Carbon free renewables will always be a partial solution. People aren't willing to endure rolling brownouts because of low winds or long stretches of overcast weather, and the storage required to solve those issues are never baked into the cost estimates under which these technologies are considered competitive.
People have been saying we would have rolling brownouts once we got to 5% renewables. Then when that happened without any ill effects, they said it would happen at 10%. Then 15%. It doesn't matter, because it has always been a false talking point, without any basis in fact. It simply doesn't make sense unless one can only imagine large thermally driven plants and you don't want to have to change grid management from what you were doing in the 1960.
We can do 90% renewable energy, and even 100%, with storage and curtailment. How much we need of each is simply a cost trade off. If we could build nuclear now for less than $100/MWh, it may have a place in this cost optimization problem, but we can't, so it doesn't have a place until nuclear technology catches up to the 21st century.
>...People have been saying we would have rolling brownouts once we got to 5% renewables.
Who ever claimed that?
>...We can do 90% renewable energy, and even 100%, with storage and curtailment.
That would not be very difficult with current technology. Trying to rely only on intermittent power sources has huge storage requirements due to weather along with daily/seasonal variation. If grid energy storage was a simple problem it would have been done decades ago.
For example, one estimate is that for Germany to rely on solar and wind would require about 6,000 pumped storage plants which is literally 183 times their current capacity:
>...Based on German hourly feed-in and consumption data for electric power, this paper studies the storage and buffering needs resulting from the volatility of wind and solar energy. It shows that joint buffers for wind and solar energy require less storage capacity than would be necessary to buffer wind or solar energy alone. The storage requirement of over 6,000 pumped storage plants, which is 183 times Germany’s current capacity, would nevertheless be huge.
I disagree. Renewables will be able to supply 100% of the world's energy needs, more cheaply than nuclear ever could. A nd yes, this includes the cost of storage.
Claims that renewables cannot handle things typically make the stupid assumption that long term variations in demand/supply are to be covered with batteries.
