Combining expansion in pulp capacity with production of sustainable biofuels – Techno-economic and greenhouse gas emissions assessment of drop-in fuels from black liquor part-streams

Yawer Jafri,Elisabeth Wetterlund,Sennai Mesfun,Henrik Rådberg,Johanna Mossberg,Christian Hulteberg,Erik Furusjö

doi:10.1016/j.apenergy.2020.115879

Abstract

Drop-in biofuels from forest by-products such as black liquor can help deliver deep reductions in transport greenhouse gas emissions by replacing fossil fuels in our vehicle fleet. Black liquor is produced at pulp mills that can increase their pulping capacity by upgrading some of it to drop-in biofuels but this is not well-studied. We evaluate the techno-economic and greenhouse gas performance of five drop-in biofuel pathways based on BL lignin separation with hydrotreatment or black liquor gasification with catalytic synthesis. We also assess how integrated biofuel production impacts different types of pulp mills and a petroleum refinery by using energy and material balances assembled from experimental data supplemented by expert input. Our results indicate that drop-in biofuels from black liquor part-streams can be produced for ~80 EUR2017/MWh, which puts black liquor on the same footing (or better) as comparable forest residue-based alternatives. The best pathways in both production routes have comparable costs and their principal biofuel products (petrol for black liquor gasification and diesel for lignin hydrotreatment) complement each other. All pathways surpass European Union’s sustainability criteria for greenhouse gas savings from new plants. Supplementing black liquor with pyrolysis oil or electrolysis hydrogen can improve biofuel production potentials and feedstock diversity, but better economic performance does not accompany these benefits. Fossil hydrogen represents the cheaper option for lignin hydrotreatment by some margin, but greenhouse gas savings from renewable hydrogen are nearly twice as great. Research on lignin upgrading in industrial conditions is recommended for reducing the presently significant performance uncertainties.

Highlights

Reducing greenhouse gas (GHG) emissions in the transport sector to a meaningful extent requires both short and long-term interventions [1]
We evaluate the techno-economic and greenhouse gas performance of five drop-in biofuel pathways based on BL lignin separation with hydrotreatment or black liquor gasification with catalytic synthesis
All pathways integrated with a given mill use the same quantity of BL or BL lignin, which amounts to 104 MW, 71 MW and 56 MW for Model Mill, Sodra and SKKP, respectively

Summary

Introduction

Reducing greenhouse gas (GHG) emissions in the transport sector to a meaningful extent requires both short and long-term interventions [1]. As bio-hydrocarbons that are functionally equivalent to fossil transport fuels, drop-in biofuels are fully compatible with today’s vehicle fleet and petroleum refining infrastructure [3,4]. Wider deployment of drop-in biofuels in the short-to-medium term has been identified as vital to the realization of transport GHG reduction targets [5,6]. The economics of drop-in biofuels can be enhanced by co-locating and integrating production with petroleum refineries, thereby providing valuable access to hydrogen [2,3]. The lack of, and need for, representative experimental data on the hydrogen consumption and hydrocarbon product yields of different drop-in biomass-based feeds has been strongly highlighted recently [8]

Methods

Results

Conclusion