I posted this on Streetsblog yesterday. It’s somewhat NYC-centric and doesn’t mention climate change, but it’s indicative of how fast opinion and, hence, policy can change, especially now, during the pandemic. — CK.

“Live long enough,” the saying goes, “and you’ll see everything.”

So it is. On Friday, we saw perhaps the first-ever NY Times link to “Banning Cars from Manhattan,” the seminal 1962 samizdat essay that suggested another urban world was possible. We also saw a 3,000-word essay revivify the truths in the classic 1980s underground sticker, “Ban cars from the city: They pollute, they kill people, they take up space.”

All this, and more, in a piece provocatively titled, “I’ve Seen a Future Without Cars, and It’s Amazing” by Times opinion columnist Farhad Manjoo — with a subtitle that dared to ask, “Why do American cities waste so much space on cars?”

Farhad Manjoo’s “The End of Cars” article led the New York Times’ Sunday Review section yesterday.

To paraphrase jazz immortal Sun Ra, space is place for us urbanists. To me, what makes Manjoo’s essay so distinctive is its focus on the immense space cars and driving require. That, plus its conviction that New York and other cities can and must be transformed, now — during and post pandemic; plus that it appeared in the New York Times, automatically giving it currency and gravity.

Space — the word — appears 19 times in the essay. Its close cousin, land, shows up for 15. “If cars are our only option, how [after the pandemic] will we find space for all of them?,” Manjoo muses. Cities’ “worst mistake [was] giving up so much of their land to the automobile,” Manjoo declares:

Automobiles are not just dangerous and bad for the environment, they are also profoundly wasteful of the land around us: Cars take up way too much physical space to transport too few people. It’s geometry.

Cars wasting space is old hat to anyone who spends much time biking in New York City. And the hopeless geometry of cars in cities has been a thing on “Transit Twitter” for some time. But I’ll bet Manjoo’s message struck Gray Lady readers as fresh and new. Even if they’re now schooled in tailpipes and carbon and crashes, most “normies” probably haven’t thought that “as roads become freer of cars, they grow full of possibility.”

Manjoo is speaking to this car-cocooned majority, sagely anticipating their objections and trying to help them get over, with passages like this:

What’s that you say? There aren’t enough buses in your city to avoid overcrowding, and they’re too slow, anyway? Pedestrian space is already hard to find? Well, right. That’s car dependency.

Without cars, Manjoo explains, “Manhattan’s streets could give priority to more equitable and accessible ways of getting around.” Crucially, these better ways aren’t ride-hails or Teslas or self-driving cars. Indeed, one of the essay’s notable feature is its kiss-off to digerati fantasies of melding technology, automobiles and cities. (Manjoo, a former reporter, covered Silicon Valley.)

No faux disrupter, Manjoo is going sustainable and long, urging bike superhighways and bus rapid transit and congestion pricing and ample sidewalks — elements of a wholesale repurposing of the vast space taken up by moving cars, parked cars, cruising-for-parking cars, stuck-in-traffic cars, refuel stations and the like.

In Los Angeles, “land for parking exceeds the entire land area of Manhattan, enough space to house almost a million more people at Los Angeles’s prevailing density.” And just in Manhattan, “nearly 1,000 acres … is occupied by parking garages, gas stations, car washes, car dealerships and auto repair shops.” (Central Park covers 840 acres.)

“The amount of space devoted to cars in Manhattan is not just wasteful, but, in a deeper sense, unfair to the millions of New Yorkers who have no need for cars,” Manjoo writes, before teeing up this killer quote from urban planner Vishaan Chakrabarti: “It really does feel like there is a silent majority that doesn’t get any real say in how the public space is used.”

Chakrabarti, whose Practice for Architecture and Urbanism firm provided underpinning for Manjoo’s column, here joins the Regional Plan Association in demanding that politicians stop coddling the pro-car NIMBY’s who overpopulate city community planning boards and problematize virtually every measure that might take space from cars.

“Cars aren’t just greedy for physical space,” Manjoo writes, “they’re insatiable,” calling out the true meaning of induced demand: “an unwinnable cycle that ends with every inch of our cities paved over” (an outcome sadly familiar to aficionados of Streetsblog’s Parking Madness tournaments).

Shortening of commute times in map assume 60% reduction in traffic in Manhattan, with “ripple” reductions in neighboring areas.

“Cars make every other form of transportation a little bit terrible,” Manjoo adds, perhaps understating. “The absence of cars, then, exerts its own kind of magic — take private cars away, and every other way of getting around gets much better.” That goes for walking, biking, scootering, even taxis and Ubers, Manjoo notes, but, above all, for buses, as the graphic at right showing time savings from removing Manhattan car traffic makes clear.

