Editing IPCC:AR6/WGIII/Chapter-3 (section)

=== 3.4.2 Energy Supply ===

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Without mitigation, energy consumption and supply emissions continue to rise ( ''high confidence'' ) ( [[#Kriegler--2016|Kriegler et al. 2016]] ; [[#Bauer--2017|Bauer et al. 2017]] ; [[#Riahi--2017|Riahi et al. 2017]] ; [[#Mcjeon--2021|Mcjeon et al. 2021]] ) ( [[IPCC:Wg3:Chapter:Chapter-6#6.7|Section 6.7]] ). While the share of renewable energy continues to grow in reference scenarios, fossil fuel accounts for the largest share of primary energy ( [[#Bauer--2017|Bauer et al. 2017]] ; [[#Price--2017|Price and Keppo 2017]] ; [[#Riahi--2017|Riahi et al. 2017]] ). In scenarios that limit warming to 2°C or lower, transition of the energy-supply sector to a low- or no-carbon system is rapid ( [[#Rogelj--2016|Rogelj et al. 2016]] , 2018b; [[#Grubler--2018|Grubler et al. 2018]] ; [[#Luderer--2018|Luderer et al. 2018]] ; [[#van%20Vuuren--2018|van Vuuren et al. 2018]] ). CO 2 emissions from energy supply reach net zero around 2041 (2033–2057) in pathways limiting warming to 1.5°C (&gt;50%) with no or limited overshoot and around 2053 (2040–2066) in pathways that limit warming to 2°C (&gt;67%). Emissions reductions continue, with emissions reaching –7.1 GtCO 2 yr –1 (–15 to –2.3 GtCO 2 yr –1 ) in 2100 in all pathways that limit warming to 2°C (&gt;67%) or lower.

All pathways that limit warming to 2°C (&gt;67%) or lower show substantial reductions in fossil fuel consumption and a near elimination of the use of coal without CCS ( ''high confidence'' ) ( [[#Bauer--2017|Bauer et al. 2017]] ; [[#van%20Vuuren--2018|van Vuuren et al. 2018]] ; [[#Grubler--2018|Grubler et al. 2018]] ; [[#Luderer--2018|Luderer et al. 2018]] ; [[#Rogelj--2018|Rogelj et al. 2018]] a,b; [[#Azevedo--2021|Azevedo et al. 2021]] ; [[#Mcjeon--2021|Mcjeon et al. 2021]] ; [[#Welsby--2021|Welsby et al. 2021]] ) (Figure 3.22). In these pathways, the use of coal, gas and oil is reduced by 90%, 25%, and 41%, respectively, between 2019 and 2050 and 91%, 39%, and 78% between 2019 and 2100; coal without CCS is further reduced to 99% below its 2019 levels in 2100. These pathways show an increase in low-carbon energy, with 88% (69–97%) of primary energy from low-carbon sources in 2100, with different combinations of low-carbon fuels (e.g., non-biomass renewables, biomass, nuclear, and CCS) ( [[#Rogelj--2018|Rogelj et al. 2018]] a,b; [[#van%20Vuuren--2018|van Vuuren et al. 2018]] ) (Sections 3.4.1 and 6.7). Across all pathways that limit warming to 2°C and below, non-biomass renewables account for 52% (24–77%) of primary energy in 2100 ( [[#Creutzig--2017|Creutzig et al. 2017]] ; [[#Pietzcker--2017|Pietzcker et al. 2017]] ; [[#Rogelj--2018|Rogelj et al. 2018]] b) ( [[IPCC:Wg3:Chapter:Chapter-6|Chapter 6]] and Figure 3.22). There are some studies analysing the potential for 100% renewable energy systems ( [[#Hansen--2019|Hansen et al. 2019]] ); however, there are a range of issues around such systems (Box 6.6).

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[[File:97e33177bc24a702d855ec3eb5601c51 IPCC_AR6_WGIII_Figure_3_22.png]]

'''Figure 3.22 | Primary energy consumption across scenarios: total primary energy (a), fossil fuels (b), coal without CCS (c), non-biomass renewables (d), and biomass (e).''' Scenarios are grouped by their temperature category. Primary energy is reported in direct equivalent, where one unit of nuclear or non-biomass renewable energy output is reported as one unit of primary energy. Not all subcategories of primary energy are shown.

Stringent emissions reductions at the level required to limit warming to 2°C (&gt;67%) or 1.5°C are achieved through increased electrification of end use, resulting in increased electricity generation in all pathways ( ''high confidence'' ) ( [[#Rogelj--2018|Rogelj et al. 2018]] a; [[#Azevedo--2021|Azevedo et al. 2021]] ) (Figure 3.23). Nearly all electricity in pathways ''likely'' to limit warming to 2°C and below is from low- or no-carbon fuels ( [[#Rogelj--2018|Rogelj et al. 2018]] a; [[#Azevedo--2021|Azevedo et al. 2021]] ), with different shares of nuclear, biomass, non-biomass renewables, and fossil CCS across pathways. Low-emissions scenarios also show increases in hydrogen use (Figure 3.23).

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[[File:d63dc577f037f7f4f4d240d4783e8fe1 IPCC_AR6_WGIII_Figure_3_23.png]]

'''Figure 3.23 | Electricity (top left),share of low-carbon electricity (top right), and hydrogen (bottom left) production across all scenarios, grouped by the categories introduced in Section 3.''' '''2.''' Low carbon includes non-biomass renewables, biomass, nuclear, and CCS.

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