How green is my aircraft?

As I have mentioned before, this is a busy time of year for me. A lot of my time is spent flying places. Well, actually, the bulk of the time is spent waiting for a plane or sitting on the thing waiting for it to go somewhere. In other words, there is lots of “idle” time. I spend that time in various ways. Firstly, there is eating and drinking – first rule of business travel is “eat when food presents itself – you never know where the next meal is coming from”. I spend some time working and I enjoy reading. [But why can I not use my Kindle except when the seatbelt sign is off? Does anyone know?] I also spend my time thinking.

A recent train of thought was “just how environmentally unfriendly is all this flying?” …

We are always told that it is not green to fly – aircraft engines contribute massively to carbon dioxide dumped into the atmosphere. I have no doubt that this is true. I am certain that those who deny the existence and significance man-made climate change are deluding themselves. However, what I wanted to know is just how bad is flying, from an environmental perspective?

What I wanted was some figures that I could understand and relate to. I had seen reports of how many tons of carbon dioxide are emitted, but the numbers did not make much sense to me. Then I found some statistics that gave me a basis for understanding. I was glancing at the in-flight magazine [must have been during the Kindle blackout period] on a Scandinavian Airlines flight, reading the specifications for their fleet of aircraft. [See how boring it can get!] This included the fuel consumption, which I thought must a be clue to environmental impact.

I understand that fuel consumption is not the same as carbon dioxide emission, but it must have some bearing. I also appreciate that aviation fuel is different from the gasoline or diesel that we put in our cars – it has a different calorific value and the exhaust gas probably contains a different proportion of carbon dioxide, but I felt that these fuel consumption figures give us something to work with.

There were 10 models of plane listed – mainly Boeing and Airbus models, but there was also an MD-82 [which I guess is a much older and less efficient model]. The fuel consumption was quoted in liters per seat per kilometer. The lowest value was 0.028 for a Boeing 737-800 and the highest was 0.041 for the MD-82 [no surprise there]. I noted down all the figures and put them into a spreadsheet, which enabled me to translate to miles per gallon [I used US gallons – UK readers need to multiply by 1.25]. This yielded figures of 80mpg and 55mpg respectively.

These numbers compare favorably with a car. My car delivers around 40mpg, for example. I appreciate that these numbers are likely to relate only to the plane running with an optimal passenger load [probably full], but it should also be borne in mind that aircraft fly in fairly straight lines [compared with a car’s typical route]. So, my conclusion is that flying is not quite so bad after all. If you can suggest a serious flaw in my logic or calculations, please email or comment. If you want a copy of my spreadsheet just say.

I am sometimes told by those close to me that I think too much. To quote an old English saying: “Sometimes I sits and thinks. Other times I just sits.” Good advice perhaps.