Integration of solar thermal energy in a conventionaf power plant: The Colon solar project

1 Phys. IV F ance 9 (1 999) P 3-189 in eg a ion o sola he mal ene gy in a con en iona powe plan : The Colon sola p ojec M. Sil a, M. Blanco* and V. Ruiz G upo de Te modinamica, Escuela Supe io de Ingenie os, Camino de 10s Descub imien os s/n, 4 1098 Se illa, Spain * CIEMAT, Pla a o ma Sola de Alme ia, Ca e e a de Senes s/n, Tabe nas, Alme ia, Spain Abs ac . This pape epo s on he i s phase o he Col6n Sola P ojec , o iginally concei ed as he hyb id epowe ing o an exis ing he mal powe plan , wi h he addi ion o a gas u bine in a opping con igu a ion in eg a ing he mal ene gy (s eam) p oduced by a sola sys em. Howe e , he p ojec de eloped in a changing economic en i onmen , in which a new legal s uc u e, s ill incomple e, as o Janua y, 1998 has libe alized he elec ici y gene a ion ma ke . This o ced he o iginal con igu a ion o be modi ied, esul ing in an all-new combined cycle wi h sola ene gy in eg a ed in o a Hea Reco e y Boile . Basic plan enginee ing placed special emphasis on he mos impo an sola componen s (helios a and ecei e ), and an economic analysis showed ha he plan is p o i able unde he assump ions o he analysis. Ne e heless, he ela i ely low IRR, as well as he unce ain y o ealiza ion o some o hose assump ions, made he u ili y pos pone i s decision o build he plan . Since Janua y 1, 1998, he Spanish powe ma ke has been libe alized. This means ha om now on, i s ope a ion will be based on a sys em o supply and demand, unde which he exis ing powe demand a any gi en momen is co e ed by he p oduc ion plan s o e ing he cheapes kwh. Thus hose powe p oduc ion plan s o uni s ha can o e he cheapes kWh a e he i s o ope a e o supply he demand, and he e o e, hose ha ha e he bes possibili y o su i ing in he new compe i i e en i onmen . Wi hin his new de egula ed amewo k, howe e , a kWh c edi is planned (no ye exp essly enac ed), o sola o o he enewable ene gy-based p oduc ion. Such a c edi o elec ici y p oduced om enewable esou ces would p o ide some e y ad an ageous oppo uni ies o sola he mal echnology, which, when in eg a ed in o hyb id powe plan s, could be he key o hei lowe ing con en ional gene a ion cos s (because o he mu ual syne gies o he con en ional and sola echnologies) enabling hem o compe e on he new ma ke . I he sa is ac o y in eg a ion o sola he mal and con en ional plan s can be demons a ed, i will hen be he ma ke ha demands he sola echnology, and, accompanied by he ad ances now unde way in R&D, will lead o i s wide-scale u iliza ioa in he Medi e anean basin and elsewhe e. This demons a ion is one o he main objec i es o he Colon Sola P ojec , which is suppo ed by he The mie p og am o he Eu opean Commission. The ecen ly comple ed i s phase o his p ojec in ol ed 9 o ganiza ions (u ili ies, equipmen manu ac u z s, enginee ing i ms and esea ch cen e s) om 4 di e en Eu opean coun ies, led by one o he u ili ies, Se illana de Elec icidad. This is one o he dis inc i e aspec s o he p ojec compa ed o o he sola ene gy p ojec s, since he leade is a inal use o he echnology, ins ead o an R&D ins i u ion. A icle published online by EDP Sciences and a ailable a h p://dx.doi.o g/10.1051/jp4:1999328 JOURNAL DE PHYSIQUE IV 2. BACKGROUND Fi s concei ed as hyb id epowe ing o an exis ing he mal powe plan wi h a opping con igu a ion based on he exis ing plan , an added gas u bine and an in eg a ed sola ield, he Col6n Sola P ojec employs he SOLGAS concep [I], as de eloped in he APAS SOLGAS P ojec [2]. The SOLGAS concep pos ula es hyb idiza ion o high-e iciency powe plan s (combined B ay on-Rankine cycle, cogene a ion cycles) and he use o Cen al Recei e Sys ems (CRS) as a ealis ic and iable pa h owa ds ma ke able sola he mal ene gy applica ions. Hyb idiza ion has adi ionally been conside ed a means o o e ide he mos signi ican d awbacks o sola ene gy, which is in e mi en and andom, o elec ici y p oduc ion. This poin o iew concei es he ossilpa o he hyb id powe plan p ima ily as auxilia y suppo o adap p oduc ion o he demand when sola ene gy is una ailable o insu icien . Howe e , despi e he conside able p og ess in sola echnology in ecen yea s, none o he p oposals o build sola (hyb id o s and-alone) powe plan s has succeeded, wi h he ema kable excep ion o he SEGS plan s in Cali o nia. Sola he mal echnology seems o be apped in a icious ci cle [2] impeding ma ke access. The concep o he Op imized Powe Plan , which is he co e