Paul Krugman has weighed in with an anecdotal example of how companies can find ways to conserve energy:

After 2008, when oil prices rose sharply, shipping companies — which send massive container ships on regular “pendulum routes”, taking stuff (say) from Rotterdam to China and back again — responded by reducing the speed of their ships. It turns out that steaming more slowly reduces fuel consumption more than proportionately to the reduction in speed

Interesting, but Mark Buchanan makes the point that total energy use keeps increasing even as efficiency per unit of GDP decreases (the Krugman article was actually a response to this one):

Growth inevitably entails doing more stuff of one kind or another, whether it’s manufacturing things or transporting people or feeding electricity to Facebook server farms or providing legal services. All this activity requires energy. We are getting more efficient in using it: The available data suggest that the U.S. uses about half as much per dollar of economic output as it did 30 years ago. Still, the total amount of energy we consume increases every year.

Data from more than 200 nations from 1980 to 2003 fit a consistent pattern: On average, energy use increases about 70 percent every time economic output doubles. This is consistent with other things we know from biology. Bigger organisms as a rule use energy more efficiently than small ones do, yet they use more energy overall. The same goes for cities. Efficiencies of scale are never powerful enough to make bigger things use less energy.

I have yet to see an economist present a coherent argument as to how humans will somehow break free from such physical constraints. Standard economics doesn’t even discuss how energy is tied into growth, which it sees as the outcome of interactions between capital and labor.

Brian Czech further attacks the Krugman article:

Let’s not let Krugman delude us. “Growing real GDP” isn’t about an efficiency gain here and there. It means increasing production and consumption of goods and services in the aggregate. It entails a growing human population and/or per capita consumption. It means growing the whole, integrated economy: agriculture, extraction, manufacturing, services, and infrastructure. From the tailpipe of all this activity comes pollution.

Krugman seems to have fallen for the pixie dust of “dematerializing” and “green growth” in the “Information Economy.” He may want to revisit Chapter 4 of The Wealth of Nations, where Adam Smith pointed out that agricultural surplus is what frees the hands for the division of labor. In Smith’s day that included the likes of candle-making and pin manufacturing. Today it includes everything from auto-making to information processing, but the fundamentals haven’t changed. No agricultural surplus, no economic growth. And agriculture is hardly a low-energy sector.

Now, I think it’s possible to have a vision of truly clean energy, which could one day allow us to grow energy use without increasing our environmental footprint. But to get there, we have to turn the corner where the reduction in impact per unit increase in energy use is greater than the overall increase in energy use. And we are nowhere near turning that corner yet.