Optimization of pressure retarded osmosis process and estimation of Indian blue energy capacity

Abstract The combination of long coastline (about 7500 km) and abundant river water (9.76 × 1011 m3/year) flowing into the sea across the southern peninsula of the Indian sub-continent provides the best conditions for blue energy extraction. The objective of this study is to estimate the Indian blue energy potential by mixing river and seawater before discharging into the sea through the optimized pressure-retarded osmosis (PRO) process. The model-based optimization approach is solved to establish an optimal process condition for integrated PRO + ERD (energy recovery device) process with respect to actual Indian river and seawater salinity. The PRO experiments are performed using syntactic seawater and river water as a draw solution (DS) and feed solution (FS), respectively. The PRO process optimization strategy is proposed to maximize the net power produced using river and seawater by manipulating operating conditions and module length. Three different objective functions are evaluated to maximize the extraction of the blue energy generation. The optimized PRO process was able to generate a net power of 0.07 kWh per 1m3 of river water supplied to the PRO system. The blue energy generation from the Indian major rivers discharging along the Indian coastal area was estimated to be 12.34 TWh/year.