Delbouy: Ocean wave-powered seawater reverse osmosis desalination systems

Abstract

Historically, most ocean wave energy conversion systems have been designed as large-scale electricity producers. Such devices require solution of serious storage, phasing, and distribution problems and usually must be of large scale for satisfactory economy. Alternatively, an ocean wave energy system under development since 1976 directly links ocean wave power with the production of freshwater from seawater using reverse osmosis (RO) technology. The device, referred to as DELBOUY, utilizes no motors, generators or electronics and makes extensive use of engineering polymers for constructing major system components. The DELBUOY combines with a wave driven buoy, linear pump and an anchor system with well-proven single-pass seawater RO membranes to produce potable water. The systems are modular in nature, allowing arrays to be sized to suit specific site requirements, from as little as 6 m 3/D. Unlike many of the other wave energy devices currently under development, the DELBUOY is an economic alternative to conventional desalination systems in wave fields as small as one meter. The DELBUOY system is especially useful in areas that are remote, have insufficient or unreliable power supplies or have high power costs. The research and development of the device, performed at the University of Delaware, USA, encompassed wave tank testing, mathematical modelling, materials testing and system sea trials. Starting in 1985 the commercialization of the DELBUOY was undertaken by ISTI Delaware, Inc. Since that time the system has undergone production engineering, supported by five full-scale sea trials and commercial installations. Operating experience obtained to date indicate that with only a five year amortization period, the DELBUOY system is an economic alternative to conventionally powered desalination systems in areas where power costs are high. This paper describes the system's design and operating principle, sea trial results, site selection and deployment considerations, the economics of direct wave-powered desalination, and the commercial status of the technology.