Moving forward towards low cost, dispatchable and competitive STE

Transcription

1 Moving forward towards low cost, dispatchable and competitive STE by Manuel Collares Pereira (Renewable Energies Chair-REC)

2 Solar Thermal Electricity (STE): the role of storage Quick review of present day technologies for STE R&D goals,drivers and constraints to be faced Thermal Energy Storage -dispatchability PV and complementarity Linear concentrators : PT and LFR Advanced Optics (N.I.O.) is an essential part of a final solution Some recent solutions and specific proposals Final remarks 2

3 Main STE technologies LFR PT 2D- linear concentration technologies, PT anf LFR 3D- tower technology

4 Parabolic Trough Technology (PT) - 50MW Plants 2 x 50 MW, 7 h St. ~7,7 hours of storage molten salts

5 HTF- Dowtherm A (393ºC) and a two tank molten salts storage system 5

6 STE costs are still not the same as those of PV, ( market ~4,2 GW vs ~400 GW of PV), but getting there Required value of a 25 years PPA for a 150 MW, 4 hours storage, without any public financial aids and no escalation Stars corresponds to normalized PPAs or FiTs at their respective locations in Spain, India, Morocco, Israel and South Africa 2100 Storage value (NREL) 3-5 c/kwh Hypothesis: GW will be built at that time. Some breakthroughs might accelerate this trend. Source: ESTELA Position Paper

7 Storing Energy: electricity, heat In batteries Today: euro/kwhe stored Soon (2-3 years) (?!) 150 a 200 euro/kwhe Duration: 10 years? As heat: Today : 20 a 40 euro/kwhe Within 2-3 anos: 10 a 15 euro/kwhe Duration: 20 years? Factor X of diference in cost, today (and in the future?!!) Out Manuel Collares Pereira 7

8 and so PV, no batteries : the cheapest solar electricity today-grid parity on roof top - autoconsumo; centralized production costs for grid injection already at or below fossil fuel production STE- CSP with storage (7 to 15h at nominal power); dispatchable electricity, much cheaper than PV with batteries; also closer to being competitive by itself Out Manuel Collares Pereira 8

9 PV versus STE? Not in competition! Complementarity is clear PV decentralized (roof top, etc) and centralized production during the day STE- centralized dispatchable production Abril 2016 Manuel Collares Pereira 9

10 Abril 2016 Manuel Collares Pereira 10

11 The Challenge for STE Low cost electricity: 1) -increase efficiency in solar to electricity conversion 2) -reduce number of components and system cost + O&M costs add storage (to add value: dispatchability) 1) This really means going up in temperature (today : 565ºC!) 2) Reduce costs: the three main technological options have diferent costs: LFR, perhaps, has the lowest potential cost, but, today still also the lowest efficiency! 11

12 PT Field size (50MWe) 7.7 hr storage : 2*A 2*A= m2 Receiver lenght= 86,7 Km Total tube volume= (0.22l/m - 70mm pipe) = 19m3 6m Can the number of lines, components, pipe lenght be reduced? 12

13 Storage size: molten salts mixture Binary mixture: NaNO3-KNO3 (60-40%); (T fusion= 223ºC) Storage sensible heat ; 290ºC<T<390ºC ΔT for sensible heat storage- 100ºC Cp : kj/kg 50MWe*7.7h= 385MWh E=M*Cp* ΔT*ƞe M = 385 * 10^6 * 3.6*10^6 / 1600/100/0.33 (kg) M= ton! 13

14 Increasing operating temperature; effect on storage volume 14

15 Simplified plant scheme: Linear concentrator field and a 2 tank molten storage concept 540 C 550 C 292 C a need for higher concentration!?

16 Further research- Molten salts High operating temperature is achievable with concentrators, but: - problems: materials corrosion at high temperatures - Mixture stability/degradation - Cost! - Operational problems ( we need operating experience): start up, cloudy periods, turn off/drain or keep warm - ( ) 16

17 NEWSOL (H2020) A systematic tackling of the following problems: - molten salts for sensible liquid heat storage - high temperature performance: can concrete be used? structural concrete -concrete based high temperature thermal insulation -slag materials for solid sensible heat storage -PCMs latent heat storage Abril 2016 Manuel Collares Pereira 17

18 Horizon (Coord) University of EVORA Portugal 2 ACCIONA Spain (Industry) 3 CSIC Spain (R&D) 4 SECIL Portugal (Industry) 5 DLR Germany (R&D) 6 LNEG Portugal (R&D) 7 YARA Norway (Industry) 8 SINTEF Norway (R&D) 9 AIMEN Spain (R&D) 10 SSensor Italy (SME) 11 ACCIONA Ingeniería Spain (Industry) 12 ApEHR Denmark (SME) 13 ETH Switzerland (R&D) Abril 2016 Manuel Collares Pereira 18

19 Salts: the low temperature end Solidification/Fusion at 223ºC: is it too high? Come as close to ambient as possible Find other salts and mixtures: Ternary, quaternary mixtures, ( ) 19

