Using sCO₂ Combined Cycles to Produce Power and Data-Center-Grade Cooling from Waste Heat
Using sCO₂ Combined Cycles to Produce Power and Data-Center-Grade Cooling from Waste Heat
A supercritical CO₂ turbine operating at 750°C can simultaneously deliver megawatt-class electricity and data-center-grade chilled liquid cooling. The critical design choice is not thermodynamics alone, but which bottoming strategy delivers the most cooling per dollar.Introduction: Turning Waste Heat into a Cooling AssetModern data centers increasingly operate with hot liquid cooling loops, often rejecting coolant in the 30–45°C (86–113°F) range before secondary chilling. When paired with a high-temperature supercritical CO₂ (sCO₂) turbine, this thermal profile creates an opportunity: convert fuel or waste heat into both electricity and chilled liquid cooling, without water consumption.This article evaluates a 1 MW cluster-mesh sCO₂ turbine system operating at 750°C turbine inlet temperature, where the bottoming function is dedicated solely to cooling, not additional power generation. The ambient heat-rejection sink is a dry cooler at 70°F (21°C)—a favorable but realistic condition.Baseline System: 1 MW sCO₂ Topping CycleAt 750°C, a recuperated sCO₂ Brayton cycle can realistically achieve ~45% fuel-to-electric efficiency at the module level.For a 1 MW electrical output:Fuel input ≈ 2.22 MW thermalWaste heat remaining ≈ 1.22 MW thermalWith a well-designed fired heater, recuperator, and economizer, approximately 85–90% of this waste heat is available above useful temperatures for a thermal cooling process.Recoverable drive heat available for cooling:≈ 1.0–1.1 MW thermalThis is the thermodynamic “budget” that all bottoming cooling strategies must share.Target Cooling Conditions (Data Center Compatible)Assumptions aligned with modern liquid-cooled data centers:Chilled supply temperature: ~7–15°C (45–59°F)Return temperature: ~20–30°C (68–86°F)Heat rejection: dry cooler at 70°F ambientThese conditions favor high COP cooling, particularly for electrically driven heat pumps, while remaining compatible with absorption and ejector systems.Cooling Strategy OptionsOption 1: Bottoming Cycle Power → Electric Heat Pump(Highest thermodynamic ceiling, highest cost)ThermodynamicsBottoming heat → electricity efficiency: ~15–20%Electric heat pump COP (70°F ambient): 5–7Effective thermal COP: 0.75–1.4Cooling OutputFrom ~1.05 MW thermal drive:~0.8–1.5 MW cooling~2.7–5.1 million BTU/hrCostBottoming power turbine: $500/kWElectric heat pump: $250/kWHigh capital complexity, rotating machinery, controlsAssessmentThermodynamically strong, but financially heavy. This approach only makes sense if:electrical power from the bottoming cycle has independent value, orextremely low chilled temperatures are required.Option 2: Direct Heat-Driven Absorption Cooling(Balanced performance, moderate cost)ThermodynamicsDouble-effect absorption COP: ~1.0–1.2Very well matched to 750°C exhaust and recuperator heatCooling OutputFrom ~1.05 MW thermal drive:~1.0–1.25 MW cooling~3.4–4.3 million BTU/hrCostAbsorption systems (effective equivalent): ~$200–300/kWNo compressors, low parasitics, proven reliabilityAssessmentThis is often the engineering optimum for steady, baseload cooling. However, absorption chillers are heavier, slower to ramp, and less modular than ejector-based systems.Option 3: Heat-Driven Ejector Cooling(Lowest cost, simplest architecture)ThermodynamicsThermal COP: ~0.4–0.6Performance improves at higher drive temperature and lower liftCooling OutputFrom ~1.05 MW thermal drive:~0.4–0.65 MW cooling~1.4–2.2 million BTU/hrCostEjector cooling hardware: ~$50/kWNo moving parts, minimal controls, extremely durableAssessmentEjector cooling delivers the lowest cost per ton of cooling, even if COP is lower. For data centers already using warm liquid cooling, ejectors can provide substantial cooling value with minimal capital risk.Cost-Normalized Comparison (Cooling Value per Dollar)| Cooling Strategy | Cooling (MW) | Approx Cost ($/kW) | Value Profile || • | --• | --• | -• || Bottoming + HP | 0.8–1.5 | ~$750 | High output, poor ROI || Absorption | 1.0–1.25 | ~$250 | Best thermodynamic balance || Ejector | 0.4–0.65 | ~$50 | Best cost efficiency |Conclusion: What Makes the Most Sense?For a 1 MW sCO₂ cluster-mesh turbine serving data-center-grade cooling:Ejector cooling delivers the highest cooling per dollar, with unmatched simplicity and durability.Absorption cooling offers the best thermodynamic balance, ideal for steady, high-capacity sites.Bottoming power → heat pump achieves the maximum theoretical cooling, but at a capital cost that is difficult to justify unless electricity has secondary value.Strategic RecommendationFor most deployments, the optimal architecture is:High-temperature sCO₂ topping cycle for powerEjector or absorption cooling for waste-heat utilizationDry cooling at 70°F ambientNo bottoming power turbineThis configuration maximizes system ROI, minimizes mechanical complexity, and aligns naturally with the thermal characteristics of modern liquid-cooled data centers.
Infinity Super Turbine
Infinity Turbine Sales | Plans | Consulting TEL: 1-608-238-6001 Email: greg@infinityturbine.com
For Data Centers Gas Turbine Waste Heat to Power Owners of Cat Solar Gas Turbine Generators and the new Boom Aero Derivative Gas Turbines Generators: Take your waste heat and make additional Combined Cycle power or generate cooling for your data center... More Info
IT250 Supercritical CO2 Gas Turbine Generator Silent Prime Power $999,000 250 kW (natural gas, solar thermal, thermal battery heat) ... More Info
IT1000 Supercritical CO2 Gas Turbine Generator Silent Prime Power $3M 1 MW (natural gas, solar thermal, thermal battery heat) ... More Info
IT50MW Supercritical CO2 Gas Turbine Generator Silent Prime Power $50M (natural gas, solar thermal, thermal battery heat) ... More Info
Data Center Consulting Prime power and energy consulting for AI and data centers... More Info
Quantum Super Turbine... Developing in 2026: High efficiency topping cycle turbine generator with bottoming cycle cooling, specifically designed for Data Centers with back-end combined cycle modules for cooling, hydraulic, or heat pump capabilities... More Info
CONTACT TEL: 1-608-238-6001 Email: greg@infinityturbine.com
(Standard Web Page) | PDF