Assessing VOC dispersion from hydrocarbon storage tanks: a case study on emission temporal resolution

Volatile Organic Compound emissions from hydrocarbon storage tanks are a key source of industrial air pollution and odour nuisance. This study evaluates odour impact predictions using annual average emissions versus time-resolved emissions from fixed roof tanks and external floating roof tanks that store different hydrocarbon products, including crude oil and refined products such as gasoline, diesel, kerosene, fuel oil, and bitumen. Odour emission rates are derived from field measurements and laboratory data and implemented in CALPUFF dispersion modelling. The results show that for fixed roof tanks, time-resolved emissions predict odour separation distances up to four times greater than annual averages, with central domain differences reaching 300% and boundary variations between 50–100%. In contrast, floating roof tanks show minimal variation (<10%) between the two methods. These findings highlight that odour perception is driven by short-term peaks rather than long-term averages and that using annualized emissions may significantly underpredict odour impacts, especially for fixed roof tanks. Accurate temporal characterization is thus essential for realistic odour assessments and effective regulatory compliance.