Editing IPCC:AR6/WGIII/Chapter-2 (section)

=== 2.5.4 Rapid Adoption Accelerates Energy Transitions ===

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The transition to a more sustainable energy system depends not just on improvement in technologies, but also on their widespread adoption. Work since AR5 has also substantiated the bidirectional causal link between technology improvement and adoption. Cost reductions facilitate adoption, which generates opportunities for further cost reductions through a process of learning by doing ( ''medium confidence'' ). The rate of adoption is thus closely related to the speed at which an energy transition is possible.

Results of integrated assessment models (IAMs) show that scale-up needs are massive for 2°C scenarios. Using logistic growth rates of energy shares as in previous work ( [[#Wilson--2012|Wilson 2012]] ; [[#Cherp--2021|Cherp et al. 2021]] ), most of these technologies include annual adoption growth rates of 20% in the 2020s and 2030s, and are in line with recent adoption of wind and solar. However, it is important to realise that IAMs include faster adoption rates for some mitigation technologies than for others (Peters et al. 2017). Growth rates in IAMs for large-scale CCS – biomass, coal, and gas – are between 15–30% (25th and 75th percentiles) (Figure 2.24). So few plants have been built that there is little historical data to analyse expected growth; with only two full-scale CCS power plants built and a 7% growth rate, if including industrial CCS. In contrast, IAMs indicate that they expect much lower rates of growth in future years for the technologies that have been growing fastest in recent years (wind and solar), without strong evidence for why this should occur.

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[[File:aa274c0efa249285c9725ca1942153f7 IPCC_AR6_WGIII_Figure_2_24.png]]

'''Figure 2.24''' '''|''' '''Growth of key technologies (2020–2040) in Paris-consistent mitigation scenarios compared to historical growth.''' Comparisons of historical growth (grey bars) to growth in 2020–2040 mitigation scenarios (dots). Values on the vertical axis are logistic annual growth rates for share of each technology in electricity supply. Horizontal arrangement of dots within technology categories indicates the count of scenarios at each growth rate. Source: data on scenarios from Chapter 3; historical data from [[#BP--2021|BP (2021)]] .

The overall pattern shows that IAMs expect growth in small-scale renewables to fall to less than half of their recent pace, and large-scale CCS to more than double from the limited deployment assessed ( ''high confidence'' ). The emerging work since AR5 showing the rapid adoption and faster learning in small-scale technologies should prompt a keener focus on what technologies the world can depend on to scale up quickly ( [[#Grubb--2021|Grubb et al. 2021]] ). The scenario results make it quite clear that climate stabilisation depends on rapid adoption of low-carbon technologies throughout the 2020–2040 period.

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