Extended Data Fig. 6: Are wind and solar power on track to the Paris targets in 2030 and 2050? A comparison with an alternative approach.
The Figure contains the replication and analysis of ref’s8 assessment of whether wind and solar power are on track to attain Paris climate targets. On all panels, dashed lines replicate ref’s. 8 logistic curves fit to 2010 values and saturating at the ‘2050 Paris benchmarks’ defined by ref. 8 as median 2050 values for 1.5 °C scenarios (purple diamonds, also indicating median scenario values for 2030). For this replication we use the range of ‘emergence rates’ (year-on-year growth rates at the early stages) from ref. 8 of 15%, 20%, 25% for wind and 25%, 30%, 35% for solar. For each technology, we mark the central case in black and the high and low cases in grey. Panels (a) and (c) indicate yearly growth rates (G) at the inflection points of these curves normalised to the size of the global electricity system. The G’s for these considerably exceed the maximum growth rates we estimate for any large country so far (Supplementary Fig. 5). The orange and blue lines represent Gompertz and logistic model fits (with inflection points) to the empirical timeseries of global wind and solar power deployment using the approach in this paper (Methods). These models project much lower values for 2030 and 2050 than the models from ref. 8. Panels (b) and (d) zoom the same curves and data on 2010-2020 and indicate Residual Sum of Squares (RSS)74 for the replicated curves and our two model fits vs. 2010-2018 empirical data. The RSS for the replicated logistic curves are between 10 and 280 times larger than our best fit for wind and 400 and 1000 times larger than our best fit for solar, which indicate that the replicated curves from ref. 8 match the empirical data with considerably lower accuracy than our models.
