Performance and Feasibility Study of a Standing Column Well (SCW) System Using a Deep Geothermal Well

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1 energies Article Performnce Fesibility Study Sting Column Well (SCW) System Using Deep Georml Well Jeong-Heum Cho 1, Yujin Nm 1, * Hyoung-Chn Kim 2 1 Deprtment Architecturl Engineering, Pusn Ntionl University, 2 Busehk-ro 63, Geomjeong-gu, Busn , Kore; pepero0201@nver.com 2 Division Geologic Environment, Kore Institute Geoscience Minerl Resources, 124, Ghng-no, Yuseong-gu, Dejeon , Kore; khc@kigm.re.kr * Correspondence: nmyujin@pusn.c.kr; Tel.: ; Fx: Acdemic Editor: Kmel Hoomn Received: 7 December 2015; Accepted: 4 Februry 2016; Published: 17 Februry 2016 Abstrct: Deep georml pump systems hve considerble energy sving potentil for ing cooling systems tht use stble ground temperture groundwter s ir sources. However, deep georml systems hve severl limittions for rel pplictions such s very high instlltion cost lck recognition s ing cooling systems. In this study, we performed fesibility ssessment Sting Column Well (SCW) system using deep georml well, bsed on rel-scle experiment in Kore. The results showed tht temperture source incresed up to C in borehole fter ing experiment, which is bout 30 C higher thn tht norml shllow georml wells. Furrmore, coefficient performnce (COP) pump during 3 months opertion 5.8, but system COP only 3.6 due to reltively high electric consumption pump. Moreover, pybck period system using deep well for controlled horticulture in glss greenhouse clculted s 6 yers compred with using diesel boiler system. Keywords: deep georml well; Sting Column Well system; pump; controlled horticulture 1. Introduction Renewble energy sources hve ttrcted ttention in recent yers, due to concerns bout nucler power plnts depletion fossil fuels. Since nnouncement Solr Heting Cooling Demonstrtion Act in 1974 [1], United Sttes (US) hve promoted policies supporting use renewble energy sources. Jpn estblished New Energy Development Orgniztion (NEDO) in 1980 to support development renewble energy systems promote use renewble energy [2,3]. In Kore, Act on Promotion Development, Use, Diffusion New Renewble Energy revised in According to regultion, public fcilities more thn 1000 m 2 must cover 12% ir energy needs with renewble energy [4]. Therefore, vrious renewble energy systems hve been introduced in Kore. The instlltion Ground Source Het Pump (GSHP) systems for ing cooling buildings is rpidly growing in Kore. Generlly, GSHPs re divided into closed loop systems, which re bsed on circultion crrier fluid into buried pipe loop, open loop systems, which re bsed on exchnge with groundwter [5]. Anor clssifiction cn be mde ccording to depth crossed by ground exchngers, which re thus divided into shllow (up to 300 m) deep (over 300 m) georml pumps, with shllow systems lrgely previling over deep systems. Although deep georml Energies 2016, 9, 108; doi: /en

2 Energies 2016, 9, ing systems re more efficient thn shllow systems, reserch technologicl development se systems is still fr from being stisfctory, since instlltion costs re still very high. An investigtion physicl rml properties trget re ground, long with quntittive nlysis vilble, is required for use deep georml energy, which hs considerble potentil due to high temperture source. In ddition, time trend energy needs fcility should be known. For utiliztion deep georml energy in industril public welfre sectors, initil costs (considering potentil deep georml energy) should be considered, n objective Life Cycle Cost (LCC) is lso necessry. Nguyen et l. [6] evluted influence groundwter flow in frctured quifers using numericl coupled model Sting Column Wells (SCW) systems. With ir model, y chieved good greement with reference numericl solutions. Prk et l. [7] studied Ground Wter Het Pump (GWHP) systems through field test numericl studies. The nlysis confirmed tht rml dispersivity is very importnt design fctor when deling with lrger GWHP systems. Cssso et l. [8] developed model rml recycling in GWHPs, which hs been vlidted by numericl simultions with FEFLOW. This tool cn be utilized for design GWHPs. Lo Russo et l. [9 11] modeled GWHPs to ssess hydrogeologicl sustinbility wter reinjection in plnt instlled t Politecnico di Torino (Itly) for cooling vrious buildings. Different scenrios were nlyzed tht differ significntly in terms both overll plnt costs (investments, mintennce, totl electricity consumption) environmentl impct. In order to evlute Thermlly Affected Zone (TAZ), numericl simultions were performed. Mine [12] conducted n experiment in ing-cooling mode two sting column wells tht were shllower thn closed-loop system. The uthor concluded tht ing performnce system without n rtificil groundwter exchnge is reltively high for limited periods time. Efficient