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) much fun they had doing without the label telling them what to do, he explained this record will be more like "Swan Songs" than "American Tragedy". He also revealed the album will be released on January 8, 2013. On December 11, the band announced that they will embark on a headlining tour titled "The Underground Tour", to promote "Notes from the Underground". Tour dates range from January 8, 2013, to January 23, starting in Hollywood, California. A video was released in promotion of the upcoming tour. On October 29, 2012, the first official single from "Notes from the Underground", titled