Driverless Cars: More Gas, More Pollution?

The introduction of driverless cars has been touted as a potential solution to the problem of vehicle emissions, which are a major contributor to climate change. While autonomous vehicles have the potential to reduce greenhouse gas emissions, there are also several factors that could lead to an increase in gas pollution. For example, a shift towards autonomous vehicles could lead to an increase in the number of cars on the road if people opt for personal transport over public transit. Additionally, the increased weight of the extra hardware required for self-driving cars may lead to higher energy demands.

Self-driving cars' extra hardware and weight increase energy demands

The shift towards self-driving cars may increase a vehicle's energy demands due to the extra hardware required. Self-driving cars are equipped with advanced cameras, lasers, and various other sensors to navigate complex environments, adding weight and reducing aerodynamic efficiency. This extra hardware also increases computational demands, requiring powerful computers to process the vast amounts of data generated, which in turn, increases power consumption.

A University of Michigan study found that the additional hardware and computing power required for self-driving cars resulted in a 2.8 to 4.0% increase in onboard power consumption. This extra power is needed to run the computers and sensors, as well as to compensate for the increased weight of the vehicle. The weight of the extra hardware adds more inertia to the vehicle, demanding more energy to accelerate and decelerate.

The placement of this hardware is also a factor. Adding equipment to the exterior of the vehicle, rather than integrating it into the frame, further reduces aerodynamic efficiency, increasing drag and, thus, energy consumption. Additionally, the computational demands of self-driving cars are expected to increase with the development of higher-resolution maps and the transition to 5G networks, which could boost power consumption by a third or more.

The energy demands of self-driving cars are a significant concern, as they have the potential to negate the environmental benefits of autonomous vehicles. The increased power consumption leads to higher fuel usage or reduced range in electric vehicles. This problem is particularly prominent in larger vehicles with substantial sensor arrays, such as the Waymo Pacifica minivan test bed, which showed a 5% increase in net energy consumption due to the added weight and aerodynamic drag of its rooftop sensors.

To address these challenges, manufacturers are working on improving hardware efficiency and reducing power consumption. For example, chipmakers like Nvidia are developing specialised processors that deliver more computing power while consuming less energy. However, there is still a long way to go to make self-driving cars energy efficient, and further advancements in hardware and computational efficiency are necessary to keep computing-related emissions in check.

Driverless cars may encourage more driving and emissions

While driverless cars are often touted as a solution to road safety and congestion issues, there are concerns that they may also lead to an increase in driving and emissions. This is because the convenience and comfort of autonomous vehicles may encourage longer trips and a preference for personal transport over public transit.

Increased Driving

Research suggests that the stress-free experience of riding in a driverless car may make people more willing to sit through longer trips and endure more traffic. The promise of a comfortable commute could even incentivize some people to move farther away from their workplaces, contributing to suburban sprawl. Additionally, the ability to send cars on "zero-occupancy" trips, such as running errands without passengers, could effectively double the number of miles driven.

Preference for Personal Transport

The convenience and door-to-door service offered by driverless cars may make them an alluring option for most people, especially in cities with limited public transportation, biking, or walking infrastructure. This shift towards personal transport could result in a decrease in public transit ridership, leading to more cars on the road and higher emissions.

Energy Demands of Technology

The advanced technology required for self-driving cars, such as cameras, lasers, and sensors, also contributes to increased energy demands. The added hardware means more weight, which increases the amount of energy needed to move the vehicle. Additionally, the computational capacity needed to process the vast amounts of data generated by these sensors can further increase energy consumption.

Policy Approaches

To mitigate the potential negative impacts of driverless cars on the environment, policymakers can take several approaches. One suggestion is to require all autonomous vehicles to use zero-emission technology, such as electric power. However, this must be coupled with a transition to a 100% carbon-free electricity system to truly reduce emissions.

Another approach is to implement user fees or charges based on the number of vehicle miles traveled, location, time of day, congestion levels, vehicle occupancy, and type. These fees could encourage travelers to consider more efficient modes of transportation, such as public transit, walking, or bicycling. Additionally, promoting shared fleets of automated vehicles, similar to ride-sharing services like Uber and Lyft, could help reduce the number of cars on the road and lower emissions.

People may live further from work, increasing commute distances

The introduction of driverless cars may lead to an increase in gas pollution if people start living further from their workplaces. This is because longer commutes would result in higher fuel consumption and, consequently, greater emissions.

