This study addresses the development of environmental database using Japanese input-output (I-O) tables for Life Cycle Inventory analysis (LCI). Many LCI case studies have been performed using Japanese I-O tables. However, most of these studies have focused only on CO2 emissions due to lack of high quality data concerning other substances that influence the environment. The objective of this study is to supply CO2 and CH4 emission factors of commodities estimated using the latest Japanese input-output table (1995). In general, emission factors are estimated using Japanese I-O table based on the assumption that all commodities are produced in Japan. In this paper, however, a method that permits to reflect the actual activities at the overseas production of import goods is used. The results show, (1) CH4 is not negligible when performing Life Cycle Assessment (LCA) from viewpoint of global warming, and (2) CO2 and CH4 emission factors estimated using the conventional method are very different from those using the method proposed in this paper because of the difference of technologies used in Japan and abroad.
The price of product oil is influenced by the costs of hydrogen and utility (power) supplied to the coal liquefaction plant, in which there are many choices for processes, raw materials and fuels. In this study, it is presumed that the coal liquefaction plant is located in the coal production area and the natural gas is not available. Furthermore, as the hydrogen production process, the steam reforming of the off-gas produced from the coal liquefaction plant and the gasification of raw coal and residue were selected. The boiler turbine generator (BTG) and integrated coal gasification combined cycle (IGCC) were selected for power generation. By using Linear Programming (LP) techniques, the production costs of hydrogen and power were minimized in the combination of these production processes for the coal liquefaction plant. As a result of this LP study, the capital cost and production cost were reduced by introducing the steam reforming of off-gas along with the gasification of raw coal and residue, and were minimized at BTG in comparison with IGCC. It is expected that technical improvement of IGCC in future would lead to cost reduction of coal liquefaction.
Properties of coal-derived liquids were investigated for proper scaleup design of the NEDOL demonstration plant (DP) from the 150t/d capacity pilot plant (PP). Empirical and semi-empirical equations to estimate intrinsic, thermodynamic and transport properties were formulated on the basis of observed results in PP operation together with existing investigations for characterization of narrow boiling-point range distillates obtained by superfractionation. It was shown that the properties of coal-derived liquids in PP differ from those in 1t/d process supporting unit (PSU), the coal-derived liquids from which have a different composition of aromatic and paraffin compounds. It was also suggested that, for design of industrial coal liquefaction process, it is necessary to obtain engineering data under conditions where the process recycling liquids have attained equilibrium in the process after a sufficiently long term run.