Hot dry rock geothermal energy as a separate state from that of the continuum of permeable rock—just as one would consider a completely closed faucet as distinct from one that is open to any degree, whether the flow be a trickle or a flood. In the same way, HDR technology should be regarded as totally distinct from EGS. A definitive book on HDR development, including a full account of the experiments at Fenton Hill, was published by Springer-Verlag in April 2012. Hot dry rock geothermal energy Hot dry rock (HDR) is an abundant source of geothermal energy available for use. A vast store of thermal
More Hot Rocks (Big Hits & Fazed Cookies) it was recalled and something a little more practical was compiled (ABKCO would revisit this concept with 1975's "Metamorphosis"). The result was "More Hot Rocks (Big Hits & Fazed Cookies)". Featuring the hits that could not be shoehorned onto its predecessor, as well as first-time release of many previously UK-only releases, the double album was quickly pressed and distributed into North American shops in December 1972, reaching No. 9 in the US and going gold. Like "Hot Rocks 1964–1971", "More Hot Rocks (Big Hits & Fazed Cookies)" would not see an official UK release until 21 May 1990. Allmusic's Richie