Hot dry rock geothermal energy makes use of hot fluids found naturally in basement rock; but such HWR conditions are rare. By far the bulk of the world’s geothermal resource base (over 98%) is in the form of basement rock that is hot but dry—with no naturally available water. This means that HDR technology is applicable almost everywhere on earth (hence the claim that HDR geothermal energy is ubiquitous). Typically, the temperature in those vast regions of the accessible crystalline basement rock increases with depth. This geothermal gradient, which is the principal HDR resource variable, ranges from less than 20 °C/km to over 60 °C/km,
Notes from the Underground (Hollywood Undead album) 3rd song off of "Notes From The Underground's" "Another Way Out" was the official theme song for WWE's pay-per-view event Payback on June 16, 2013. The music video for "Dead Bite" was released on August 20, 2013. Much of the music on this album remains rooted in hip-hop. Notes from the Underground received generally positive reviews from music critics. Rick Florino of Artistdirect gave "Notes from the Underground" 5 out of 5 stars, noting that it is the best album of 2013 and best album Hollywood Undead has done to date, describing that the album "practically bubbles over with intoxicating,