o he SOLGAS p oposal, is a ealis ic, inno a i e app oach o hyb idiza ion, emphasizing iabili y in he eal-wo ld scena io, in which a la ge sola ac ion o he hyb id plan is no longe ele an . In he p esen si ua ion, any p og ess in ma ke ing sola he mal echnology makes sense. In he same ega d, he SOLGAS concep ad oca es he use o p o en, eliable componen s o he Cen al Recei e Sys em (CRS) echnology, in o de o con ince po en ial use s (u ili ies) and inancial ins i u ions ha he sola he mal (and mo e speci ically, CRS) echnology is no imma u e. This does no imply ha o he mo e ambi ious schemes ha ake ull ad an age o sola adia ion's po en ial o high exe gy a e o go en o may no be easible in he u u e. The sola sys em, which s a s up a sligh ly unde he sa u a ion poin , is used o boil wa e , wi h he ollowing ad an ages: a) Fo he hea exchange ( he "hea eco e y" uni ): I lessens he empe a u e d op be ween he ho gases lea ing he u bine and he coolan in he Rankine cycle. I all bu elimina es he hea -exchange pinch. I does no was e high- empe a u e gas in he ene gy-guzzling e apo a i e p ocess. b) Fo he sola sys em: I alle ia es ope a ing condi ions by elimina ing high empe a u es and ins abili ies associa ed wi h supe hea ing. I inc eases he he mal e iciency o collec ion by aking ad an age o wo-phase hea ans e h oughou mos o o he en i e ecei e . I elimina es he need o s o age. I signi ican ly educes plan s a up ime. c) Fo he o e all sys em: I enables all o he collec ed sola ene gy o be used as a subs i u e o he ossil uel. The sola con ibu ion jus i ies a modes amoun o combus ion in he Rankine cycle, o main ain boiling du ing cloudy pe iods o ea ly and la e in he day 3. PROJECT ORGANIZATION The i s phase o he p ojec in ol ed 10 o ganiza ions led by one o he u ili ies, Se illana de Elec icidad. This is one o he dis inc i e aspec s o he p ojec compa ed o o he sola ene gy p ojec s, since he leade is a inal use o he echnology, ins ead o an R&D ins i u ion. The pa icipan s we e: STCT 9 P 3-191 U ili ies: Se illana de Elec icidad, ENDESA (Spain), EDP (Po ugal) Manu ac u e s / Enginee ing i ms: ABB S all (Sweden), INABENSA, BWE (Spain), PROET (Po ugal) Resea ch ins i u ions: CIEMAT, AICIA (Spain), DLR (Ge many). The h ee g oups we e coo dina ed by Se illana. 4. RESULTS As a consequence o he changes in he legal amewo k since he p ojec was i s p oposed (June, 1996), he ini ial scheme ( opping) p o ed economically un easible in he new elec ici y gene a ion scena io. The plan con igu a ion e ol ed du ing p ojec de elopmen in o a hyb id powe plan in which he powe block is a comple ely new combined cycle (Figu e 1) o which only some auxilia y sys ems o he exis ing powe plan a e eused. Na u al Ga The ABB GTX-100, 43-MW nominal powe gas u bine wo ks a ull load unde no mal ope a ing condi ions. The dual p essu e Hea Reco e y Reco e y Boile , has wo Boile addi ional bu ne s o con ol he low o s eam o he s eam u bine in di e en ope a ing modes and in he e en o sudden changes in sola adia ion. S eam Tu bine design powe is 30-MW, wi h a s eam low o 78.8 /h a 510°C in he high-p essu e (99.8 ba ) sec ion and 15.5 lh a 181°C in he low- S eam Tu bine p essu e (2.76 ba ) sec ion. Table shows he main Figu e 1. Colon Sola plan inal con igu a ion pe o mance pa ame e s o he Colon Sola Plan . Table 1. Main pe o mance pa ame e s o he Colon Sola Plan The Colbn Sola powe plan is loca ed in Huel a (Sou he n Spain) whe e annual i adiance is 2063 kWh/m2. The sola pa is a Cen al Recei e Sys em wi h a collec o subsys em o 489 helios a s (each wi h a 70-m2 e lec i e su ace) and a 21.8 MW,,, s eam ca i y ecei e (powe o luid unde design condi ions), on a owe a a heigh o 109 m. The land allo ed o he p ojec is app oxima ely iangula , bu non-symme ical, c ossed by powe lines and supply duc s. Because o hese cha ac e is ics, he helios a ield (Figu e 2) and he lux on he abso be a e no symme ical and he owe is alle han usual. Howe e , he sola sys em pe o mance pa ame e s a e no e y di e en om hose o a symme ical ield and ecei e beha io is una ec ed. Wi h Sun 28.4 42.7 71.1 70.4 114.8 61.3 Wi hou Sun 20.0 42.7 62.7 60.0 114.8 54.0 S eam Tu bi ie Powe Gas Tu bine Powe To al G oss Powe To al Ne Powe Fuel Consump ion Ne E iciency Uni MW MW MW MW MW s/LHP % s/LHP P 3-192 JOURNAL DE PHYSIQUE IV Figu e 2. Colon Sola helios a ield The main cha ac e is ics and pe o mance pa ame e s o he sola sys em a e p esen ed in Table 2. STCT 9 P 3-193 Table 2. Main cha ac e