Learning Curve for Seawater Reverse Osmosis Desalination Plants: Capital Cost Trend of the Past, Present, and Future

Seawater reverse osmosis (SWRO) desalination is expected to play a pivotal role in helping to secure future global water supply. While the global reliance on SWRO plants for water security increases, there is no consensus on how the capital costs of SWRO plants will vary in the future. The aim of this paper is to analyze the past trends of the SWRO capital expenditures (capex) as the historic global cumulative online SWRO capacity increases, based on the learning curve concept. The SWRO capex learning curve is found based on 4,237 plants that came online from 1977 to 2015. A learning rate of 15% is determined, implying that the SWRO capex reduced by 15% when the cumulative capacity was doubled. Based on SWRO capacity annual growth rates of 10% and 20%, by 2030, the global average capex of SWRO plants is found to fall to 1,580 USD/(m(3)/d) and 1,340 USD/(m(3)/d), respectively. A learning curve for SWRO capital costs has not been presented previously. This research highlights the potential for decrease in SWRO capex with the increase in installation of SWRO plants and the value of the learning curve approach to estimate future SWRO capex. Plain Language Summary Seawater desalination is expected to play a pivotal role in helping to secure future global water supply as water demand surges and freshwater resources diminish. While there are various seawater desalination technologies, the dominant desalination technology is expected to be seawater reverse osmosis (SWRO). The aim of this paper is to understand how the capital cost of SWRO plants has changed in the past as more plants were built and operated. This is based on the "learning by doing'' concept that illustrates the relationship between cost reduction in industries and the increase in production output. The relevance for SWRO plants is studied by assessing 4,237 plants that were operated from 1977 to 2015. It is found that as the cumulative global capacity of SWRO plants doubled, the average capital cost reduced by 15%. The results suggest that for every future doubling of SWRO capacity, the capital cost will reduce by 15%. This is the first such observation presented for SWRO plants and can be used to project the future capital costs of SWRO plants.