The energy sector is of paramount importance and has significant impacts on today's world. As part of the virtual 71st Canadian Chemical Engineering Conference (Montréal, 2021), an energy symposium was organized with a diverse range of presentations on novel technologies and innovative research in this field. Chemical engineering plays a major role within the energy sector and its future technological evolution. In this special issue section of The Canadian Journal of Chemical Engineering, selected papers based on presentations at the symposium are published.The following papers are included. Galatro et al. [1] investigate the second life of lithium-ion batteries, emphasizing the impact of cell spreading. Assis and Chirwa [2] analyze the fuel properties and combustion performance of hydrochars generated by the hydrothermal carbonization of different recycling-paper-mill wastes. Zeman and Breuvart [3] discuss CO 2 utilization in eastern Canada, including the effects of sources, sites, and the grid. Ahmadi et al. [4] present a molecular dynamics simulation study on the effect of bitumen molecular fractions on the diffusivity and rheology of bitumen under high-temperature conditions. Finally, Shevani et al. [5] synthesize and evaluate a sustainable bio-adsorbent for thermal-energy storage for space-heating applications.The papers in this special issue section-which cover experimental studies, modelling work, and impact analysisrepresent the variety of technological investigations and proposed solutions discussed during the symposium. KEYWORDS alternative energy sources, CO 2 utilization, energy storage, oil and gas AUTHOR CONTRIBUTIONS Clémence Fauteux-Lefebvre: Writingoriginal draft; writingreview and editing.