Robust pathway analysis of electricity investments under net-zero uncertainties

Policy-makers and planners are looking to make robust power system investments under deep uncertainty and conflicting objectives. This paper presents a robust pathway approach to address a range of uncertainties and multiple objectives and provides a proof-of-concept applied to U.S. electric sector decisions under deep decarbonization. Results show the importance of considering a range of criteria: considering cost alone or CO₂ alone resulted in just two non-dominated pathways in each case; adding in the consideration of co-pollutants increased the number of non-dominated pathways to six of the nine considered. This analysis highlights the importance of considering fuel price uncertainty and, in particular, the possibility of high natural gas prices, which can lead to high co-pollution in otherwise low-polluting pathways. Results illustrate trade-offs between emissions and costs; as well as between CO₂ and co-pollutants, which is largely due to carbon removal use. The robust pathway framework is illustrative; we discuss how future work with harmonized multi-model outputs and spatially explicit pollutant metrics can provide additional insights.