I posted that graphic on Twitter in response to concerns that barring most private autos from Manhattan and upgrading bus service to BRT, as Manjoo suggests, “wouldn’t serve equity.”

“On what planet,” I asked, “is cutting super-double-digit minutes off bus commutes in/around NYC not a win for equity?”

Of course, a win for equity like humane and efficient buses is a poor stand-in for an across-the-board commitment to equity, as was pointed out in response.

“A true commitment to equity changes the power structure for making decisions,” added another commenter — and I fully agree.

But I don’t think it’s helpful to fault Manjoo’s article, or their vision, for failing to confront power structures that enforce economic inequality or white supremacy. Dismantling those structures is the paramount work of our time, in my view. And I want no part of any measures that would further entrench them. Yet making New York and other cities safe, sustainable and habitable for their hundred million or more inhabitants is also vital. I’ve seen nothing suggesting that aggressively reducing car dependence along the lines urged by Manjoo will either interfere with that work or worsen conditions for communities of color and other underserved constituencies.

The 2021 races for mayor, public advocate, comptroller and city council are fast approaching, and Manjoo has sent NYC livable-streets advocates a clear signal to elevate our game. The signoff from their column gets the last word (emphases added):

Many of the most intractable challenges faced by America’s urban centers stem from the same cause — a lack of accessible physical space. We live in a time of epidemic homelessness. There’s a national housing affordability crisis caused by an extreme shortage of places to live. And now there’s a contagion that thrives on indoor overcrowding. Given these threats, how can American cities continue to justify wasting such enormous tracts of land on death machines?

How, indeed?

Five years ago, novelist and technologist Ramez Naam published a series of articles, collectively titled How Far Can Renewables Go? Pretty Darn Far, in which he wove empirical data into declining-cost curves for wind power, solar photovoltaic cells and battery storage that pointed, in his estimation, to prodigious future growth paths for renewables in the U.S.

Now, in a new post, Solar’s Future Is Insanely Cheap, Raam carries optimism about solar photovoltaics to a new height.

A classic early-stage growth curve: year-on-year increments increase, but year-on-year percent changes decrease.

He demonstrates that costs of utility scale solar electricity in the U.S., China, India and the world as a whole have dropped by a factor of five since 2010, putting them at around $50 per megawatt-hour (5 cents per kWh), the low end of the cost range for new fossil-fuel generating plants. He points out that most forecasts, including his own, have underestimated the speed of decline in solar costs.

Predictions

This 10-year record of plummeting solar PV costs is impressive and heartening. But what can it tell us about the next 10 or more years? To predict the cost of solar electricity going forward, Naam uses a “learning curve” approach based on Wright’s Law, a staple of industrial engineering that states that, for many technologies, each doubling of cumulative production leads to a constant percentage decline in the cost of that technology. (The decline rate varies across technologies but tends to be constant for each.)

By Naam’s account, Wright’s Law has been found to apply to at least sixty technologies. Naam demonstrates it via falling prices for Henry Ford’s Model T as its production grew steadily through the period 1909 to 1923. He then compares the cost of utility-scale electricity with global cumulative installed capacity of solar, and, just as Wright’s Law would predict, finds a smooth and steady decline, which he depicts in the chart at right, below.

Reproduced from Ramez Naam, “Solar’s Future Is Insanely Cheap,” May 2020 (see link in text).

By plotting these data on a log/log scale (not shown here), as befits “power laws” like Wright’s Law, Naam finds that the cost of utility-scale solar generating facilities has dropped by 30% to 40% for each doubling of installed capacity. This coefficient is at the high end of “doubling elasticties” in those sixty or so technologies that are said to conform to Wright’s Law.

If ever there was cause for optimism that solar power (and perhaps its renewable-power cousin, wind turbines) can keep getting cheaper at a fast enough rate to permit and justify massive deployment (which in turn will keep driving down costs), it is Raam’s May 2020 post. Think of it: just two more doublings in cumulative production (and installed capacity) will drive down costs by another one-half to two-thirds. Affordable, irresistible solar is coming to save us from fossil fuels and climate change.

There’s a problem with this approach, however. The solar costs that Naam has plotted are total installed costs. Thus, they include not only the cost of the solar panels (modules) but the costs of inverters, trackers, cabling, mounting systems, land and labor, not to mention the business relationships and contractual arrangements necessary to actually bring each job to fruition. These so-called balance of system (BoS) costs currently account for 2/3 of the cost of solar installations, by Naam’s admission. And while it is true that the “inertia” in BoS costs means that the costs of the modules themselves have fallen even faster since 2010 than the 80 percent overall drop in solar costs in that time (that’s the 5-fold drop we noted earlier), this same inertia seems almost certain to drag down the rate of cost decline going forward.

