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

SLIDE 1

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

ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 DLR.de • Chart 1

SLIDE 2

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

ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 DLR.de • Chart 2

SLIDE 3

Air-operated CSP Plants (Solar Tower Jülich/STJ)

HTF: Air at atmospheric pressure,

heated up to about 700ºC and then powering a steam generator.

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Sensible heat storage : TES by

temperature increase (cp ∆T)

Latent heat storage : TES by phase

transition (∆ hsl)

Thermochemical storage : TES by

chemical reaction (∆ hR) 7m x 7m x 6m

S. Zunft, et al.:SolarPACES, (2009); (2010); JSEE (2011); Energy Procedia, (2014).

SLIDE 4

From TES with sensible heat to hybrid sensible-thermochemical storage with redox oxides

> 14 ECERS, Toledo, Spain > Agrafiotis, Becker, deOliveira, Roeb, Sattler > June 21-25, 2015 DLR.de • Chart 4

General Atomics: GA–C27137: THERMOCHEMICAL HEAT STORAGE FOR CONCENTRATED SOLAR POWER THERMOCHEMICAL SYSTEM REACTOR DESIGN FOR THERMAL ENERGY STORAGE ; Phase II Final Report, 2011

Increase the volumetric storage density instead of the storage volume: “coat with/ make of” honeycombs with redox oxide

MO2x+1→ MO + xO2

SLIDE 5

Cascaded ThermoChemical Storage (CTCS)

A cascade of different redox oxide

materials can be combined with various porous structures along as well “across” the reactor/heat exchanger.

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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).

HTF flow when discharging

SLIDE 6

Tests Scale Evolution (single-oxide or cascaded testing)

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TGA Lab-scale furnace test rig Solar receivers

SLIDE 7

TGA (DSC) rig: Cyclic reduction – oxidation protocol weight change (vs. stoichiometric) = f(T)

> 14 ECERS, Toledo, Spain > Agrafiotis, Becker, deOliveira, Roeb, Sattler > June 21-25, 2015 DLR.de • Chart 7

100 200 300 400 500 600 700 800 900 92 93 94 95 96 97 98 99 100 101

Tplateau oxidation Tplateau reduction

Weight change (%) Time (min)

200 400 600 800 1000 1200

MexOy reduced MexOy oxidized Ar Air

Temperature (

C)

Tredox = ?

C

MexOy: Tplateau reduction > Tredox > Tplateau oxidation

t=1 hr t=1 hr

Reaction Tred (oC) Max. wt. loss ( %) 2 BaO2 + ΔH → 2 BaO + O2 690 ‐9.45 2 Co3O4 + ΔH → 6 CoO + O2 870 ‐6.64 6 Mn2O3 + ΔH → 4 Mn3O4 + O2 950 ‐3.38 4 CuO + ΔH → 2 Cu2O + O2 1030 ‐10.01

SLIDE 8

TGA: Co3O4 /CoO

Co3O4 can operate in a quantitative,

cyclic and fully reversible reduction/

xidation mode within 800-1000oC

(950oC).

As powder, coated on honeycombs/

foams or shaped in foams.

ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 DLR.de • Chart 8

400 800 1200 1600 2000 2400 2800 92 93 94 95 96 97 98 99 100 101 102

Coating powder Cycles 1-30: Coated cordierite foam 3, loading 64% (overall); calculated per mass of loaded powder

Weight change (%) Time (min)

6.69 %

2000
1000

1000

Temperature (

C)

Co3O4-loaded Cordierite foam 985-785

C, 5
C/min; long-term cycling

500 1000 1500 2000 2500 92 93 94 95 96 97 98 99 100 101 102

Co3O4 powder, 30 cycles: 985-785

C, 5
C/min

Weight change (%)

Weight change (%) Time (min)

200 400 600 800 1000 1200

Temperature

Temperature (

C)

90 91 92 93 94 95 96 97 98 99 100 101 102

Co3O4 made foams, cycles 1-30 Foam, 30 ppi, No 1

Weight change (%)

Weight change (%) Time (min)

800 1000 Temperature

Temperature (

C)

Agrafiotis, Roeb, Schmücker, Sattler, Solar Energy, Parts I, II, III (2014), (2015).

SLIDE 9

TGA: Mn2O3/Mn3O4

Mn2O3: reduction fast, stoichiometric;

but large temperature “gap” between reduction (950oC) - oxidation (780- 690oC) !!

Very narrow temperature range (690-

750oC) within which Mn2O3 re-

xidation is significant.
Mn2O3 re-oxidation is slow and needs

extended dwell at the optimum temperature (range) for completion.

Can be also achieved with slow rates

and no dwell as shown below.

ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 DLR.de • Chart 9 100 200 300 400 500 600 700 800 900 1000 95 96 97 98 99 100 101

Weight change (%)

Weight change (%) Time (min)

Wt loss: 3.68 %

Tdwell oxidation: 900

C

200 400 600 800 1000 1200

T = 1000

C

Temperature

Temperature (

C)

Trdxn = 950

C

Mn2O3, 10

C/min

Tox = 780

C

100 200 300 400 500 600 700 800 900 1000 95 96 97 98 99 100 101

Weight change (%)

Weight change (%) Time (min)

Wt loss: 3.68 %

Tdwell oxidation: 900

C

650

C

200 400 600 800 1000 1200

T = 1000

C

Temperature

Temperature (

C)

Mn2O3

100 200 300 400 500 600 700 800 900 1000 95 96 97 98 99 100 101

Weight change (%)

Weight change (%) Time (min)

Wt loss: 3.68 %

Tdwell oxidation: 900

C

750

C

650

C

200 400 600 800 1000 1200

Temperature

Temperature (

C)

Mn2O3

100 200 300 400 500 600 700 800 900 1000 95 96 97 98 99 100 101

Weight change (%)

Weight change (%) Time (min)

Wt loss: 3.68 %

Tdwell oxidation: 900

C

750

C

690

C

650

C

200 400 600 800 1000 1200

Temperature

Temperature (

C)

Mn2O3

100 200 300 400 500 600 700 800 900 1000 95 96 97 98 99 100 101

Weight change (%)

Weight change (%) Time (min)

Wt loss: 3.68 % Wt loss: 3.70 % Wt re-gain: 3.51 %

Tdwell oxidation: 900

C

750

C

720

C

690

C

650

C

200 400 600 800 1000 1200

Temperature

Temperature (

C)

T = 950

C

Mn2O3

T = 780

C

T = 870

C

SLIDE 10

TGA: Other oxides

CuO/Cu2O: reduction temperature

very close to m.p. of Cu2O (shrinkage and sintering); could not work reproducibly even for few (5 cycles).

BaO2/BaO: BaO reacts with CO2

present in air to BaCO3

Perovskites: loose/gain (little) weight

continuously with T (perhaps plus in a cascade but ∆H also very low):

ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 DLR.de • Chart 10

100 200 300 400 500 600 92 93 94 95 96 97 98 99 100 101

Wt re-gain: 0.6 %

Weight change (%)

Weight change (%) Time (min)

La SrFeO3

Wt loss: 1.35 %

400 800 1200

Temperature

Temperature (

C)

Reaction ΔH (kJ/mol) Tred (oC) Tox (oC) 2 Co3O4 + ΔH → 6 CoO + O2 202.5 895 875 6 Mn2O3 + ΔH → 4 Mn3O4 + O2 31.9 950 720

Favourable Ts for oxidation but entire

cascade needs T > 950oC during reduction

SLIDE 11

Furnace test rig: “Visualization” of Hybrid Sensible-TCS

vs. Sensible-only storage effect

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200 400 600 800 1000 200 400 600 800 1000 1200

Temperature (C°) Time (min)

Temperature at reaction zone end 370 sccm

200 400 600 800 1000 10 20 30 40 50 60

Co3O4-Coated honeycombs

O2 concentration (% in air)

Total Co3O4 coated mass = 98 g O2 concentration 370 sccm

200 400 600 800 1000 200 400 600 800 1000 1200

Temperature (C°) Time (min)

Temperature at reaction zone end 2500 sccm

200 400 600 800 1000 10 20 30 40 50 60

Co3O4-Coated honeycombs

O2 concentration (% in air)

Total Co3O4 coated mass = 98 g O2 concentration 2500 sccm

200 400 600 800 1000 200 400 600 800 1000 1200

Temperature (C°) Time (min)

Temperature at reaction zone end 5000 sccm

200 400 600 800 1000 10 20 30 40 50 60

Co3O4-Coated honeycombs

O2 concentration (% in air)

Total Co3O4 coated mass = 98 g O2 concentration 5000 sccm

200 400 600 800 1000 200 400 600 800 1000 1200

Temperature (C°)

Difference between Sensible and Thermchemical effect Coated vs. non-coated honeycombs

Air flow rate = 5000 sccm Temperature at reaction zone end: Coated honeycombs Non-coated honeycombs

200 400 600 800 1000 10 20 30 40 50 60

O2 concentration

O2 concentration (% in air) Time (min)

SLIDE 12

Solar furnace test rig: Receiver – storage modules assembly; 1st tests: T along non-coated storage module (sensible-only storage)

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SLIDE 13

Comparative testing of storage module and (SiC) receiver types (190 slm)

ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 DLR.de • Chart 13

SiSiC honeycomb 90 cpsi; Schunk Weight 1404 g Length = 15 cm 3 SiSiC foams 10 ppi; ERBICOL Weight  246 g Length = 12 cm ReSiC honeycomb 90 cpsi; Stobbe TC Weight  584 g Length = 10 cm 3 Cordierite foams 30 ppi; L = 12 cm 1 Cordierite honeycomb 400 cpsi L = 12 cm

SLIDE 14

Comparative performance of SiC receivers tested

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100 200 300 400 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 100 200 300 400 50 100 150 200 250

Receiver: SiSiC honeycomb

Temperature (

C)

Time (min)

T1 T2 T3 T4 T5 T6 T7 T9 T8

100 200 300 400

Air Flow: 190 slm Receiver: SiSiC foams T1 T3 T4 T5 T6 T7 T9 T8

Time (min)

100 200 300 400

Receiver: ReSiC honeycomb

Time (min)

T1 T3 T4 T5 T6 T7 T9 T8 Tcamera

50 100 150 200 250

T31030oC T3930oC T3930oC T5 975oC T5915oC T5875oC T6 725oC T6755oC T6775oC

SLIDE 15

Conclusions:

The construction modularity of the current state-of-the-art storage system in air-
perated STPPs provides for implementation of concepts like cascades of

different redox oxide materials and spatial variation of solid material porosity in three dimensions, to enhance utilization of heat transfer fluid and storage of its enthalpy.

However: limited variety of redox oxides available within the particular

temperature range. Co3O4: the most “reliable”, demonstrating full, quantitative cyclability within a narrow temperature range (“model system”).

Mn2O3: low cooling rates required for oxidation; large “temperature gap”

between reduction/oxidation temperature. This “disadvantage” though, can be rendered to benefit within a cascaded structure.

Relatively high reduction temperatures of both Co3O4 (Tred  895oC) and Mn2O3

(Tred  950oC ).

Could be achieved in the solar furnace with currently available SiSiC honeycomb

receivers: capability of solar-heating incoming air to  1050oC, and two cordierite foams downstream ( 8 cm) to  950oC demonstrated.

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SLIDE 16

Acknowledgements:

To EU for financing this work under

the MARIE CURIE ACTION Intra- European Fellowships (IEF) Call: FP7- PEOPLE-2011-IEF, Grant 300194: Thermochemical Storage

f

Solar Heat via Advanced Reactors/Heat exchangers based on Ceramic Foams (STOLARFOAM)

To DLR Programmdirektion Energie

(PD-E) for funding through Project Thermochemical storage for CSP- applications based

n

Redox- Reactions – from materials to processes (REDOXSTORE).

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SLIDE 17

Thank you for your attention !

christos.agrafiotis@dlr.de
martin.roeb@dlr.de
christian.sattler@dlr.de

> ASME Power Energy 2015, San Diego, CA, U.S.A. > Agrafiotis, Becker, deOliveira, Roeb, Sattler > July 1st, 2015 DLR.de • Chart 17