Hybrid sensible/thermochemical storage of solar energy in cascades - PowerPoint PPT Presentation

DLR.de • Chart 1 ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 Hybrid sensible/thermochemical storage of solar energy in cascades of redox-oxide-pair-based porous ceramics Christos Agrafiotis, Andreas Becker, Lamark deOliveira, Martin Roeb, Christian Sattler Institute of Solar Research DLR/ Deutsches Zentrum für Luft- und Raumfahrt/ German Aerospace Center Linder Höhe, 51147 Köln, Germany

DLR.de • Chart 2 ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 Outline: • Solar Energy Storage in air-operated Solar (Tower) Thermal Power Plants (STPPs) • ThermoChemical Storage (TCS) principles and redox oxide pairs • Some new ideas on redox-oxide- based porous ceramics for TCS in STPPs • From laboratory to solar testing • Conclusions, current and future work

DLR.de • Chart 3 ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 Air-operated CSP Plants (Solar Tower Jülich/STJ) • HTF: Air at atmospheric pressure, heated up to about 700ºC and then powering a steam generator . • Sensible heat storage : TES by temperature increase (cp ∆ T) • Latent heat storage : TES by phase transition ( ∆ h sl ) • Thermochemical storage : TES by chemical reaction ( ∆ h R ) 7m x 7m x 6m S. Zunft, et al.:SolarPACES, (2009); (2010); JSEE (2011); Energy Procedia, (2014).

DLR.de • Chart 4 > 14 ECERS, Toledo, Spain > Agrafiotis, Becker, deOliveira, Roeb, Sattler > June 21-25, 2015 From TES with sensible heat to hybrid sensible-thermochemical storage with redox oxides MO 2x+1 → MO + xO 2 Increase the volumetric storage density instead of the storage volume: “coat with/ make of” honeycombs with redox oxide General Atomics: GA–C27137: THERMOCHEMICAL HEAT STORAGE FOR CONCENTRATED SOLAR POWER THERMOCHEMICAL SYSTEM REACTOR DESIGN FOR THERMAL ENERGY STORAGE ; Phase II Final Report, 2011

DLR.de • Chart 5 ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 Cascaded ThermoChemical Storage (CTCS) • A cascade of different redox oxide materials can be combined with various porous structures along as HTF flow when discharging well “across” the reactor/heat exchanger . F. Dinter, M. Geyer, R. Tamme, Springer-Verlag, Berlin, (1991); Michels and Pitz-Paal, Solar Energy, 81 829–837, 2007 . TCS reactor/heat exchanger with spatial variation of functional materials and porosity in three dimensions, (C. Agrafiotis and R. Pitz-Paal, Patent Application Filed 2013).

DLR.de • Chart 6 ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 Tests Scale Evolution (single-oxide or cascaded testing) TGA Lab-scale Solar receivers furnace test rig

DLR.de • Chart 7 > 14 ECERS, Toledo, Spain > Agrafiotis, Becker, deOliveira, Roeb, Sattler > June 21-25, 2015 TGA (DSC) rig: Cyclic reduction – oxidation protocol weight change (vs. stoichiometric) = f(T) 1200 101 T plateau reduction 100 t=1 hr 1000 99 Weight change (%) 800 98 Temperature ( T redox = ? o C t=1 hr 97 600 96 T plateau oxidation o C) 400 95 94 Me x O y oxidized Me x O y reduced Air 200 Ar 93 Me x O y : T plateau reduction > T redox > T plateau oxidation 0 92 0 100 200 300 400 500 600 700 800 900 Time (min) Reaction T red ( o C) Max. wt. loss ( %) 2 BaO 2 + ΔH → 2 BaO + O 2 690 ‐9.45 2 Co 3 O 4 + ΔH → 6 CoO + O 2 870 ‐6.64 6 Mn 2 O 3 + ΔH → 4 Mn 3 O 4 + O 2 950 ‐3.38 4 CuO + ΔH → 2 Cu 2 O + O 2 1030 ‐10.01

DLR.de • Chart 8 ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 TGA: Co 3 O 4 /CoO 1200 1000 102 102 102 • Co 3 O 4 can operate in a quantitative, Co 3 O 4 -loaded Cordierite foam 985-785 o C, 5 o C, 5 o C/min; long-term cycling o C/min Co 3 O 4 powder, 30 cycles: 985-785 1000 101 800 cyclic and fully reversible reduction/ 101 101 100 1000 oxidation mode within 800-1000 o C 100 100 99 (950 o C) . 0 99 99 Weight change (%) 98 800 Weight change (%) Weight change (%) Temperature ( Temperature ( Temperature ( 97 • As powder, coated on honeycombs/ 98 98 96 600 foams or shaped in foams. 97 97 0 -1000 o C) 95 o C) 96 96 o C) 94 400 95 95 93 6.69 % -2000 92 94 94 200 91 Co 3 O 4 made foams, cycles 1-30 93 93 Weight change (%) Foam, 30 ppi, No 1 Coating powder Temperature Weight change (%) Cycles 1-30: Coated cordierite foam 3, loading 64% (overall); calculated per mass of loaded powder 90 Temperature 0 92 92 0 0 400 500 800 1000 1200 1500 1600 2000 2000 2400 2500 2800 Time (min) Time (min) Time (min) Agrafiotis, Roeb, Schmücker, Sattler, Solar Energy, Parts I, II, III (2014), (2015) .

