Planes, Trains or Automobiles? – Carbon Emissions Compared for Different Forms of Transport

Which forms of transport have the least carbon emissions? I previously wrote about the carbon emissions of travelling from Buenos Aires to London via cargo ship vs. by flying. One of our readers suggested comparing other forms of transport so, hey presto – here’s a chart. And the results aren’t necessarily what you would have expected.

What the graph below is showing is ‘greenhouse gas equivalent emissions in grams per passenger kilometre’. Sounds a bit technical, I know, but it’s basically a measure of how much you contribute to climate change when you use choose a particular form of transport.

travelemissionschart2 Planes, Trains or Automobiles?   Carbon Emissions Compared for Different Forms of Transport

Transport Carbon Emissions (Equivalent) Chart


What does ‘Greenhouse Gas Equivalent’ mean?
Well, engines don’t just produce carbon dioxide – they also produce nitrous oxide and methane and these are both greenhouse gases. Basically, a greenhouse gas equivalent amount of CO2 has been increased to take account of the impact on climate change that these other gas emissions have. Why just measure CO2?
Emissions from Flying – Not a Simple Calculation
The emissions from flying are complex to calculate. Half of the weight of a 747 at takeoff is its fuel and so it gets lighter as it flies along. Sometimes it refuels half way. Taking off and landing use more fuel than cruising. Number of passengers is critical. Luggage needs to be taken account of. It’s also important to remember that greenhouse gases emitted at altitude can have a much larger impact on global warming (in the region of double). It’s not possible to calculate this as there’s no conclusive data and it depends on what altitude you’re at, so I’ve not adjusted the figures. Basically, if you want to calculate and/or offset your emissions from flying, you should use a carbon calculator.

Thoughts about (100%) Electric Cars:
This is an interesting one. Lots of ‘green car’ website and electric car manufacturers claim that electric cars as ‘zero emissions’. Electric cars don’t have any exhaust pipe emissions, so they’re great for improving air quality in cities. However, the electricity used to charge the car will come from a mixture of fossil fuels, nuclear and renewables, depending on what country you’re in. In the UK, an electric car has emissions of 75g CO2/km which is lower than any other car in production according to the EcoMetrica report. If you plug your car into the mains in France, you’re only producing 10% of the emissions you’d be producing if you charged the same car in China. The difference here is the high proportion of nuclear energy in France compared to the coal used in China. If you buy your own solar panels, then you genuinely have no emissions from fuel, only from manufacturing the car and batteries (and solar panels!). Another option is to sign up to a renewable electricity supplier or plan, then your car’s electricity consumption will be offset, which is good.

There are mixed reports about the efficiency of electric cars. Some argue that they’re efficient because of the few moving parts and others argue they’re inefficient because of distribution losses through powerlines. The important thing is they have low emissions, are much cheaper to run and can be entirely run on renewable energy.

Cars have impacts during production, too, and electric cars have a signficant impact from the batteries that they use. However, a report published by Ricardo finds that “electric and hybrid cars have a higher carbon footprint during production than conventional vehicles, but still offer a lower footprint over the full life cycle”.

Basically, renewable energy is the future. It has to be, it’s renewable. That means electric cars, electric trains and bicycles are the future. That’s why Frog Design has been working on this amazing electric bike concept. I love the way the form rejects the icon of the internal combustion engine by having a negative space where the combustion engine would normally appear. Nice. That’s also why I recently posted 44 of the latest electric cars in the form of Top Trumps cards.

Having said all that, there’s nothing greener than getting on your bicycle and bicycles, like electric cars, have seen a big surge in popularity in the last few years.

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Frog Electric Bike, Copyright Frog Design

Notes about Data:
The chart above is based on 2011 UK data from DEFRA, except the emissions from electric cars which are taken from a report by EcoMetrica, as this data data was absent from the DEFRA data.

2011 DEFRA report with assumptions where most of the data came from.
EcoMetrica report about emissions of electric cars.
Ricardo report about lifecycle impacts of electric cars vs. petrol.