20 Examples of possible molten salt mixtures with lower fusion points 20

21 Environmental Issue with heavy metals Leakage of heavy metals into the soil and ground water High emissions due to Acidic Mine Drainage (PH 1,5 2,5 in superficial groundwater) Possible aquifer contamination e) Melchsee-Frutt, 04th March

22 SSA 8/12 SSA 0/4 Experimentation Calcium Aluminate Cement w/ slag incorporation (CAC+) SCA 6/12 SCA 0/6 SSA 4/8 Two different concrete dosages were considered, maintaining the same type and content of binder but varying the type of aggregate: CAC mix (w/c=0,5) refers to CAC concrete prepared with 100% siliceous aggregates CAC+ mix (w/c=0,57) refers to CAC concrete prepared with a mix of 75% siliceous aggregates + 25% Slag Adjustment of aggregates dosage for the concrete was made following Bolomey calculations 22

23 Higher efficiency T: 565ºC? High Concentration is necessary! Thermal losses are proportional to receiver area (A receiver) C= A aperture/a receiver Iow thermal losses means a smaller receiver and that means higher C This has already been already proposed and achieved with 3D- tower technology 23

24 24

25 Central Receiver (CR) technology 19MW TORRESOL: 19MWe + 15 hours of storage 25

26 2D- Linear concentrators? Tube diameter is a constraint The choice of (evacuated) receiver tubes for high temperature performance is more or less fixed on the market! Diameter: 70 mm! (perhaps 80mm, 90mm ) 26

27 Higher concentration means a larger aperture size And that- in itself- has a very positive (cost reduction!) side: 2D- high concentration means that there will be less collector rows, for the same power capacity, thus there will be less piping less HTF as well less pumping losses and other parasitics less O&M But how wide can the aperture be? 27

28 Higher concentration PT 565ºC 28

29 Concentration for a parabola with a tubular receiver C=a/2πr= 1/sin (θ) * sin(φ)/π +θ -θ a mirror (2ϴsun=0.52º) ϴ=2.5xϴsun C= 27 (φ=90) φ 2r=70mm a= 5.93m 29

30 Are there limits to a? Etendue - a reminder Etendue is a geometrical quantity that measures the amount of room available for light to pass through du= da*cos θ *dω Spatial room : da * cos θ (light is crossing da in a direction θ) Angular room (the solid angle) : dω

31 High efficiency Etendue Conservation of Etendue through AB (from three identical flashlights) with an angular spread α associated is the same as Etendue (same three flashlights!) through the smaller area CD but now has a larger angular spread β

32 Maximal Concentration? The problem is: given radiation incident on an aperture a within a certain angular range (± ), how much can it be concentrated- Cmax? Conservation of Etendue applied to the problem of maximal concentration (2D)? C=Cmax=a/b=1/sin (θ) Non Imaging Optics (Ideal Optics) 32

33 A parabola is not an ideal concentrator! It is very far from the limit, just like any focussing type optics!!! C=1/sin (θ) * sin(φ)/π φ Cmax 33

34 CAP: a useful definition Cmax=1/sin (θ) sin (θ)*c= CAP <=1 CAP is the Concentration Acceptance-Product θ is the half-acceptance angle of the concentrator with concentration C For a PT, CAP is <= 1/π ~ 0.3 Abril 2016 Manuel Collares Pereira 34

35 Larger trough : go from ~6m to ~8m ~8m trough, same tube It means a smaller θ, i.e. higher mechanical manufacturing and tracking accuracies! 35

36 Larger θ and higher C: second stage C XX-SMS solution 36

37 XX-SMS solution Comparison with Conventional PT η opt0 C g CAP φ (deg) Aspect ratio (Height/Width) Aperture Width (m) Mirror length (m). [. PT XX SMS [. Tel Aviv February

38 Alternative : Linear Fresnel Technology? PSE Gmbh m 6m

39 But conventional Linear Fresnel is also far from the n.i.o. limits CAP=C*sin(θ) < 0.45 (<0.3 for tubes) Incident light with aperture 2*θ C=a/R C/Cmax=0.45 for the best case a ψ=40.4º (rim angle) 39

40 Besides etendue is not conserved i.e. less light goes toward the receiver than is incident on the reflectors (shading and blocking) Large room for improvement September18, 2009

41 Improvements CLFR (concept proposed by D. Mills et al.) it is a multiple receiver concept Improves on EM- etendue matching, but does not achieve the highest possible efficiency Does not use ideal second stage optics

42 Improvements Solutions with second stage concentrator: they improve the optical performance by using non-imaging optics They do not (attempt) maximize EM yet, and the nature of the optics used, limits collector width, i.e., forces the absorber to be at considerable height (Picture from NOVATEC) 42

43 Advanced LFR technology : high concentration can be more easily obtained Evolution of (C )LFR technology: -Enhancing average anual efficiency: new optics (seek Etendue Conservation ) -Enhancing concentration (seek maximal concentration) -Keeping solar field costs low, as with the conventional LFR technologies ( flat mirrors) -the receiver is fixed ( )