DLR.de • Chart 9 ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 TGA: Mn 2 O 3 /Mn 3 O 4 1200 1200 1200 1200 1200 101 101 101 101 101 • Mn 2 O 3 : reduction fast, stoichiometric; Mn 2 O 3 Mn 2 O 3 Mn 2 O 3 Mn 2 O 3 o C/min Mn 2 O 3 , 10 but large temperature “gap” between o C T = 1000 o C T = 1000 1000 1000 1000 1000 1000 100 100 100 100 100 reduction (  950 o C) - oxidation (  780- T rdxn = 950 T = 950 o C o C Temperature ( Temperature ( Temperature ( Temperature ( Temperature ( Weight change (%) Weight change (%) Weight change (%) Weight change (%) Weight change (%) 690 o C) !! 800 800 800 800 800 99 99 99 99 99 o C T = 870 o C o C T = 780 T ox = 780 Wt loss: Wt loss: Wt loss: Wt loss: Wt loss: 3.68 % 3.68 % 3.68 % 3.68 % 3.68 % • Very narrow temperature range (  690- Wt loss: 3.70 % 600 600 600 600 600 98 98 98 98 98 750 o C) within which Mn 2 O 3 re- Wt re-gain: o C) o C) o C) o C) o C) 3.51 % oxidation is significant. 400 400 400 400 400 97 97 97 97 97 • Mn 2 O 3 re-oxidation is slow and needs 200 200 200 200 200 96 96 96 96 96 o C o C o C o C o C T dwell oxidation : T dwell oxidation : T dwell oxidation : T dwell oxidation : T dwell oxidation : 900 900 900 900 900 extended dwell at the optimum o C o C o C 750 750 750 o C 720 o C 690 690 o C Weight change (%) Weight change (%) Weight change (%) Weight change (%) Weight change (%) 650 o C o C 650 o C 650 650 o C Temperature Temperature Temperature Temperature Temperature temperature (range) for completion. 0 0 0 0 0 95 95 95 95 95 0 0 0 0 0 100 100 100 100 100 200 200 200 200 200 300 300 300 300 300 400 400 400 400 400 500 500 500 500 500 600 600 600 600 600 700 700 700 700 700 800 800 800 800 800 900 900 900 900 900 1000 1000 1000 1000 1000 • Can be also achieved with slow rates Time (min) Time (min) Time (min) Time (min) Time (min) and no dwell as shown below.

DLR.de • Chart 10 ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 TGA: Other oxides Reaction Δ H T red T ox • CuO/Cu 2 O: reduction temperature ( o C) ( o C) (kJ/mol) very close to m.p. of Cu 2 O (shrinkage 2 Co 3 O 4 + Δ H → 6 CoO + O 2 202.5 895 875 and sintering); could not work reproducibly even for few (5 cycles). 6 Mn 2 O 3 + Δ H → 4 Mn 3 O 4 + O 2 31.9 950 720 • BaO 2 /BaO: BaO reacts with CO 2 present in air to BaCO 3 • Perovskites: loose/gain (little) weight continuously with T (perhaps plus in a cascade but ∆ H also very low): 101 Wt loss: 1200 1.35 % 100 Wt re-gain: 0.6 % 99 Temperature ( Weight change (%) 98 800 97 96 o C) 95 400 • Favourable Ts for oxidation but entire 94 93 cascade needs T > 950 o C during reduction La SrFeO 3 Weight change (%) Temperature 92 0 0 100 200 300 400 500 600 Time (min)

DLR.de • Chart 11 ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 Furnace test rig: “Visualization” of Hybrid Sensible-TCS vs. Sensible-only storage effect 1200 1200 1200 1200 60 60 60 60 Coated vs. non-coated honeycombs Co 3 O 4 -Coated honeycombs Co 3 O 4 -Coated honeycombs Co 3 O 4 -Coated honeycombs Air flow rate = 5000 sccm O 2 concentration (% in air) 1000 1000 1000 1000 50 50 50 50 Temperature at reaction zone end: Temperature at reaction zone end Temperature at reaction zone end Temperature at reaction zone end O 2 concentration (% in air) O 2 concentration (% in air) O 2 concentration (% in air) Coated honeycombs 5000 sccm Non-coated honeycombs 2500 sccm 370 sccm Temperature (C°) Temperature (C°) Temperature (C°) Temperature (C°) O 2 concentration 800 800 800 800 40 40 40 40 Total Co 3 O 4 coated mass = 98 g Total Co 3 O 4 coated mass = 98 g Total Co 3 O 4 coated mass = 98 g O 2 concentration O 2 concentration O 2 concentration 5000 sccm 2500 sccm Difference between Sensible 600 600 600 600 370 sccm 30 30 30 30 and Thermchemical effect 400 400 400 400 20 20 20 20 200 200 200 200 10 10 10 10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 200 200 200 200 200 200 200 200 400 400 400 400 400 400 400 400 600 600 600 600 600 600 600 600 800 800 800 800 800 800 800 800 1000 1000 1000 1000 1000 1000 1000 1000 Time (min) Time (min) Time (min) Time (min)