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 at LP Underground, as well as a limited free download of a live version of "Crawling", featuring Chris Cornell. Songs from the Underground Songs from the Underground is the second extended play released to the public by American rock band Linkin Park. It features songs previously released through the Linkin Park Underground fan club, as well as two previously unreleased live tracks from Projekt Revolution. "Songs from the Underground" features numerous songs released through Linkin Park Underground, the band's official fan club, as well as two live tracks from Projekt Revolution 2008. "And One" and "Part of Me" were included