The development of the Pressure Exchanger has culminated in a very promising technology for energy recovery of processing liquids. Potential savings of more than 60% of pumping work is possible in seawater RO-desalting. Moreover, the operational characteristic will reduce the need for a large number of production trains and this will further reduce the capital and operational cost of larger plants. This device was initially under development and assessment at Doha Reverse Osmosis Plant (DROP) in Kuwait, but the joint R&D program with Kuwait Institute for Scientific Research (KISR) was suspended in 1990, due to the Gulf war. An extensive development program has been ongoing throughout 1991-92 together with the German submarine manufacturer Thyssen Nordseewerke for using a Pressure Exchanger (PE) in a Closed Cycle Diesel (CCD) propulsion system. Several pilot projects are now underway in various applications including adsorber duties and RO-desalting.