Oriented, lightweight and compact graphite-sheet-fin-based solid ammonia carriers enabling risk-free, sustainable onboard ammonia energy supply

Abstract

Employing carbon-free ammonia as a fuel is a crucial technical approach for decarbonizing the transportation sector such as long-distance trucking, shipping and aviation. Currently, ammonia combustion fuel relies on a high-risk liquid ammonia supply method, and leak risk poses a significant threat to the safety of personnel on board. Herein, we present novel oriented and lightweight graphite-sheet-fin-based solid ammonia carriers for risk-free, sustainable ammonia energy supply. A comprehensive advancement for solid ammonia carriers has been accomplished, encompassing novel sorbent synthesis, component engineering, system application and a full-chain operation framework. Radial liquid-nitrogen freeze casting coupled with a mechanical compression-induced construction method is proposed to produce large-sized, oriented, aligned and compact graphite-sheet fins embedded within solid sorbents, which synergistically establishes lightweight thermally conductive and mass transfer networks, achieving excellent intralayer heat transfer and ordered interlayer mass transport. The sorbent exhibits high-pressure charging and low-pressure discharging behavior, achieving an ammonia uptake of 0.36 kg kg⁻¹, corresponding to an ammonia storage density of up to 216.9 kg m⁻³, while also reducing weight by 38.4% compared to the conventional metal-fin-based sorbent, complying with the lightweight and compact design requirements for transportation equipment. Solid ammonia carriers complete rapid charging within approximately one hour, and controlled ammonia gas release is achieved by utilizing mass flow controllers. We propose a novel integrated system for low-carbon ammonia-blended combustion and NO_x pollutant treatment, and engineer graphite-sheet-fin solid ammonia carriers driven by a free engine cylinder jacket water heat source. A full-chain framework for sustainable solid ammonia energy supply from production to end distribution is also established. Our work demonstrates a scalable pathway to solid ammonia carriers for safe onboard ammonia energy supply in the transportation sector.