Query on excise duty on coal ash ( not sold)

Query :

Company "A" is a having coal fired power plant for exclusively own consumption of power & stream . As fly ash is not sold but sent to dumping ground, does the Finance Act 2011 impose excise duty on generation of fly ash and payment of duty on subsequent disposal with out any commercial value realisation.

Please guide with case laws , if any.

Thanks in advance

J Boonnerjee