EnergyAustralia last night reported a drop between seven and 12 per cent in energy consumption in Sydney’s CBD during Earth Hour. On a typical Saturday night the city would use 231.8 megawatts of electricity. Last night’s figure was 212.4 megawatts.
Which sounds like an amazing feat but there’s more to it than meets the eye. My first doubts come from when I saw the following graph here after last year’s event.
Notice the massive peak before the actual hour. I’m assuming people went and used all their appliances ahead of time so they could turn them off during the actual hour and then actually ended up using more power in total than on previous Saturdays.
Now let me start on one of the caveats of using this publicly available data. Firstly, the above graph is for the state of NSW as a whole. It doesn’t isolate the CBD’s power consumption (something which energy utilities are obviously in a much better position to do). What it does show is how, despite looking pretty, the CBD’s contribution to Earth Hour doesn’t have much of an effect on the power usage of the whole state.
I have prepared graphs for the 2008 event showing a state-by-state breakdown and a total figure.
There does seem to be a creeping up of power usage in preparation for the hour, just as the 2007 data suggests. This isn’t a strong statistical correlation because we only have two Earth Hours worth of data, but by the same token I find it hard to believe people can be so sure that it succeeded when there are simply so many variables to power usage.
Here’s some more notes (and caveats).
* I’ve added comparisons to previous Saturdays in March of this year. In my mind there is absolutely no point in comparing energy usage to the previous days in the week (as some people are doing) due to them being weekdays.
* The data is sourced from NEMMCO, the National Electricity Market Management Company. You can find the data I used here, although if you’re reading this more than two months after Earth Hour then you’ll find the data here.
* There isn’t much information with the NEMMCO data so I have no idea what the unit is on the demand figure. I’m guessing Megawatt-hours but I could be wrong.
* If you look at the raw data they quote ‘periods’ not time of the day. The discrete points on my graphs are the average demand for the previous 30 minutes.
* Due to NSW/VIC, QLD and SA all being in three different timezones I’ve normalised all of them to local time (thanks for pointing that out Berry/Dana). This is why the x-axis of the total curve is shorter than for the other graphs (because there’s fewer time periods when I have data for all states).
* I haven’t started the y-axes at zero to exaggerate the fluctuations during the day (i.e. I’m trying to make the fluctuations look larger than they actually are, which inflates the opposite point of view to mine. Hey, they need some help!).
* The vast differences in the SA figures between the first two and last two weeks is due to the maximum temperature in Adelaide being 40 an 38 degrees for the 8th and 15th, compared with 23 and 18 degrees on the following two Saturdays. It just goes to show that having a hot (or really cold) day has far more effect on power consumption than people intentionally minimising their power usage.
* I have no idea what happened in NSW and VIC on the 15th of March to cause usage to be so much higher than the other three Saturdays.
* I can’t do WA because I don’t have the data. I didn’t do Tasmania out of choice.
* The spreadsheet I used can be found here.
* I’ve probably missed something else. Please tell me (catchwa[at]gmail[dot]com) if I have.
There are reports of swarms of people driving their cars (which of course burn fossil fuels) to the city in order to see the spectacle of a lack of light. Ironic (or rather, moronic)? People who light candles during Earth Hour are quite likely just as misguided, judging by this back of the envelope calculation. Finally, even if we reduced the demand for electricity to zero for a whole hour the power stations would still burn oil/coal/gas/unicorns because you can’t simply shut down a power station for an hour and kick it back up again at 8:59.
So if there isn’t any positive environmental impact from Earth Hour what does it achieve? Publicity for the environment? Was a Nobel Prize and and every other news story from the past few years not enough? Can we give it a rest, please?