Hollow Fiber Membranes for Osmotic Power Generation via Pressure Retarded Osmosis (PRO)

Technology Overview: Osmotic energy is a completely renewable source that utilizes the mixing entropy of two solutions with different salinity. In the 1970s pressure retarded osmosis (PRO) as a membrane-based separation process was proposed to extract the osmotic energy from the sea. In this process water is drawn naturally from a low salinity feed solution across a semi-permeable membrane to a pressurized high salinity draw solution; power is then obtained by depressurizing part of the diluted draw solution through a hydroturbine. The two solutions typically used are seawater and river water. This technology relates to thin film composite hollow fiber membranes that can be used in PRO for power generation forward osmosis for water reuse as well as in low pressure reverse osmosis. Besides for PRO applications the membrane is also suitable for use in forward osmosis as the water flux reaches at least 65 LMH when 1M NaCl and DI water are used as the draw solution and feed respectively. The relatively high salt rejection of 97.6% of the membrane at 5 bar with a pure water permeability of 3.3 LMH also makes it suitable for use in low pressure RO processes. The hollow fiber configuration confers an advantage as hollow fiber low pressure RO membranes are not commonly available commercially. Applications: · Osmotic power generation via PRO · Forward Osmosis for water reuse · Low-pressure Reverse Osmosis (RO) Development Status: The membranes have been fabricated as hollow fibers and tested in a lab scale module. Test results are described in the above sections. It is possible to scale up membrane production with commercially available equipment. Patent: · Patent Pending Opportunity: · Licensing · Partnership for future development