Dynamic Accounting for End-Use CO2 Emissions From Low-Carbon Fuels in Energy System Optimization Models

Energy system optimization models are widely used worldwide to assess the effectiveness of decarbonization strategies. The correct accounting of greenhouse gas emissions, mainly CO2, is crucial in this field. Sectorial emissions are typically computed using commodity-specific factors based on a given (static) fuel composition. For fuels generated by combining fossil and low-carbon commodities, however, the share of the low-carbon component can change throughout the model time horizon. As an alternative to static accounting, this work proposes a dynamic accounting method for the emissions avoided thanks to the contribution of hydrogen, biofuels and synfuels. The static accounting method provides an overestimation of the emission levels compared to the proposed accounting method results, which then helps boost new low-carbon technologies in the future energy mix.