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Monday, 8 October 2007
On the Rebound?
Last week I made reference to the 'rebound effect'. I like to illustrate this concept with a little story. Back in December 2003, I wrote off my Ford Ka in a smallish prang. I replaced it with a Golf TDi, for two reasons:a. I want to have the option of using biodiesel (but that's another story...).
b. It did 55mpg compared with the Ka's 40mpg.
Brilliant - cut my fuel consumption by 28% and saved £250 each year.
But....
1. Statistics show that I'm likely to lose about a fifth of that saving by driving more because it has become cheaper. This is the 'direct rebound effect'.
2. £250 is exactly the cost of a return flight from Newcastle to New York. Given my love of travel, this is a real option. If I take it, then I've just doubled the annual carbon emissions I had in the Ka. This is the 'indirect-' or 'respend-' rebound effect (or, as energy economists call it, the Khazzoom-Brookes Postulate). If we save money through efficiency, we can easily wipe out the eco-benefits by choosing to buy or do something even more environmentally damaging with the windfall.
So what effect does this have in practice? The Khazzoom-Brookes Postulate is hotly debated in academic circles - certainly the prominent energy guru Amory Lovins once told me rather tersely that there was no empirical evidence for its existence.
In my opinion this is down to changing consumption patterns. Some time ago I immersed myself in consumer data and found that the fastest growing areas of expenditure were on telecommunications and home entertainment which are less carbon intensive (per pound/euro/dollar) than, say, road or air travel. A back of the fag packet calculation suggested that the rebound effect would not result in environmental damage getting worse, but that only about 50% of expected efficiency benefits would be delivered in practice.
The title of Lovins' own famous book, "Factor 4: doubling wealth, halving resource use", backs this up - a factor 4 improvement in resource efficiency will only result in a factor 2 reduction in resource use - the rest we enjoy in increased quality of life. I haven't seen him since to run this by him!
The bottom line is: with resource efficiency you never quite get the environmental benefits you expect, but it's still worth doing.
Labels: amory lovins, factor 4, rebound effect, resource efficiency, sustainable production and consumption
# posted by Gareth Kane : 08:32
0 Comments
Friday, 15 June 2007
Big Push for Energy Efficient IT
The BBC is reporting that a consortium of big IT industry names: Google, Microsoft, Intel, HP, Sun, Dell and Yahoo, is working to radically reduce the amount of energy consumed in PCs and servers - "enough to cut [carbon dioxide] emissions by 54 million tonnes a year - equal to 11 million cars or 20 coal-fired power plants". The initiative is an extension of the WWF's Climate Saver's programme.One worry about this is the "rebound effect" - the tendency for efficiency gains to get lost in favour of other benefits. For example, microprocessors' speed is limited by the amount of heat they generate. If the energy efficiency measures reduce the amount of heat given off by the chips, then the commercial pressure will be to increase processor speed rather than reduce overall energy consumption.
On the other hand, the involvement of so many software companies in the consortium, suggests that the focus may be on energy consumption during 'sleep' or standby modes. This approach would be less likely to be affected by the rebound effect.
Whichever way it goes, it will interesting to see what the actual energy benefits are.
Labels: energy efficiency, IT, rebound effect
# posted by Gareth Kane : 08:05
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