Energy penalty estimates for CO₂ capture: Comparison between fuel types and capture-combustion modes

Carbon capture from power plants holds the key to any significant reduction in CO₂ emissions. This work considers the energy penalty related to CO₂ capture from coal, natural gas and fuel oil-based power plants. We evaluate the minimum thermodynamic work for CO₂ capture, and then estimate achievable targets. All the three modes of capture-combustion: pre-combustion, post-combustion, and oxy combustion, are considered. The low CO₂ concentration in natural gas-based power plants translates into the highest capture energy per ton of CO₂. However, the lowest energy penalty of 10% is obtained with pre-combustion capture in natural gas-based power plants (versus 17% for coal-based power plants). The highest energy penalty of about 20% is found for oxy combustion capture from coal-based power plants. In general, pre-combustion capture seems to provide the lowest energy penalties. - Highlights: • High-level thermodynamic comparison of energy penalties for CO₂ capture. • Different fuel types and combustion processes compared. • Lowest energy penalty for pre-combustion capture. • Among fuels, lowest energy penalties for natural gas. • Thermodynamic baseline for more detailed process simulations.