Calculating carbon footprints

I've just seen this (from Strange Attractor at XTech):

AMEE - the "Avoiding Mass Extinction Engine"

:: Measurement
Access to standardised co2 data and calculations (including the official UK Government figures)

:: Profiling
Store and retreive personal footprints

:: Sharing and Transparency
Help develop, extend, share and collaborate on the measurement of energy consumption.

It's designed as a service for other websites and campaigns that provides a REST API of CO2 data and related calculations. It can also be used to keep track of your users' carbon footprints over time.

Very interesting.

It reminds me of something I never got round to posting about tracking your daily transport habits (and hence, potentially, your carbon footprint). I was set off on this track by, I think, reading something by Julian Bleecker and playing around with some electronics. Could you use an embedded accelerometer or GPS, carried on your person, to automatically log what form of transport you are using?

An accelerometer would, I think, give you different patterns of acceleration and turning which could correlate with transport types. So frequent regular jolts would correspond to walking (as per a pedometer), lots of stopping, starting and turning would correspond to a car, smooth acceleration with gentle turns would correspond to a train and stopping every 3 minutes or so would correspond to the Underground (maybe!). It is just a hypothesis but I suspect there would be some trends there. And you should also be able to integrate the acceleration data to get approximate speed and distance.

I had a quick look at the accelerometer (Sudden Motion Sensor) in my iBook, trying out the processing API while on my daily train journey, but this only seems to give vertical acceleration or tilt data.

And you could also use GPS data, possibly in conjunction with the accelerometer. Again I would expect different patterns in the directional data from the GPS. But for what I'm proposing I think the accelerometer is more practical - that is, building a small, standalone, embedded electronics device, using something like Arduino, that is small enough to carry around with you all day. It stores all the timestamped accelerometer data and syncs every evening with your computer. This then analyses the acceleration data to give an estimate of your travel profile each day. Something like this would easily produce an (almost) real-time portrait of an individual's carbon footprint for travel and could be a very powerful tool to help people cut their footprint.