Hydrogen production from coal gasification

High temperature applications include coal gasification, hydrogen production from methane or water, and high temperature process steam. High temperature applications of gas cooled reactors have been addressed in two lAEA-TECDOCs [XV-13, XV-14], summarized below. 

Several new concepts under development for hydrogen production from coal were also described. The HyPr-RING method combines coal gasification, C02 separation, and water-gas shift reaction in a gasifier to produce hydrogen. 

Shiying L., Michiaki H., Yoshizo S. and Hiroyuki H., Hydrogen Production from Coal by Separating Carbon Dioxide during Gasification, Fuel, 81, 2079-2085, 2002. 

The (additional) costs of C02 capture in connection with hydrogen production from natural gas or coal are mainly the costs for C02 drying and compression, as the hydrogen production process necessitates a separation of C02 and hydrogen anyway (even if the C02 is not captured). Total investments increase by about 5%-10% for coal gasification plants and 20%-35% for large steam-methane reformers (see also Chapter 10). 

Today, different processes (steam reforming, autothermal reforming, partial oxidation, gasification) are available and commercially mature for hydrogen production from natural gas or coal. These processes would have to be combined with technologies for C02 capture and storage (CCS), to keep the emissions profile low. A power plant that combines electricity and hydrogen production can be more efficient than retrofitted C02 separation systems for conventional power plants. 

Hydrogen production from coal gasification results in about twice the carbon emissions of hydrogen production from the reforming of natural gas. CCS technology achieves a reduction of about 85 percent in atmospheric carbon emissions from either feedstock. 

There is available proven technology for hydrogen production from resid, natural gas, coal, biomass, and waste, as well as for hydrocracking of oil resid. In fact, as shown in Figure 11.26, as natural gas price increases in recent years, it makes more sense to make H2 from coal and/or resid via gasification followed by WGS reaction. 

In the hydrogen production from fossil fiiels, if it is chemical to chemical conversion such as by tire steam-coal gasification reaction or by tire steam-methane reforming reaction, there is no such thermodynamic limitation by the Carnot efficiency. 

In tire hydrogen production from fossil fiiels, either by the steam-coal gasification reaction or by the steam-nietlrane reforming reaction, the endothermic heat of reaction is conventionally supplied by combustion of fossil fiiels. If this endothermic heat is supplied from nuclear heat, full stoichiometric conversion of fossil fiiels to hydrogen moles and effective conversion of nuclear heat to hydrogen heat can be achieved. 

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. 

Pig. 7.1 Hydrogen production from coal gasification based on the conventional gasifier and the novel membrane gasification reactor concept... 

Rutkowski MD, Buchanan TL, Klett MG, Schoff RL. Capital and operating cost of hydrogen production from coal gasification. Final Report, Contract DE-AM26-99FT40465, Subcontract 990700362, Task 50611, April 2003. 

Figure 5.3 Traditional process for hydrogen production from coal gasification Modified from Smart et al. (2010).

Li, Y., Guo, L., Zhang, X., Jin, H., Lu, Y. (2010). Hydrogen production from coal gasification in supercritical water with a continuous flowing system. International Journal of Hydrogen Energy, 35, 3036—3045. 

Currently hydrogen is produced by the steam reforming of natural gas, coal gasification, and water electrolysis. While various thermochemical and photochemical means for hydrogen synthesis have been proposed, full commercial application will not be possible for many years. Thus, the only viable means for hydrogen production from non-fossil energy is the electrolysis of water, with the electricity provided either by hydroelectric generation or nuclear power. 

M.D., Buchanan, T.L., Klett, M.G., and Schoff, R.L. (2003) Capital and Operation Cost of Hydrogen Production from Coal Gasification. Tech. Rep., US Department of Energy, National Energy Technology Laboratory. 

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