New research by scientists at the University of Leeds, University of Washington and Oak Ridge National Laboratory highlights the possibility the introduction of driverless vehicles could intensify car use, reducing or even eliminating promised energy savings and environmental benefits.
Development of autonomous driving systems has accelerated rapidly since the unveiling of Google’s driverless car in 2012, and energy efficiency due to improved traffic flow has been touted as one of the technology’s key advantages.
Dr Wadud said: “There is no doubt that vehicle automation offers several efficiency benefits, but if you can work, relax and even hold a meeting in your car that changes how you use it.
“That, in turn, may change the transport equation and the energy and environmental impact of road transport.”
The study uses analysis of self-driving technology combined with data on car and truck use, driver licenses, and vehicle running costs to model the impact on energy demand of various levels of automation on US roads by 2050.
It identifies several efficiency benefits of self-driving cars and predicts ranges of likely energy impacts, depending on the extent of adoption of the technology and other factors:
- More efficient computer-directed driving styles (0% to 20% reduction in energy use)
- Improved traffic flow and reduced jams because of coordination between vehicles (0% to 4% reduction)
- “Platooning” of automated vehicles driving very close together to create aerodynamic savings (4% to 25% reduction)
- Reduced crash risks mean that cars can be lighter (5% to 23% reduction)
- Less emphasis from car buyers on high performance (5% to 23% reduction).
But the study also predicts that the very attractiveness of self-driving technology could reduce or even outweigh the efficiency gains.
It estimates a 5% to 60% increase in car energy consumption due to people choosing to use highly automated cars in situations where they would have previously taken alternative transport (e.g. trains or planes).
Dr Wadud said: “When you make a decision about transport, you don’t just think about the out-of-pocket costs of the train ticket or the car’s petrol; you also take into account non-financial costs.
“Car owners might choose to travel by train to relatively distant business meetings because the train allows them to work and relax.
“The need to drive is part of the cost of choosing the car, just as standing on a cold platform is part of the cost of the train. If you can relax in your car as it safely drives itself to a meeting in another city that changes the whole equation.”