Boosting transportation efficiency by standing still

Electrifying transportation goes far beyond EVs, and includes many stationary applications.

This post is a companion piece to an article published this month in Policy magazine.

Miles per gallon or liters per 100km? And is there anyone who can do the conversion in their head? Whatever your preference, chances are when we talk about efficiency in transportation, fuel economy is what you’re likely to think of.

But what if I told you that some of the most remarkable advances in vehicle energy efficiency have nothing to do with movement?

As it turns out, commercial vehicles like long-haul trucks expend a great deal of energy when they are stopped. That’s because when a driver pulls into a truck stop to spend the night, he doesn’t shut down the engine. He keeps it running to power the lights, heat and various electronics in the sleeper cab.

Now consider the fuel he could save if it were possible to simply plug into the local electrical system, shut down the engine and run the sleeper cab with grid power. How much of a difference would this make?

We have an idea because the Electric Power Research Institute (EPRI) has studied exactly this scenario and found that at current prices, a typical trucker could save $4,000 per year in fuel costs alone.

A similar approach to powering stopped vehicles is already in use at some airports.

Southwest Airlines, like most major carriers, relied on diesel generators to provide power to planes parked at the gate, but these units operate at higher cost and with greater noise and emissions than grid power. A single aircraft would consume 34-42 gallons of diesel to operate ventilation and other onboard systems during a typical stopover. So, Southwest shifted to plugging in its planes and is reaping a company-wide savings of $50 to $60 million per year, mostly in avoided fuel costs.

In the shipping industry—that is, the part of it that involves ships—the virtues of shore side power connections are well known. Some of the busiest container ports in the world, like the Port of Rotterdam in the Netherlands, now offer shore side power that allows ships to silence their engines while in port. This is particularly appreciated by local residents who frequently face not only noise but significant air quality issues due to the emissions associated with idling ships.

Shore-to-ship power isn’t limited to container vessels, though. Cruise ships also make use of it, for example, when docked at Port Metro Vancouver, which installed shore side connections in 2009.

Perhaps the most exciting example of “stopping power,” even if it isn’t strictly about powering a stationary vehicle, can be found on the rail network of the Southeastern Pennsylvania Transit Authority (SEPTA). The agency recently installed a first-of-its kind energy storage system that captures the energy of decelerating trains that would otherwise be lost in the form of heat during braking. Now, instead of the energy going to a resistor on the vehicle’s roof, it is captured in a battery energy storage system. The system is used to give a boost to trains as they pull away, but it also provides on-demand power back to the surrounding grid, a service for which SEPTA is paid.

Initial results are encouraging: SEPTA estimates that between energy savings and additional revenues, its energy storage system produced a return of $250,000 in its first six months.

There are many ways we can improve the energy efficiency of transportation, but they are not always intuitive and, as the above examples illustrate, may involve “bodies at rest” as much as “bodies in motion.”

Feature image credit: retinent under a cc license via flickr