LCOH for Solar Thermal Applications

Transcription

1 Descriptin: Date: 06/03/2017 Authrs: Guideline fr levelized cst f heat (LCOH) calculatins fr slar thermal applicatins Yann Luvet (University f Kassel), Stephan Fischer (ITW Stuttgart), Simn Furb (Technical University f Denmark), Federic Givanetti (ISFH), Franz Mauthner (AEE Intec), Daniel Mugnier (Tecsl), Daniel Philippen (SPF) Dwnlad pssible at: Intrductin In the framewrk f the IEA-SHC Task 54 appeared the need f assessing the csts f the heat prduced by slar thermal systems ver their life time in rder t cmpare different designs and technlgical slutins with ne anther. The levelized cst f heat (LCOH), a measure based n the cncept f levelized cst f energy, widespread in the electrical pwer sectr, was chsen. This inf sheet builds n the wrk f the FRNT prject [1] wh laid the fundatins fr the applicatin f the methd t any heating technlgy. It aims at detailing the methdlgy t calculate the levelized cst f the heat substituted by slar thermal energy. Furthermre, an extensin f the cncept is suggested in rder t estimate the cst f the heat generated by the entire slar assisted heating system, r the cnventinal surces f heat supply. General frmulatin The LCOH fr slar thermal applicatins can be derived frm the fllwing frmula, based n [1] and [2]: I 0 S 0 + T C t (1 TR) DEP t TR t=1 (1 + r) LCOH = t RV (1 + r) T E T t t=1 (1 + r) t Where: LCOH: levelized cst f heat in /kwh I 0 : initial investment in S 0 : subsidies and incentives in C t : peratin and maintenance csts (year t) in TR: crprate tax rate in % DEP t : asset depreciatin (year t) in RV: residual value in E t : saved final energy (year t) in kwh r: discunt rate in % T: perid f analysis in year Ntes: 1) It is pssible t input the cst variables C t, DEP t and RV either in current r in cnstant eurs. The discunt rate shuld be chsen accrdingly, respectively nminal r real (adjusted fr inflatin). As a cnsequence ne might btain tw different LCOH values, depending n the discunt rate selected: the LCOH in nminal terms and the LCOH in real terms. By definitin, the LCOH in nminal terms is always larger than the ne in real terms (as r nminal > r real ). 2) All csts are net csts (excluding VAT). 1

2 Cnventinal reference system The calculatin f the LCOH substituted by slar thermal energy requires the definitin f a cnventinal reference heating system. This cnventinal reference system is a theretical heating system which wuld supply the same amunt f energy t the end user as the slar thermal system, but withut slar assistance. It is needed t calculate I 0 and E t (see belw). Main assumptins fr slar thermal applicatins This sectin fcuses n the LCOH substituted by slar thermal energy. All cst variables (I 0, S 0, C t, DEP t and RV) thus nly refer t the cmpnents dedicated t slar thermal heat prductin and integratin, mainly cllectrs, buffer stre, pumps, heat exchangers, pipe wrks and cntrl unit. Initial investment (I 0 ): The cst f the strage frm the cnventinal reference system and the assciated installatin csts shuld be subtracted frm I 0 if applicable. In case f building integrated slar thermal systems bth fr new buildings r building renvatin, the cst f the building cmpnent (rf r wall sectin) substituted with slar thermal cllectrs and the assciated installatin csts shuld be subtracted frm I 0 if applicable. The size f the strage in the cnventinal reference system strngly depends n the applicatin. Sme guidelines might be used, as [3] fr dmestic ht water systems fr instance. Subsidies and incentives (S 0 ): The user might decide t include r nt subsidies and ther incentives in the calculatin. Operatin and maintenance csts (C t ): C t = O t + M t where O t and M t respectively crrespnds t the peratin and maintenance csts. It is recmmended t use a single fixed value fr O t and M t (O and M): C t = O + M Operatin csts (O) crrespnd t the pwer cnsumptin f the pump and cntrller and depend n the electricity price, different frm cuntry t cuntry. The running time f the pump can nly be determined with numerical simulatins. Fr refined calculatins, it is pssible t apply an electricity price index increase different frm the inflatin. In this case it is necessary t adjust the index fr inflatin if the cst variables are given in cnstant eurs. Usually 0.01 I 0 < M < 0.02 I 0 [4]. Fr a mre detailed analysis, the values given in [5] might als be used. Crprate tax rate (TR) and asset depreciatin (DEP t ): Only apply t the industrial and cmmercial sectrs. Fr the residential sectr ne shuld take TR = DEP t = 0. 2