And in fact since 2010, costs of modules have dropped approximately 10-fold; twice as much as solar installations as a whole, which means that the other parts of solar costs fell less impressively (see this and this). The slower learning rate for BoS solar costs suggests that while the modules, with their very high learning rate, might theoretically cost next to nothing, the inertia in at least some BoS costs could mean that, no matter how many megawatts and gigawatts of solar are installed here and globally, the full cost of solar electricity may level off and be unable to fall below a certain level.

Even if we assume as Naam does that a 30% to 40% learning rate applies more or less uniformly to all solar costs, including modules and BoS items, cumulative installed capacity will have to double to achieve each approximate 35% drop in cost. Successive doublings in generating capacity require larger and larger absolute increases. World solar generating capacity was about 1 gigawatt in 2000. It was over twice that in 2003, and twice that, about 4 gigawatts, in 2005. Today world solar generating capacity is about 600 gigawatts. Growing from 600 to 1200 gigawatts, and then again from 1200 to 2400 gigawatts, requires vastly more production of panels and other necessary materials than growing from 1 to 2 gigawatts and then from 2 to 4 gigawatts, etc.

In order for cumulative installed solar capacity to double and then double again by 2030, for example, solar’s rate of growth would have to maintain exponential growth in the range of 15% per year. Whether such a continued high rate of growth is at all feasible is a fair question.

Chart by author from data in U.S. DOE 2018 Transportation Energy Data Book.

Learning from History: Autos, Railroads, Electricity

U.S. solar growth has slowed of late, taking three years for its most recent doubling, from 2016 to 2019, which Naam refreshingly acknowledges, noting that “solar growth has very clearly slowed over the past few years.” This slowdown in solar’s growth in the face of continued dramatic declines in costs signals that other factors are involved than cost alone.

In short, cost declines following Wright’s law may not translate directly to increased deployment. Take Naam’s example of the Model T. U.S. motor vehicle ownership grew exponentially from around 1900 to 1920 but then settled into a long period or more of less linear growth, as indicated in the chart above.  (In this figure and the two following it, exponential growth rates were selected that produce curves that approximately match actual data for the early years.)

Chart by author from data in “Train Factory” exhibit and sources noted therein, Franklin Institute, Phila. PA, 2016.

Another example, shown at left, is U.S. railroad track mileage, which surged in the 1850s and 60s and then also settled into a long period of linear growth.

A third example, shown further below, is U.S. electricity generation. An exponential growth rate of about 9% per year is apparent from 1900 until the mid-1950s. Exponential growth slowed around then, and by 1970 growth had settled into a more-or-less linear pattern.

Few technologies — or natural systems, for that matter — grow in an exponential manner for long (Smil, 2014, Kramer & Haigh, 2009.) Instead, “growth curves” are characterized by an early exponential period that transitions to a linear phase, adding a more-or-less constant increment each period, which eventually levels off as constraints increasingly come into play and limit further growth.

Chart by author from data in “Energy” tab of Carbon Tax Center carbon-tax spreadsheet, accessed June 6, 2020.

Growth in both motor vehicle ownership and railroad track mileage became linear despite ongoing innovations in the technologies themselves and improvements in manufacturing methods as production continued to increase. A similar pattern is apparent with U.S. electricity generation; growth gradually transitioned from exponential to linear during the ‘60s and ‘70s, as decades of declining costs (which enabled utilities to discount rates for big users) ground to a halt. Since 2005 growth in electricity use has ceased altogether, primarily due to large-scale dissemination of energy efficiency (see reference to Komanoff analysis, below).

How fast will solar electricity production grow?

Naam’s discussion of solar electricity’s declining costs is important because it can shed light on how far and fast solar electricity generation is likely to grow. In particular, can solar output grow rapidly enough to displace enough coal and natural gas to help avert climate catastrophe?

To be sure, growth in solar electricity is already pushing out fossil fuel use in the United States and other countries. In the U.S., the roughly 100 TWh increase in solar electricity production since 2005 was great enough to avert burning coal and gas that would have emitted 74 million metric tons of carbon dioxide in 2019, according to an analysis released last month by Carbon Tax Center director Charles Komanoff.

Yet that accomplishment pales beside the 1,618 million metric tons actually emitted by U.S. power plants last year. And the need for large-scale electrification of transport and heating — in order to displace petroleum — only magnifies the growth required of solar (and wind), and perhaps from other advanced energy sources such as next-generation nuclear and enhanced geothermal, to fully decarbonize the  economy.-

Unfortunately, Naam doesn’t venture to predict the pace of solar growth, either for the U.S. alone or for the world as a whole. That is probably wise, seeing as that at this point, and probably for some time to come, there is no way to divine whether to extrapolate past growth figures linearly or exponentially. We’ll revisit this issue in a follow-on post scheduled for the first week of July.