Self-driving cars and the environment

With the advent of any large change in technology, it’s important to consider the potential environmental impact. What are the environmental costs? What are the benefits? Is this change a positive one for the world we live in?

Self-driving cars, or CAVs, are approaching our roads. We’re going to take a look at the environmental impact of self-driving cars, and at some of the benefits.

Powered by electricity

Most CAVs are expected to be powered by electricity, rather than fossil fuels. After all, the autonomous systems will need electricity to work, so it makes sense to power the entire car using the same method.

Electric cars do still have an impact on the environment, of course. The electricity used to power them isn’t always produced by clean means. However, Transport & Environment reports that electric cars produce much lower carbon emissions than cars powered by fossil fuels: ‘petrol and diesel cars emit almost 3 times more CO2 than the average EU electric car’. This conclusion takes the production of electricity and batteries into account.

In 2020, the UK generated more electricity through renewable sources than from burning fossil fuels, and the trend towards renewables is likely to continue. This means that existing electric vehicles are likely to keep getting cleaner and more sustainable as time goes by, whereas a vehicle that was created to run on fossil fuels will always rely on fossil fuels.

Electric motors are also more efficient than fuel-burning combustion engines. And efficiency is important, as we’re about to discuss.

Energy-saving efficiency

As mentioned above, electric motors are efficient. Internal combustion engines waste most of the energy from the fuel as noise and heat; this is why petrol-powered cars are so loud. Electric cars are naturally much quieter because most of the electricity is converted into movement rather than noise, although, for the safety of pedestrians, electric vehicles can be designed to make noise under certain circumstances.

Self-driving cars can also move more efficiently than cars operated by a human. A study by Zhu et al. found that vehicles in adaptive cruise control mode, which partly automates driving, consumed about 5 to 7% less fuel than vehicles driven without adaptive cruise control. With higher levels of automation, we might expect to see lower levels of fuel consumption, and therefore greener journeys.

The US Department of Energy’s Oak Ridge National Laboratory found in a 2017 study that ‘aggressive driving’, such as speeding and sudden braking, can increase fuel consumption dramatically. Aggressive driving is generally a result of human frustration, so it’s unlikely to be a large problem for autonomous vehicles, although of course autonomous vehicles can still brake suddenly in emergencies.

When multiple autonomous vehicles travel together, the need to accelerate or brake suddenly is reduced even further. As we mentioned in our article on 5G applications, a convoy of autonomous vehicles could communicate with each other in order to accelerate and brake simultaneously, with the front vehicle setting the pace. In this case, each vehicle knows exactly what the one in front is doing, meaning that there’s no need to brake suddenly in response to the vehicle in front unexpectedly slowing down. Acceleration and braking can be a smoother process, and therefore a more fuel-efficient one.

The problems that remain

Electric autonomous vehicles don’t solve every environmental problem caused by cars. For example, tyres send rubber particles into the air as they wear down on roads, contributing to air pollution. This problem would remain even if all cars on the road became electric. In fact, the Times reports that electric vehicles with large, heavy batteries can release more particles from tyre and road wear than petrol or diesel cars.

Replacing traditional petrol-powered cars with electric cars would make a positive difference to CO2 pollution, but it’s also important to carry out research into the issues that electric vehicles don’t solve. In late 2020, Autocar reported on research by Stanford University and the SLAC National Accelerator Laboratory into creating lighter batteries for electric vehicles. The Tyre Collective, meanwhile, is working on a device that captures airborne particles from tyres as they wear down.

The road to more sustainable transport is a winding one. There are many problems to be solved and many aspects to be considered; for example, it’s important not to focus solely on road vehicles and neglect investment in trains. But, if we see some of today’s human-driven, petrol-powered vehicles replaced with self-driving electric cars, it’s likely to have a positive impact overall.

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