Carbon capture brought to life by tweaking the plumbing

In an advance that takes industrial carbon capture a step closer to commercial viability, researchers at Khalifa University have shown that relatively straightforward modifications to power plant ‘plumbing’ can reduce the amount of additional energy needed to capture carbon emissions.

Combined cycle gas turbine (CCGT) power plants are a more flexible, fuel-efficient and environmentally friendly method of energy generation than coal or oil-fired power plants. By routing waste heat from the gas-turbine exhaust to a steam turbine, CCGT plants can generate up to 50% more power than conventional gas-fired power plants for the same amount of fuel. They are also readily configurable for carbon capture and storage (CCS), bringing the potential to greatly reduce carbon emissions.

“With these enhancements it is possible to lower the energy penalty of carbon capture and storage, with significant reductions in both capital and operational costs, offering a viable path forward for decarbonizing industry.”

Ahmed Alhajaj

Capturing carbon from carbon dioxide (CO₂) exhaust gas, however, comes at a cost. Additional technology and equipment are required, and energy is used in the capture cycle.

As part of a long-term effort to establish CCS as a commercially viable technology for CCGT power generation, researchers Nahyan Arshad and Dr. Ahmed Alhajaj from the Research and Innovation Center on CO₂ and Hydrogen (RICH Center) at Khalifa University have identified key process enhancements that can improve CCS efficiency.

“While many efforts are aimed at developing new ‘sponges’ for better carbon capture, we are looking at how tweaking the system’s ‘plumbing’, adjusting the process and setup used to capture carbon, can lead to significant energy and cost savings,” says Alhajaj.¹

Through a comprehensive analysis of different process technologies using a multifactor approach accounting for both financial costs and energy consumption, Alhajaj and Arshad Identified several standard technologies that can yield substantial improvements when combined.

“We found that cooling solvents more effectively, and splitting and compressing gases differently can make capturing carbon cheaper and less energy intensive,” explains Alhajaj.

“Many efforts are aimed at developing new ‘sponges’ for better carbon capture, we are looking at how tweaking the system’s ‘plumbing’ … can lead to significant energy and cost savings.”

Ahmed Alhajaj

The best enhancement was obtained with a cool/rich/lean combination. Here absorber inter-cooling is used to cool the CO₂ absorber column for higher absorption efficiency, rich solvent splitting maximizes temperature differential in the column for reduced energy losses, and lean vapor compression reduces the energy input needed to regenerate the absorption column. Together, these enhancements reduced overall financial costs by 8.95% and energy consumption by 6.25%.

“Our unique approach provides a comprehensive view of both economic and energy impacts, ensuring the proposed solutions are both economically and environmentally viable,” Alhajaj says. “With these enhancements it is possible to lower the energy penalty of CCS to 2.8 gigajoules per ton of CO₂ captured, with significant reductions in both capital and operational costs, offering a viable path forward for industry.”

Reference

Arshad, N. and Alhajaj, A. Process synthesis for amine-based CO₂ capture from combined cycle gas turbine power plant. Energy 274, 127391, 2023. | Article