Sunday, September 5, 2010

Tsao & Waide: "The World’s Appetite for Light"

Following up yesterday's post I looked at the study that provided the background for the paper studied there:

Jeffrey Y. Tsao and Paul Waide:
"The World’s Appetite for Light: Empirical Data and Trends Spanning Three Centuries and Six Continents"
LEUKOS VOL 6 NO 4 APRIL 2010 PAGES 259 – 281

This paper gives a figure of per capita light consumption and GDP/cost of light:

I drew the thick black line on the chart which represents an alternative curve fit. I know it is very crude but I couldn't draw a nice smooth curve with my software. I'm not saying that this is a best fit curve, just that it is a vaguely plausible alternative. If something like this model was fitted then the rebound effect is less than 100%. Tsao and Waide do not test alternatives to their linear model that assumes an income elasticity of one and a price elasticity of minus one of lighting demand. I think more research in this area is definitely warranted though I praise Tsao and Waide's pioneering attempt to bring together different sources of data and begin the empirical analysis.

Whatever the truth, the Economist's proposal to just stick with incandescent lighting is wrong. Even if there were no energy savings from introducing solid state lighting, as Tsao et al. state people would have more lighting services for a given energy input. There are environmental impacts to having too much outdoor light. These should be addressed separately, not by halting technological progress. If regulation limited the amount of outdoor light then these innovations would result in saving of energy...

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