Membrane processes and renewable energies

In this work, an overview of the interconnections between membrane technology and renewable energy sources (biomass, salinity gradient power, wind, solar) is given. Regarding biomass, membrane processes such as membrane reactors and bio-reactors, membrane contactors, membrane distillation in the logic of process intensification strategy may be opportunely integrated in the production processes of green fuels. Their advantages such as reduction of the separation load and stage number, improved yields and selectivities compared to conventional processes imply low direct energy consumption, lower footprint area occupied by the processes plants. Moreover, the possibility of integration these advanced membrane processes with other traditional membrane operations such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), pervaporation (PV) allows the reduction of indirect energy consumption through the recycling and reuse of raw materials and secondary materials minimizing the formation of wastes. Both Pressure Retarded Osmosis (PRO) and Reversed Electra Dialysis (RED), the only two technologies for which salinity gradient power-based demonstration projects are running, use membranes. In this article, key points and challenges to be faced for both PRO and RED are reported. On the other side, membrane desalination plants, are more often considered excellent locations to install wind and solar power generators. Most advanced research in the field is focused on solar assisted membrane distillation (MD). In the logic of fully sustainable desalination, highly innovative technologies such as Microbial desalination cells (MDCs) could be integrated as pre-treatment stage in membrane desalination plants in remote, arid regions. (C) 2014 Elsevier Ltd. All rights reserved.