Deep peat fire persistently smouldering for weeks: a laboratory demonstration

Abstract

Background. Peatlands are becoming more vulnerable to smouldering fires, driven by climate change and human activities. Aims. This work explores the persistent burning, propagation, and emission of the deep peat fire. Methods. Laboratory experiments are conducted with a 1-m deep peat column, and smouldering fires are initiated at different depths. Key results. We found localised burning and multi-directional smouldering fire spread in deep peat layers. The smouldering temperature first decreases with depths up to −40 cm (from around 550 to 350°C) and then remains at about 300°C in the deeper layers. High moisture content can slow down in-depth fire propagation and reduce the burning duration. Conclusions. Peat fire can burn in deep layers for weeks, and its combustion is incomplete with small mass loss, because of a limited oxygen supply and low smouldering temperature. Measuring the carbon monoxide concentration near the surface can detect underground fire and monitor its intensity. Implications. This work helps reveal the underlying mechanism of the in-depth smouldering wildfires in peatland and supports future larger-scale peat fire experiments in the field.

Thermal Decomposition and Combustion Analysis of Malaysian Peat Soil Samples Using Coats Redfern Model-free Method

“…Upon ignition, smouldering peat fires possess the potential to persist for hours initially and then continue to smoulder over extended periods, spanning months to even years (Goldstein et al, 2020;Rein, 2013). Within controlled laboratory conditions, the persistence of smouldering peat fires can extend over several weeks (Qin et al, 2022). This observation emphasises the need for further research on their thermal behaviour in this domain.…”

IX International Conference on Forest Fire Research and 17th International Wildland Fire Safety Summit: introduction to special issue (Part 1)

“…Recognising that in wildland-urban interface fires, particulates from combustion of natural vegetative and human-made fuels may have deleterious effects on the environment, the authors took particulate samples during both flaming combustion and smouldering combustion states and found that the morphology of the generated particulates was greatly influenced by the state of combustion for both types of fuels. Qin et al (2023) performed a laboratory study of the smouldering of a deep layer of peat fire and showed that smouldering can persist for weeks. The authors recognise that smouldering fire in peatland is one of the largest wildfire phenomena on Earth that can burn slowly deep underground without flame.…”

The initiation of smouldering peat fire by a glowing firebrand

“…Smouldering peatland fires were brought to the forefront of scientific debate following the 1997 extreme haze event in south-east Asia from burning peatlands during a particularly strong El Nino season (Page et al 2002). Following this event, many research studies have targeted understanding the characteristics of smouldering peat fires, including combustion chemistry (Huang and Rein 2016), ignition (Lin et al 2019;Cui et al 2022;Santoso et al 2022), fire spread (Prat et al 2015;Yang and Chen 2018;Huang and Rein 2019;Qin et al 2022aQin et al , 2022bZhang et al 2024), emissions (Hu et al 2018;Kohlenberg et al 2018;Lin et al 2021b), detection (Atwood et al 2016;Rein et al 2017), and suppression (Ramadhan et al 2017;Santoso et al 2021;Mulyasih et al 2022). A recent review paper provided a comprehensive overview of smouldering wildfires, together with their associated environmental and health issues, as well as the challenges in prevention and mitigation (Rein and Huang 2021).…”