Assessing the Integration of Biomass Gasification-Based Production of Chemicals — Case Study of an Oxo Synthesis Plant

Licentiate thesis, 2014

The chemical industry sector is energy-intensive and highly dependent on fossil feedstock. The primary long-term option to reduce fossil feedstock dependence and greenhouse gas (GHG) emissions is to switch to renewable feedstock. One promising technology is thermochemical gasification of lignocellulosic biomass feedstock into a raw syngas which can be processed into a spectrum of possible products. This study aims at assessing different opportunities to integrate biomass gasification-based processes in the production of chemicals. The work was conducted in the form of a case study involving a conventional oxo synthesis plant processing syngas derived from partial oxidation of natural gas, and olefins into various specialty chemicals. The following options were investigated: (i) retaining the existing syngas production unit and fully substituting the natural gas feedstock by either importing or producing biomass-derived synthetic natural gas (bio-SNG) onsite; (ii) scrapping the existing syngas generator and directly producing biomass-derived syngas fulfilling the specifications for downstream oxo synthesis. The results show that the direct route to bio-syngas requires less lignocellulosic biomass compared with the route via intermediate bio-SNG production. Although the bio-SNG route features a higher heat recovery target for production of heat and power, the direct route achieves the highest thermodynamic performance, particularly if LP steam is exported to the oxo synthesis plant. Furthermore, the direct bio-syngas route shows promising opportunities to perform well from both an economic and GHG emission reduction perspective. For price projections based on current policies, a production cost lower than via the fossil route is indicated. The results also indicate that for future energy market conditions associated with major climate emission constraints, there is no direct economic incentive for switching to biomass-based syngas production, suggesting that other policy measures than a CO2 emissions charge will be necessary to achieve switching from fossil to biomass feedstock in the chemical process industry.