Carbon Sequestration requires the removal of CO2 from the...

Carbon Sequestration requires the removal of CO2 from the atmosphere i.e. through algae growth, trees (noting that at a certain point in a tree life cycle they actually output as much CO2 as they take in) etc.

Depositing fly ash into the soil is no different to what they do by placing it in pellets, mixing into concrete etc it only solves the issue of where to place the by product but does no sequester any CO2 from the atmosphere.

On a side note when sequestering CO2 using plantation trees the trees can only be used to sequester for 50% of their life cycle i.e. carbon credits can only be claimed for 4yrs if the tree is cut down at say year 8 etc.

My company develops systems for CO2 sequestration by the way..