dehumidifiction in free cooling mode is not chievble. Closed-loop open-loop systems, using shllow georml energy, re predominntly used in reserch technologicl development in order to pply georml to buildings globlly. Little reserch hs been conducted regrding source temperture chnges mount energy usge. The Kore Institute Geoscience Minerl resources (KIGAM) conducted n evlution deep georml fesibility, imed t Koren peninsul, in order to ssess domestic georml energy reserves. According to survey, temperture 90 C mesured t depth 2385 m. Assuming sme ground temperture grdient below depth 2 km or more, georml reservoir temperture 180 C could be obtined t depth 5 km [13,14]. Thus, in this study, rel-scle testing equipment constructed, ctul energy vilbility clculted for deep georml well instlled in Soenggok-ri, Heunghe-eup, Pohng-si, South Kore in order to evlute vilbility deep georml energy. On bsis results, n evlution performed on ech re for its potentil use in controlled horticulture. Furrmore, on bsis LCC, economics deep georml system were nlyzed, comprison mde with existing ing boilers. 2. Summry Heting Experiment 2.1. Site Description The trget loction this experiment is Heunge re norrn Pohng, Gyeongbuk, in South Kore. South Kore lies t ltitude N longitude E. In regrd to wer in Pohng, which is locted in soustern prt Koren peninsul, where nnul men temperture precipittion re 14.2 C 1152 mm, respectively. Pohng fces Est Se hs moderte climte due to presence ocen wrm current [15]. The ground surfce this re is depositionl surfce belonging to Gyeongsng supergroup from Cretceous period. The stony crystl tuff, biotite grnite, felsite, crystl tuff re distributed throughout region, constituting bedrock Pohng bsin [13]. The loction experiment

3 Energies 2016, 9, is one lrge energy potentil res in South Kore [16]. In reserch strted in 2003, deep borehole 3 13 deep georml energy resource development ing experiment crried 3 13 out using one borehole plced between four deep georml wells Summry Experiment Heting System 2.2. Summry Experiment Heting System 2.2. Summry Experiment Heting System In this study, ing experiment performed using SCW, s shown in 1. In se In this study, ing experiment performed using SCW, s shown in 1. In se plnts, study, sme deep georml well is performed used bothusing for bstrction injection In this ing experiment SCW, s shown in 1. In se plnts, sme deep georml well is used both for bstrction injection groundwter, which is used s source for pump. plnts, sme deep georml well is used both for bstrction injection groundwter, groundwter, which is used s source for pump. which is used s source for pump. Energies 2016, 9, 108 instlled for Energies 2016, 9, Sting StingColumn ColumnWell Well (SCW) (SCW) system. system. 1. Sting Column Well (SCW) system. SCW systems hve ttrcted incresing ttention due to ir dvntges such s low construction SCW systems hve ttrcted incresing ttention due dvntges such s construction SCWhigh systems ttrcted ttention due to to ir ir dvntges such s low lowbecuse construction cost hve exchnge rte incresing per well depth compred to closed loop system, y cost high exchnge rte per well depth compred to closed-loop system, becuse y cost high exchnge rte per well depth compred to closed loop system, becuse y directly use groundwter s sink, thus mintining constnt temperture [17,18]. A rel scle directly use groundwter s sink, thus mintining constnt temperture [17,18]. A rel-scle directly use groundwter s sink, thus mintining constnt temperture [17,18]. A rel scle lbortory constructed GSHPs experimentl equipment used to exmine fesibility lbortory constructed experimentl equipment used to to exmine fesibility lbortory constructed GSHPs GSHPs experimentl equipment used exmine fesibility deep SCW. The lbortory is locted in Heunghe eup, Pohng, South Kore, deep SCW. The lbortory is locted in Heunghe-eup, Pohng, South Kore, constructed deepusing SCW. continer The lbortory is locted Pohng, South Kore, constructed structure 12 m2inin Heunghe eup, re. 2 shows schemtic digrm using continer structure 12 m2 in re. 2 shows schemtic digrm equipment 2 in re. constructed using continer structure 12 m 2 shows schemtic digrm equipment system developed in this study. The system configurtion includes exchnger, system developed indeveloped this study. in Thethis system configurtion includes exchnger, pump, study. system configurtion includes exchnger, equipment pump,system lod side units, s shown in The Tble 1 [14,18]. lod-side units, s shown in Tble 1 [14,18]. pump, lod side units, s shown in Tble 1 [14,18]. 2. Schemtic Schemtic digrm digrm Ground Ground Source Het Pump (GSHP) systems. Reproduced Reproduced with with 2. Schemtic digrm Ground Source Het Pump (GSHP) systems. Reproduced with permission permission from from [14,18]. [14,18]. permission from [14,18].

