Energy in South Australia and trap in the deeper heat. Due to the low permeability of granite, the hot rocks must undergo hydraulic fracturing and be stimulated to allow a flow of water through the system to produce energy. This heat is slowly conducted to shallower rocks near the surface. Petratherm propose developing the geothermal energy in the more permeable sedimentary rocks that overlay the hot granite, a process called Heat Exchange Within Insulator (HEWI). While somewhat cooler, in many cases they do not require hydraulic fracturing. It is estimated that one percent of geothermal energy shallower than five kilometres below the earth's surface
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