This study investigates the impact on the economy of the Italian region of the Sardinia generated by a new biomass power plant that will be fed with locally cultivated cardoon. The cardoon will also serve the production of biopolymers. The impact is assessed at an economy-wide level using a multiregional mixed-variable closed I-O model that allows taking into account the whole supply chain activated and the cross-regional effects generated by trade across local industries. The effects are computed under alternative scenarios simulating different degrees of substitution of existing agricultural productions with the new activity (the cardoon). Results show how the overall impact may be substantially influenced and even reversed according to the level of substitution.