In these boiling days of July, it’s easy to blame the sun for our high electric bills, but scientists have discovered that 44 terawatts, or 44 trillion watts, of heat continually flow from inside the Earth’s core and mantle into space. Using 20,000 boreholes across the globe, researchers from the Lawrence Berkeley National Laboratory and KamLAND are figuring out exactly what causes our planet to produce so much heat.
While we know (or we’re 97 percent certain) that the radioactive decay of potassium, thorium, and uranium comprise about half of the Earth’s heat, KamLAND scientists have published findings in Nature Geoscience (press release) that give a far more precise look at what goes on deep below our feet. Using what’s called a KamLAND anti-neutrino detector, which is a vessel filed with a thousand metric tons of scintillating mineral oil and linted with 1,800 photomultiplier tubes,” the researchers continually look for neutrinos (they’re practically invisible) by detecting antineutrinos. We’ll save you the complicated science behind it all, but using this detector, we now have a much more precise breakdown of what causes the Earth’s heat. The problem is that we can still only account for about half of it.
Here’s the breakdown:
- Uranium and Thorium: 20 terawatts
- Other isotope decays: 3 terawatts
- Still unknown: 21 terawatts
Before this study, we had far more imprecise estimates that still accounted for only 20 terawatts of heat. So what’s causing all this heat? Well, we don’t exactly know yet, but now we can rule out one culprit: “One thing we can say with near certainty is that radioactive decay alone is not enough to account for Earth’s heat energy, said Stuart Freedman of the U.S. Department of Energy’s Berkeley Lab. “Whether the rest is primordial heat or comes from some other source is an unanswered question.”
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