106In the present case, an advantage granted by the national legislature, that is, the tradability of NOx emission allowances, could entail an additional burden for the public authorities in the form of an exemption from the obligation to pay fines or other pecuniary penalties (see, to that effect, Case C-295/97Piaggio [1999] ECR I-3735, paragraph 42). By establishing the ‘dynamic cap’ scheme, the Kingdom of the Netherlands gave to the undertakings covered by the measure in question the possibility of buying emission allowances in order to avoid the payment of fines. In addition, the consequence of that system is the creation, without real consideration supplied to the State, of emission allowances which, because of their tradable character, have an economic value. It must be concluded that the Member State could have sold such rights, or where appropriate put them up for auction, if it had structured that scheme differently (see, in that regard, paragraphs 63, 64 and 86 to 96 above).