Improved energy recovery from yard waste by water-starved hydrothermal treatment: Effects of process water and pressure

Qiaozhi Zhang; Yang Cao; Mingjing He; Hanwu Lei; Hocheol Song; Daniel S Alessi; Daniel C W Tsang

doi:10.1016/j.biortech.2023.130211

Improved energy recovery from yard waste by water-starved hydrothermal treatment: Effects of process water and pressure

Bioresour Technol. 2024 Feb:394:130211. doi: 10.1016/j.biortech.2023.130211. Epub 2023 Dec 17.

Authors

Qiaozhi Zhang¹, Yang Cao², Mingjing He², Hanwu Lei³, Hocheol Song⁴, Daniel S Alessi⁵, Daniel C W Tsang⁶

Affiliations

¹ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576, Singapore.
² Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
³ Department of Biological Systems Engineering, Washington State University, Richland, WA 99354-1671, USA.
⁴ Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul 04763, South Korea.
⁵ Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada.
⁶ Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China; State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China. Electronic address: cedan@ust.hk.

PMID: 38113950
DOI: 10.1016/j.biortech.2023.130211

Abstract

This study investigated the feasibility of a high-loading process with less water consumption for the valorization of wet biomass waste through hydrothermal carbonization (HTC) with and without N₂ pressurization from the views of water saving, carbon utilization, and energy recovery. The results revealed that reducing the liquid-to-solid ratio from 10 to 2.5 significantly improved carbon storage in hydrochar due to preferential carbon sequestration as the solid phase (59.9%) instead of being lost in the liquid phase (∼10%). The pressurized HTC process resulted in a higher stability hydrochar through the devolatilization of secondary char that was less stable, yet resulted in ∼10% 15% more carbon transformation to the gas phase. A cost-benefit analysis further demonstrated the potential of the high-loading HTC process for enhancing energy recovery while minimizing energy consumption during hydrochar production from high-moisture yard waste.

Keywords: Biochar/hydrochar; Biomass densification; Carbon storage; High-loading thermochemical process; Hydrothermal carbonization; Waste management/recycling; Water saving.

MeSH terms

Biomass
Carbon*
Physical Phenomena
Temperature
Water*

Substances

Water
Carbon