Methodology for Evaluating the CO₂ Sequestration Capacity of Waste Ashes

Area of Science:

• Environmental Science
• Geochemistry
• Materials Science

Background:

• Rising atmospheric carbon dioxide (CO2) concentrations drive global warming and climate change.
• CO2 sequestration is a key strategy for climate change mitigation.
• Accelerated carbonation of ashes offers a promising CO2 capture method, but ash suitability varies.

Purpose of the Study:

• To develop and apply a methodology for evaluating the CO2 sequestration potential of ashes.
• To identify ashes with high CO2 uptake capacity through accelerated carbonation.
• To quantify CO2 sequestration efficiency in various combustion ashes.

Main Methods:

• Ashes were subjected to accelerated carbonation under controlled conditions (4% CO2, 50-85% RH, 20 °C).
• CO2 uptake was measured over time until maximum saturation was achieved.
• Quantification of sequestered CO2 was performed using thermogravimetry (TG).
• Evaluation involved theoretical calculations, XRF, XRD, DTA-TG, and calcimetry.

Main Results:

• Wood biomass bottom ash exhibited the highest CO2 sequestration capacity (33.8%).
• The highest carbonation efficiency reached 67.9% for wood biomass bottom ash.
• The developed methodology was successfully applied to eight different combustion ashes.

Conclusions:

• Wood biomass bottom ash is a highly effective material for accelerated CO2 sequestration.
• The proposed methodology provides a reliable framework for assessing CO2 storage potential in ashes.
• This approach can be extended to evaluate other carbon storage materials.