Sorry, I haven’t started memorizing Fediverse handles yet. Tim Morgan measures ECoE in percent, and real GDP is GDP minus debt, or x units of debt produce a fraction of that in GDP. Plus ECoE accounting. His model is proprietary, so nobody exactly knows how it’s computed but he himself.
That IRENA model seems to link some large spreadsheets and notes on that page. No idea how complete that is.
As to investments necessary, some two decades ago I estimated we’d need some 3 TUSD/year, inflation-adjusted, for the next 40 years to transition. As a rough estimate that’s as good as any other guess, not facturing in extraction of progressively depleting resources.