The use of non-fossil derived hydrogen; a possible role for coal conversion

Abstract

The paper summarises some results of a study on the use of non-fossil derived hydrogen in coal conversion processes carried out by the National Coal Board under two contracts to the European Communities. Under the first contract the study consisted of a technical and economic evaluation of the use of non-fossil derived hydrogen on three coal conversion processes. These are methanol synthesis, solid phase hydrogenation (hydrogasification) for substitute natural gas production, and liquid phase hydrogenation (liquefaction) for the manufacture of liquid fuels. The introduction of non-fossil derived hydrogen generally resulted in an increase in the conversion efficiency and carbon utilization, and a reduction in the number of component stages of the process. Economic evaluations were carried out to determine the price at which non-fossil derived hydrogen would have to be available for its use in coal conversion processes to be preferable to the conventional (self-contained) route. The manufacture of synthetic fuels from non-fossil derived hydrogen was also compared with the direct use of hydrogen. It was concluded that market conditions could exist in which the use of non-fossil derived hydrogen in coal conversion would be preferable to both conventional coal conversion and the direct use of the hydrdogen, irrespective of the coal price. At present the study is being extended under a second contract to include two further coal conversion processes. These are substitute natural gas production from synthesis gas (methanation) and the production of liquid fuels from synthesis gas by a Fischer-Tropsch synthesis route. The results of the technical and economic evaluations reinforce those of the first study. In addition there are available preliminary results of a comparison of the economics of overall systems of hydrogen production from nuclear power and electrolysis and utilization in coal conversion processes with conventional coal conversion technology.