Enhancing Responsiveness of Gas Turbine Generators through Retrofitting with Exhaust Gas Recycle and a Phase-Change CO2 Capture Process

ARPA-E Project Image

North Carolina
Project Term:
05/21/2021 - 08/20/2022

Critical Need:

Power plants equipped with carbon capture and storage (CCS) technologies can reduce the cost of net-zero carbon systems, but the addition of variable renewable energy (VRE) sources like wind and solar can make them difficult to design and operate while limiting their commercial potential. Increased cyclic operation of electricity generators could also reduce capacity factor and efficiency, increase operations and maintenance costs, and potentially increase CO2 emissions. Improving CCS processes and designs could enable a low-cost, net-zero carbon electricity system.

Project Innovation + Advantages:

8 Rivers Capital seeks to enhance the profitability and responsiveness of gas turbine generators in high variable renewable energy environments. This project would retrofit existing plants with Exhaust Gas Recycle (EGR) and a novel phase-change solvent CO₂ capture system known as UNO MK3, offering a lower cost pathway than new gas turbines with capture. The UNO MK3 process captures 90% of exhaust gas CO2 using a benign precipitating solvent at high concentration to reduce circulation rates and decrease energy usage. Additional innovations of a smaller novel solids-tolerant absorber and a novel concentric absorber design, which halves plant footprint, could reduce capital costs by 60-65%. UNO MK3 allows CO₂ to be withdrawn and stored as solid potassium bicarbonate during high energy demand, enabling profitable solvent regeneration when electricity prices are low.

Potential Impact:

Improvements in the design and processes of CCS-equipped plants in high VRE environments could dramatically reduce the cost of a net-zero carbon system. Benefits include:


Flexible CCS systems can enable the continued use of low-cost domestic fuel for electricity generation and increase the reliability of a deeply decarbonized electricity system.


Flexible CCS systems can achieve high CO2 capture rates from flue gas. Enabling deep turndown of natural-gas fired plants at times of high VRE output will reduce fuel consumption and CO2 emissions.


Flexible CCS systems can reduce the cost of a net-zero carbon electricity system by providing dispatchable power to a high-VRE grid.


ARPA-E Program Director:
Dr. Scott Litzelman
Project Contact:
Dr. Navid Rafati
Press and General Inquiries Email:
Project Contact Email:

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