Biomass gasification-based syngas production for a conventional oxo synthesis plant-greenhouse gas emission balances and economic evaluation

Artikel i vetenskaplig tidskrift, 2015

The long-term primary option for the chemical industry to reduce fossil feedstock dependence and greenhouse gas emissions is to switch to a renewable feedstock. This study investigates the global greenhouse gas emission balances and process economics of switching the natural gas-based syngas feedstock of a conventional oxo synthesis plant to a biomass-based feedstock. Two biomass gasification-based concepts are considered: (i) replacing the natural gas with biomass-derived synthetic natural gas; and (ii) replacing the syngas directly with biomass-derived syngas. The work is based on previously conducted work by the authors in which process modeling, integration opportunities, and the thermodynamic performance of the proposed biomass-based concepts were investigated. The assessment approach is to compare two different biomass-based process routes to the same end-product by switching the introduction point in the fossil-based process value chain. The different concepts are compared in terms of greenhouse gas emission reduction potential and change in production cost of oxo products compared with the conventional route. A system boundary expansion approach is applied to estimate the global greenhouse gas emission balances, thus eliminating the need to define the final use of the oxo product. Sensitivity analyses are conducted with respect to future material and energy prices, carbon dioxide emission charges, capital cost estimations, and reference grid electricity generation technologies. The direct biomass-based syngas route is shown to achieve promising environmental and economic performance levels. The results indicate that producing biomass-based syngas directly can be economically competitive with natural gas-based syngas for price projections based on current policies. However, for future policies associated with major greenhouse gas emission constraints, no direct economic incentive for switching to biomass-based syngas production is achieved. These results suggest that policy measures other than a carbon dioxide emission charge can be necessary to achieve a transition to renewables for the production of oxo products. (C) 2015 Elsevier Ltd. All rights reserved.