|Source: The Conversation|
Note: that's capacity not output. Applying reasonable capacity factors, we get these percentages of new output:
Coal's contribution to electricity supply is now the largest of all, even with a capacity factor of just 60% (most new coal plants are being built in India and China and their capacity factors are much lower than the theoretical limit of 90% because of burgeoning renewables supply.) Capacity factors in solar are creeping up, but you can't get away from the fact that the sun doesn't shine for half the day, and is low in the sky for a quarter. Wind capacity factors are also lifting, with new turbines able to turn even at low speeds.
To stop global warming, we need to cease deployment of new coal power, and start retiring existing coal power stations. Gas is an OK gap-filler temporarily, until storage costs fall low enough.
However, the roll out of wind and solar is likely to be exponential rather than linear. Wind and solar now contribute 5.5% of world electricity demand. 10 years ago they together provided 1% of total world electricity demand. Solar capacity has been doubling every 2 years since at least 2000 (a 40% per annum growth rate), wind every three (26% p.a. growth rate.)
Global electricity demand is growing by 3% p.a., and that ignores the roll-out of EVs. In the US, EVs will add 1/3rd to electricity demand, in Europe less, because Europeans drive less than Americans. China and India would be less than that now because of low car ownership, but that will rise over the next 25 to 30 years. So let's assume that EVs add 33% to electricity demand over 20 years. That's an additional 1.5% p.a., so world electricity demand will grow by 4.5% p.a.
Wind and solar are already cheaper than coal, and are getting even cheaper every year. Assume solar continues to grow by 40% per annum, and wind by a more relaxed 16% per annum, because increasingly, utilities will prefer solar over wind. On these assumptions, wind and solar would supply (very back of envelope calcs) 68% of total global electricity demand by 2028. (Most of the rest will come from hydro, nuclear, etc.)
Note chart is using a log scale. What the exponential model shows is that the ground gained by renewables is very slow in early years, but accelerates every year. Over the next decade, the rise is huge, from 5.5% of total electricity to 55%. In passing, I point out that my rough calcs suggest that incremental growth in renewables will exceed incremental growth in total global electricity demand in 2020. That's when emissions will really start to fall. That's just 3 years away. So, optimism, anyone?