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Marisol: When Does “Sea–Salt Cooling” Actually Pay Off? A Marisol-type system will never win a beauty contest on upfront CAPEX alone. For the same 10 MW of cooling, a classic chiller plant might cost 10–15 MUSD; a full Marisol coastal system (seawater intake, brine ponds, DAHU/IEC, PCM storage) is more like 28–40 MUSD. The story flips when you look at what kind of watts you avoid. In a hot-humid coastal grid, Marisol typically: - Cuts cooling electricity use by ≈60% → less fuel burned, fewer blackouts - Shaves 4–5 MW off peak demand for a 10 MW district → fewer transformers, fewer diesel gensets - Eliminates HFC refrigerants → no Kigali/phase-out risk - Uses seawater instead of freshwater for heat rejection → tens of thousands of m³/year saved If your power is cheap and the grid is strong, that’s “nice but not decisive.” If your power is 0.15-0.25 USD/kWh, diesel-backed, or capacity-constrained, it becomes decisive: - Net energy savings alone can reach ~2 MUSD/year for a 10 MW cluster - Add avoided grid upgrades + diesel backup and you’re closer to 2.5–3 MUSD/year in system value - Add 6-8 kt CO₂/year avoided and you’re eligible for climate finance on top In that world, the extra 18-25 MUSD of CAPEX is no longer a sunk cost – it’s a way to buy your way out of future fuel, grid and carbon costs, with payback in roughly 6-9 years and a low-teens IRR over 20 years. So the real investment question isn’t “Is Marisol cheaper than chillers?” It’s: “Where is avoided peak, avoided diesel and avoided CO₂ already more expensive than steel, ponds and pipes?”