When I wrestle with climate denialists and fossil fuel spruikers, they keep on saying that wind and solar only provide a small percentage of total electricity generated world wide. And therefore (a) we might as well give up, and (b) we simply have to keep on using coal. Forever. Never mind the rise in global temperatures. Well, no. It's perfectly true that renewables still make up just a small percentage of global electricity generation. But that completely misses the point.
From 2000 to 2015, the percentage of electricity generated from solar has doubled 7 times. Over the same period, the percentage of electricity generated from wind has doubled 4 times. That means solar has risen 128 fold and wind 16 fold, over 15 years. In fact, the percentage of solar in total global electricity supply has been doubling every two years for over 30 years, a growth rate of 41% per annum. As costs have fallen, so more solar has been installed, which has led to further cost falls. A classic virtuous cycle, or learning curve. The wind percentage, meanwhile, has doubled every 3 years, which is a growth rate of 26% per annum.
Together, wind and solar now produce about 5% of global electricity. This means that together they are just 4 and a half doublings away from 100%. Obviously as we get closer to 100%, growth rates will slow. But over the next few years, as costs continue to decline, and the concern about global warming continues to grow, growth rates are likely to remain high. At 25% growth, the percentage of electricity from wind and solar will reach 15% in 5 years, 45% in 10 years, and would exceed 100% within 15 years. In fact, all we need to reach 100% renewables over the next 20 years is a mere 16% growth per annum. And that ignores nuclear and hydro. Eminently doable.
A similar dynamic is happening with electric cars. They make up just over 1% of the world car sales. But sales are doubling every 18 months. That means that in ten years 100% of car sales could be electric.
We doubt these forecasts because our brains think linearly. Exponential growth at some deep level make no sense to us. But you have to ask yourself, using the logical analytical parts of your brain: why would growth rates slow before we reach close to 100% saturation? Prices keep on falling; awareness of these new technologies keeps on rising, the cost advantage keeps on improving. And technology take up S-curves are extremely common. Think mobile phones, DVDs, microwaves, the telephone, colour television, electricity itself, etc, etc, as this beaut graphic shows.
What could stop 100% renewable electricity? Well, the only thing, now that cost is no longer a hindrance, is that renewables are intrinsically variable in output. And as we get closer and closer to 100% renewables, we will need progressively more storage. That will add to the total all-inclusive costs of wind and solar, so their uptake will slow. But a grid with mixed sources of supply might need one day's storage (the CSIRO in Australia estimates that only half a day's storage is needed to reach 100% renewables). And in 15 years, batteries and perhaps other storage will be one tenth of current costs. So I don't think that will be too big a factor. I think growth in wind and solar will continue to barrel along for another decade or more.
The implications for fossil fuel producers--and for policy makers and governments-- are clear. Beware the carbon bubble. Change is happening faster than our linear-constrained brains realise or feel comfortable with. And getting it seriously wrong could be disastrous, for everybody. We don't need more coal mines. And oil companies should stop exploring for new oil, because we won't need it.