Cultivating Ciona intestinalis to counteract marine eutrophication: Environmental assessment of a marine biomass based bioenergy and biofertilizer production system

In this paper the utilisation of the marine evertebrate organism Ciona intestinalis (tunicata), cultivated in the North Sea and used as feedstock for biogas and biofertilizer production is suggested and assessed. The greenhouse gas (GHG) emissions performance of the concept and it's consequences on marine eutrophication are investigated applying life cycle assessment. Results show that at full scale biogas production from C. intestinalis reduces GHG emissions by more than 65% compared to fossil transportation fuels. In addition, the results show that accounting for the system consequences of other products and services such as biofertilizer replacing mineral fertilizers and decreased marine eutrophication largely increase the environmental benefits provided by the concept. Approx. 3.7 g-Neq/MJbiogas of nitrogen are removed from the marine environment during the cultivation of C. intestinalis.