4 Energies 2016, 9, Energies 2016, 9, Tble 1. System configurtion. Tble 1. System configurtion. System Sides System Sides Composition Composition Specifictions Specifictions Dimeter Dimeter m m Georml Het Exchnger Borehole Borehole Depth Depth m m Georml Het Exchnger Het Het Source Groundwter Submersible Pump Pump kw kw Circultion Circultion Pump Pump Flow FlowRte Rte Mx Mx L/min L/min Heting 4.79 RT Heting 4.79 RT Het Het Pump Pump Cooling Cooling RT RT Het Pump Het Pump Het Het Exchnger Exchnger Plte Plte Circultion Circultion Pump Pump Flow Flow Rte Rte Mx Mx L/min L/min Storge Tnk Storge Tnk 200 L 200 L Circultion Pump Flow Rte Mx 333 L/min Lod-Side Lod Side Circultion Pump Flow Rte Mx 333 L/min Heting kw Fn Coil Unit Heting kw Fn Coil Unit Cooling 7.43 kw Cooling 7.43 kw The ground exchnger is SCW, with depth 2383 m, s shown in 3; wter is bstrcted The ground using exchnger kw submersible is SCW, pumps. withthe depth pump 2383system m, s(wterfurnce, shown in Wyne, 3; wter NJ, is bstrcted USA) is composed using kw plte type submersible exchnger, pumps. The pump with system 5 RT (WterFurnce, cpcity for ing Wyne, NJ, USA) cooling, is composed circultion plte-type pump. The exchnger, lod prt (SHINWOO, pumppju, withsouth 5 RT Kore), cpcity is composed for ing cooling, 200 L rml circultion storge pump. tnk The Fn lod Coil prt Unit (SHINWOO, (FCU) with Pju, 14.5 South kw Kore), cpcity isfor composed ing, 200 L rml circultion storge pump. tnkin Fn order Coil to Unit nlyze (FCU) with temperture 14.5 kwchnge cpcity wter for ing, within borehole circultion pump. In order system to performnce, nlyze temperture monitoring chnge crried wter out by within instlling borehole temperture sensor, system flow performnce, meter, power meter round plumbing pump, s shown in Tble 2. A totl six monitoring crried out by instlling temperture sensor, flow meter, power meter round temperture sensors were instlled s shown in 3 in order to mesure temperture plumbing pump, s shown in Tble 2. A totl six temperture sensors were instlled source. The circultion flow mesured using n electronic flow meter, single phse s shown in 3 in order to mesure temperture source. The circultion flow two wire power meter used to mesure mount electricity consumed in opertion mesured using n electronic flow meter, single-phse two-wire power meter used circultion pumps. A dt logger used to sve dt mesured in SCW to mesure mount electricity consumed in opertion circultion pumps. system in this study [14,18]. A dt logger used to sve dt mesured in SCW system in this study [14,18] Conceptul sketch sketch deep georml well. Reproducedwith with permissionfrom from [14,18]. [14,18].

5 Energies 2016, 9, Tble 2. Monitoring equipment. System Sides Specifictions Number Electricity meter 4 20 ma 4 Flow meter Electronic type 3 Thermometer PT Dt logger GR100-12ch Experiment Method Tble 3 shows test methods used during ing opertion system. A simulted cooling lod instlled inside lbortory, tking into ccount lck ing lod during dy. Tble 3. Summry experiments. Opertion Mode Mode 1 Mode 2 Experiment Period 18 November December December Februry 2015 Flow Rte 70 L/min 50 L/min FCU Temperture 30 C 22 C Submersible Pump Power Consumption 2.50 kw 1.75 kw Operting mode Continuous Opertion A ing opertion test performed in order to nlyze mximum ing lod tht could be provided by system, in continuous opertion, without regrd bleeding opertion SCW. The ing test conducted over period 3 months from 18 November 2014 to 11 Februry The source temperture within well, s well s system performnce (in ccordnce with flow rte chnge FCU set temperture) were compred nlyzed. The pump lod-side temperture set t 45 C. The temperture difference ( T) t exchnger set t 5 C. When deep georml wells re pplied in controlled horticulturl frms, quntittive nlysis energy consumption, per plnt, is needed to determine ing set temperture. Therefore, n FCU temperture chnge (from 30 to 22 C) set. The power consumption instlled submersible pump 15.3 kw during drwdown test t 416 L/min. Lower flow rtes L/min were used in experiment, power consumption pump hence proportionlly diminished to kw, respectively. 3. Experimentl Results 3.1. Temperture Chnge Het Source Wter 4 shows chnge wter temperture during ing opertion systems by using deep georml well. T1 (Het source_in) T2 (Het source_out) re time series wter temperture t inlet outlet borehole, respectively. After ing opertion t 70 L/min 30 C FCU set point hd ended, tempertures entering return wter were C, respectively; se tempertures incresed to C in second period t 50 L/min 22 C FCU set point. A mximum entering wter temperture chieved C, which n decresed to C t end experiment; this is considered to relibly respond to ing lod, per crop, when deep georml well is predominntly used in controlled horticulture frm. T3 (Het pump_in) T4 (Het pump_out), in 4, re wter temperture time series t outlet pump, which is connected to plte type exchnger. In T5 (Lod side_in) T6 (Lod side_out), in 4, source wter temperture lod side, men inlet outlet tempertures during ing opertion were mesured s C, respectively, s

