New avenues for the large-scale harvesting of blue energy

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New avenues for the large-scale harvesting of blue energy, Nature Reviews Chemistry 1, Article number: 0091 (2017)

 

Access to sustainable, abundant and inexpensive sources of energy is one of the key challenges faced by our modern society. Since the beginning of the industrial revolution, fossil fuels (in the form of coal, oil or gas) have been our primary source of energy. However, the high environmental impact of burning fossil fuels has led to widespread eco-friendly sentiments in the past decade. Several sources of clean energy (associated with low post-production carbon emissions) have been identified, including solar, wind and water power ; however, to date, none of these power sources can replace fossil fuels, mainly because of the limited efficiency of generating and storing electrical power, their moderate availability, their intermittency and the prohibitive cost associated with energy conversion.

 

 

In this Perspective, we have discussed technologies for the conversion of the energy originating from the mixing of solutions with different salinities. Although the potential of this new source of clean and renewable energy is huge, its large-scale exploitation is still prohibited because of the low efficiency of current conversion schemes. Commercial viability is expected to be achieved for an extracted power of approximately 5 W m−2 of membrane used, but the actual value obtained with standard approaches (PRO and RED) is lower than a few watts per square metre.

Recent findings of extremely high osmotic power densities using new materials as membrane supports have revived the field. These results indicate new avenues for the development of dedicated membranes based on highly reactive materials. It is now necessary to further explore the class of materials that matches the conditions for a scalable osmotic power production. We also noted the high potential of nonlinear transport to further boost energy conversion, suggesting the design of asymmetric membranes. The roadmap towards this objective is quite clear.

Blue-energy conversion is an emerging field at the interface between chemistry, materials science and nanofluidic transport. It is a rich playground in which fundamental science can be directly applied to boost the blue-energy harvesting performance. There is hope that this renewable, clean and democratic source of energy can reach a level where it becomes viable at a large-scale. This is definitely an exciting time.

 

Résumé: 

Nature Reviews Chemistry 1, Article number: 0091 (2017)

 

Salinity gradients have been identified as promising clean, renewable and non intermittent sources of energy — so-called blue energy. However, the low efficiency of current harvesting technologies is a major limitation for large-scale viability and is mostly due to the low performances of the membrane processes currently in use. Advances in materials fabrication with dedicated chemical properties can resolve this bottleneck and lead to a new class of membranes for blue-energy conversion. In this Perspective, we briefly present current technologies for the conversion of blue energy, describe their performances and note their limitations. We then discuss new avenues for the development of a new class of membranes, combining considerations in nanoscale fluid dynamics and surface chemistry. Finally, we discuss how new functionalities originating from the exotic behaviour of fluids in the nanoscale regime can further boost energy conversion, making osmotic energy a tangible, clean alternative.

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New avenues for the large-scale harvesting of blue energy

 

Alessandro Siria, Marie-Laure Bocquet and Lydéric Bocquet

 

Nature Reviews Chemistry 1, Article number: 0091 (2017)

 

doi: 10.1038/s41570-017-0091