What is the most energy efficient form of transport?
Posted by Alex Barrett on 12 April 2017 at 1:40 pm
Many of you will be planning a long journey this bank holiday weekend and it’s worth considering which method of transport will be the most environmentally friendly. As you are probably aware, some transport methods are much more energy intensive than others and some have higher greenhouse gas emissions. Let’s pick a long journey, so that taking a plane isn’t an unreasonable option. We’ll start in London, and assume that we would be flying from Heathrow, the largest UK airport. We’ll travel to Newcastle.
By car, this is a journey of around 480 km (300 miles).
There are various online tools for calculating carbon footprints , so we’ll use tonnes of CO2 equivalent (CO2e) to measure the impact of the different transport methods. A small car burning petrol will emit 95 kg CO2e while driving from London to Newcastle. The same journey in a diesel car emits 100 kg CO2e. For every additional 45 kilograms in your vehicle, fuel economy decreases by one to two percent, so these figures will go up as the number of passengers in the car increases, but not as rapidly as adding extra passengers to the plane.
The same calculator suggests that the same journey by plane, around 400 km, will produce 134 kg CO2e for each passenger. So the cost of the plane is much higher than a petrol fuelled car, but only slightly higher than one using diesel. Larger, or less fuel efficient cars will narrow this gap somewhat.
So far so good, but this isn’t the whole story. When driving you can go straight to your destination, but public transport has a set route, or destination. Airports are not evenly distributed across the UK, with far more located around London and the Midlands than in the north of England. Unless you live right underneath an airport, then you will probably need to take a bus or taxi in order to catch your flight, and another at the far end. Depending on the distance you need to travel, this could considerably increase the carbon footprint of the flight.
How about taking the train? Like a plane, the carbon footprint is split between more people so it’s a more efficient means of transportation. Virgin trains estimate that the distance from Kings Cross to Newcastle is 245 miles. Traveling this distance on one of their trains would emit 20.56 kg CO2e but this does not take into account the carbon required to get across London on the underground. For comparison, Virgin trains estimate that the same journey by car would release 44.48 kg CO2, while going by plane would release 46.26 kg CO2e . Another calculator  estimates that traveling 480 km by coach emits 10 kg of CO2e compared to 40 kg CO2e for rail, or 120 kg of CO2e in a car or taxi.
Getting the coach or the train is looking like our best bet, while a car is only slightly better than a plane. This is unsurprising as public transport is generally more energy efficient than private vehicles. Larger vehicles have higher emissions, but they are split between more people. A Boeing 747-400 of the type operated by British Airways has a capacity of 345 passengers, while an electric pendolino train can carry more than 600 people. Consequently, the energy intensive plane gives us quite a similar CO2 emission per passenger to the car and the train is much better per person. Coaches can transport fewer people, but have lower overall emissions to split between their passengers.
However, this does assume that a vehicle is full. Airlines generally try to fill their flights to capacity, but the same isn’t always true of trains and busses. At some times of day they are packed. At others they might be largely empty and but will carry on running regardless. Most of the time, however, public transportation will be the more energy efficient option than taking a car. It might not be as convenient, but it will be much better for the environment.References
Image credit: Highways England via Flickr
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