6 Energies 2016, 9, pump temperture set t 45 C. The temperture source in this system grdully incresed with time, indicting tht georml energy potentil is greter thn tht resulting from experiment. Energies 2016, 66 Energies 2016,9, 9, experimentl results Temperture Temperture experimentl experimentlresults. results. 4. Temperture Heting Heting Performnce Performnce Het Het Pump Pump 3.2. Heting Performnce Het Pump 55 shows shows verge verge exchnge exchnge rte rte electric electric power power consumption consumption 5 shows verge exchnge rte electric power consumption system system system during during ing ing opertion opertion GSHPs. GSHPs. The The exchnger exchnger rte rte clculted clculted using using during ing opertion GSHPs. The exchnger rte clculted using Eqution (1): Eqution Eqution (1): (1):. Q T QQ C p ˆ mw ˆ ΔT ΔT (1) (1) (1). C), m :: flow Q: Het exchnge rte (kw), specific (kj/kg C), (L/s), whereq: Q:Het Hetexchnge exchngerte rte(kw), (kw),ccc specific (kj/kg (kj/kg C), rte (L/s), (L/s), ΔT: ΔT: temperture temperture where T: p p:p::specific w flow rte difference C). difference(( C). ( C) Het Hetexchnger exchnger rte rte power power consumption consumption system. system. The The verge verge exchnge exchnge rte rte system system is is kw kw t t flow flow rte rte L/min L/min kw kw t t flow flow rte rte L/min. L/min. This This is is due due to to continuous continuous increse increse temperture temperture source. source. The The men men power power consumption circultion pump on source lod sides is 0.5 kw, power consumption circultion pump on source lod sides is 0.5 kw, power consumption consumption pump pump is is kw. kw.

7 Energies 2016, 9, shows COP pump (HP.COP) whole system (S.COP) during ing experiment, clculted using Equtions (2) (3): Energies 2016, 9, HP.COP = (2) The verge exchnge rte system is kw t flow rte 70 L/min kw t flow rte 50 L/min. S.COP = (3) This is due to continuous increse temperture source. The men power consumption where ΣQ: totl ing circultion power pump (kw), on ΣWhp: source electricity consumption lod sides is 0.5 kw, pump power (kw), consumption ΣWp: electricity consumption pump is 4.7circultion kw. pump (kw). The verge 6 shows COP COP pump pump is 5.5 (HP.COP) 5.8 for first whole system second (S.COP) prt during ing ing experiment, experiment, respectively, clculted i.e., t using flow rtes Equtions 70 (2) 50 L/s, (3): respectively. These vlues re noticebly higher thn 3.1, i.e., minimum strd vlue ccording ř to [17]. The source temperture kept incresing up to C, s shown Q HP.COP in 4. řthus, we consider tht exchnge rte (2) system pump performnce would Whp be much higher under optiml operting conditions. The verge system COP, reflecting power ř consumption ech fcility system is 3.1 Q 3.6 t flow rte L/s, S.COP respectively. ř The Whp ` ř reson why system COP is much lower (3) W thn tht pump is tht power consumption p submersible pump reltively where high compred ΣQ: totl to ing tht power closed loop (kw), ΣW hp system. : electricity If consumption submersible pump were pump optimized, (kw), ΣW p system : electricity COP consumption could be improved substntilly. circultion pump (kw) Heting Heting performnce performnce GSHP: GSHP: COP COP pump pump (HP.COP, (HP.COP, blue blue dimonds) dimonds) whole whole system system (S.COP, (S.COP, red red squres), squres), with with rml rml power power exchnged exchnged (H.P_HER, (H.P_HER, green green tringles). tringles). 