I checked out your article - very interesting take on the subject! I am glad to see some calculations behind the science and to see someone else discussing deep geothermal! Thank you for the resteem!

I appreciate your question regarding my sources. Most of the sources that I included are web-based embedded hyperlinks, but in the end I felt that it was appropriate to include some more detailed and formal research studies on the matter. To be transparent, I did not pay for any of these studies but formerly had access to the journals through a University. Many public academic institutions and libraries have free access to the same journals and (depending on where you live) you can sometimes get guest access without paying anything.

If someone really wants to read in-depth about the thermal conductivity of soils in different physical conditions or the latest cutting-edge research into ground source heat pump systems, these are some of the most detailed sources available. Even without direct access, most people should still be able to read the abstract and get the gist of the publication.

Thanks for your comment and your support!