Comment by jandrese
1 year ago
Ahh, the classic case of seeing the bottom half of an S curve and projecting it out to infinite exponential growth.
The number of times things have experienced infinite exponential growth in all of history starting from the Big Bang: 0.
Nobody said "infinite".
The upper asymptote of an S-curve is often called its "carrying capacity". We expect an inflection point about halfway toward this point. What do you think the maximum capacity of global solar energy is? The total amount of solar energy hitting Earth is about 4.4 * 10^16 watts -- 44,000 Terawatts. If we covered 1% of the Earth in solar panels at a meager 10% efficiency, that's 44 Terawatts -- this is a reasonable low estimate for the "carrying capacity" from total solar irradiance. We're at about 1 Terawatt right now. A high estimate (remember, this is the absolute maximum) might be 10% of the Earth at 20% efficiency -- 880 Terawatts. Of course, if we run out of space on Earth, there's always more space in ... well, space.
Another "carrying capacity" could be the materials needed for production. As TFA illustrates, we have enough different ways of producing solar panels that we are not anywhere near maxing this out either.
So I think there's pretty good justification to think we're still at the very early part of this S-curve.
> 44,000 TW
Check your arithmetic; it's considerably more than that.
There's a considerable difference between the amount that hits the atmosphere and the amount that hits the surface of the Earth. My number includes average cloud cover. It's this order of magnitude, and a higher number only strengthens my point.
173,000 terawatts [1]
So, 1% at 20% capacity is 346 terawatts. That seems like a reasonable upper limit for earth systems.
[1] https://sos.noaa.gov/catalog/live-programs/energy-on-a-spher...
Sure, but until we see the inflection point we can't know how much longer the bottom half of the S curve lasts— it might be 2, 5, 10 years, or it might have already passed; either way we'll only know in retrospect.
Those different options make a big difference on how much PV is part of the long term global energy picture.
Ah the classic case of rounding a two digit number to infinity to make a strawman point?
Isn't the universe expanding exponentially since the Big Bang?
The expansion rate slowed down dramatically after the big bang and then sped up again, from Wikipedia:
> Cosmic expansion subsequently decelerated to much slower rates, until at around 9.8 billion years after the Big Bang (4 billion years ago) it began to gradually expand more quickly, and is still doing so.
/jk just wait long enough and that zero will go to Infinity