4. Fesibility Anlysis Controlled Horticulture Scenrio The verge COP pump is for first second prt ing experiment, 4.1. Simultion respectively, Summry i.e., t flow rtes L/s, respectively. These vlues re noticebly higher thn 3.1, i.e., minimum strd vlue ccording to [17]. The source temperture kept incresing A quntittive up to nlysis C, s shown energy in consumption 4. Thus, we in consider buildings tht served by exchnge georml rteplnt is system required in order to ssess pump performnce fesibility would utiliztion be much higher georml under optiml energy. operting Thus, in conditions. this study, The ing verge lod system nlysis COP, reflecting performed power considering consumption strd echmterils fcility system used is for 3.1greenhouse 3.6 t covers flow rte in Kore; 70 i.e., 50 glss, L/s, polyethylene, respectively. The reson polycrbonte why system [19] ( COP is 7). much The stwre lower thn TRNSYS tht (University pump Wisconsin, tht power Mdison, consumption WI, USA) 17 submersible dopted for pump dynmic reltively energy high simultion compred to se tht strd closed-loop greenhouses. system. TRNSYS If submersible is ble to pump model were complex optimized, energy system systems, COP which couldre be improved reproduced substntilly. by ssembling modulr components modeled by librries (Types). The simultion conditions re summrized in Tble 4. The wer dt from Meteonorm utilized, which is 4. in Ulsn, Fesibility ner Anlysis Pohng. The product Controlled cultivted Horticulture in controlled Scenriohorticulturl frms is ssumed to be pprik, indoor temperture set t 18 C. The indoor temperture control 4.1. Simultion Summry A quntittive nlysis energy consumption in buildings served by georml plnt is required in order to ssess fesibility utiliztion georml energy. Thus, in this study,

8 Energies 2016, 9, ing lod nlysis performed considering strd mterils used for greenhouse covers in Kore; i.e., glss, polyethylene, polycrbonte [19] ( 7). The stwre TRNSYS (University Wisconsin, Mdison, WI, USA) 17 dopted for dynmic energy simultion se strd greenhouses. TRNSYS is ble to model complex energy systems, which re reproduced by ssembling modulr components modeled by librries (Types). The simultion conditions re summrized in Tble 4. The wer dt from Meteonorm utilized, which is in Ulsn, ner Pohng. The product cultivted in controlled horticulturl frms is ssumed to be pprik, indoor Energies 2016, 9, 108 temperture set t 18 C The indoor temperture control greenhouse is performed by ventiltion, mount ventiltion set t 1.57 times/h ccording to prescriptions greenhouse is performed by ventiltion, mount ventiltion set t 1.57 times/h Koreccording Rurl Development to prescriptions Administrtion Kore (RDA) Rurl Development [20]. In this study, Administrtion opertion (RDA) [20]. greenhouse In this time study, set sopertion 24-h continuous greenhouse opertion, time set s ing 24 h energy continuous required opertion, unit re ing (ccording to energy opertion required conditions per unit re (ccording greenhouse) to opertion clculted. conditions greenhouse) clculted. 7. Greenhouse model. 7. Greenhouse model. Tble 4. Simultion condition. Tble 4. Simultion condition. Trget Fcility Controlled Horticulture Trget FcilityAre Controlled 375 Horticulture m 2 Wer Dt Ulsn Set Fcility Temperture Are Crops Pprik 375 Heting m 2 18 C Wer Monthly Dt Ventiltion 1.57 Ulsn times/h Set Temperture Opertion Schedule Crops Pprik All times (8760 Heting h) 18 C Monthly Ventiltion 1.57 times/h Opertion Schedule All times (8760 h) 4.2. Simultion Results 8 Tble 5 show results ing lod nlysis. The results, ccording to 4.2. Simultion Results cover type, showed tht totl nnul ing lod is MWh/yer for glss, MWh/yer 8 Tble for polyethylene, 5 show results MWh/yer ingfor lod polycrbonte. nlysis. The It results, confirmed ccording tht to coverglss type, greenhouse showed tht consumes totl bout nnul 1.6 ing times more lodenergy is thn MWh/yer greenhouse for glss, covered with MWh/yer or mterils, becuse higher trnsmissivity (U vlue). The solr energy trnsmittnce (G vlue) for polyethylene, MWh/yer for polycrbonte. It confirmed tht glss greenhouse polycrbonte is lower thn tht polyethylene, hence ing consumption consumes bout 1.6 times more energy thn greenhouse covered with or mterils, becuse polycrbonte greenhouse is higher, due to lower solr gins. The pek ing lod higher trnsmissivity (U-vlue). The solr energy trnsmittnce (G-vlue) polycrbonte is clculted s kw for glss, kw for polyethylene, kw for polycrbonte. lowerassuming thn tht tht polyethylene, GWHP hs flow hence rte 300 ing m 3 /dy, consumption estimted rml polycrbonte power is greenhouse kw, is higher, which due is sufficient to lower to cover solr gins. pek The lod pek ing polyethylene lod clculted polycrbonte s greenhouse, kw for glss, 58.64but kwnot fortht polyethylene, glss covered greenhouse. kw for polycrbonte. Assuming tht GWHP hs flow rte 300 m 3 /dy, estimted rml power is kw, which is sufficient to cover pek lod polyethylene polycrbonte greenhouse, but not tht glss-covered greenhouse.

