Revolutionizing Transportation while Saving Money and Decreasing Energy Consumption

A title so unbelievable it almost sounds like a clickbait

Over the past years cars have become increasingly more automated. Twenty years ago a driver would have to (almost) solemnly control the car, but recently Artificial Intelligence (AI) has been taking over more and more tasks of the driver. Many modern cars have convenient AI tools such as lane assist, automated parking or automatic braking systems. Various car producers (Toyota,  Tesla, BMW, etc.) are working hard to develop a completely autonomous car and are suggesting that within five years these cars will become reality. However, there has been some concern regarding this development. Most concerns are with regard to the safety of the AI systems or the AI capability of driving the car,  however, some concerns are also with regard to the energy cost of the AI that is controlling these cars. In a recent article in “het Financieele Dagblad” Prof. Dr. Max Welling discusses intelligence per kilowatt-hour and gives the example of what we will eventually be paying to drive around in autonomous cars. However, this statement is a bit out of context as autonomous cars have various positive side-effects, eventually making us not worse off money/energy-wise.

Let’s start of by first addressing the energy (and thus money) consumption of the AI in autonomous cars at the moment. Welling claims that with current technologies autonomous cars use at least around 2000 Watts extra to drive around. Humans take around 20 Watts to control a car, so indeed this number seems to be out of proportion. To put this in perspective, the writer calculates that with a billion cars on the road globally, all travelling roughly an hour a day, we find ourselves with a total cost of 200 billion euros per year to be driven around autonomously. Yes, this does seem worrying, but I am writing this article to take away your worries! So let’s start by putting this 200 billion euros price tag in perspective.

According to the National Motor Vehicle Crash Causation Survey Report carried out by the National Highway Traffic Safety Administration 90% of the crashes in the United States are caused by human errors. Therefore, if we were to completely automate the American traffic fleet we could theoretically get rid of these crashes. Bertoncello and Wee conducted a follow-up research calculating how much money potentially could be saved for the U.S. economy if these crashes were prevented. Their calculation came to the absurd number of 190 billion U.S. dollars per year. Even if we were to correct for currency and for example assume that autonomous cars cannot prevent 100% (let’s say it takes care of 75%) of the crashes caused by humans, we will still already have covered far more than half (115 billion euros) of the costs of autonomous driving AND we haven’t even looked outside the U.S.!

So, the money matter is already non-existent, but one might still argue that we will be using a lot more energy to drive around in our autonomous cars. Before we start talking about the energy efficiency increases of an autonomous car it would be useful to know how many Watts a car consumes when in use. Although this value depends heavily on your speed and your acceleration/braking pattern, averages can be found using data gathered by the Dutch Government and Statistics Netherlands (Centraal Bureau voor de Statistiek, CBS). Together they have (Dutch) data on the total energy consumption of the traffic, travelling times and the amount of cars. Combining this data we can find that a typical Dutch passenger car (we are only considering passenger cars as they are the main energy consumer in traffic and will be the first to be automated) uses roughly 55000 Watts, which is a good average applicable in many locations around the world. We can already note that an increase of 2000 Watts will only increase this amount by 3.6%, so if we were to find an increase in energy efficiency of 3.6%, due to automation, the problem of the increased energy consumption will already be dealt with. So let’s dive into the various advantages of autonomous cars.

First of all, as computers have faster reaction speeds than humans, cars will be able to follow much closer to each other than what humans will be ever be able to safely do. This tailgating is known as platooning and the positive effect of this is a reduction in aerodynamic drag experienced by the tailgating car. Research has shown that the second car (in a group of two sedans) experiences a drag reduction of around 25%, while the leading car experiences a small increase in drag. Combining the two values, the average decrease in drag is 10% per car (at 30 m/s).1 It is important to realize that drag is not the only energy consumer of a moving car, however on a highway it is by far the key energy consumer of a car (for more information about car energy consumption, I suggest Mackay). Also note that now the effect has split over two cars, but if more cars are available for platooning the decrease in drag can be significantly higher than 10% per car. But let’s assume a worst-case scenario where there are on average only two cars available on the highway. As we use less energy during platooning we can allow ourselves to use extra energy when we are not platooning. Making a short calculation we conclude that for every second of platooning 2.778 seconds can be driven without additional energy consumption.

Another interesting energy efficiency increase is the nearly perfect driving style of an autonomous car. Researchers developed an energy management system in combination with a driving cycle optimization algorithm, which was able to increase fuel efficiency up to 56%-86% for fossil-fuel cars. For plug-in hybrid cars it was even able to boost energy efficiency up to 115%.2 However, other researchers claimed to have only found decreases in fuel efficiency in the range of 30%-50%.3 As we are talking about fuel efficiency a 100% increase in fuel efficiency means a 50% decrease in energy consumption. Therefore, even if the researchers with the lower estimates turn out to be more accurate our additional energy consumption of the AI is more than compensated.

A critical note towards this blog post is that a possible increase in car use, due to automation, has not be taken into consideration. However, I do not believe this to be problematic. Even if actual efficiency increases in fuel consumption of autonomous cars will be according to the lowest scientific estimates, we will still have a decrease in energy consumption of around 12% (even without including energy efficiency increases due to platooning), which will act like a buffer for the growth in use. Furthermore, an increase in car usage will most likely mean a decrease in alternative transportation methods, thus decreasing energy consumption in these sectors. Lastly, it is speculated that with the coming of the autonomous car, the sharing economy, which has been growing over the past years, will also grow strongly within the car sector. Therefore, increasing for example the amount of carpooling while simultaneously reducing the total amount of cars needed for transportation, thus limiting actual additional energy consumption from increased usage.

In conclusion we can say that a transition to autonomous cars will indeed save us money and decrease energy consumption within the transportation sector. Thus, after all, the title was not a clickbait.

References:

1  Simulation of the aerodynamic interaction of two generic sedans moving very closely (2011). Zhu et al.

2 Forward power-train energy management modeling for assessing benefits of integrating predictive traffic data into plug-in-hybrid electric vehicles (2012). He et al.

3 Help or hindrance? The travel, energy and carbon impacts of highly automated vehicles (2016). Wadud et al.

14 thoughts on “Revolutionizing Transportation while Saving Money and Decreasing Energy Consumption

  1. Not trying to kill your buzz cause I actually think you wrote a very nice and interesting blogpost, but did you know self driving cars had their first victim two days ago? When Uber was testing an autonomous car in the US, a woman was ran over and passed away. Uber has decided to stop testing autonomous cars, at least for now. Do you think this incident is a major set back for the development of autonomous cars?

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  2. Yes I am aware of the incident that occurred. However, police have reported that the incident cannot be blamed to Uber as for now, since “the accident was hard to prevent for both a self-driving car as wells a human driver”. The National Transportation Safety Board is currently further investigating the accident, so any further discussion can only be continued after this investigation has been completed and a verdict has been made. For more information please visit: https://www.sfchronicle.com/business/article/Exclusive-Tempe-police-chief-says-early-probe-12765481.php

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  3. Interesting and informative blogpost! How long do you think that it will take before a country like the Netherlands will (completely) transition from regular cars to self-driving cars (if they would be accepted/perceived as the best choice by everyone)? And what do you think would the best way to ‘guide’ such a transition? Through, for example, economical instruments (taxes/subsidies)?

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  4. To be honest, I believe the process wil be very natural once the technology is perceived as the best choice by everyone. The main reason I believe this is because commuting is taking up a lot of time for a wide audience. Autonomous cars give the possibility to spend this time otherwise. Therefore, the technology will be appealing to many people and thus a specific guide for this transition will not be necessary per se.
    As for when a complete transition to autonomous cars will be completed; I have no idea. If it is perceived to be the best choice by everyone, people will always buy an autonomous vehicle when buying a new car. So, to figure out when a complete switch has been made, you would have to look up the total amount of cars in the Netherlands, figure out the yearly growth (of cars), and then figure out how many new cars are being sold every year. Combining this data will provide you with a rough estimate.
    Nevertheless, if you want to have a faster transition than this natural one you could implement certain taxes that make the use of older models unfavorable, therefore incentivizing more people to buy a new model sooner. In general you can think of similar strategies that have been applied to promote the use of electric cars.

