Freezing Seawater with CO₂: A Path to Energy‑Efficient Desalination

INFINITY TURBINE LLC We specialize in designs, plans, licensing, consulting, design services, and surplus spare parts. We no longer manufacture turbines or CO2 systems. More Info...

Please email for first contact with request for more information

Email: greg@infinityturbine.com

Infinity Turbine CO2 Turbine Development and Testing Cart Supercritical CO2 Turbine Development Cart using high pressure filter canisters for rapid prototyping and commercialization for 1-25 kWh Power Generation... More Info

ORC and sCO2 Performance Charts: R134a, R245fa, CO2 – 2026 Edition Updated 2026 edition of Infinity Turbine’s ORC and supercritical CO2 performance curves: R134a, R245fa and CO2 charts, CO2 heat-rate tables from 100 to 700 °C, sCO2 turbine types, and data-center applications. 62-page PDF... More Info

Supercritical CO2 Turbine Generator Plans (Transcritical) Rankine Cycle Lab format for development ... More Info

Matra Concentrated Solar Project Using Infinity Turbine Generator for Power Production Solar thermal power production using a reflective dish concentrator... More Info

Cluster Mesh Supercritical CO2 Power System for Data Centers and AI Pairing Cluster Mesh Supercritical CO2 Power System with Small Modular Reactors enables hyperscalers to convert high-grade nuclear heat into ultra-efficient, dispatchable power with a compact, modular footprint tailored for AI-scale demand. More Info

ORC and Products Index Infinity Turbine ORC Index... More Info

A Generator Without Magnets Switched Reluctance is the simplest rotating electrical machine there is: a rotor of stacked steel laminations with salient teeth, and a stator carrying concentrated coils. The rotor has no magnets, no windings, no bars and no slip rings... More Info

Freezing Seawater with CO₂: A Path to Energy‑Efficient Desalination Introduction Desalination is typically associated with energy‑intensive processes like reverse osmosis or multi‑stage flash distillation. An alternative approach is freeze desalination, which takes advantage of the natural tendency of ice crystals to exclude salt as seawater freezes. By using a closed‑loop CO₂ refrigeration cycle, this process can freeze seawater, separate fresh ice, and produce potable water with minimal thermal stress and potentially high efficiency. --- How CO₂ Freeze Desalination Works 1. CO₂ Refrigeration Loop: A closed loop of CO₂ serves as the working fluid. It is first cooled and condensed in a heat exchanger, then pressurized by a pump (subcritical) or compressor (transcritical). 2. Expansion and Cooling: The pressurized CO₂ is expanded, producing a low‑temperature stream that provides the cooling duty for a seawater crystallizer. 3. Ice Formation: Seawater exposed to temperatures around –2 to –5 °C begins to freeze. The forming ice crystals naturally reject salt, leaving behind a concentrated brine solution. 4. Separation and Washing: The ice slurry is sent to a separator where the brine is drained off. A small amount of fresh melt water is used to wash the ice, ensuring minimal salt contamination. 5. Fresh Water Recovery: Washed ice is melted to produce fresh water, while concentrated brine is discharged. --- Advantages of Freeze Desalination with CO₂ Intrinsic Salt Rejection: Ice crystals contain minimal salt, simplifying the desalination process. Lower Scaling Risk: Operating below 0 °C reduces the tendency for mineral scale formation. Natural Refrigerant: CO₂ is non‑flammable and has negligible global warming potential compared to synthetic refrigerants. Energy Efficiency Potential: Using a liquid CO₂ pump in subcritical mode can reduce power consumption versus conventional compression. --- Key Design Considerations Crystallizer Type: Scraped‑surface or suspension crystallizers help maintain ice mobility and control crystal size. Avoiding Dry Ice: Maintain CO₂ suction pressure above 5.2 bar to prevent solid CO₂ formation. Water Quality: Final washing is required to achieve potable water standards. Material Selection: Seawater‑exposed surfaces should use stainless steel, titanium, or corrosion‑resistant coatings. --- Conclusion A CO₂‑based freeze desalination system offers a compelling alternative to conventional methods in suitable climates or integrated with waste heat and cold resources. By freezing seawater and harvesting nearly salt‑free ice, it delivers fresh water while using a natural refrigerant in a high‑efficiency cycle.