Editing IPCC:AR6/SR15/Chapter-4 (section)

==== 4.3.1.1 Renewable electricity: solar and wind ====

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All renewable energy options have seen considerable advances over the years since AR5, but solar energy and both onshore and offshore wind energy have had dramatic growth trajectories. They appear well underway to contribute to 1.5°C-consistent pathways (IEA, 2017c; IRENA, 2017b; REN21, 2017) <sup>[[#fn:r86|86]]</sup> .

The largest growth driver for renewable energy since AR5 has been the dramatic reduction in the cost of solar photovoltaics (PV) (REN21, 2017) <sup>[[#fn:r87|87]]</sup> . This has made rooftop solar competitive in sunny areas between 45° north and south latitude (Green and Newman, 2017b) <sup>[[#fn:r88|88]]</sup> , though IRENA (2018) <sup>[[#fn:r89|89]]</sup> suggests it is cost effective in many other places too. Solar PV with batteries has been cost effective in many rural and developing areas (Pueyo and Hanna, 2015; Szabó et al., 2016; Jimenez, 2017) <sup>[[#fn:r90|90]]</sup> , for example 19 million people in Bangladesh now have solar-battery electricity in remote villages and are reporting positive experiences on safety and ease of use (Kabir et al., 2017) <sup>[[#fn:r91|91]]</sup> . Small-scale distributed energy projects are being implemented in developed and developing cities where residential and commercial rooftops offer potential for consumers becoming producers (called prosumers) (ACOLA, 2017; Kotilainen and Saari, 2018) <sup>[[#fn:r92|92]]</sup> . Such prosumers could contribute significantly to electricity generation in sun-rich areas like California (Kurdgelashvili et al., 2016) <sup>[[#fn:r93|93]]</sup> or sub-Saharan Africa in combination with micro-grids and mini-grids (Bertheau et al., 2017) <sup>[[#fn:r94|94]]</sup> . It could also contribute to universal energy access (SDG 7) as shown by (IEA, 2017c) <sup>[[#fn:r95|95]]</sup> .

The feasibility of renewable energy options depends to a large extent on geophysical characteristics of the area where the option is implemented. However, technological advances and policy instruments make renewable energy options increasingly attractive in other areas. For example, solar PV is deployed commercially in areas with low solar insolation, like northwest Europe (Nyholm et al., 2017) <sup>[[#fn:r96|96]]</sup> . Feasibility also depends on grid adaptations (e.g., storage, see below) as renewables grow (IEA, 2017c) <sup>[[#fn:r97|97]]</sup> . For regions with high energy needs, such as industrial areas (see Section 4.3.4), high-voltage DC transmission across long distances would be needed (MacDonald et al., 2016) <sup>[[#fn:r98|98]]</sup> .

Another important factor affecting feasibility is public acceptance, in particular for wind energy and other large-scale renewable facilities (Yenneti and Day, 2016; Rand and Hoen, 2017; Gorayeb et al., 2018) <sup>[[#fn:r99|99]]</sup> that raise landscape management (Nadaï and Labussière, 2017) <sup>[[#fn:r100|100]]</sup> and distributional justice (Yenneti and Day, 2016) <sup>[[#fn:r101|101]]</sup> challenges. Research indicates that financial participation and community engagement can be effective in mitigating resistance (Brunes and Ohlhorst, 2011; Rand and Hoen, 2017) <sup>[[#fn:r102|102]]</sup> (see Section 4.4.3).

Bottom-up studies estimating the use of renewable energy in the future, either at the global or at the national level, are plentiful, especially in the grey literature. It is hotly debated whether a fully renewable energy or electricity system, with or without biomass, is possible (Jacobson et al., 2015, 2017) <sup>[[#fn:r103|103]]</sup> or not (Clack et al., 2017; Heard et al., 2017) <sup>[[#fn:r104|104]]</sup> , and by what year. Scale-up estimates vary with assumptions about costs and technological maturity, as well as local geographical circumstances and the extent of storage used (Ghorbani et al., 2017; REN21, 2017) <sup>[[#fn:r105|105]]</sup> . Several countries have adopted targets of 100% renewable electricity (IEA, 2017c) <sup>[[#fn:r106|106]]</sup> as this meets multiple social, economic and environmental goals and contributes to mitigation of climate change (REN21, 2017) <sup>[[#fn:r107|107]]</sup> .

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