Modeling life‐cycle inventory for multi‐product biorefinery: tracking environmental burdens and evaluation of uncertainty caused by allocation procedure

Abstract

Life‐cycle inventory (LCI) is a fundamental phase in the quantification of the environmental performance of products. However, when it comes to the LCI of a multi‐product system, discussions about the choice of the appropriate methodology to allocate environmental impacts still continue. A further system subdivision and the implementation of a mechanism allowing environmental burdens to be tracked would help to improve model accuracy. This study focuses on the LCI modeling of a lignocellulosic biorefinery producing ethanol, lignin oligomers, and electricity, and demonstrates the application of the matrix‐based approach for detailed system subdivision and environmental burden tracking. Forty scenarios utilizing process‐specific allocation methods were tested to account for the global warming potential of outputs. The main findings of the paper are: (i) the importance of specific allocation methods applied to combined heat and power plants that stress the key role of internal energy supply in carrying environmental burdens; (ii) a negligible effect of allocation methods applied to wastewater treatment facilities; (iii) the inconsistency of results obtained via two allocation methods, one based on the total mass and the second based on the dry mass allocation, which raises questions about the validity of water accounting in the allocation procedure of related products; (iv) the role of upstream greenhouse gas (GHG) emissions in lignin‐derived outputs, which emphasizes the importance of a proper allocation methodology to be applied to this residue; and (v) an important role of the biomass pretreatment and lignin solvolysis processes in the accumulation of emissions, which highlights the importance of decreasing the amount of solids and methanol content in the processes discussed here. © 2021 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

Environmental and Economic Assessment of a Novel Solvolysis-Based Biorefinery Producing Lignin-Derived Marine Biofuel and Cellulosic Ethanol

“…The discordance between these groups of allocation methods is supported by a similar observation concerning the inconsistency of LCA results obtained via two opposite allocation scenarios, including or excluding water from the allocation base [27]. The distortion observed might be highlighting the importance of the elimination of so called "dead" mass (e.g., blending agents, water) from the allocation procedure.…”

“…The allocation procedure can have a significant impact on the environmental profiles of biorefinery products imposing the necessity to test different allocation methods to decrease the related methodological uncertainty [27]. To that end, additional scenarios were set to analyse those impacts as summarized in Table 2.…”

“…The allocation issue has been widely discussed by LCA practitioners [27,43,44]. In general, the consistency of results obtained via different allocation approaches points at their reliability [27].…”

“…To reflect the underlying physical relationship between material and energy inputs on one hand, and process outputs on the other, within the base scenario, methanol was regarded as a blending agent and excluded from the allocation (see Appendix A, Tables A2 and A3). The allocation procedure was applied to a sub-divided product system following the methodology described in Obydenkova et al [27,28].…”

Lignin for energy applications – state of the art, life cycle, technoeconomic analysis and future trends

“…per GJ. 328 Hermansen et al ran different allocation scenarios on the lignin produced from a Kraft mill. The results varied between 0.18 to 0.64 kg CO 2 eq .…”