Sustainable hydrogen production for ammonia from black liquor gasification integrated with modern pulp mills for carbon-neutral systems

Abstract

Climate change mitigation and energy security serve as significant drivers for the development of innovative sustainable technologies aimed at evaluating diverse sustainability factors to achieve efficient future energy systems. With an established infrastructure, pulp and paper mills can concurrently produce bio-chemicals, biofuels, and electricity alongside pulp and paper products utilizing waste black liquor. This study highlights key sustainability aspects of hydrogen production leading to ammonia synthesis derived from various black liquor gasification systems integrated with modern pulp mills. The study is novel as it comprehensively presents the detailed aspects of black liquor as a sustainable feedstock, emphasizing its availability as a byproduct in the pulp and paper industry, along with its environmental benefits and includes a comparison of the key sustainability aspects of green ammonia production with traditional methods. Furthermore, the paper conducts an environmental impact assessment, analyzing the implications of such integration, encompassing aspects such as greenhouse gas emissions, air and water pollution, and other environmental factors. Economic viability and technological advancements are critically assessed, along with an exploration of the socio-economic and policy implications. From a technical perspective, the integrated catalytic hydrothermal gasification (CHG) system demonstrated the highest energy efficiency among studied systems but at a cost of highest additional biomass import to offset the energy deficit of the reference mill. The paper summarizes the key findings related to the sustainability aspects emphasizing its pivotal role in advancing sustainable energy transitions and reducing carbon emissions. The current study builds new knowledge on black liquor-based hydrogen production leading to ammonia synthesis to key stakeholders and contributes to understanding the potential for sustainable and environmentally friendly green chemical solutions.