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Energy Department Announces New Investments in Supercritical Transformational Electric Power (STEP) Program

December 10, 2015 - 1:05pm


WASHINGTON -- The U.S. Department of Energy’s Supercritical Transformational Electric Power (STEP) program is awarding a total of $3.9 million to three competitively-selected teams to develop conceptual plans to support the design, cost and schedule for a 10 MWe (megawatts electrical) Supercritical Carbon Dioxide (sCO2) Brayton Cycle test facility.  The awardees selected for funding are Echogen Power Systems in Ohio, the Gas Technology Institute in Illinois, and the Southwest Research Institute in Texas.

Work by the three teams will support the future commercialization of sCO2 Brayton cycle energy conversion systems to help meet national climate and energy goals, promote domestic job creation, facilitate industrial competitiveness, maintain U.S. technology leadership, and provide the nation with cleaner and more affordable power.

“sCO2 technology has the potential to improve the efficiency of our power plants significantly.  Use of the technology in electric power generation could reduce greenhouse gas emissions that contribute to climate change, and also boost our economy,” said Franklin Orr, Under Secretary for Science and Energy at the U.S. Department of Energy.  “This funding will help these three teams develop proposals for a sCO2 test facility, which ultimately will bring us closer to our goal of deploying this technology on a commercial scale.”

The program can have a wide variety of applications and is sponsored by DOE’s Nuclear Energy in cooperation with Fossil Energy and Energy Efficiency and Renewable Energy offices.  This effort is an example of Secretary of Energy Ernest Moniz’s “crosscutting” initiatives, which encourage collaborative work across the Department’s various offices and programs to tackle shared challenges and opportunities.

The sCO2 Brayton cycle energy conversion system transforms heat energy to electrical energy through the use of a supercritical fluid (i.e. sCO2) rather than through traditional steam and water (Rankine cycle) systems commonly in use today in nuclear, coal, gas, and concentrating solar plants.  The sCO2 Brayton cycle has the potential to reach thermal efficiencies much greater than the Rankine cycle. The average efficiency percentage of U.S. fleet of Rankine cycle power plants is in the lower 30 percent range and the thermal efficiencies of modern supercritical steam cycles are in the low to mid-40 percent range.

The sCO2 Brayton cycle, by comparison, has the potential to attain efficiencies of greater than 50 percent and reduce water use.

Implications of a significantly higher-efficiency power cycle are far-reaching.  They represent an opportunity for a multi-billion dollar market for the technology and could lead to billions of dollars in energy cost savings.

And the relatively high density of sCO2 leads to compact turbomachinery of significantly reduced size when compared to an equivalent steam Rankine.   This could potentially lead to reduced capital costs for power plants.

This investment will enable DOE to work with industry to develop and mature the technology at the pilot scale in order to facilitate the commercialization of sCO2 Brayton Cycles and spur the development of necessary designs, materials, components, operation and control systems, sensors, and understanding and characterization needed for larger scale sCO2 power conversion systems.