In order to promote a low-carbon society, fossil fuels are being increasingly used in the power generation sector. The main fuel used in biomass power generation is wood chips, the quality of which varies by region of origin. In biomass fuel production and storage facilities, the balance between heat generation and heat dissipation changes, which may increase the risk of fire. This paper introduces recent accident cases in woody biomass fuel production and storage facilities in Japan and Europe, the mechanism of heat storage, thermal analysis techniques for analyzing heat storage phenomena, and trends in prevention of heat storage fires. In addition, based on the results of the investigation of the cause of a serious fire caused by refuse derived fuel (RDF) in Mie Prefecture in 2003, knowledge on fire prevention in biomass power generation is summarized.

Torrefied biomass pellets are promising to replace fossil fuels with benefits to reduce carbon dioxide emissions from coal-fired power plants. However, the pellets may carry a risk of causing spontaneous combustion when the amount of the pellets exceeds a certain amount. This paper provides an overview of characteristics of spontaneous combustion and management of stockpiles of torrefied biomass pellets. The heat accumulation rate generated in a stockpile depends on the balance between heat generation rate in the stockpile and heat release rate to the external of the stockpile. It is natural to say that low-temperature oxidation of the pellets has an important role on self-heating of the pellets. From the point of view of safety, counter measures based on the concept considering risk identification, detection, monitoring, control and management are required to avoid fire caused by spontaneous combustion of stockpiles. It is also important to understand the characteristics and limitations of each storage facilities or stockyard in order to establish appropriate counter measures.

Biomass can ignite due to biological and chemical oxidation. If this phenomenon (spontaneous combustion) can be controlled, biochar could be produced at a lower cost without the need for an external heat source. In this study, the effects of inorganic substances in woody biomass on self-heating were investigated using cedar sawdust and bark chips as samples. As a result, it was found that bark chips with high ash content have excellent self-heating properties and can be sufficiently carbonized by self-heating. The inorganic matter in the biomass was removed by washing with water, and the exothermic behavior of the washed biomass was compared with that of the normal biomass. This suggests that inorganic substances in the biomass may have an effect on self-heating. The low-moisture content sample was tested for self-heating by oxidation reaction alone, but the amount of heat generated by the oxidation reaction at low temperatures was small and the exothermic behavior was unstable, suggesting that heat storage by microbial activity is important for stable self-heating of biomass.

The authors presented a method for detailed evaluation of self-heating characteristics (heat generation by oxidation and water adsorption) of coal using a highly sensitive thermogravimetric analysis and differential scanning calorimetry (TG-DSC) apparatus at the range of 40–80 °C. Using this apparatus, the heat generated by oxidation could be sufficiently quantified even at the low temperature of 40 °C, which had not been accurately measured in the past. Additionally, we presented the results of evaluating water adsorption characteristics for different coal types under varying ambient temperatures at a dew point of 20 °C. Furthermore, this method made it possible to quantify the total heat generation of dry samples, which is defined as the sum of the heat generated by oxidation and water adsorption, and the contribution of heat generated by water adsorption at each temperature.

Ammonia (NH₃) is recognized as a promising carbon-neutral fuel, as it can be produced on a large scale via the Haber-Bosch process without carbon emissions. NH₃ combustion faces several challenges, including poor flame stability and high ignition energy requirements, slow flame speed, and excessive nitric oxide emissions. The addition of hydrogen to NH₃ results in improved flame stability and expanded flammability boundaries, while increasing the flame temperature and the concentrations of radicals, including H, OH, and O. However, it also enhances NOx production. The flame stability and flame structure of NH₃/H₂ combustion and the chemical kinetics were reviewed in this paper. The flame structure analysis reveals that the addition of H₂ increases flame temperature and the concentration of key radicals, albeit resulting in higher NOx emissions. Chemical kinetics models are developed to describe the oxidation of NH₃ and the interactions between NH₃, H₂, and other species. However, there are gaps in understanding NH₃ combustion behavior that require further refinement of the chemical kinetic models.

Laser Induced Thermal Grating Spectroscopy (LITGS) is an anticipated technique for the quantitative temperature measurement especially for high pressure environment with high accuracy. In general, higher spatial resolution is required for flame measurement. However, the detailed discussion on the spatial resolution in LITGS has not been sufficient. To understand the spatial resolution in LITGS, quantitative temperature measurements to non-reacting jet with two different configurations, i.e., (a) non-reacting jet with quasi-one-dimensional temperature gradient and (b) non-reacting jet from a micro nozzle, were conducted. Non-reacting acetone/air premixture was employed for the measurement object. For the experiment (a), the direction of the probe volume in LITGS was aligned in the perpendicular and the parallel directions to the temperature gradient, i.e., the former has no temperature gradient in the probe volume, but the latter has temperature gradient in it. In addition, the size of probe volume was adjusted by the adjustment of crossing angle and the beam separation in the pump beams of LITGS. As a result, the measured temperature using LITGS showed good agreement with the temperature measured by thermocouple when there was no temperature gradient in the probe volume. On the other hand, the difference of measured temperature was observed when there was temperature gradient in the probe volume. In the experiment (b), temperature could be measured even though the size of the measurement object was smaller than that of the probe volume although the signal intensity was decreased. However, the signal-to-noise ratio decreased, and the uncertainty of the measured temperature increased compared to the case that the scale of measurement target was sufficiently large compared to the probe volume.