From knowledge gaps to technological maturity: A comparative review of pathways to deep emission reduction for energy-intensive industries

Energy intensive industries, such as steel, cement, basic chemicals, aluminium, glass as well as pulp and paper contribute substantial amounts of greenhouse gas emissions, which further accelerate climate change. The emissions from industry are generally considered hard-to-abate and technological solutions are often not yet mature. Additionally, the ideal technologies for each industry sector are not yet clearly researched in a structured and comparative manner, which is the key research gap addressed by this study. To focus on this, an extensive, systemic literature review has been conducted, following a strict protocol. A vast number of studies have been carefully read and information obtained. The comparative approach of the study is expressed in a Likert-type scale-based scoring approach, providing a robust framework to gain insights into favourable pathways, which is the first of its kind. It could be demonstrated that the steel industry is the best researched industry sector while knowledge gaps exist for the cement and glass industry. The results further show that secondary production via recycling serves as a low-risk option for most industry sectors, providing benefits such as high technological maturity, energy efficiency, and low production costs, without compromising sustainability standards. Direct electrification of heat and green electricity-based hydrogen feedstocks are essential to reach zero emissions for primary production. The results indicate that substantial efforts are imperative for achieving significant emission reductions in energy-intensive industries, necessitating robust financial support from governments. Emphasis should be placed on renewable electricity, green hydrogen, and recycling as pivotal components of these efforts.