Alice J. Friedemann’s new book When Trucks Stop Running explains concisely how dependent American cities are on truck transport, and makes a convincing case that renewable energies cannot and will not power our transportation system in anything like its current configuration.

But will some trucks stop running, or all of them? Will the change happen suddenly over 10 years, or gradually over 40 years or more? Those are more difficult questions, and they highlight the limitations of guesstimating future supply trends while taking future demand as basically given.

Alice J. Friedemann worked for more than 20 years in transportation logistics. She brings her skills in systems analysis to her book When Trucks Stop Running: Energy and the Future of Transportation (Springer Briefs in Energy, 2016).

In a quick historical overview, Friedemann explains that in 2012, a severely shrunken rail network still handled 45% of the ton-miles of US freight, while burning only 2% of transportation fuel. But the post-war highway-building boom had made it convenient for towns and suburbs to grow where there are neither rails nor ports, with the result that “four out of five communities depend entirely on trucks for all of their goods.”

After a brief summary of peak oil forecasts, Friedemann looks at the prospects for running trains and trucks on something other than diesel fuel, and the prospects are not encouraging. Electrification, whether using batteries or overhead wires, is ill-suited to the power requirements of trains and trucks with heavy loads over long distances. Friedemann also analyzes liquid fuel options including biofuels and coal-to-liquid conversions, but all of these options have poor Energy Return On Investment ratios.

While we search for ways to retool the economy and transportation systems, we would be wise to prioritize the use of precious fuels. Friedemann notes that while trains are much more energy-efficient than heavy-duty trucks, trucks in turn are far more efficient than cars and planes.

So “instead of electrifying rail, which uses only 2% of all U.S. transportation fuel, we should discourage light-duty cars and light trucks, which guzzle 63% of all transportation fuel and give the fuel saved to diesel-electric locomotives.” Prioritizing fuel use this way could buy us some much-needed time – time to change infrastructure that took decades or generations to build.

If it strains credulity to imagine US policy-makers facing these kinds of choices of their own free will, it is nevertheless true that the unsustainable will not be sustained. Hard choices will be made, whether we want to make them or not.

A question of timing

Friedemann’s book joins other recent titles which put the damper on rosy predictions of a smooth transition to renewable energy economies. She covers some of the same ground as David MacKay’s Sustainable Energy – Without The Hot Air or Vaclav Smil’s Power Density, but in more concise and readable fashion, focused specifically on the energy needs of transportation.

In all three of these books, there is an understandable tendency to answer the (relatively) simple question: can future supply keep up with demand, assuming that demand is in line with today’s trends?

But of course, supply will influence demand, and vice versa. The interplay will be complex, and may confound apparently straight-forward predictions.

It’s important to keep in mind that in economic terms, demand does not equal what we want or even what we need. We can, and probably will, jump up and down and stamp our feet and DEMAND that we have abundant cheap fuel, but that will mean nothing in the marketplace. The economic demand equals the amount of fuel that we are willing and able to buy at a given price. As the price changes, so will demand – which will in turn affect the supply, at least in the short term.

Consider the Gross and Net Hubbert Curves graph which Friedemann reproduces.

While the basic trend lines make obvious sense, the steepness of the projected decline depends in part on a steady demand: the ultimately recoverable resource is finite, and if we continue to extract the oil as fast as possible (the trend through our lifetimes) then the post-peak decline will indeed be steep, perhaps cliff-life.

But can we and will we sustain demand if prices spike again? That seems unlikely, particularly given our experience over the past 15 years. And if effective demand drops dramatically due to much higher pricing, then the short-term supply-on-the-market should also drop, while long-term available supply-in-the-ground will be prolonged. The right side of that Hubbert curve might eventually end up at the same place, but at a slower pace.

The most wasteful uses of fuels might soon be out of our price range, so we simply won’t be able to waste fuel at the same breathtaking rate. The economy might shudder and shrink, but we might find ways to pay for the much smaller quantities of fuel required to transport essential goods.

In other words, there may soon be far fewer trucks on the road, but they might run long enough to give us time to develop infrastructure appropriate to a low-energy economy.