Life Cycle Carbon Dioxide Emissions from Ammonia-Based Power Generation Technology

Abstract

Hydrogen energy carriers are expected to play vital roles in realising hydrogen economy and carbon neutrality. However, their low-carbon potential should be evaluated from a life cycle perspective. Here, life cycle inventory (LCI) analyses were conducted to understand the low-carbon potential of using ammonia (NH₃) in the power generation sector. The NH₃ was produced overseas from natural gas, both with and without carbon capture and storage (CCS), or from renewable energy, was imported to Japan and used in NH₃ co-firing with coal and NH₃ mono-firing power plants. The CO₂ emissions both from the operations and the capital goods related to the NH₃ value chain and power generation were calculated. Foreground data related to the supply chain were obtained from literature, and the Japanese LCI database was used to calculate the emissions. The results confirmed that the life cycle CO₂ emissions from the NH₃ mono-firing power plant, which had a low-carbon NH₃ value chain, were lower than those from coal power generation conducted with CCS. The results indicate that CO₂ emissions attributed to the capital goods of the fuel value chain may have an enormous impact on life cycle emissions, especially when utilising a variable renewable energy source with a low capacity factor.