I crunched the latest IRENA data for renewable energy trends, as it now includes 2017. At the global level the increase in renewable energy capacity is amazingly stable, averaging 8.5% per year since 2011 with only a very small variance year over year.
The contribution from hydro has been falling, from 3% growth toward 2%.
The growth in wind has more than halved, from over 20% to now 10%.
The growth in bio-energy did the same, from 21% to 12% annual growth.
The growth in solar also fell, from above 70% to 32% (stable for the past 5 years).
As the installed base of non-hydro has greatly increased, a lower rate of non-hydro growth is required to keep the growth rate at 8.5%. Given that the growth in renewables is migrating to lower-utilization technologies (hyrdo to other; wind to solar), the growth in actual electricity generation will be less than the 8% growth in capacity levels. i.e. the growth in actual renewable energy generation is on a slowly declining trend.
At 8% annual growth, capacity will double every 9 years (rule of 72) - about 18 years to make all electricity renewable at that continued growth rate, but will take longer given growth in electricity demand. With a possible 30% growth in energy demand (IEA), it would take about 21 years. Of course, the scale of that last 8% would be incredible - over 10% of current electricity production replaced in a single year with renewables (8% plus 30% growth). A slow down in growth rates can be assumed given this scaling issues. Much more focus on energy efficiency per unit of GDP would help by reducing demand growth.
Given the low forecast rates for hydro, wind and bio-energy growth (by their own industry associations), the continuance of rapid growth in pv will be critical to keeping the global growth rate at 8%. In the past few years China has been critical to keeping the pv capacity growth rates high. India has had recent very rapid growth, so this may help if it continues.
Even if China put in 70GW of pv in 2018 (more than in 2017), the China pv growth rate would fall from 70%+ to 50%+, showing the incredible challenge of keeping these growth rates up. At the global level, the addition of a little bit more pv capacity this year than last will significantly reduce the growth rate for pv to about 26%.
https://www.pv-tech.org/news/bnef-hedging-bets-on-chinas-solar-installations-in-20182017 global capacity (MW):Hydro 1,270,496
Wind 513,939
Solar 390,625 (130,646 in China, with 70%+ growth in past 2 years; India 100% growth in 2017 from low base - now 19,275)
Bio-Energy 109,213
http://www.irena.org/-/media/Files/IRENA/Agency/Publication/2017/Mar/IRENA_RE_Capacity_Statistics_2017.pdfThe actual carbon intensity of bio-energy is being seriously questioned, such as burning wood pellets from the US in UK power stations, so the growth rate of bio-energy may be adversely impacted by policy changes. This is just for electricity of course, transport, space heating, and concrete/metal production will need very major changes to become electrified.