Energy efficiency isn't just a good idea from an environmental perspective; it makes business sense as well. But once companies commit to large hardware—say an aircraft or heavy machinery—there's often not a lot that can be done to improve the equipment's use of fuel. The primary option is to use the hardware as efficiently as possible.

That's gotten a lot easier over the last several years, primarily because of developments in electronics. Aircraft and trains now come equipped with GPS receivers that provide precise positional information, and these vehicles have processors sufficient to run sophisticated software if necessary. That software can then be used to control certain aspects of their operations to provide a more efficient trip.

We recently talked to Lucas Malta, who leads a team that helps develop transportation software for GE. He described two projects the group is working on, both focused on this exact problem—improving the use of fuel by large equipment.

The first initiative involves aircraft landings. You might expect that, given the fact that the aircraft is descending, approaches would be one of the least energy-intensive parts of the flight. But Malta said that an approach requires lots of intervention from the pilots to keep the plane level and on track, and these interventions frequently involve the engines. As a result, saving on approach time can lead to significant fuel savings.

In general, approaches have been laid out based on local geography, avoiding things like mountains and, at lower altitudes, heavily populated neighborhoods. To follow the designated approaches, pilots have typically followed a series of ground-based stations that directed them along the topographically preferred route.

But the station-based navigation wasn't all that precise, and the pilots tended to make a lot more adjustments than necessary—letting the plane slip below the recommended altitude, then pushing the engines harder to compensate. "You end up having a lot of variation from pilot to pilot, and you especially end up having a totally sub-optimal landing," Malta said. "You end up spending more fuel and having more track miles for your approach to a given airport." Malta works on a technology called "required navigation performance" that can help eliminate much of this.

To begin with, the basic approaches to an airport get redesigned with fuel efficiency in mind. Then, relying on ground stations is eliminated. Instead, the aircraft relies on its own internal positioning systems to figure out where it is. Software then guides the aircraft along an extremely precise route. Malta told Ars you "optimize the approach using GPS and updated information on the aircraft. Now you could follow a very, very... it's like having a tunnel. So the aircraft needs to follow that tunnel, and everything is controlled by the aircraft."

Convincing both the civilian aviation authorities and the airlines that this was a good idea might be expected to be a challenge. But Malta said GE had a big advantage: it had acquired a company that stores and analyzes flight data for the airlines. So it was relatively easy to show them numbers that demonstrated the system's benefits.

You might think that there's almost no relationship between landing aircraft and running a train—after all, the rails make sure it takes no effort to keep a train running through what's effectively a tunnel. But there's still room for computers to influence fuel efficiency here. "Trains are very complicated machines. For example in Brazil, we have a mining company named Vale here," Malta said. "And Vale is driving trains that are 40,000 tonnes, and they have 330 cars, many miles long. The train can be going up and down and up and down at the same time. And you have a person which needs to take care of that. And usually you don't have one locomotive; for Vale for example, they have three locomotives spread out over the train."

But there are a lot of details available about the train and its route. This data includes the location (onboard GPS), weight and engine distribution, along with information about the weather and the slope, curve, and speed limits of the track. Trip Optimizer is software that incorporates all of these into a physics-based model, using it to figure out the most fuel-efficient way of getting a train to its destination within a set time limit. While an engineer might hit the brakes hard on a downhill then push the engines hard on an ensuing uphill, Trip Optimizer only hits the brakes enough to keep the train within safety margins. This saves a lot of momentum to allow the engines to work less on the ensuing uphill.

Malta's group is working on taking an already successful product and trying to add features to improve train handling—managing the forces within the train to ensure that couplings between cars don't get unduly stressed. It's not easy. "It's amazing," Malta said when asked about the processing power that he has available for the task. "It's a computer that's way, way weaker than this cell phone. It's a huge challenge to come up with those algorithms that run in a computer from the '70s."

The payoffs have been significant: fuel savings that average out to about seven percent a trip, according to GE. That's because railroads had accumulated the equivalent of what you might call folklore about how to operate their equipment, Malta said:

There are a lot of rules that were introduced over the years by the railroads—so we shouldn't do that in those specific circumstances. It's tribal knowledge, it's not real. So we've been replacing that with physics-based solutions. So let's actually calculate the forces, or make a model that is actually calculating the forces and make those decisions based on this model, so you end up removing a lot of restrictions—you're able to go faster, to save more fuel. Because now you're only acting when you really need to.

The other useful thing about obtaining all the data—for both the aircraft and trains—is that it allows the performance of the software to be constantly evaluated. So as good as things are now, future versions may be even better able to optimize the balance between performance and fuel use.