroleum-derived fuels under certain market conditions and prices (25). However, the high capital requirements and long planning and construction lead times create substantial risks. Additionally, the limited introduction of some of these technologies poses significant technical risks which may be unacceptable to project developers and investors. 

The hydroformylation or oxo reaction has been chosen for particular study for several reasons (a) The reaction was discovered by Roelen 2) in the course of an investigation of the mechanism of the Fischer-Tropsch reaction, and a study of the hydroformylation reaction could furnish information on the course of this heterogeneously catalyzed synthetic fuel process (6) hydroformylation involves the activation of hydrogen by a molecularly dispersed catalyst (c) there are few side reactions (d) the catalyst for the reaction, Co2(CO)s, is easily prepared, is relatively nontoxic, and is consequently readily available for study and (e) the reaction is of great industrial importance. 

South Africa turned to CTL during its apartheid period as a way of surviving trade embargoes. CTL now supplies about 30% of South Africa s domestic demand. The South African Oil Company (SASOL) claims its synthetic fuel is economically competitive at oil prices above 30 /bbl. SASOL is helping China plan and build two 50000 barrels-per-day pilot facilities located near coal mines. China is an obvious place for many more of these facilities to be built. China has significant coal reserves the fuel can be manufactured right near the coal mines and the sulfur content of the fuel is as low as 5 parts per million, compared to diesel products now available with diesel contents of 2000 ppm. 

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