CO2 injection below the Venice Lagoon: a numerical study

The existence of the historical setting of the city of Venice and the environmental ecosystem of her lagoon is jeopardized by the increasing frequency of floods occurred over the last decades. The endless debate on the most appropriate solution for the Venice safety seems to have recently come to a final conclusion with the official approval of MOSE, an impressive engineering project consisting of 79 mobile barriers planned to close the lagoon inlets during the most severe storms, thus preventing the sea from flooding the city. However, MOSE has still many opponents who do not believe it can work effectively to preserve both the city and the lagoon ecosystem. We present here a new solution which has none of the environmental consequences charged to MOSE and can complement it in duration and safety. This is concerned with the injection of anthropogenic CO2 in a brackish sandy aquifer lying 600-800 m below the lagoon. Based on new recent hydrogeological and geomechanical information of the Northern Adriatic basin, a numerical study is performed with the aid of multiphase flow and geomechanical models showing that a set of vertical injection wells properly located in the lagoon area can uniformly raise Venice up to 12 cm over a 10 year time, with a partial mitigation of most of the high tides that threat the existence of the city. Moreover, CO2 sequestration in a safe geological formation can also contribute to meet the requirements of the 1997 Kyoto protocol on the reduction of greenhouse gas emissions. The proposed solution appears to be a promising strategy to be investigated with further analyses.