44 Go further: advanced solution A multiple receiver solution It nearly matches etendue (highest collection efficiency) It approaches ideal maximal concentration, through the use of a secondary; optimization of primary and secondary toghether September18, 2009

45 Possible solutions for A-LFR Heliostats on an etendue conserving curve

46 C=66x Operating temperature 565ºC Receiver height ~7m Module width (30m) Primary mirror area: ~750m2 A first prototype proposal

47 Linear Fresnel Etendue matched LFR XX-SMS C=74x (CAP~0.57) 70mm tube acceptance angle=0.88 deg (~3 suns) m SolarPACES 2014, Beijing 47

48 Latest proposal MSALFR brings it all together 48

49 Latest proposal MSALFR bringing it all together PrimaryTot width (m) Total mirror aperture width (m) Receiver Height (m) Number of mirrors Mirror width (m) φ ( ) C (X) θ ( ) CAP η opt0 MSALFR Optic L~24m 49

50 A- LFR plant: some operating details and storage integration 50

51 Expected results Location DNI (kwh/m2) Total average yearly efficiency Faro Portugal (37ºN) Hurghada : Egypt (27ºN) MW plant in Faro 565ºC: molten salts as HTF and 7 hours storage Steam 540ºC- 110bar (if LFR installed cost: euro/m2 ) < 8-10eurocent/kWh 51

52 Évora Molten Salt Platform - EMSP University of Evora + DLR YARA Industrial GmbH TSK Flagsol Engineering GmbH Steinmüller Engineering GmbH Leoni Kerpen GmbH Eskom Holding SOC - South Africa T<580 C; with energy storage and steam generation (540 C, 100bar) MWth - TSK- Flagsol - 1.0MWth - ALFR Ematched April 2018 Manuel Collares Pereira 52

53 Solar Concentrators Testing Platform- PECS April 2018 Manuel Collares Pereira 53

54 In conclusion N.I. Optics + Advanced LFR: a fair shot at low cost dispatchable electricty High concentration enhances efficiency (lower thermal losses) and substantially reduces: Number of rows Fluid volume Parasitic power consumption Fixed receiver substantially facilitates engineering, O&M Many other possible configurations to be evaluated and demonstrated (Ex: mirrors on an Etendue Matching curve, diferent mirror widths, etc) 54

55 In conclusion PV and STE are not competitors PV- decentralized production + some centralized production (during the day) STE- centralized production with storage (4-15 hours?) (coming into the grid, while the sun goes down, or when there is no sun!) Thermal Energy Storage is key! Thank you for your attention! euro/kwh, today, going to euro/kwh in the near future. 55

56 How far can we go? The importance of storage How far can we go? A concept proposed by David Mills,Robert Morgan [ISES Beijing paper (2007)] Big Solar i.e. solar for full power? Including the supply of base load on a large scale? 56

57 Abril 2016 Manuel Collares Pereira 57

58 US Solar Resources 100% US Power 147x147 km2 park BIG SOLAR!!! 34

59 Big Solar (a concept with storage on a daily scale) California Electricity Grid (CAISO) hourly data for 2006 Turbogenerator capacity matched to peak California load Collector: CLFR (2007) Calculation hour by hour for whole year SM1 means array produces at peak exactly the energy required by the turbine at peak; SMX array has X times the area of SM1

60 No Storage concept (8-9hr production) Copyright Ausra, Inc. 2007

61 8 hr production: Storage Storing heat on a large scale and low cost (7-21 euro/kwh) Copyright Ausra, Inc. 2007

62 92% correlation with SM3, no costly peaking plant needed!!!; peak turbine /peak load 50GW Abril 2016 Manuel Collares Pereira 62

63 Texas- Grid 63GW turbine/peakload; again ~92% correlation Abril 2016 Manuel Collares Pereira 63

64 California and Texas grid combined: ~96% correlation with 16 hours storage, SM3 US grid (scaled to 103GW peak) fed from California and Texas ; 96% correlation 30

65 Maturing the concepts Big Solar + storage renders obsolete the concern with solar (Renewables?) not being for base load STE has useful daily and seasonal correlations with load; coal and nuclear do not. Little or no costly peaking plant is required (can use existing Hydro) Is this the time to start thinking that solar energy can be a MAJOR electricity provider on a par with conventional sources??! New Molten salt solutions and higher efficiencies Energy STORAGE: a very hot topic!!!!

66 Abril 2016 Manuel Collares Pereira 66

67 Évora Molten Salt Platform - EMSP T<580ºC; University c/ armazenamento of Evora de energia + e produção de vapor (540ºC, DLR 100bar) YARA Industrial GmbH - TSK 3.2 Flagsol MWth -Engineering TSK- FlagsolGmbH - Steinmüller 1.0MWth - Engineering LFR Ematched GmbH Leoni (MSALFR Kerpen financ. GmbHCCDRA) Eskom Holding SOC - South Africa Maio 2016 Manuel Collares Pereira 67