Comparative life cycle assessment of seawater desalination technologies enhanced by graphene membranes

Graphene oxide (GO)-enhanced membranes are being developed to solve major limitations in both reverse osmosis (RO) and membrane distillation (MD) technologies, which include high electricity and thermal energy consumption. This study performed, for the first time, a life cycle assessment to determine the effects of using GO-enhanced membranes on the environmental impacts of seawater desalination via RO and MD. Four scenarios were evaluated and eighteen environmental impacts were quantified according to the ReCiPe impact assessment method. The average impacts for the RO-GO scenarios were lower than those of RO by 3-7 %. The reduction in the climate change impact was 3-8 %, which could avoid the release of 380-850 kt CO2 eq. per year globally if these membranes were used in current seawater RO systems. The MD-GO scenarios had, on average, 27-34 % lower impacts than the MD scenarios. Overall, the RO-GO systems were the most favourable, with lower impacts than MD-GO for most categories. However, using solar-thermal energy instead of natural gas in MD desalination would lead to 43-93 % lower impacts in nine categories than RO powered predominantly by fossil fuels. This includes climate change, which would be 64 % lower; however, freshwater ecotoxicity would be more than four -times higher. The results of this work indicate the potential environmental benefits of GO-enhanced membranes and discuss the future developments needed to improve the performance of RO and MD.