9 Energies 2016, 9, 108 Energies Energies2016, 2016,9,9, Heting lod lod ech ech cse. 8.8.Heting Heting lod echcse. cse. Tble 5.5.Simultion Simultion Tble results ech echcse. cse. Tble5. Simultionresults results ech cse. Cse Annul Heting Lod Cse Annul HetingLod Lod Cse Annul Heting Glss 146,746 kwh Glss 146,746 kwh Glss 146,746 kwh Polyethylene 85,305 Polyethylene 85,305kWh kwh Polyethylene 85,305 kwh Polycrbonte 96,014 Polycrbonte 96,014kWh kwh Polycrbonte 96,014 kwh Pek Pek Lod PekLod Lod kW kw kw kW kw kw kW kw kw Pek Lod per Are Pek Lod perper Are Pek Lod Are W/m W/m W/m W/m W/m W/m W/m W/m W/m Economic EconomicAnlysis Anlysis 5. Economic Anlysis Summry SummryEconomic EconomicAnlysis Anlysis 5.1. Summry Economic Anlysis Depending Depending on on outer outer cover cover type type greenhouse, greenhouse, hence hence on on ing ing lod, lod, Depending on outer cover type greenhouse, hence on ing lod, comprtive economic nlysis crried out s shown in 9. The Life Cycle Cost (LCC) comprtive economic nlysis crried out s shown in 9. The Life Cycle Cost (LCC) comprtive economic nlysis crried out s shown in 9. The Life Cycle Cost (LCC) Return On Investment (ROI) were clculted dopting present vlue nlysis method, Return On Investment (ROI) were clculted dopting present vlue nlysis method, is described by following equtions: which Return On Investment (ROI) were clculted dopting present vlue nlysis method, which is which is described by following equtions: described by following equtions: (4) PFF == F (4)(4) PP F p1 ` iqn A rp1 ` iq 1s PAPPA = i p1 ` iqn A= (5) (5)(5) P PP== + =PPPFF + + PPPAA (6) (6)(6) F A : present present vlue future csh, nnuity, F: cost incurred fter where where PFPP : F cpitliztionfctor fctor nnuity, cost incurred fter F: presentvlue vlue future futurecsh, csh,ppaaa:::cpitliztion cpitliztion fctor nnuity, F:F: cost incurred fter where n yers, A: nnul cost, i: discount vlue. n yers, A: A: nnul cost, i: i:discount n yers, nnul cost, discountvlue. vlue. 9.9.Schemtic economic nlysis. 9. Schemticdigrm digrm Schemtic digrm economic economicnlysis. nlysis.

