All Energy Sources Are Unsustainable

Physics professor Tom Murphy from UC San Diego has a very interesting blog post in which he debunks the idea that as long as we have energy sources, we can keep consuming more and more energy, ad infinitum. For the past 400 years or so, our energy use has grown at about 3% per year. If that continues, we will tap out the entire energy of the sun in the year 3200 and the total energy of all the stars in the galaxy in the year 4500. That might seem ridiculously far off, because it’s a whole 2500 years in the future — until you realize that 2500 years in the past, the Greeks were at the height of their civilization.

But as grim as that seems, there’s an even worse problem: a long time before we even get to consuming the entire energy of the sun, the Earth’s surface will get way too hot to sustain life simply due to the heat that energy use gives off as a by-product. At 3% yearly growth in energy consumption, we only have about 200-300 years until that happens — so hopefully the global population will stop growing and our energy demands will taper off long before then. (There’s also the unlikely scenario that someone will invent a way to convert energy without producing heat.)

Al Gore and his carbon/temperature graph in An Inconvenient Truth


A very intriguing idea in his post, however, is that energy use causes global warming, simply due to the laws of thermodynamics. Coincidentally, energy consumption has been increasing steadily over the past 60 years, along with, as Al Gore showed in An Inconvenient Truth, carbon and global temperature levels. However, he correlated the temperature increase only with carbon in the atmosphere and concluded that carbon was the cause and global warming was the effect, because the increase in carbon preceded the increase in temperature. But correlation is not causation. For instance, since virtually all energy consumption (e.g., burning oil or coal) creates both atmospheric carbon and heat, what if the real cause of global warming is actually energy consumption, not carbon? In other words, it could be that energy use makes both the extra carbon and the extra heat: that the problem is thermodynamic, not chemical.

This makes a lot of sense, logically speaking: for decades, our various machines (cars, computers, air conditioners, heaters, etc) have been generating a LOT of heat: where is it all going? Couldn’t all that extra heat be responsible for the increase in global temperatures? It would certainly be nice to see a graph showing energy consumption rates along with atmospheric carbon and temperature. If this is true, then the kicker is that even if we switch to alternative energy sources like solar, and the carbon in the atmosphere goes back down to normal levels, global warming will continue simply because we’re still using as much energy as we were before.

From Do The Math, via Slashdot


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