Currently, in the US, 75% of people drive to work, with the average American travelling 16 miles each way to their office. This trend of long-distance commuting is likely to be exacerbated by the advent of self-driving cars, which offer the convenience of a hands-free commute where people can work, watch videos, or relax. As a result, individuals may be more willing to tolerate longer commutes, leading to an increase in the distance between residential and commercial areas.

The appeal of a comfortable and productive journey may also encourage people who previously used public transportation or shared rides to switch to driverless cars, further contributing to longer commutes. Additionally, the convenience of driverless cars may make it more feasible for people to live in distant suburbs or exurbs, as they can utilise their commute time productively or enjoyably.

Furthermore, the increased use of driverless cars could lead to a rise in the number of vehicles on the road. This is because the ease and flexibility of autonomous vehicles may attract new drivers who usually do not drive or cannot drive due to age or disability. The influx of new drivers on the road would contribute to longer commutes and increased congestion, resulting in higher fuel consumption and emissions.

While the impact of driverless cars on commuting distances is speculative, it is a significant factor to consider in the broader discussion of the potential environmental impact of this technology. The increased fuel use and emissions associated with longer commutes would counteract the potential benefits of reduced congestion and improved routing efficiency that driverless cars may offer.

Cheaper driverless cars may increase overall car usage

The cost of driverless cars is a significant factor in their adoption and the subsequent impact on the environment. If driverless cars are made cheaper, it could increase overall car usage, which may lead to more gas pollution.

The high cost of car transport is due to several factors, including fuel, tolls, depreciation, and maintenance. In most Western nations, the average car owner spends about a third of their net wage on their car. As a result, cost is the most important factor for car sales. Electric vehicles, for example, are less popular than gasoline-powered cars despite being more environmentally friendly because they are more expensive.

Driverless cars are predicted to be three to four times the average cost of a new car in the US, excluding the vehicle itself. The high cost of this technology is due to the advanced hardware required, such as cameras, lasers, and sensors, which add weight and reduce energy efficiency. However, prices are expected to drop over time, and companies like German engineering firm Robert Bosch are working on developing "affordable mass-market" driverless technology.

If driverless cars become significantly more affordable, it could lead to an increase in car usage and a subsequent rise in gas pollution. This is because cheaper cars would make vehicle ownership more accessible to a larger portion of the population. Additionally, as mentioned earlier, people may be more inclined to opt for car travel over alternative modes of transportation if the cost of driverless cars becomes more competitive.

Furthermore, the convenience and comfort of driverless cars may encourage longer trips and a greater willingness to sit in traffic. People may also be more inclined to send their cars on "`zero-occupancy` trips, such as sending the car home after parking downtown instead of paying for parking. These factors would contribute to increased vehicle miles traveled and, consequently, higher gas pollution.

To mitigate these potential negative impacts, regulators and communities should implement measures to make car travel less appealing. This could include putting a price on car travel, especially for zero-occupancy trips, or adopting user fees or charges based on vehicle miles traveled. Additionally, promoting shared fleets of automated vehicles, similar to ride-sharing services like Uber and Lyft, could help reduce the number of cars needed and, consequently, lower emissions.

Electric driverless cars rely on fossil fuels for electricity

Electric driverless cars may not be as eco-friendly as they seem, as they rely on electricity that, in many places, is still generated using fossil fuels. In 2014, 19.1% of the UK's electricity was produced from renewable sources, while 30% came from gas and 30% from coal. This means that electric vehicles are simply moving the combustion of fossil fuels from inside the car to another location, rather than eliminating it.

The environmental benefits of electric cars are dependent on how the electricity they use is generated. While they can reduce dangerous nitrogen oxide and particulate matter emissions in urban areas, they do not address the broader issue of greenhouse gas emissions if the electricity they use is still generated from fossil fuels.

Additionally, electric driverless cars face challenges related to their increased power demands. The advanced hardware and computational capacity required for self-driving technology add weight and increase power consumption. This can lead to higher energy demands compared to traditional vehicles, which may offset any potential emissions reductions.

However, the shift towards electric and driverless vehicles is expected to reduce the number of individually-owned cars and increase the use of shared mobility services. This could result in a net decrease in fuel demand, as predicted by BP, which forecasts a dip in fuel demand from the world's car fleet by 2040.

Furthermore, the increased usage intensity of electric cars, which are expected to be driven about two and a half times more than internal combustion cars, can accelerate the adoption of electric vehicles and contribute to a decline in fossil fuel demand. The combination of shared mobility and electric engines may lead to a significant reduction in fuel use and a shift towards a more sustainable transportation system.

Frequently asked questions