is ics and pe o mance pa ame e s o he sola sys em The mos signi ican componen s o he sola plan , helios a s and ecei e enginee ing ha e been wo ked ou in g ea de ail. Powe o luid (desipn poin ) .Helios a ield e icienc (desim poin ) Recei e e icienc (design ooin ) Sola s s em e iciency (sola o he mal, design ooin ) Ene gy collec ed by luid (excludins ope a ional losses. ea l ) Helios a ield e icienc ( ea ly) Sola sys em e ciency (yea ly) The non-symme ical shape o he land a ailable (Figu e 2) and he es ic ions on i s use made necessa y a new helios a design ha would make he bes possible use o he land. 21.8 MW 0.805 0.935 0.753 43.5 GWh 0.747 0.619 A helios a p o o ype wi h 21 3-x-1.1-m ace s, 70-mZ e lec i e su ace and no cen al gap has been designed and buil and es ed a he Pla a o ma sola de Alme ia. Tes esul s show ha he helios a mee s he speci ica ions ( o al e o I 2.9m ad) wi h low powe consump ion. The sa u a ed s eam ecei e has been designed o maximum eliabili y and pe o mance. The mal and s ess analyses show ha hese objec i es ha e been achie ed wi h a simple, du able design. The ecei e demons a es excellen e iciency (abo e o close o 90% in an ope a ing ange up o 20% pa load) and due o wo-phase luid condi ions du ing mos o i s ansi h ough he ecei e ubes, limi ed empe a u e g adien s. Figu e 3. F on iew o he Colon Sola helios a JOURNAL DE PHYSIQUE IV 5. ECONOMIC AND PROFITABILITY ANALYSIS The p ojec budge was based on o e s om quali ied supplie s. Acco ding o hese o e s, he o al Col6n Sola Plan in es men will be 7933 Mp as., 36% o which co esponds o he sola pa . Among o he hypo heses, he p o i abili y analysis assumes ha subsidies om he EU and o he will be 2417 Mp as and c edi (p ice suppo ) o he elec ici y o sola o igin will be 15 p as/kWh. Elec ici y sales and ope a ing cos s o a 15-yea pe iod unde he new egula ions we e es ima ed using a model o ha gene a ion scena io. Acco ding o his model, he plan is p o i able, wi h IRR o 8.36% and NPV o 1085 Mp as, assuming a 12%.discoun a e. Howe e , because o he unce ain y ega ding he abo e men ioned assump ions (enac men o he law egula ing subsidies o enewable elec ici y is s ill in p ocess) and he ac ha he IRR is lowe han ha equi ed by he u ili y o new in es men s led o he u ili y's decision o pos pone he decision o build he plan . 6. CONCLUSIONS The new de egula ed legal amewo k o he powe gene a ion ma ke subs an ially modi ied some o he p emises ha led o he o iginal Coldn Sola p oposal, equi ing addi ional e o o adap o his changing en i onmen , while main aining he quali y o he p ojec and keeping, in so a as possible, on schedule. The mos ele an conclusions o his phase o he p ojec a e he ollowing: The o iginal plan con igu a ion ( epowe ing he C is dbal Coldn The mal Powe Plan Uni I wi h a opping scheme), was disca ed in a o o a con igu a ion based on a new combined cycle, in which sola gene a ed s eam is in eg a ed in o he Hea Reco e y Boile ). This new con igu a ion mee s he echnical and economic c i e ia o iabili y in he compe i i e en i onmen . Economic analysis o he new con igu a ion showed ha he Col6n Sola p ojec is iable in he new compe i i e en i onmen , p o ided ha he hypo heses used in he analysis (c edi o sola powe p oduc ion, subsidies om he UE and o he inancing bodies, p ices o na u al gas and elec ici y) a e ealized, in which case, Coldn Sola plan income would be g ea e han i s ope a ing cos s. Howe e , p ojec e u ns (IRR = 8.36%) a e s ill less han equi ed by he u ili y o new in es men s. This, in iew o he unce ain y ega ding some o he hypo heses o he economic analysis, led he u ili ies o pos pone hei decision o build he plan un il he unce ain ies a e esol ed. When designing he main plan sys ems, special emphasis was placed on he non-con en ional equipmen , ha is, sola ecei e , helios a s and hea eco e y boile ecei ed. Comme cial quo a ions o sys em componen s ecei ed om expe ienced manu ac u ing and enginee ing i ms a e no only a eliable basis o a plan cons uc ion budge , bu also show ha he e is a sound echnological base in he indus y, which a i ms he ma u i y o he Cen al Recei e Sys em echnology. Bibliog aphy [I] M. Blanco and V. Ruiz. The Solgas P ojec . P oceeding o he Eu opean Con e ence and Con ac o s Mee ing. Venice, I aly. No embe , 1995. [2] M. Blanco (coo dinado ) e al . SOLGAS P ojec ,: Hyb id Combined Cycle Cogene a ion Plan Based on Cen al Recei e Technology. Final Repo . Con a c APAS RENA-CT94-0043. Se illa, 1996.