Air pollutant emissions and environmental impacts of charcoal and wood briquettes used for grilling

There are growing environmental and health concerns surrounding using charcoal and wood for grilling because charcoal combustion releases significant pollutants that contribute to global warming, air pollution, and adverse health effects. The study assessed the emissions and performance quality of selected types of charcoal briquettes and wood briquettes available on the market. Sixteen (16) samples were collected for this investigation including 8 charcoal briquette samples and 8 wood briquette samples. The samples were selected to represent the most common barbecue offerings in the Italian market. The samples were subjected to proximate analysis according to the procedures established under the international EN ISO standards. All parameters were determined in triplicate. Proximate analysis was conducted to determine the Ash content (AC), Moisture content (MC), Volatile matter (VM), and Fixed carbon (FC) of the samples. The experimental procedures were conducted in a controlled laboratory setting for 4 to 6 weeks, with each test repeated for accuracy and comparability. Lower Heating Value on a dry basis (LHVdry) and the Higher Heating Value on a dry basis (HHVdry) were determined using a bomb. Combustion tests were also conducted to assess the concentration of Carbon monoxide (CO), Volatile organic compound (VOC) and Total suspended particle (TSP) emitted during charcoal combustion. Results showed that for proximate analysis parameters such as moisture content, wood briquettes exhibited higher values than charcoal briquettes. This indicates that wood briquettes may require more energy for evaporation during combustion, potentially reducing combustion efficiency. For ash content, wood briquettes had significantly lower ash content as compared to charcoal briquettes, suggesting that wood briquettes produced less residue, which could impact post-combustion waste management. Wood briquettes also had higher volatile matter, implying an ease of ignition and rapid energy release during combustion. Charcoal briquettes, however, outperformed wood briquettes in the fixed carbon content and heating values, 54.04% for charcoal briquettes and 14.95% for wood briquettes, indicating that charcoal briquettes can sustain combustion for a longer period, as fixed carbon is responsible for the prolonged heat release during grilling. Charcoal briquettes outperformed wood briquettes, with mean lower heating values of 22.20 MJ/kg and higher heating values of 23.52 MJ/kg, compared to 18.26 MJ/kg (LHVdry) and 19.58 MJ/kg (HHVdry) for wood briquettes. Finally, the CO, VOCs, and TSP emissions were relatively higher from charcoal briquettes than those from wood briquettes. Although charcoal briquettes present better energy characteristics for grilling, they are associated with higher emissions. Perhaps wood briquettes should be preferred over charcoal for grilling. However, more investigations are needed to sustain these results. The work needs to be extended to other types of wood and charcoal briquettes.