One of the worst forms of transport for CO2 emissions is domestic and short haul flying. Research from the BBC via BEIS/Defra in 2019 revealed that flights on routes of 700km (438 miles) or less produce 29% more CO2 per person per km or mile travelled than longer flights. But self-driving battery-electric vehicles could drastically reduce the need for this form of transport, or even render it obsolete, and slash emissions in the process.
The BBC research argued that a domestic flight would produce 254 g/km of CO2 per passenger, compared to 195 g/km for long haul. In contrast, even a diesel car emits just 171 g/km on average. Stick a family of four in it and that drops to 43 g/km. People don’t choose their transportation based on carbon footprint that much yet, though, even if that is changing. The reason short haul flights are popular is speed.
A flight from London to Edinburgh takes around 1.5 hours. Even if you factor in another 1.5 hours to check in, an hour to get to the airport, and another hour at the end to reach your final destination, that is still only 5 hours in total. Driving it yourself, it would take 7.5-8 hours if you’re lucky, and you’d probably have to stop halfway for a break. You would also be tired when you arrived, so this would not be a good solution if you plan to spend a day in meetings once you reach your destination.
Of course, trains can be extremely low carbon, but they are generally slower than flying. Going back to that BBC report, domestic rail is 41 g/km per passenger and the Eurostar from London to Paris an incredible 6g/km. But in the UK and in other parts of the world, trains are an expensive form of transport – often more than flying – and you still have the inconvenience of having to go to a station to take a train. That probably won’t take as long as going to an airport, but it can add a couple of hours to the trip. So the 4.5-hour train journey from London to Edinburgh might take about the same time door-to-door as driving, and a few hours more than flying.
This is where self-driving electric cars could dramatically alter the balance. In theory, a BEV emits 0 g/km, although that entails using entirely renewable energy sources. Let’s say we’re sticking with the UK and that London to Edinburgh journey but using the average UK grid balance. Last year, the UK national grid averaged 181g of CO2 per kWh – its greenest year yet. Most BEVs manage at least 3 miles per kWh, and some more than 4 miles per kWh. But let’s assume the worst and say 3. That gives us 60g of CO2 per mile, or 37.5 g/km. Put four people in the car, and it drops to 9.4 g/km per person – in other words, much better than UK domestic rail or coach travel, and getting close to the electrified Eurostar.
Read more: Forbes