sCO2 R&D Focus Areas

Department of Energy

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Using supercritical CO2 as the working fluid, sCO2 may enable a power plant to generate the same amount of electricity from less fuel, compared to traditional steam systems. This higher efficiency reduces emissions and operating costs. The higher fluid density of sCO2 (relative to steam) also enables the use of much smaller turbomachinery, lowering capital costs.

Key challenges in developing this technology include designing system components that take full advantage of sCO2 properties. Components must be far smaller than those in traditional steam cycles and able to function reliably over long periods in the presence of CO2 under high pressures and temperatures—necessitating advanced materials and joining techniques. Effective heat recovery and reuse are essential to achieving potential efficiency gains, so advanced heat recuperators are needed. Integrating these novel components into overall systems that operate optimally for each application requires detailed modeling of potential system configurations.

Higher Thermal Efficiencies Lower Electricity Costs

Turbomachinery

  • Designs for high gas density, high power density, and real gas effects of CO2 near the critical point
  • Identification of materials/coatings compatible with sCO2 temperatures/pressures during operation
  • Bearings and low-leakage seals with long performance lives under high temperature/pressure conditions
  • Pressure containment and thermal management

Advanced Heat Recuperation

  • Design low-cost, compact heat exchangers with high surface area (surface area density > 700 m2/m3)
  • Identify materials compatible with sCO2 at temperatures (>700°C) and pressures (up to 30 MPa) of the cycle
  • Develop designs for high temperature/pressures and high pressure differentials (up to 30 MPa) between streams
    • Mechanical stability
    • Pressure containment
    • Minimal leakage
  • Identify scalable manufacturing techniques
  • Optimize pressure drop, heat transfer coefficient, approach temperature
  • Balance capital cost versus efficiency

Advanced Materials

  • Evaluate material performance at high temperatures (1,300⁰F) and pressures in sCO2 environments
    • Oxidation
    • Carburization
    • Erosion
    • Mechanical properties
  • Develop new materials for use in sCO2 applications
  • Study effects of sCO2 on joining techniques

Systems Integration, Modeling, and Optimization

  • Integrate the sCO2 power cycle with specific heat sources
  • Develop boiler design, including heat exchanger, to deliver higher temperature required for the sCO2 working fluid
  • Address heater surface (boiler) cost challenge due to high temperature and pressure conditions

Supporting National Laboratories

National Energy Technology Laboratory: Lab Lead for sCO2 Initiative:  

Advanced Concepts for Direct-Fired Cycles 

www.netl.doe.gov/research/coal/energy-systems/sco2-technology

Sandia National Laboratory:  

Materials chemistry 

Brayton laboratory 

CSP applications: incorporating an sCO2 loop into tower for testing with the existing particle receiver and a direct sCO2 receiver 

Systems integration 

http://energy.sandia.gov/energy/renewable-energy/supercritical-co2/)

National Renewable Energy Laboratory:  

High-efficiency solar receivers for sCO2 cycles  

System Advisor Model (SAM), a renewable energy performance and financial model  

Optimization analyses of cycle configurations

Oak Ridge National Laboratory:    

Advanced structural materials   

CSP

INDUSTRIAL AND ACADEMIC PARTNERS

GE Global Research, Echogen, Southwest Research Institute (SwRI), GTI, Brayton Energy, Thar, Altex, NET Power, EPRI, Oregon State University, Georgia Tech, and University of Central Florida.