At the current pace, autonomous vehicles (AVs) – or self-driving cars – are likely to take over the global transportation sector. Despite this field being still very much in its infancy, there is no doubt among experts that an increasing amount of people will shift away from vehicles operating on fossil fuels to semi or fully autonomous vehicles once technologies take over the commercial market. Despite the many advantages that come with owning a driverless car, there are societal and environmental implications that cannot be ignored. We examine the pros and cons of self-driving cars to understand if they can represent a solution to the global transition to carbon neutrality.

It was in 1939 that the world heard the term ‘self-driving car’ for the first time, as General Motors – the American automotive manufacturing corporation – presented the first-ever autonomous vehicle (AV) at the World’s Fair. Humans have spent the following decades building on that idea, expanding research and investment in order to improve this technology. However, the real breakthrough happened just recently. By the mid-2010s, the autonomous car industry was in full swing, with major car companies like Ford, Mercedes-Benz, and BMW as well as American car service company Uber starting to invest millions of dollars in developing new self-driving technologies. As of today, several fairly successful AV formats are being developed and slowly launched on the market, from Google’s fully autonomous driving vehicles to Tesla’s driver-assisted cars. 

As the name suggests, self-driving cars do not require a person to mutually control them, allowing a computer system to take over all driving responsibilities. An increasing number of experts agree that a future where the transportation sector is dominated by AVs on the roads is a matter of when, not if. The several benefits associated with driverless cars have sparked research and innovation within the field as well as demand among consumers, who are attracted by the increased comfort and reduced stress that come with owning such a vehicle.

As the world is considering all possible ways to slow down the imminent and potentially catastrophic consequences of global warming, the automobile industry is a key part of the equation. Being still heavily reliant on fossil fuels, this sector alone accounts for up to 45% of global oil demand and consequently for a staggering amount of emissions. In the US, transportation is the leading contributor to greenhouse gas emissions, with nearly  30% deriving from gasoline and diesel-powered vehicles. A similar trend can be seen in Europe, with nearly one-quarter of GHG emissions coming from the fuel for transportation. 

As the car industry is about to undergo a massive revolution, experts are starting to evaluate its societal and environmental implications. While most autonomous vehicles have electric engines, this does not necessarily mean that their footprint is null. We explore the main pros and cons of self-driving cars to understand the potential impact of a fully autonomous future. 

How Much Do Self-Driving Cars Emit?

As we know, the biggest environmental issue related to gas engine cars has to do with the emissions they generate. But what about self-driving cars?

Most AVs developed today have highly efficient and extremely advanced electric engines that offer huge opportunities for emission savings. This is because they generate very little emissions over their lifetime when compared to conventional vehicles with internal combustion engines operating on fossil fuel. Yet, while tailpipe emissions from electric vehicles are zero, how much AVs actually pollutes depend on where they get their electricity from. If batteries of Autonomous Electric Vehicles (A-EVs) are charged by clean energy sources, their environmental impact is minimal. Yet, not all countries get their power from renewables. In several US countries, for example, most of it is still generated by coal plants, making driving EVs less sustainable than in those relying for the most part on green energy sources.  

Undoubtedly, a rise in electric vehicles coupled with the global expansion of renewables will lead to a significant decrease in transport-related emissions. And looking at experts’ forecasts, this might happen sooner than we expect. Investment bank UBS predicts that by 2025, 20% of all new cars sold globally will be electric. Furthermore, the convergence of electric and autonomous vehicles is perfectly aligned, as it is much easier for computers to drive cars with electric propulsion systems. As for renewable energy, clean sources such as hydroelectric, solar, wind, biomass, and geothermal are on the rise worldwide and in 2021 alone, they generated a combined 38% of the world’s electricity

How Efficient Are Autonomous Vehicles?

AVs have a massive potential to curb emissions simply because they operate much more efficiently than conventional vehicles. The amount of gas burned by conventional vehicles is affected by the driving style. Typically, more battery is consumed when repeated braking or continuous shifts from low to high speed occurs, for example during traffic congestion. 

The highly advanced computers controlling autonomous cars that allow for a much smoother driving experience – with speed and acceleration under control and thus a more efficient fuel use – make them a more environmentally friendly alternative in terms of electricity consumed and overall air pollution generated. According to estimates by the ​​US Department of Energy, this driving style – which industry experts refer to as automated ‘eco-driving’ – can reduce fuel consumption by 15 to 20%.