10 Energies 2016, 9, Clcultion Initil Cost The initil cost clculted s shown in Tble 6, bsed on ing pek lod on which required power pump/boiler depends. Tble 6. Initil cost ech system. Cse Pek Lod (kw) GSHP (won) Diesel Boiler (won) Glss ,655,400 2,695,000 Polyethylene ,943,200 1,878,000 Polycrbonte ,544,600 1,878,000 The initil cost boiler tken from price list Kiturmi Compny in South Kore [21]. Assuming depth 1 km for SCW, excvtion cost georml exchnger clculted, bsed on estimtes from Koren GSHP compnies. The cost pump, depending on power, tken from [22]. The initil cost georml ing system is 38 to 46 times higher thn tht oil boiler, s reported in Tble 6. Two oil boilers were considered, Boiler 1 with power kw n efficiency 83%, Boiler 2 with power 81.4 kw n efficiency 82% Clcultion Opertion Cost The LCC ech system clculted considering both energy mintennce costs. Tble 7 reports price diesel in Kore s June 2015 [23] ing vlue diesel in n idel boiler considering efficiency Boilers 1 (83%) 2 (82%). Tble 7. Diesel price diesel efficiency. Item Boiler 1 Boiler 2 Price Diesel won/l Heting Vlue Diesel 9.80 kwh/l Heting Vlue by Using Diesel Boiler 8.04 kwh/l 8.14 kwh/l The pump COP should consider vriety effects, such s opertion method system, ground properties etc., in order to clculte operting cost GSHP. For this reson, opertion costs were clculted by setting pump COP to 3.1, ccording to minimum performnce strd vlue reported in [17]. The specil triff Kore Electric power Corportion used to clculte cost electricity to feed pump [24]. For mintennce costs, it ssumed tht oil boilers need to be replced fter 10 yers, while pump does not need to be replced in 20 yer lifespn. Tble 8 reports nnul energy consumption ech system. Tble 8. Annul energy consumption ech cse. Cse Diesel Consumption (L) Electricity Consumption (kwh) Glss 16,963 48,929 Polyethylene 10,582 28,443 Polycrbonte 11,911 32,014 Tble 9 reports nnul opertion costs oil boiler GSHPs. The nnul opertion costs re reduced by 19 million South Koren won (SKW) for bout 12 million SKW in plstic greenhouse, bout 13 million SKW in polycrbonte greenhouse, when using diesel oil s source.

11 Energies 2016, 9, Energies 2016, 9, Tble 9. Annul opertion costs ech cse. Tble 9. Annul opertion costs ech cse. Cse Cse Diesel Price Diesel Boiler (won) Electricity Electricity Price Price GSHPs GSHPs (won) (won) Glss 21,062,722 2,233,090 Polyethylene 13,139,830 1,320,012 Polycrbonte 14,789,458 1,479, Pybck period Periodnlysis Anlysis An ROI nlysis performed using present vlue nlysis method, converting ll costs (nnul opertion system mintennce costs, costs, etc.) etc.) tht tht occur occur in in life cycle life cycle energy energy supply supply system. system. The verge The verge vlue vlue three-yer three yer expirtion expirtion Tresury Tresury bond for bond 10 yers for 10 ( ), yers ( ), in in Kore Kore Bnk economic Bnk economic Sttistics Sttistics System System 3.94% 3.94% [25]. [25]. In In cse cse oil boiler, boiler, ssuming ssuming tht tht boiler boiler replcement instlltion instlltion costs costs re incurred re incurred every every 10 yers, 10 yers, non-recurring non recurring cost cost clculted. clculted. 10 shows 10 shows LCC nlysis LCC nlysis diesel oil diesel boiler boiler GSHPs for GSHPs different for different cover mterils. cover mterils. An economicl An economicl benefit benefit dopting dopting GSHPs isgshps found is forfound ll mterils, for ll mterils, s pybck s pybck period is period shorter is thn shorter 15thn yers plnt 15 lifetime yers plnt considered lifetime in our considered nlysis, in i.e., our bout nlysis, 6 yersi.e., for bout glss 6 yers greenhouse for (which glss greenhouse is chrcterized (which by higher is chrcterized energy consumption), by higher energy boutconsumption), 9 yers for bout polyethylene 9 yers greenhouse, for polyethylene 8 yers greenhouse, for polycrbonte 8 yers for greenhouse. polycrbonte greenhouse. 6. Conclusions 10. Life Cycle Cost (LCC) comprtive pybck period nlysis. In this study, system system performnce vilbility vilbility deep georml deep georml energy were energy nlyzed were nlyzed through empiricl through empiricl ing experiments ing experiments on SCW-type on SCW type deep georml deep georml well instlled well ininstlled Pohng-Si, in Pohng Si, South Kore. South Also, Kore. ing Also, lod ing nlysis lod nlysis conducted ccording conducted toccording outer cover to mterils, outer cover by mterils, using dynmic by using rml dynmic nlysis rml simultion nlysis tool. simultion Bsed tool. results Bsed on energy results simultion, energy simultion, economics economics deep georml well deep were georml nlyzed, well compring were nlyzed, it with conventionl compring it oil with boiler. conventionl The followingoil results boiler. were The obtined. following results were obtined. The ing experiment t t deep deep georml well well showed showed tht tht temperture temperture incresed incresed over over time, time, chieving chieving finl finl vlue vlue C. The C. performnce The performnce nlysis nlysis GSHPs GSHPs showed showed tht tht verge verge HP.COP HP.COP is 5.5 is with 5.5 with flow flow rte rte L/min L/min FCU FCU set set temperture 30 C, C, 5.8 with flow rte 50 L/min FCU set temperture 22 C. C. Such performnceis much greter thn minimum strd strd vlue vlue specified specified in ASHRAE. in ASHRAE. A deep A deep georml georml well well for for greenhouse greenhouse with with dominnt dominnt ing ing lod is lod refore is refore expected expected to operte to operte efficiently efficiently in in long term. long term. The The LCC nlysis results for for ech ech outer cover type, type, when replcing n n existingdiesel dieseloil oilboiler with GSHPs, show show economic economic prits prits fter fter bout bout 6 6 yers yers for for greenhouse greenhouse glss, glss, fter fter 9 yers 9 yers for for polyethylene, polyethylene, fter fter 8 yers 8 yers for polycrbonte. for polycrbonte. In future, optiml operting conditions design methods will be estblished during long term ing opertion, using deep georml well, through continuous monitoring systems.

