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Will driverless cars solve our energy problems — or just create new ones?

Self-driving cars are all the rage these days. Companies like Google are building vehicles that can drive themselves with sensors and algorithms. Futurists are raving about how this will revolutionize transportation: fewer accidents, easier parking... It's reached the point where even Newt Gingrich is offering a "short course" on driverless cars.

And that got us wondering. If self-driving cars ever do become the future of transportation, what would that mean for energy, oil use and climate change in the decades ahead?

Some backdrop: Last week, the National Academy of Sciences released a big report on how the United States could cut gasoline use and transport emissions 80 percent by 2050 — a key step toward addressing global warming and U.S. oil dependency. It would be difficult, the report said, but a big push on electric vehicles, advanced biofuels and efficiency could get us there.

In a follow-up post, David Roberts criticized the NAS for thinking too prosaically. The report assumed our transportation system would look basically the same in 2050, only with somewhat cleaner vehicles. And that might well be wrong. What if self-driving cars become ubiquitous and utterly transform the way we get around? The task of getting off oil and curbing emissions could be much easier — or much harder — than anyone thinks.

Now, a future filled with driverless cars might be far-fetched, but it's interesting to ponder. So here are a few very speculative thoughts on how self-driving cars could conceivably affect energy use in the decades ahead — assuming they ever catch on:

How driverless cars could curb energy use and be great for the environment:

Driverless cars will be far more fuel-efficient. That's the idea, anyway, laid out in this report from KPMG. Once we no longer need clumsy human drivers, then self-driving cars and trucks will be able to bunch close together at steadier speeds. Traffic jams and accidents will become a thing of the past. The robots will be driving as efficiently as possible.

The hope is that this could save thousands of lives. It could also have massive effects on energy use. The Rocky Mountain Institute estimates that the reduction in wind drag alone from vehicles traveling closely together could reduce fuel use 20 percent to 30 percent:

Driverless vehicles could also, in theory be much, much lighter — since collisions will no longer be a big concern. Cars that currently weigh 4,000 pounds could one day weigh just 750 pounds. That development  alone there would nearly double energy efficiency.

Driverless cars will waste less fuel on things like looking for parking. One MIT study found that in congested urban areas, about 40 percent of total gasoline use in cars is spent as drivers look for parking. Presumably, intelligent self-driving cars wouldn't have this problem.

Driverless cars will make car-sharing more popular, which will mean fewer vehicles on the road. Lots of self-driving-car enthusiasts have argued that car-sharing will be a popular model — after all, most privately owned cars are currently parked and idle 90 percent of the time. Wouldn't it make more sense for the self-driving car to make itself useful during that period? Car-sharing could mean fewer cars overall.

Driverless cars will make the transition to electric vehicles easier. Lighter, more efficient cars will be able to go much farther on a single battery charge, which means that "range anxiety" will be less of an issue for plug-ins.

Driverless cars will increase the appeal of walking and biking. Since self-driving cars will (in theory) be much, much safer than human drivers, it'll be less dangerous to bike on the road. At the margins, that could be a boon to pedestrians.

Cities will become more appealing. If traffic gets less crazy, if walking and biking become more attractive, and if parking is no longer a huge hassle, denser urban living might become more attractive. Since cities tend to be more energy-efficient than the suburbs, that could reduce energy use. (Although see below for a counterpoint.)

The flip side: How driverless cars could lead to a huge surge in energy demand.

More and more people will drive. Think about all the people who are not allowed to drive right now. Everyone under 16. The elderly. The disabled. People who are intoxicated or on medication. People who are sleeping. That's a huge portion of the population. And all of those people will be able to ride in driverless cars. And that means we could see many more car trips.

That's a huge plus for mobility. But it also has big energy implications. At the moment, vehicle miles-traveled in the United States appears to have peaked back in 2005 — in part because fewer and fewer young people are getting their licenses and driving. Could self-driving cars reverse that trend?

Public transportation could lose its appeal. If driverless cars or driverless taxis catch on, then trains and buses could find themselves displaced. You can read or zone out in a driverless car just as easily as you can on the subway. Depending on how this all shakes out, it could mean more driving and higher energy demands.

Urban sprawl could greatly expand. Arielle Duhaime-Ross has a good post on this. Right now, there's a serious limit to how sprawled-out a city can get — people tend to prefer to keep their commutes under an hour. But if driverless cars can offer quick, efficient transportation, then we could see more people spread out to the suburbs. It's possible this could mean bigger environmental effects. (That said, it would be a big gain for public health if commuting became less stressful and arduous.)

Cars might need to be replaced more frequently. If car-sharing became widespread, then driverless cars would be on the road and in motion far more often. This might mean cars would have a lifespan similar to that of police vehicles, about three to five years, rather than their current 11 years. It's hard to say what this would mean for energy use — cars could be upgraded more quickly as new technology became available — but it's another angle here.

No doubt there are a million other possibilities I haven't thought of or missed, so feel free to add more in comments.

Further reading:

-- Some interesting thoughts on driverless cars from David Roberts, Issi Romem, the Rocky Mountain Institute, Felix Salmon, Arielle Duhaime-Ross and Timothy Taylor.

-- Also note that the biggest hurdles currently facing driverless cars are legal impediments. That could well change in the years ahead, but safety concerns and other regulations could very well thwart a driverless-car boom.

-- Also, if this all sounds absurdly unrealistic, then check out the National Academy of Science's report on how to cut gasoline use in half by 2030 with more incremental technologies like hybrids and biofuels. Not as fun to think about, but perhaps more feasible.