Gasifications environmental advantages

General Atomics is developing Supercritical Water Partial Oxidation (SWPO) for the efficient and environmentally advantageous gasification of and hydrogen production from low-grade fuels such as biomass, municipal/solid waste (MSW) and high-sulfur coal. 

The catalyst is not sensitive to sulfur or other oxo poisons, which is another environmental advantage. Together with the simple but effective decantation, which allows the withdrawal of organic and other byproducts at the very moment of separation, accumulation of activity-decreasing poisons in the catalyst solution is prevented. Therefore no special treatment or purification step is necessary. This reduces the environmental burden still further. For a considerable time the oxo units at Ruhrchemie s plant site were even supplied with syngas derived from coal produced by the TCGP (Ruhrchemie/Ruhrkohle s version of the Texaco coal gasification process). In various cases this can be an important factor as far as local resoruces are concerned. 

This section summarizes the important environmental aspects of coal gasification technology, emphasizing emission sources, emission limits, and operating data for all three areas of concern air, water, and solid waste. A discussion of the environmental advantages of coal gasification over direct coal combustion also appears. In addition, the special provisions of the Clean Air Act Amendments of 1990 which affect coal gasification are addressed. 

Similar to current situations with demonstration scale coal gasification processes, the greatest amount of development activity is in entrained-flow coal gasification processes. This is likely due to the inherent operating and environmental advantages of entrained flow gasification. 

One advantage of modem coal gasification combined cycle systems is excellent environmental performance. Not only are regulatory standards met, but emissions and effluents are well below accepted levels (13,16,28). 

Although the gasifier product itself has low levels of NOx, the total systems emissions of this product must be carefully scrutinized. When clean biogas is eventually burned, NOx will be produced, as it is in most combustion systems with all fuels. The use of biogas rather than solid biomass fuels provides the opportunity to better control the combustion process, which can potentially result in lower NOx emissions. As such, gasification offers potential environmental emissions advantages over combustion alternatives. However, NOx may still occur as the gas is burned, and appropriate NOx control technologies may be needed. 

A similar opportunity exists for the public utility industry in the potential of LBG and MBG. The reduced environmental impact of a coal gasification plant which produces a perfectly clean fuel equivalent to natural gas, compared to direct combustion of coal may allow increased use of coal in areas where increased pollutant emission is barred. As these PSD areas increase in number, the advantages of coal gasification become more apparent. The potential of more efficient combined cycle generation systems which can be used with coal-derived gases is an added factor for implementing coal gasification. 

None of these current processes has a distinct advantage over the other two in all situations of coal gasification. However, we believe that the Winkler is best suited for the production of methanol because it yields a clean gas with a low inerts content. Other advantages include the plant s low environmental impact, the minimal coal preparation required and the simple construction of the Winkler gasifier. 

Biomass is an environmental benign source of energy and a COj-neutral fuel for heat and power generation. Wood can be used either directly from forestry or also as waste product from wood processing industry, e.g. saw dust. The advantage of gasification... 

The environmental externalities cost of coal gasification will always be lower than for direct coal combustion. The size of this advantage depends on the /ton emission charges assigned each emission. Nevertheless, environmental externalities costs are sure to rise due to increasing concern about sustainable development and relationship... 

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