12 Energies 2016, 9, In future, optiml operting conditions design methods will be estblished during long-term ing opertion, using deep georml well, through continuous monitoring systems. Acknowledgments: This reserch supported by Bsic Reserch Project Kore Institute Geoscience Minerl resources (KIGAM) funded by Ministry Science, ICT Future Plnning Kore (GP ) Bsic Science Reserch Progrm through Ntionl Reserch Foundtion Kore (NRF) funded by Ministry Eduction, Science Technology (2015R 1D 1A3A ). Author Contributions: All uthors contributed eqully to this work. All uthors designed experiment simultions, discussed results implictions commented on mnuscript t ll stges. Conflicts Interest: The uthors declre no conflict interest. References 1. U.S. Government Accountbility Office (GAO). Avilble online: EMD (ccessed on 15 Jnury 2016). 2. Renewble Energy Country Priles Asi; Interntionl Renewble Energy Agency (IRENA): Abu Dhbi, UAE, New Renewble Energy White Pper; New Renewble Center Kore Energy Agency: Yongin, Kore, Kore Ministry Government Legisltion. Ntionl Lw Informtion Center. Avilble online: (ccessed on 8 July 2015). 5. Nm, Y.J.; Che, H.B. Numericl simultion for optimum design ground source pump system using building foundtion s horizontl exchnger. Energy 2014, 73, [CrossRef] 6. Nguyen, A.; Psquier, P.; Mrcotte, D. Influence groundwter flow in frctured quifers on sting column wells performnce. Geormics 2015, 58, [CrossRef] 7. Prk, B.H.; Be, G.O.; Lee, K.K. Importnce rml dispersivity in designing groundwter pump (GWHP) system: Field numericl study. Renew. Energy 2015, 83, [CrossRef] 8. Cssso, A.; Sethi, R. Modeling rml recycling occurring in groundwter pumps (GWHPs). Renew. Energy 2015, 77, [CrossRef] 9. Russo, S.L.; Civit, M.V. Open-loop groundwter pumps development for lrge buildings: A cse study. Geormics 2009, 38, [CrossRef] 10. Russo, S.L.; Tddi, G.; Bccino, G.; Verd, V. Different design scenrios relted to n open loop groundwter pump in lrge building: Impct on subsurfce primry energy consumption. Energy Build. 2011, 43, [CrossRef] 11. Russo, S.L.; Tddi, G.; Verd, V. Development rmlly ffected zone (TAZ) round groundwter pump (GWHP) system: A sensitivity nlysis. Geormics 2012, 43, [CrossRef] 12. Mine, V. Experimentl investigtion relibility residentil sting column pump systems without bleed in cold climtes. Appl. Therm. Eng. 2013, 52, [CrossRef] 13. Hwng, S.H.; Prk, I.H.; Song, Y.H. Interprettion geophysicl well logs from deep georml borehole in Pohng. J. Geophys. Geophys. Explor. 2007, 10, Development Technology for CO 2 Geologicl Storge Securing Green Energy Resources in Deep Geo-Environment: Chrcteriztion Georml Anomlies Georml Resource Assessment in Soustern Prt Koren Peninsul; Kore Institute Geoscience Minerl Resources (KIGAM): Dejeon, Kore, Kore Meteorologicl Administrtion Resources (KMA). Avilble online: (ccessed on 2 July 2015). 16. Web site Kore Institute Energy Reserch (KIER). Avilble online: GEO/GEO.HTML (ccessed on 17 Jnury 2016). 17. Georml Het Pump Mnul: A Design Instlltion Guide for New York City; New York City Deprtment Design Construction: New York, NY, USA, Cho, J.H.; Kim, H.C.; Nm, Y.J. Study on performnce test georml pump system using deep well. In Proceedings SAREK 2014 Winter Annul Conference, Seoul, Kore, 28 November 2014; pp

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