Energetic regimes of the global economy – past, present and future

Abstract. For centuries both engineers and economists have collaborated to attempt to raise economic productivity through efficiency improvements. Global primary energy use (PEU) and gross world product (GWP) data 1950–2018 reveal a the effects of aggregate energy efficiency (AEE) improvements since the 1950's have been characterised by two distinct behavioural regimes. Prior to the energy supply shocks in the 1970s the AEE of the global economy was remarkably constant such that PEU and GWP growth were fully coupled. We suggest this regime is associated with attempts to maximise growth in GWP. In contrast, in the 1970s the global economy transitioned to a lower growth regime that promoted maximising growth in AEE such that GWP growth is maximised while simultaneously attempting to minimise PEU growth, a regime that appears to persist to this day. Low carbon energy transition scenarios generally present the perceived ability to raise growth in AEE at least three fold from 2020 as a tactic to slow greenhouse gas emissions via lower PEU growth. Although the 1970s indicate rapid transitions in patterns of energy use are possible, our results suggest that any promise to reduce carbon emissions based on enhancing the rate of efficiency improvements could prove difficult to realise in practice because the growth rates of AEE, PEU and GWP do not evolve independently, but rather co-evolve in ways that reflect the underlying thermodynamic structure of the economy.