My contribution to global warming

22.04.2009 9:00

With today being the Earth Day, I went on and did some calculations on my more-or-less daily commute to Ljubljana.

Almost exactly a year ago I bought a car, since I got fed up with the bad state of Slovenian bus and rail public transport. I tried to stay away from this inefficient mode of transportation for as long as possible, but train delays and long bus rides pretty much made any life outside of Zemanta's office impossible.

Having a bit of a bad feeling about all that I tried to chose a car that wouldn't be that bad for the environment. So I paid close attention to the official fuel consumption and mg CO2/km figures when buying. In the end I decided on a Citroën C3 1.4i 16v

I also kept a log of the distance I've driven and how much gas I've bought. So now after one year I have some data which I can compare with those official specifications.

  • In one year I've driven 14000 km and burned 920 l of unleaded gasoline.
  • That gives fuel consumption of 6.4 l/100 km (37 miles per gallon for you imperial types). Not surprisingly, that's a bit higher than the official 6.2 l/100 km (combined urban/extraurban figure).
  • Burning 920 l of gasoline gives around 2100 kg of CO2. For comparison, the recently built solar power plant in Ljubljana is said to save 35000 kg of CO2 emissions per year.
  • Total chemical energy content of 920 l of gasoline is approximately 32 GJ or 8.9 MWh. That same solar power plant will produce 75 MWh per year.
  • This amount of gasoline cost me a little below 1000 €. The equivalent amount of electrical energy at last year's average residential prices would cost 890 €

According to official figures there were 1 million cars registered in Slovenia two years ago. If every one of those cars consumed the same amount of energy as mine per year, then two more nuclear power plants like Krško would be required in case everyone switched to hydrogen or electric propulsion (plus major upgrades to the distribution network).

Another interesting thing is this graph of fuel efficiency versus time. The yellow band is the time I used winter tires (ignore the peaks - they are the result of measurement error when I bought less than a full tank of gasoline).

Fuel efficiency versus time

I can see no significant difference in efficiency between summer and winter, which is surprising, since everyone seems to claim that winter tires are less efficient.

Posted by Tomaž | Categories: Life

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