CONICET | Buscador de Institutos y Recursos Humanos

The increase of energy demand added to the concern for the environmental pollution linked to the energy generation based on the combustion of fossil fuels has motivated the study and development of new eco-friendly ways for energy harvesting. Among the different alternatives, the opportunity to generate energy by exploiting the osmotic pressure difference between water sources of different salinities has emerged as a promising method. It is well-known that this objective can be accomplished by employing ion-selective dense membranes. However, so far, the current state of this technology has shown limited performance which hinders its real application. In this context, advanced nanostructured membranes (nanomembranes) with high ion flux and selectivity enabling to enhance the output power emerged as a promising strategy to overcome the existing barriers in this technology. While the utilization of nanomembranes for osmotic power generation is a relatively new field and therefore, its application for large-scale production is still uncertain, there have been major developments in recent years that demonstrate its huge potential. In this review, we introduce a comprehensive analysis of the main fundamental concepts behind osmotic energy generation and how the utilization of nanomembranes with tailored ion transport can be a key facing the development of high-efficiency blue energy harvesting systems. Also, the document discusses experimental issues related to the different ways to fabricate this new generation of membranes and the different experimental set-ups for the energy-conversion measurements. We highlight the importance of optimizing the experimental variables through the detailed analysis of the influence in the energy capability of geometrical features related to the nanomembranes, surface charge density, concentration gradient, temperature, building block integration, and others. Finally, we summarize some representative works in up-scaled membranes and discuss the main challenges and perspectives of this emerging field.