Heat is transferred from the interior to the surface through several methods. One is simply the conduction of sensible heat through the crust - I would guess this accounts for most of it. But some is also transferred through another route: when crust is subducted, it becomes dehydrated, which absorbs heat. Elsewhere, new crust is created and becomes hydrated, which releases heat. The net effect is the transfer of heat from the interior to the surface, but it is transferred in the form of hydration enthalpy rather than sensible heat. A similar process is serpentinisation, which transfers energy in the form of chemical bonds.

I'm looking for data about the total (net) amount of energy that is transferred from the interior to the surface in the form of hydration enthalpy and heat of serpentinisation, as opposed to sensible heat? Is it a substantial fraction of the total ~45TW figure?

  • $\begingroup$ Can you really relate two processes that are seperated by thousands of miles like this? Most water in a subducting slabs returns to the earth's surface during volcanism not sea floor spreading? Also it is my humble opinion based on multiple lines of evidence that low energy nuclear reactions initiated by the presence of seawater at depth is an unaccounted for source of energy in the earth's heat budget cited in the question. $\endgroup$ Apr 25, 2016 at 22:24
  • $\begingroup$ @MichaelWallace I guess most of the water that returns due to volcanism is not involved in hydration of minerals but was just subducted in the liquid state, but it would be very interesting and relevant to know if I'm wrong in that assumption. Also if you have good numbers for the near-surface nuclear contribution that would be useful too. (The question is two years old, but I am still somewhat interested in knowing the answer.) $\endgroup$
    – N. Virgo
    Apr 26, 2016 at 5:51
  • $\begingroup$ Heat Flux from the earth is about 47 TW +/- 2 TW Davies,J.H.,Davies,D.R.,2010.Earth’s surface heat flux.Solid Earth 1,5‐24. A very detailed breakdown of the origin of the heat flux is in this paper. arxiv.org/abs/1111.6099 There is a discrepancy of about 20 TW that can't be completely explained by known or legacy heat sources within the earth. My father and I suggest in our book Terrestrial Nuclear Processes createspace.com/3823397 the discrepancy is possibly explained by low energy nuclear reactions in the crust and upper mantle. $\endgroup$ Apr 27, 2016 at 14:55
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    $\begingroup$ @MichaelWallace I'm not sure it's important that the processes be linked directly. All OP is doing is taking the net of some nonobvious but similar heat transportation mechanisms. $\endgroup$
    – Spencer
    Oct 20, 2018 at 14:41


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