While the innovative systems running AVs make them substantially more efficient than conventional vehicles, powering the heavy computational needs for a large number of devices – from cameras and radars to different sensors and the engine itself – requires great amounts of energy. The data collected by these different apparatuses need to be combined, sorted, and sent to the computers in the form of instructions and all this sparks huge electricity demand. A report published by the University of Michigan Center for Sustainable Systems highlighted that AV systems could increase vehicle primary energy use and GHG emissions by 3% to 20% due to more power consumption, weight, drag, and data transmission. Because of these massive power requirements, making self-driving cars electric makes even more sense. Indeed, running such energy-intensive computers on combustion-engine vehicles would only increase fuel consumption tremendously. 

All things considered, this downside to self-driving cars does not make these types of vehicles worse than conventional cars, as the overall emissions they emit are still far lower than those generated by fossil fuel-powered automobiles. Furthermore, while AV technologies are still in their infancy, experts agree that continuous research and development will significantly improve these divides in the coming years, making them smaller, more capable and, most importantly, more energy-efficient. 

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The Impact of Self-Driving Cars on Traffic

Another important point to take into consideration when discussing the pros and cons of self-driving cars has to do with their capacity to reduce traffic congestion. Traffic not only increases fuel consumption but leads to a rise in carbon dioxide emissions, outdoor pollution, and an increased exposure time of the passengers to the highly toxic chemicals released into the air. 

AVs can intelligently interact with each other and the road infrastructure. The instructions that these vehicles receive from different computers allow for a smarter usage of the street through better route calculation and efficient road occupancy, subsequently reducing fuel consumption and cutting down on emissions. Closely interconnected cars also tend to drive closely together, forming a train on the road with a minimum safety distance. This phenomenon – known as ‘platooning’ – leads to the enhancement of safety, mobility, and energy savings. Depending on the number of vehicles, their separation, and characteristics, studies suggest that platooning can reduce the energy consumption from 3% up to 25%.  

Overall, when cars interact, traffic moves more steadily, resulting in less congestion and a reduction in energy use of up to 4%. Furthermore, some experts highlight the fact that a smoother traffic flow could encourage people who work downtown to move to the city’s outskirts or rural areas as their commute time would drastically improve. 

How Do Self-Driving Cars Affect Drivers’ Habits?

One last aspect of AVs is that experts often point out that switching to self-driving cars on a large scale would contribute to a reduced amount of vehicles on the road. For example, families that often have more than one automobile could potentially rely on a single autonomous one to fit all the necessities. A driverless car could indeed drop both parents at work, kids at school, and drive back home independently. Some reports estimate that by 2030, there will be more than 11 million shared driverless vehicles operating on the roads globally, serving an average of 64 users per vehicle.

While this is encouraging, an increasing number of studies also point out that self-driving cars will impact drivers’ habits in other, not necessarily more environmentally friendly ways. For instance, AVs allow people to send their cars on ‘zero-occupancy’ trips: instead of paying for parking – for example – one could decide to send the car back home while at work, only to summon it at the end of the day. While this is certainly convenient, it is not necessarily sustainable from an environmental point of view.

Another point that researchers often make is that since sitting in a car as a passenger is much less stressful than driving, people might be willing to undertake longer trips. A 2019 survey conducted in California, for example, reported that 21%-35% of autonomous vehicles owners undertake more long-distance travel – especially on weekends – partially because of the automated operating systems.Pros and Cons of Self-Driving Cars

Figure 1: Driving Habits of Owners of Partially Automated Vehicles, 2019 Survey

Similarly, a study conducted in the same year in Sacramento, California, found that households receiving access to a chauffeur service – which the researchers compared to having access to a driverless vehicle – travelled nearly 60% more than usual. They also shifted away from mass transit, ride hailing, biking, and walking trips – which dropped by 70%, 55%, 38%, and 10%, respectively – toward more car use. 

These trends were again confirmed in a 2021 survey conducted on people who drive partially automated vehicles – where autopilots can assist with driving tasks – although not fully taking over. Over the course of a year, researchers found that owners of such cars drove an average of nearly 5,000 miles (approximately 8,000 kilometres) more than those who owned conventional vehicles, admitting to be more willing to sit in traffic and take more long-distance trips because of the increased comfort and reduced stress that these cars allow.

EO’s Position: When examining the pros and cons of self-driving cars, a mixed picture emerges. While the advantages of AVs in reducing traffic congestion and emissions are clear, the comfort they offer leads to new, not always environmentally friendly driving habits. A future with more automated vehicles powered by clean energy coupled with state fuel taxes, a large-scale promotion of shared vehicles, and charges for the number of vehicle miles that drivers travel is undoubtedly going to massively improve the footprint of the transportation sector. However, this requires much more time and innovation in the AV sector before it can turn into reality.