Scenarios of RO brines valorization in power plants

In this work we propose and compare three scenarios of reverse osmosis (RO) brines valorization in power plants. The comparison focuses on energy consumption and environmental considerations. The first scenario is based on using seawater reverse osmosis (SWRO) and brackish water reverse osmosis (BWRO) brines to generate power using pressure retarded osmosis (PRO) which is a membrane based process that converts the osmotic energy into electrical energy. In the second scenario the BWRO brine is used to dilute the SWRO inlet seawater. This will reduce specific energy consumption by reducing the feed pressure applied to the system. It will also ameliorate permeate quality and reduce brine salinity. The third scenario is a combination of the first and the second scenarios. The specific energy gain in the second valorization scenario is the highest representing 14% of the actual energy used for desalinating seawater. It is about 7.6 times higher than in the first valorization scenario. The last scenario looks the best from an environmental consideration as the brine has the lowest salinity at the expense of a drop of only about a third of the energy savings in the second scenario.