Has the relationship between non-fossil fuel energy sources and CO₂ emissions changed over time? A cross-national study, 2000–2013

This study investigates the possibly changing relationship between non-fossil fuel energy sources (biomass, geothermal, hydro, nuclear, solar, and wind) and CO₂ emissions over the temporal period 2000 to 2013. The results from two-way fixed effects longitudinal models demonstrate that the carbon elasticities of these energy sources change over time but not symmetrically. Wind’s association with CO₂ emissions became increasingly negative after the Great Recession (i.e., suppressed emissions at a greater rate). Nuclear’s association with CO₂ resembled a distorted U-shaped curve over time. Biomass’ elasticity fluctuated between positive and negative values. Solar and geothermal’s elasticity remained fairly consistent over the course of the analysis, and hydro’s elasticity increased over time but remained negative throughout the study’s temporal period. The study provides several tentative explanations for these findings. Overall, the results suggest there are various processes at play that influence an energy source’s relation to CO₂ emissions.