Benchmarking cost, energy, and sustainability metrics for seawater desalination in small, medium, and large facilities.

Abstract:

Seawater desalination is offering new emerging choices for drought-proof water supplies to support societal development needs. In many water-stressed coastal regions, desalinated ocean water is already making important contributions to ensure water security for enabling the economy, improving the environment and reducing unsustainable resource use. However, in comparison with the traditional sources of water supplies, seawater desalination is energy intensive and cost prohibitive. While the development of seawater reverse osmosis (SWRO) membranes has significantly advanced the desalination technology, new innovations are needed to further narrow the gap in the cost and energy requirements between seawater desalination and water production through traditional water supplies. To identify the current challenges and opportunities for technological innovations, an analytical framework is developed to benchmark the system costs and energy intensity of SWRO desalination across small, medium, and larger seawater desalination plants. Important initial factors to consider in compiling and categorizing the representative SWRO desalination plants in the U.S. include size, levelized capital cost, annual O&M cost, salinity levels, and energy intensity per volume of produced water and the long-term resiliency of the system. Three initial representative case studies are explored to analyze the details of cost and energy at each unit treatment process at individual desalination plants. In addition, facilities that have permanently ceased operation are examined to identify the lessons learned in order to guide the future development. Lastly, the benefits, risks, and trade-offs for regions moving to implement efficient seawater desalination systems as related to costs, energy, land, acceptance, and markets/finance are discussed. The study also identifies some key data, knowledge gaps, and a need for new integrated performance metrics to inform future scenario modeling, planning and decision-making.