Energy and water without carbon: Integrated desalination and nuclear power at Diablo Canyon

A seawater reverse osmosis (SWRO) desalination plant collocated with an existing nuclear plant would have low electricity costs, could share the power plant’s seawater intake and outfall, and would have zero carbon footprint during operation. Unlike thermal desalination technologies, electrically-driven SWRO is ideal for retrofitting existing power plants because the turbines and condensers would not need expensive modifications. Here, we evaluate the techno-economic feasibility of collocating a large-scale SWRO plant with an existing nuclear power plant, specifically the 2.2 GWe Diablo Canyon Nuclear Power Plant on California’s central coast. The seawater that cools the nuclear plant’s condensers provides the feed water for desalination. The desalination brine is diluted with the remaining condenser coolant before being discharged to the ocean. A brushed-screen intake structure, serving both the nuclear power plant and the desalination plant, can comply with strict California regulations protecting marine organisms. This coproduction arrangement has a significant cost advantage relative to a stand-alone desalination plant. The levelized cost of water (LCOW) ranges from US$0.77 to US$0.98 per m3 of fresh water, with water distribution to offtakers adding US$0.02 to US$0.21 per m3 over 20–185 km. In comparison, California’s largest desalination plant, in Carlsbad, has an LCOW of about US$1.84 per m3. These cost savings result from reduced power costs (about US$0.054 per kWh) and from sharing some expensive infrastructure. Further, nuclear electricity allows a Carlsbad-size SWRO to avoid 47 kt/y of CO2 emissions relative to grid electricity. Examination of substantially larger desalination plants introduces additional considerations. This study is the first to show that collocated SWRO and nuclear power are strongly coupled and have a significant economic advantage over seawater desalination at other sites. These benefits should apply to dozens of existing nuclear power plants worldwide.