You´d be hard put to find a better illustration of the old chestnut about the EMH economist whose friend tells him there´s a banknote lying in the road:
Can't be. If there was a bill on the ground, somebody would have already picked it up.
Where to begin? Most normal people would say: that´s another nail in the already well-sealed coffin of the EMH. But faced with indisputable facts about solar market prices and installation quantities, Cowen´s response is: where´s the solar boom or fossil bust in asset prices? He can´t see one, so the facts must be wrong, or more politely epiphenomenal noise. Note that the objection is not based on any falsifiable hypothesis about solar PV, such as: Germany will have to cancel its solar PV feed-in tariff as unaffordable, silicon feedstock supply will hit a new bottleneck like the one that kept prices from falling in 2004-2008, solar PV will turn out to cause cancer, impotence and obesity or at least will be thought to do so. (Now there´s a hot tip to the oil industry PR men: work up some scares.) For the record, while Germany did reduce its feed-in tariff, China has announced one.
You know, even after two years at Chicago, where like every professor tells you that same joke at least three times every semester, it never gets old, does it?
It's of course perfectly possible that markets are simply not recognizing the danger to fossil fuel stocks, and we are in for a very exciting disruption in the next ten years. (In which case, I am wrong about a carbon tax and other emissions controls; we should just wait eight years.)
On the other hand, it's also possible that people who trade those stocks for a living--some of whom may even be as smart as James Wimberly, have considered this possibility, and don't find it very likely. What might those reasons be?
1) Mindless trend extrapolation is hours of fun for the entire family, but it is incorrect at least as often as it is correct, and possibly more often.
Wimberly uses this graph:
And very possibly prices will keep falling, the way that microchips have. On the other hand, maybe they'll plateau. Wimberly points out that solar panels are fundamentally a manfuacturing business, not a resource business, which is certainly promising . . . but the prices of other manufactured goods that experienced steep declines did not necessarily keep plummeting to zero.
2) Solar panel costs are not the only cost of a solar installation. According to the Energy Bible (which comports roughly with other figures I've seen online), about half the cost, or a little more, of putting in solar panels comes from the cells. The rest comes from the other stuff you need: batteries, transformers, wiring, and labor. As far as I know, the cost of these things is not falling as fast as the cost of solar panels.
Assume that these costs have held relatively steady, with the labor component being the most unstable. Ten years ago, most of the cost of an installation would have been the solar panels. But as those prices decline, the installed cost (without tax incentives) will be increasingly dominated by labor and other materials. Assuming that that graph says what I think it does, that implies that even if cells become free, we'd plateau slightly north of the average electricity price.
3) There's a storage problem. Yes, intriguing things are being done with hot salt and so forth. But how attractive are the costs compared to home installations? What percentage of their total generation costs represent solar cells, versus labor and other things whose prices aren't falling so fast?
Putting the pieces together, our national battery occupies a volume of 4.4 billion cubic meters, equivalent to a cube 1.6 km (one mile) on a side. The size in itself is not a problem: we'd naturally break up the battery and distribute it around the country. This battery would demand 5 trillion kg (5 billion tons) of lead.
A USGS report from 2011 reports 80 million tons (Mt) of lead in known reserves worldwide, with 7 Mt in the U.S. A note in the report indicates that the recent demonstration of lead associated with zinc, silver, and copper deposits places the estimated (undiscovered) lead resources of the world at 1.5 billion tons. That's still not enough to build the battery for the U.S. alone. We could chose to be optimistic and assume that more lead will be identified over time. But let's not ignore completely the fact that at this moment in time time, no one can point to a map of the world and tell you where even 2% of the necessary lead would come from to build a lead-acid battery big enough for the U.S. And even the undiscovered, but suspected lead falls short.
What about cost? At today's price for lead, $2.50/kg, the national battery would cost $13 trillion in lead alone, and perhaps double this to fashion the raw materials into a battery (today's deep cycle batteries retail for four times the cost of the lead within them). But I guarantee that if we really want to use more lead than we presently estimate to exist in deposits, we're not dealing with today's prices. Leaving this caveat aside, the naïve $25 trillion price tag is more than the annual U.S. GDP. Recall that lead-acid is currently the cheapest battery technology. Even if we sacrificed 5% of our GDP to build this battery (would be viewed as a huge sacrifice; nearly a trillion bucks a year), the project would take decades to complete.
But even then, we aren't done: batteries are good for only so many cycles (roughly 1000, depending on depth of discharge), so the national battery would require a rotating service schedule to recycle each part once every 5 years or so. This servicing would be a massive, expensive, and never-ending undertaking.
Moreover, while some sort of battery-replacement would help deal with the base-load problem (solar and wind are more variable than conventional sources, which means they have limited applications), they don't fix the transportation problem. Batteries are heavy and expensive, and as I understand it, absent some fairly radical breakthrough, they won't work at all in aviation; the energy density isn't high enough to permit the plane to take off. They're better for autos, but people don't want the limited range those vehicles currently offer.
4) To really take the market by storm, solar (plus storage) doesn't need to beat the average cost of electricity; it needs to beat the individual cost of each fuel type. DOE seems to think that by 2016 solar is still going to be a lot more expensive per kilowatt hour than other sources:
It's a pretty long haul before they overtake new coal--much less already-existing coal plants, or advanced natural gas.
The most obvious use for solar is as a replacement for expensive peak-load natural gas power (as I understand it, air conditioning causes most of the demand for these plants, so solar would be a nice complement.) But unless it gets massive subsidies, solar (including any storage mechanism you come up with) is going to have to individually defeat each type of electricity plant on price and/or availability, not "the average retail price of electricity"--which already includes some expensive solar and wind power.
Maybe that's possible--though that would still leave transportation to worry about. But that graph doesn't show it.
I'd close by restating Tyler's question in a slightly different way: if the price of solar is really likely to keep falling until it's cheaper than coal, why don't we see this revealed in the behavior of global warming activists? Where are Greens saying "We've decided to move on to more pressing issues, because clearly, the carbon emissions problem is just about solved."
If solar panels really become cheap enough to replace most electric generation, that will be extraordinarily disruptive, in ways that will be both good and bad for the environment. But I'm not seeing a shift away from climate change in order to focus more on, say, sustainable water-use or species conservation. Everyone seems just as worried about climate change as they've ever been, even though such cheap solar panels would render the issue mostly moot.
Revealed preference and market prices certainly can't tell you everything about the future. But they can tell you a lot about what people believe about the future.