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  5. I think it is an interesting development that you are describing. However, it certainly needs more research not only regarding ethical implications (Who’s fault is it when a person in an autonomous car is involved in an accident? Even this question needs to be phrased carefully…) but also research regarding environmental impacts. It would be really interesting to see a Life-Cycle-Analysis of autonomous cars or even a MCA that compares them with “normal” cars that have already been produced. If there were economic instruments that increased people’s incentive to buy new autonomous cars, I doubt that the saved energy would make up for the energy used in the extraction of the necessary resources and the production of new cars. For me, in order to actually favour this development, I would need to take into consideration the complete emissions and environmental destruction caused by bringing them to the market. I can imagine that the transition towards autonomous cars may prevent negative environmental impacts, if this development did not imply further superfluous consumption. There is hope for this to happen if the shared economy indeed continues growing, as you mentioned it.

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  6. Indeed, this development of self-driving cars sounds very promising! However, I’d like to add something to the ethical aspect Agnes already touched upon. I’m wondering how these self-driving cars will react in a no-win situation. That is a situation in which a crash is unavoidable. How will the AV make decisions in favour of one person and against another. Especially considering a landscape in which we’ll see both AV’s and non-AVs (which is the most realistic considering the transition). There are plenty of scenario’s in which we could imagine an AV having to avoid a person (or vehicle), increasing the risk of hitting another person. In a world, with only non-AVs, the outcome of this scenario is the result of an instinctive reaction of a human being, and therefore hardly discussed. However, considering programmed AVs, this discussion all of sudden becomes a lot more complicated. What would be the ‘golden mean’ in which we allow this technology to make the ethical decisions for us?
    I’m not sure whether you’ve looked into this, but I’m personally not aware of any form of consensus with regards to this ethical decision making of AVs.

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  7. I like the topic of the post, and am interested in the potential of the self-driving cars! However, I have a questions regarding one of your statements. First you write: “Welling claims that with current technologies autonomous cars use at least around 2000 Watts extra to drive around. Humans take around 20 Watts to control a car, so indeed this number seems to be out of proportion.”, where you later say: “ a typical Dutch passenger car … uses roughly 55000 Watts..”. I am a bit confused here, as at first it seems as if it increases with 10.000% (2000 on 20 Watt extra) where you later say that the increase is only 3.6%, when you use the 55000 Watts. What exactly are the differences between the two estimations? And why are they different? Do you mind elaborating a bit on this?

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  8. @auctamara The 20 Watts refers to the amount of energy the human brain uses to drive around a vehicle. This is of course not taken in when the energy consumption of a car is considered. On the other hand AV use 2000 Watts to be able to drive around, this should be taken into consideration when the energy consumption of vehicle is calculated. On average cars use 55000 Watts to move (with a human driver), thus autonomous vehicles will use 55000 + 2000 = 57000 Watts to move. Then 2000/57000 * 100 shows that an AV only use 3.6% more energy. I hope this clarifies.
    @winocarter This is indeed a very interesting ethical question that AV raise. I think you are correct stating that there is still a lively debate about this topic. However, AV (although on halt for now) are already driving around, so apparently manufacturers have already made a decision on this. Additionally, I think situations where such an event will occur are rather rare. On the other hand, accidents where humans normally would be able to respond fast enough (which happens often) will now be preventable with AV, which I believe heavily outweighs the rare event you described. Still, I am no expert on this topic, so I am afraid I cannot provide you with a ‘golden mean’.

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  9. Julian,

    Just a brief question on this calculation: “Making a short calculation we conclude that for every second of platooning 2.778 seconds can be driven without additional energy consumption.” Just above you wrote that for two cars platooning the decrease in drag is ~10% per car at highway speed. How did you calculate the 2.778 seconds gained by just one second of platooning?

    A more general comment pertains to the human side of self-driving cars: AFAIK the ‘driver’ still needs to keep their attention to the road for safety’s sake (and arguably for the sorts of issues that Wino brings up, involving dilemma’s we don’t want a computer to decide upon). I’m not sure of such driver attention is only needed in the pre-final stage of autonomous vehicles (which you alluded to when you commented that “Autonomous cars give the possibility to spend this [driving] time otherwise”), but it has been pointed out that humans are notoriously bad at keeping their attention to what is basically a non-task: checking if everything is ok, when in all likelihood everything will be ok 99% of the time. This is too boring for the human mind. Then there’s the issue of people trusting the self-driving car, though that might be a matter of getting used to. I could imagine a situation where young folks would predominantly drive AV’s, whereas older folks would not trust the new technology enough and would continue to drive themselves, giving rise to other challenges.

