rEADing 3 "gEothErmAlEnErgy"
→ gEothErmAl EnErgy is nAturAl hEAt From thE intErior oF thEEArth thAt is ConvErtED to hEAt BuilDings AnD gEnErAtE ElECtriCity. thE iDEA oF hArnEssingEArth’s intErnAl hEAt is not nEw.As EArly As 1904, gEothErmAl powEr wAs usED in itAly. toDAy,EArth’s nAturAl intErnAl hEAt is BEing usED to gEnErAtE ElECtriCity in 21 CountriEs, inCluDing russiA, jApAn, nEw zEAlAnD, iCElAnD, mExiCo,EthiopiA, guAtEmAlA,El sAlvADor, thE philippinEs, AnD thE unitED stAtEs. totAl worlDwiDE proDuCtion is Appr0AChing 9,000 mw (EquivAlEnt to ninE lArgE moDErn CoAlBurning or nuClEAr powEr plAnts)—DouBlE thE Amount in 1980. somE 40 million pEoplE toDAy rECEivE thEir ElECtriCity From gEothErmAl EnErgy At A Cost CompEtitivE with thAt oF othEr EnErgy sourCEs. inEl sAlvADor, gEothErmAl EnErgy is supplying 30% oF thE totAl ElECtriC EnErgy usED、howEvEr, At thE gloBAl lEvEl, gEothErmAl EnErgy suppliEs lEss thAn 0.15% oF thE totAl EnErgy supply.
→ gEothErmAl EnErgy mAy BE ConsiDErED A nonrEnEwABlE EnErgy sourCE whEn rAtEs oF ExtrACtion ArE grEAtEr thAn rAtEs oF nAturAl rEplEnishmEnt. howEvEr, gEothErmAl EnErgy hAs its origin in thE nAturAl hEAt proDuCtion withinEArth, AnD only A smAll FrACtion oF thE vAst totAl rEsourCE BAsE is BEing utilizED toDAy. Although most gE0thErmAl EnErgy proDuCtion involvEs thE tApping oF high hEAt sourCEs; pEoplE ArE Also using thE low-tEmpErAturE gEothErmAl EnErgy oF grounDwAtEr in somE AppliCAtions.
gEothErmAl systEms
→
thE AvErAgE hEAt Flow From thE intErior oF thEEArth is vEry low, ABout 0.06 w/m².
this Amount is triviAl CompArED with thE 177 w/m² From solAr hEAt At thE surFACE in thE unitED stAtEs. howEvEr, in somE ArEAs, hEAt Flow is suFFiCiEntly high to BE usEFul For proDuCing EnErgy. For thE most pArt, ArEAs oF high hEAt Flow ArE AssoCiAtED with plAtE tECtoniC BounDAriEs. oCEAniC riDgE systEms (DivErgEnt plAtE BounDAriEs) AnD ArEAs whErE mountAins ArE BEing upliFtED AnD volCAniC islAnD ArCs ArE Forming (ConvErgEnt plAtE BounDAriEs) ArE ArEAs whErE this nAturAl hEAt Flow is AnomAlously high.

on thE BAsis oF gEologiCAl CritEriA, sEvErAl typEs oF hot gEothErmAl systEms (with tEmpErAturEs grEAtEr thAn ABout 80℃, or 176°F) hAvE BEEn DEFinED, AnD thE rEsourCE BAsE is lArgEr thAn thAt oF Fossil FuEls AnD nuClEAr EnErgy ComBinED、A、Common systEm For EnErgy DEvElopmEnt is hyDrothErmAl ConvECtion, ChArACtErizED By thE CirCulAtion oF stEAm AnD/or hot wAtEr thAt trAnsFErs hEAt From DEpths to thE surFACE.

gEothErmAlEnErgy AnD thEEnvironmEnt
→ thE EnvironmEntAl impACt oF gEothErmAl EnErgy mAy not BE As ExtEnsivE As thAt oF othEr sourCEs oF EnErgy, But it CAn BE ConsiDErABlE. whEn gEothErmAl EnErgy is DEvElopED At A pArtiCulAr sitE, EnvironmEntAl proBlEms inCluDE on-sitE noisE, Emissions oF gAs, AnD DisturBAnCE oF thE lAnD At Drilling sitEs, DisposAl sitEs, roADs AnD pipElinEs, AnD powEr plAnts.DEvElopmEnt oF gEothErmAl EnErgy DoEs not rEquirE lArgE-sCAlE trAnsportAtion oF rAw mAtEriAls or rEFining oF ChEmiCAls, As DEvElopmEnt oF Fossil FuEls DoEs. FurthErmorE, gEothErmAl EnErgy DoEs not proDuCE thE AtmosphEriC pollutAnts AssoCiAtED with Burning Fossil FuEls or thE rADioACtivE wAstE AssoCiAtED with nuClEAr EnErgy. howEvEr, gEothErmAl DEvElopmEnt oFtEn DoEs proDuCE ConsiDErABlE thErmAl pollution From hot wAstE-wAtErs, whiCh mAy BE sAlinE or highly CorrosivE, proDuCing DisposAl AnD trEAtmEnt proBlEms.
→ gEothErmAl powEr is not vEry populAr in somE loCAtions Among somE pEoplE. For instAnCE, gEothErmAl EnErgy hAs BEEn proDuCED For yEArs on thE islAnD oF hAwAii, whErE ACtivE volCAn