Modern and prospective technologies for hydrogen production from fossil fuels

Abstract

A study is presented assessing the technology and economics of hydrogen production by conventional and advanced processes. Six conventional processes are assessed: (1) steam reforming of natural gas, (2) partial oxidation of residual oil, (3) gasification of coal by the Texaco process, (4) gasification of coal by the Koppers-Totzek process, (5) steam-iron process and (6) water electrolysis. The advanced processes include (1) high temperature electrolysis of steam, (2) coal gasification and electrochemical shift, (3) integrated coal gasification and high temperature electrolysis, (4) thermal cracking of natural gas and (5) the HYDROCARB thermal conversion of coal. Thermochemical water splitting, high energy nuclear radiation, plasma and solar photovoltaic-water electrolysis and by-product hydrogen from the chemical industry are also briefly discussed. It is concluded that steam reforming of methane is the most economic near-term process among the conventional processes. Processes based on conventional partial oxidation and coal gasification are two to three times more expensive than steam reforming of natural gas. New gas separation processes, such as pressure swing adsorption, improve the economics of these conventional processes. Integration of hydrogen production with other end-use processes has an influence on the overall economics of the system. The advanced high temperature electrochemical systems suffer from high electrical energy and capital cost requirements. The thermochemical and high energy water splitting techniques are inherently lower in efficiency and more costly than the thermal conversion processes. The thermal cracking of methane is potentially the lowest cost process for hydrogen production. This is followed closely by the HYDROCARB coal cracking process. To reach full potential, the thermal cracking processes depend on taking credit for the clean carbon fuel by-product. As the cost of oil and gas inevitably increases in the next several decades, emphasis will be placed on processes making use of the world's reserve of coal.