Automobile manufacturers have been working for decades on improving fuel
efficiency. So why aren't the cars we drive today getting dramatically better
gas mileage?
A study by MIT
economist Christopher Knittel in the December 2011 issue of the American
Economic Review found that since 1980 the average fuel economy of American
vehicles has increased only slightly, from 23 miles per gallon to 27. Yet
Knittel found that fuel efficiency-the amount of power an engine produces per
gallon of fuel burned-increased by 60 percent during that period. What's going
on here?
Cars and trucks have become bigger and more powerful: The average
weight of passenger vehicles has increased 26 percent since 1980, while their
horsepower has risen by 107 percent. Most of the gains in fuel efficiency have
gone into compensating for the extra size and thrust. Automobiles are not the only category in
which greater efficiency has failed to translate into reduced energy
consumption. Lighting efficiency has improved during the last three centuries
by many thousand-fold, from sputtering candles to modern LEDs, as Jeff Tsao and
his colleagues from the Sandia National Laboratory note in the July 2012 issue
of the journal Energy Policy. But the result "has been an increase in
demand for energy used for lighting that nearly exactly offsets the efficiency gains."
The authors note that "when lighting becomes cheaper, economic agents
become very creative in devising new ways to use it," such as illuminating
office ceilings with LED virtual skies.
In coming decades, Tsao et al. predict,
increased demand for lighting probably will again swallow up any new gains in
energy efficiency. In another
recent study, reported in the July 2012 issue of the journal Sustainability,
Graham Palmer, technical director of an Australian heating and cooling company,
looked at trends in space heating efficiency during the last 50 years in
Melbourne. Modern houses are up to 10 times more energy efficient, Palmer
found, yet Australians are collectively using just as much energy to heat their
homes as they did a half-century ago. Why? New houses are much bigger, people
heat larger areas for longer, and fewer people live in each dwelling.
Of
course, modern Australians are much more comfortable in the winter than their grandparents
were. Similarly, a 2006 study
commissioned by the U.S. Environmental Protection Agency found that homes in
Phoenix, Arizona, that qualify for the EPA's Energy Star designation use 12
percent more energy than homes that don't. Owners of Energy Star houses may use
16 percent less energy per square foot to keep their indoors livable, but they
spend those gains on bigger houses.
This energy "rebound effect" has important
implications for efforts to restrain climate change through conservation.
Various studies have suggested that improvements in efficiency could reduce
energy consumption enough to cut global carbon dioxide emissions by as much as 25
percent during the next four decades.
This is why the CAFE standards are and have been nothing but wishful thinking ever since they began. They amount to wishful coercionist thinking, which is linear and unable to conceive of 2nd and 3rd order effects. Sadly, where this will go after they wake up and smell the economics coffee will be efforts to even further restrict the choices of the citizenry.
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