Gasification based biorefineries – technical, economic and environmental (TEE) assessment for specific case studies

IEA Bioenergy Task42 (Biorefining in the Circular Economy) aims at enhancing the commercialisation and market development of biorefinery systems and the related technologies while considering environmental, social and economic aspects. Integrated assessment (technical, economic and environmental – TEE assessment) of integrated biorefineries is performed to provide quantitative, scientifically sound, and understandable data on the technical, economic and ecological added-value of biorefining to co-produce bioenergy and bio-products in a sustainable way. This report is focused on case studies for gasification based biorefineries and is developed in cooperation with members of IEA Bioenergy Task 33 (Gasification of biomass and waste).

Gasification is not a new technology, however, gasification of biomass (or waste) and all of the sub-sequent scaling up can be considered novel. Especially the different flue gas composition is deemed a challenge. In the report, 10 gasification technologies ranging from commonly found two stage-gasification to more exotic technologies including plasma, were analysed and TRL levels were awarded accordingly. In principle, there are applications with high TRLs such as 7-8 covering a wide variety of feedstock, e.g., classic input materials such as wood chips, pellets, saw dust, and perennial crops, but also extending into municipal solid waste, SRF and RDF with lower TRL technology. But not only the generation of heat, power and syngas (and its subsequent use for the production of biofuels and/or biochemicals) are of interest, multiple technologies are also working of recovering minerals such as phosphorus in order to further improve efficiency. Factsheets were included for 4 specific gasification based biorefinery systems, with the main difference being the way the synthesis gas if further processed to advanced biofuel.

Full report:
Technical, Economic and Environmental (TEE) Assessment of Integrated Biorefineries

Case 1 & 2: Gasification & methanol/DME-to-gasoline biorefinery

These case studies analyse possibilities for integration of gasification systems with further processing and upgrading processes for the production of synthetic biofuels. The woody biomass feedstock is first converted to a biocrude through a fast pyrolysis process. The biocrude is then gasified with steam to produce producer gas which must be cleaned and conditioned to get a mixture of CO and H2 (synthesis gas / syngas). The syngas is then converted to methanol (case 1) or dimethylether (DME) (case 2) via a catalytic reaction system (methanol synthesis / DME synthesis). The final high-quality synthetic gasoline is obtained through refinery upgrading. Butane, propane & polypropylene are valuable side products.

Overall energy efficiency of the DME pathway is 67%; 34% of the energy input is contained in the gasoline product.

The methanol pathway achieves a higher overall efficiency of 87% (from gasification to final products), but only 29% of the energy input is contained in the gasoline product.

Both systems achieve >95% GHG savings compared to the reference fossil-based system providing the same fuel and product outputs, under optimal technology set up conditions and sustainable feedstock sourcing.

Figure: Basic flow chart of gasification and DME processes for high-quality gasoline & performance in terms of energy efficiency and GHG emissions

Separate factsheet available here:

01 – GASIFICATION AND METHANOL SYNTHESIS

02 – GASIFICATION AND DME SYNTHESIS

 
 

Case 3 & 4: Gasification & Fischer-Tropsch synthesis to produce gasoline and diesel substitutes

These case studies analyse possibilities for integration of gasification systems with further processing and upgrading processes for the production of synthetic biofuels. The woody biomass feedstock is first converted to a biocrude through a fast pyrolysis process. The biocrude is then gasified with steam to produce producer gas which must be cleaned and conditioned to get a mixture of CO and H2 (synthesis gas / syngas). The syngas is then converted to raw FT products via a catalytic reaction system (Fischer-Tropsch synthesis). The final high-quality synthetic gasoline and diesel are obtained through refinery upgrading of these FT products via catalytic cracking (FCC) reactions (case 3)  or a hydrocracker (HG) reaction system (case 4).

Overall energy efficiency of both pathways is around 79% (from gasification to final products). In the FCC case,  46% of the energy input is contained in the gasoline and diesel products; in the GH case this is 42%.

Both systems achieve around 97% GHG savings compared to the reference fossil-based system providing the same fuel and product outputs, under optimal technology set up conditions and sustainable feedstock sourcing.

Figure: Basic flow chart of gasification and FT processes (with FCC processing) for high-quality gasoline and diesel & performance in terms of energy efficiency and GHG emissions

Separate factsheet available here:

03 – GASIFICATION AND CATALYTIC CRACKER REACTION SYSTEM (FCC) & FISCHER-TROPSCH SYNTHESIS

04 – ENTRAINED FLOW GASIFICATION AND HYDROCRACKER REACTION SYSTEM (HG) FISCHER-TROPSCH SYNTHESIS