Abstract
The energy-intensive nature of gas thermal desorption strategies, along with their associated environmental impacts, particularly greenhouse gas emissions, has raised widespread concern. Using the life cycle assessment framework, this study conducted the first comparative analysis of in situ and on-site ex situ twin strategies, employing the same energy source and remediation principles from a unit process perspective. The results reveal that in situ gas thermal desorption exhibits significantly higher energy consumption (1.9 × ), normalized lifecycle environmental impacts (nearly 4 × ), and greenhouse gas emissions (more than 2 × ) than on-site ex situ strategy for the remediation of 1 m~3 of contaminated soil. Both technologies rely on fossil fuels for over 97% of their energy mix, with natural gas, electricity, and concrete being the primary contributors to greenhouse gas emissions. Unit process analysis further identifies that heating in the in situ strategy is the main driver of its environmental impacts, as the high temperature requirement significantly increases energy consumption. In contrast, off-gas treatment in on-site ex situ strategy is the main source of life cycle greenhouse gas emissions. Reduction potential analysis reveals that optimizing heating in in situ gas thermal desorption can reduce greenhouse gas emissions by 68.24%, while optimizing off-gas treatment in on-site ex situ strategy can reduce emissions by 51.81%. This study highlights the significant environmental performance differences between the two technologies and provides a scientific foundation for developing targeted emission reduction strategies at unit process level.
NETL
NSTL
Elsevier