    Finally, you are quite optimistic that the gain in energy efficiency won’t be ‘eaten up’ by an increase in car use. There are however many historical examples where increased efficiency has been ‘eaten up’ by increased consumption. E.g. the decrease in alternative transportation methods that you allude to could backfire in causing more private car use as opposed to public transportation. Also, I don’t directly see why AV’s would make people more inclined to carpool.

    Still, I think self-driving cars are very cool! Not sure that I’d trust them, but eh, that’s probably the age gap.

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  10. @auclimate
    It seems like you have made three points, so let’s discuss them one by one.
    1. As for the calculation, I’ve made use of the following: 10% (decrease in energy consumption per car because of platooning)/ 3.6% (increase in energy consumption due to AI in AV) = 2.7778 seconds. This is a rough estimate and no absolute proof, but it does show the effects of one of the increases in efficiency.
    2. There are various levels of autonomous driving. Current models still indeed need the attention of the driver. However, manufacturers are already very close to achieving completely autonomous cars (where no driver attention is needed). On the matter of who will be in these cars, I disagree with you. Initially, indeed predominantly younger people will make use of the AV. However, similarly to how smart phones were first predominantly used among young people and are now widespread through all age groups, AV will common used way of transportation throughout all ages in society. There is no proof of this, but smartphones were a revolutionary development within the communication sector, which eventually made smartphones a necessity. Similarly AV will be a revolutionary development but only now in the transportation sector.
    3. I’m indeed optimistic about the increase in energy efficiency not being eaten up. To answer your questions appropriately I would like to speak to you in person (I will give a short recap to other readers afterwards).

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  11. Julian,

    That calculation doesn’t sound right, which is clear just from checking the units.

    What you could deduce from these numbers is that the energy consumption for a platooning AV is 10-3.6=6.4% less than for a non-platooning non-AV car (assuming a 10% decrease in energy consumption per car because of platooning and a 3.6% increase in energy consumption due to AI in AV).

    If you were to look at just the effect of platooning, since this offers a 10% energy savings each second of platooning would provide 0.1 second of driving without extra energy consumption (or alternatively 0.064 sec if you were to compare it to a car without AI).

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  12. @auclimate You make a calculation for how long one must drive to save up enough energy to then drive “without” using energy. However, in the article I was referring to how many seconds one can drive without using additional energy compared to a normal car. Let’s give a numeric example to make it more clear.
    We have an imaginary normal car (no AI) that uses 100 Watts/s.
    According to the blogpost, in the city this car will use 100 Watts/s and while platooning only 90 Watt/s. However, now we introduce the AI part, which will then make the energy consumption 103.6 Watt/s and 93.6 Watt/s respectively.
    So let’s say we platoon for one second. This means that we use 93.6 Watts and thus save 6,4 Watts compared to a normal car. However, in the city we use more energy than a normal car. Therefore, the question becomes how long will this 6,4 Watts, which we saved during platooning, last in the city, where we use 3,6 Watts/s more than a normal car. Thus the calculation becomes: 6,4/3,6 = 1,7778 seconds. We are not done yet, as we have not yet included the 1 second of driving time while platooning. Therefore, we can drive 1,7778 + 1 = 2,7778 seconds while not using additional energy. I hope this clarifies!

    As promised, I also planned to come back at a discussion point you addressed earlier. To answer this question I highly recommend “Help or hindrance? The travel, energy and carbon impacts of highly automated vehicles” (Wadud et al. 2016) . Main point from Wadud et al.: Varying scenarios can either lead to an increase or decrease of the total energy consumption. Thus depending if you are pessimist or optimist you can make a case for both scenarios!

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  13. Today I was reminded of this blog post when I saw a parking space at the station Ede-Wageningen dedicated to a so-called WEpod car (https://www.tudelft.nl/en/ceg/research/stories-of-science/wepod/). It is an autonomous car for six people that was supposed to transport people between the station and the campus of the Wageningen University. Maybe you have heard of this experiment already in 2005 when it was supposed to first get on the streets. Although they concluded that it is not yet ready for use, it is maybe nice to know that there is being research done on AI car systems by a nearby university research institute.

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