Comparative environmental and social life cycle assessments of off-shore aquaculture rafts made in ultra-high performance concrete (UHPC)

Purpose: This paper aims to compare the environmental and social impacts of three types of rafts for mussel farming in Spain. These structures, traditionally made of wood, have a short lifespan and, because of their service conditions, require frequent maintenance in order to be fully operational. An innovative solution made with ultra-high performance concrete (UHPC) was developed in 2016 by RDC, being at the base of the pilots of the EU-funded project ReSHEALience (H2020-GA760824). Methods: In order to quantify the environmental and social impacts generated by alternative solutions for the aquaculture raft, a life cycle approach has been used. The life cycle assessment methodology, according to ISO 14040 and ISO 14044 standards, has been used for the evaluation of the environmental impacts, while the social life cycle assessment (SLCA) methodology, according to the Guidelines for SLCA of Products and the social impact assessment method developed by Ciroth and Franze (2011), has been used for the evaluation of the social impacts: the same functional unit and the same stages of the life cycle to be included in the study has been set for the alternative solutions. Results and discussion: Based on the LCA results, derived from the system boundary described in the “Goal and scope” section for the mussel aquaculture structures, the highest environmental impacts in the cradle-to-grave analysis are generated by the Traditional Raft with maintenance based on the periodic application of paints; the lowest environmental impacts are generated by the Traditional Raft with maintenance based on the progressive replacement of the damaged logs, while the Innovative Raft has an intermediate behavior in terms of environmental impact generation. Based on the S-LCA results, it can be stated that both the solutions generate high impacts; nevertheless, the Innovative solution has a slight lower impact than the Traditional solutions, which could be lowered if some precautions in the society policy are taken. Social hot-spots are identified in order to help reducing the overall social impacts. Conclusions: In conclusion, it can be stated that, from both the environmental and social points of view, the Traditional Solutions for the aquaculture raft are the most “impactful,” especially when the maintenance is based on paint application. The use of innovative concretes allows to build longer lifespan rafts with minimum (or no) need of maintenance. Moreover, the behavior of new companies is more attentive to social aspects related to their activities and has a margin of improvement, when compared to traditional companies.