Calculation of Earth’s Fuel Expected by 2025

     (CN) — It takes an enormous amount of fuel to power Earth’s magnetic field, plate tectonics and volcanoes, and scientists say that with new detectors coming online soon they’ll know how much fuel is left in the planet’s tank by 2025.
     Like a hybrid car, Earth taps two sources of energy to operate: primordial energy from assembling the planet and nuclear energy from the heat produced during natural radioactive decay. However, existing models for predicting Earth’s remaining fuel are provide estimates that vary significantly.
     Despite the challenges associated with determining the planet’s exact fuel supply, a team of researchers claims they will be able to do just that by 2025.
     “I am one of those scientists who has created a compositional model of the Earth and predicted the amount of fuel inside Earth today,” said study co-author William McDonough, a professor of geology at the University of Maryland. “We’re in a field of guesses. At this point in my career, I don’t care if I’m right or wrong, I just want to know the answer.”
     In a paper published Friday in the journal Nature Scientific Reports, the team says detecting some of the smallest known subatomic particles, called geoneutrinos, will be key to accurately measuring the planet’s fuel supply.
     Geoneutrinos are byproducts of nuclear reactions within stars, supernovae, black holes and human-made nuclear reactors. They also result from radioactive decay processes deep within Earth.
     However, detecting geoneutrinos presents several logistical hurdles. The process requires a detector the size of a small office building, which has to be about a mile underground to shield it from cosmic rays that could lead to false positive results.
     Scientists can detect geoneutrinos when the particles crash into a hydrogen atom. The collision products two characteristic flashes of light that announce the event, and the number of events scientists can detect correlates directly to the number of atoms of thorium and uranium inside Earth. The decay of these elements, along with potassium, power the majority of the heat inside the planet’s core.
     Detecting geoneutrinos has been difficult: scientists only record about 16 events per year with the underground detectors KamLAND in Japan and Borexino in Italy. But the team is optimistic that three new detectors expected to come online by 2022 — the SNO+ detector in Canada and the Jinping and JUNO detectors in China — could detect 520 more events annually.
     The Jinping detector, which will be buried under the slopes of the Himalayas, will be four times larger than existing detectors. The JUNO detector will be 20 times the size of existing detectors.
     “Knowing exactly how much radioactive power there is in the Earth will tell us about Earth’s consumption rate in the past and its future fuel budget,” McDonough said. “By showing how fast the planet has cooled down since its birth, we can estimate how long this fuel will last.”

%d bloggers like this: