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,
Songs from the Underground 2.0". "Sold My Soul to Yo Mama" (a track made by Linkin Park turntablist and sampler Joe Hahn, which includes samples from songs "Points of Authority" and "Papercut"), was released exclusively for "LP Underground 4.0". "Announcement Service Public" and "QWERTY" are found in the "LP Underground 6.0". "Hunger Strike", a song by Temple of the Dog, was performed by its lead singer Chris Cornell (whom the band toured with), and features a surprise guest appearance by Linkin Park lead vocalist Chester Bennington. Inside the physical CD, a leaflet can be found, inside which includes a free trial for a membership