3 Residual value (RV): Fr residential slar thermal applicatins, the residual value is cnsidered equal t zer: RV = 0. Fr the industrial and cmmercial sectrs hwever psitive values might be used. T calculate RV, ne shuld cmpare the perid f analysis (T) and the technical lifetime f the different cmpnents. Each cmpnent having a different technical lifetime, its replacement shuld be taken int cnsideratin when calculating RV. Typical values fr assessing the technical lifetime f cmpnents might be fund in [5] and [6]. Saved final energy (E t ): T allw the cmparisn between different slar thermal technlgies and system designs fr a given reference case, the saved final energy shuld be used here and nt the slar energy yield. Fllwing [3], E t = E cnv E aux = Q cnv,net η cnv Where: E cnv : grss (final) energy demand f the cnventinal (reference) heating system in kwh E aux : grss (final) auxiliary energy demand f the slar heating system in kwh Q cnv,net : net energy demand f the cnventinal heating system in kwh Q aux,net : net energy demand f the slar heating system delivered by the auxiliary heater in kwh Q aux,net η aux = Q d+q l,cnv η cnv Q aux,net η aux Q d : ttal heat demand in kwh Q l,cnv : heat lsses f the heat strage f the cnventinal (reference) heating system in kwh η cnv : annual utilisatin rati 1 f the heater f the cnventinal (reference) heating system η aux : annual utilisatin rati f the auxiliary heater f the slar heating system η cnv and η aux are highly dependent n the type f heater and n the perating cnditins (ntably winter vs. summer mde). Hwever fr practical reasns, η cnv = η aux as well as a single yearly value shuld be cnsidered. Values fr η cnv = η aux will be fixed within the reference slar thermal systems defined in Task 54. They will depend n the cuntry and the kind f reference heating system used. Fllwing these assumptins: E t = Q d + Q l,cnv Q aux,net η cnv Q d and Q aux,net might be determined with a single simulatin f the slar thermal system. Q l,cnv might be estimated either theretically, fr instance accrding t [3], r by means f a secnd simulatin where the slar thermal lp is turned ff. In the latter case, ne shuld nt frget t adapt the size f the heat strage. Simulatins nrmally always estimate E 1. A crrectin factr might be applied t the subsequent E t (t = [2.. T]) in rder t take int cnsideratin the ageing f the system. 1 The annual utilisatin rati takes int cnsideratin the steady-state efficiency f the heater as well as cyclic effect during transient phases and standby lsses. Indicative values are given in [4] and [7] fr instance. 3

4 Unfrtunately, nly few analyses are available n the degradatin rate f slar thermal systems. Experience shws hwever that each system shuld be cnsidered specifically as there is s far n general criterin applying t this issue. Discunt rate (r): The discunt rate is nrmally taken equal t the weighted average cst f capital (WACC). Fr single-family huse systems, the ttal system csts are usually paid up frnt. In this case, r = 0 (real discunt rate). The nminal discunt rate is derived frm the real ne with the relatinship r nminal = r real (1 + i) + i, where i is the inflatin rate. Perid f analysis (T): It is usually equal t the expected technical lifetime f the slar thermal system. This value is cuntry and system dependent. Fr dmestic systems fr instance, 20 t 25 years in Germany and 25 years in Switzerland are cmmnly cnsidered. In Denmark, 30 t 35 years are standard fr large slar heating plants. One culd als chse t cnsider the ecnmic lifetime (expected perid ver which the asset will yield benefits) rather than the technical lifetime. LCOH substituted by slar thermal energy vs. LCOH generated by the slar assisted heating system The methdlgy described in the previus sectin allws the calculatin f the levelized cst f the heat which is substituted by slar energy. A similar apprach was previusly applied in [8] and [9]. This is sufficient t cmpare different slar thermal technlgies and system designs against each ther. Hwever in rder t cmpare a slar assisted heating system with ther heating technlgies (heat pump, wd pellets biler, etc.) the levelized cst f the ttal heat generated by the slar assisted heating system has t be calculated. T d s the methdlgy described abve fr the calculatin f each term f the LCOH equatin has t be adapted as described in Table 1. Table 1. Assumptins fr the calculatins f the different terms f the LCOH equatin depending n the type f LCOH cnsidered. Parameter I 0 C t LCOH substituted by slar thermal energy Investment csts fr the slar related cmpnents f the entire heating system O&M csts related t the slar related cmpnents f the entire heating system LCOH generated by the slar assisted heating system Investment csts fr the entire heating system O&M csts fr the entire heating system; the csts f the fuel used by the auxiliary heater need t be integrated here Depreciatin f the entire heating system DEP t Depreciatin f the slar related cmpnents f the entire heating system S 0 Subsidies fr the slar related cmpnents f All subsidies given t build the entire heating the entire heating system system RV Residual value f the slar related cmpnents Residual value f the entire heating system f the entire heating system E t Saved final energy Ttal heat demand 4

5 References [1] Baez, M.J., Larriba Martínez, T., Technical Reprt n the Elabratin f a Cst Estimatin Methdlgy, N. D.3.1. Creara, Madrid, Spain. [2] Shrt, W., Packey, D.J., Hlt, T., A Manual fr the Ecnmic Evaluatin f Energy Efficiency and Renewable Energy Technlgies, N. NREL/TP Natinal Renewable Energy Labratry (NREL), Glden, Clrad, USA. [3] CEN, EN :2012 Thermal slar systems and cmpnents Custm built systems Part 2: Test methds fr slar water heaters and cmbisystems. Eurpean Cmmittee fr Standardizatin (CEN), Brussels, Belgium. [4] VDI, VDI 6002, Blatt 1 - Slare Trinkwassererwärmung Allgemeine Grundlagen Systemtechnik und Anwendung im Whnungsbau. Verein Deutscher Ingenieure (VDI), Düsseldrf, Germany. [5] VDI, VDI 2067, Blatt 1 - Wirtschaftlichkeit gebäudetechnischer Anlagen Grundlagen und Kstenberechnung. Verein Deutscher Ingenieure (VDI), Düsseldrf, Germany. [6] Suter, J.-M., Kvács, P., Hausner, R., Visser, H., Peter, M., Durability and reliability f slar cmbisystems, in: Weiss, W. (Ed.), Slar Heating Systems fr Huses - A Design Handbk fr Slar Cmbisystems. Slar Heating and Cling Executive Cmmittee f the Internatinal Energy Agency (IEA), Lndn, UK, pp [7] ASHRAE, ASHRAE handbk: heating, ventilating, and air-cnditining systems and equipment. American Sciety f Heating, Refrigerating and Air-Cnditining Engineers (ASHRAE), Atlanta, USA. [8] Mauthner, F., Herkel, S., Technlgy and demnstratrs - Technical Reprt Subtask C Part C1. AEE Intec, Gleisdrf, Austria. [9] IEA-SHC, Slar Heat Wrldwide. URL: (Accessed ). 5