A vision for the alleviation of water scarcity in the US Southwest

Solar & Desal Technology Choices

• Strong preference for PV over solar thermal: PV is simpler, more standardized, and benefits from strong learning-curve cost declines.
• Debate over batteries vs running RO only when the sun shines. Some argue intermittent operation plus large freshwater reservoirs is fine; others emphasize plant utilization and favor storage if it’s cheap enough.
• Ideas raised for storing energy as pressure or via pumped storage, but commenters note practical limits of pressurized-water storage and safety/cost issues with compressed air.

Brine Disposal and Environmental Concerns

• Brine impacts are a major focus. Cited research from other regions shows highly saline discharge can damage benthic and coastal ecosystems; disposal costs are a significant share of desal OPEX.
• Simple “pipe it back to the ocean” is seen as glossing over scale, cost, and ecological risk; dense brine tends to sink and spread along the seafloor, requiring large, engineered diffuser systems.
• Using the Sea of Cortez as a sink is widely criticized as ecologically unacceptable; some suggest redirecting discharge to deep Pacific waters instead.
• Alternatives floated: evaporation ponds in the desert, salt mining, use of the existing Salton Sea as a terminal salt lake, construction uses, or even shipping brine offshore. Volumes and residual waste remain problematic.

Economics and Feasibility

• Enthusiasts argue plunging solar and battery costs newly enable such mega-projects, potentially yielding large profits from minerals and real estate.
• Skeptics question core assumptions: if solar+RO water were truly cheap enough for agriculture, it would already be widespread; no major desal plants currently monetize brine at the proposed scale.
• A highlighted magnesium revenue calculation is called out as ignoring extraction costs and price effects of flooding the market.

Water Policy, Conservation, and Equity

• Many argue technology alone is insufficient without cutting water-intensive agriculture (alfalfa exports, almonds, red meat) and reforming over-allocated water rights.
• Others counter that supply-side engineering plus conservation is preferable to relying on large, sustained behavioral change.

Geopolitics and Siting

• Routing through Mexico and the Sea of Cortez raises international cooperation and environmental-justice concerns; some ask why California wouldn’t just use the Pacific coast instead.
• Commenters note that power is generally easier and cheaper to move than water, making coastal desal plus inland transmission more plausible than long water pipelines over rugged terrain.

Alternative Proposals and Design Tweaks

• Proposals include:
  • Flooding Mexico’s nearby Laguna de Salada as a lower-elevation basin to shorten conveyance.
  • National-scale water transfers from flood-prone eastern rivers to the Southwest using excess renewable power.
  • Atmospheric water generators to avoid brine issues (their efficiency vs RO is disputed).
  • Tidal-power sea-level canals and various cloud-seeding efforts.

Risk, Resilience, and Long-Term Maintenance

• Some see such geoengineering as inevitable to keep the Southwest agriculturally productive.
• Others view it as fragile hubris: a high-maintenance “life-support system” with unclear funding for eventual pipeline replacement, solar end-of-life, and potential replay of the Salton Sea collapse if upkeep falters.