Reducing energy consumption in seawater desalination

Water is an increasingly scarce resource and in many regions people are turning to new sources such as seawater and wastewater. Various membrane technology improvements in the last decade have led to a significant cost reduction in reverse osmosis (RO). This has triggered selection of seawater reverse osmosis (SWRO) technology for many large drinking water projects in the world. Since energy cost is the single largest factor in the cost of a seawater system (usually 20-30% of the total cost of water), it is an obvious target for cost reduction. Therefore new membrane developments have to focus on lower energy consumption. This requires the development of high productivity membrane elements and compatible design concepts that enable operation at lower pressure. This publication presents new products with higher flow (7500-9000 gpd at standard test conditions) and high rejection (99.70-99.75%) for the seawater desalination segment. The technical features of these products are explained and possible energy and other cost savings are calculated. It is shown that these products can be used across the entire seawater segment to reduce energy consumption down to levels of 2.0 kWh/m(3) or to reduce the capital cost of the membrane stage by up to 30%. Field data for these new products is presented at the end and confirms both, performance of the presented new products, and significant capital and operational cost savings.