Бурение грунтовых зондов, установка энергетических колодцев

The future of gasification is intimately intertwined with the future of energy and energy policy. It is generally recognized that human development cannot continue to base its economy on fossil fuels in the present manner forever, even if viewpoints on the timescale do diverge, sometimes dramatically. This viewpoint is put most strongly by the advocates of what is called the “hydrogen economy.” There is no doubt that the use of hydrogen in combination with fuel cells as a transport fuel will improve the microclimate of our conurbations significantly through the elimination of C02, NOx, CO, and hydrocarbon emissions from motor vehicles. And this is a pros­pect that could become reality within the next 20 years. However, it is our opinion that those proponents, who present the hydrogen economy as a solution to the C02 emissions or “greenhouse gas” issue, overstate their case. The hydrogen that we will use in our fuel cells is not ready and waiting for us to collect. It is chemically locked into other substances, the principle of which are water and to a lesser extent natural gas.

The issue remains, therefore, how to unlock this hydrogen and make it available in a useable form. There are essentially three routes to hydrogen production: electrolysis of water, steam reforming of natural gas, and gasification—whereby the fuel for the gas­ification can be anything from coal to biomass. Thus, as can be seen from Table 10-1, unless the power for electrolysis is generated without C02 emissions, hydrogen production is inevitably associated with C02 production. Furthermore, it has to be recognized that with the possible exception of nuclear energy, no C02-free power — generation technology is in the medium-term going to produce hydrogen in the quanti­ties required to supply our transport needs. We therefore need to look at the potential for a reduced C02 technology to help us on the way to a “no carbon” energy future.

It is our opinion that in the transition between fossil fuels and a fully “renewable world,” gasification can play an important role. First, in the move toward a hydrogen economy, one can expect that the hydrogen will be produced directly from fossil fuels rather than by electrolysis. Furthermore, during this transition period the implementation of polygeneration units producing both power and hydrogen will allow a gradual change over from the former to the latter. This is the only way in which an investment in power generation can be utilized for hydrogen production at

moderate cost (Simbeck and Chang 2002). Second, gasification is a key technology for more efficient power generation from coal and heavy oils with the best environ­mental performance. And third, gasification provides the best option for producing concentrated carbon dioxide streams that may have to be sequestered during the transition in order to reduce the emission of greenhouse gases.

Of course, the above remarks are not restricted to coal but apply to the gasification of any fossil fuel. Furthermore, they apply also to what may in the very long-term become the most important feedstocks, biomass, and waste—that may, in a totally “sustainable future,” have to take over the role of today’s fossil fuels.

What is seldom mentioned is that even in a “sustainable world” not only energy is required but also carbon for organic chemicals including plastics. Although gasification of waste may supply part of this requirement, the make-up will have to come from biomass, which in this idealized “sustainable world” model is the only allowable source of concentrated carbon (van der Burgt 1997). The only way to produce organic chemicals from waste and biomass is first to gasify them in order to make synthesis gas. At present, there is no process available to do this efficiently, as all biomass and waste gasification processes to date have been developed for producing fuel gas and power. Hence, although in a more renewable world hydrogen (by elec­trolysis) and electricity may be available, gasification of waste and biomass— directly or indirectly via bio-oil—are at least required to make synthesis gas for organic chemicals. The first generation of downstream technologies to allow the use of syngas (via methanol) as an alternative source for ethylene and propylene instead of the conventional naphtha cracking is already in the demonstration stage (UOP 1997; Holtmann and Rothaemel 2001).

We therefore conclude that gasification can and will have an important role to play in the coming decades, both for power generation and for the production of bulk chemicals. In the more distant future it may also develop to become an important source of base materials for all organic chemicals. It is hoped that this book will contribute to the development of a better understanding of gasification processes and their future development.

REFERENCES

Holtmann, H.-D., and Rothaemel, M. “A Cost-Effective Methanol to Propylene Route.” Petroleum Technology Quarterly (Autumn 2001).

Simbeck, D., and Chang, E. “Hydrogen Supply: Cost Estimate for Hydrogen Pathways— Scoping Analysis.” National Renewable Energy Laboratory report. NREL/SR-540-32525 (July 2002).

UOP. “UOP/Hydro MTO Process: Methanol to Olefins Conversion.” UOP Company leaflet, 1997.

van der Burgt, M. J. “The Role of Biomass as an Energy Carrier for the Future.” Energy World 246 (February 1997).

Appendix А

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