high temperature thermochemical energy storage: operation … · 2014. 8. 27. · plate heat...

High Temperature Thermochemical Energy Storage: Operation Modes of a 10kW Pilot Reactor based on

CaO/Ca(OH)2

M. Schmidt, M. Linder, C.Roßkopf, M. Haas, M. Linder, A. Wörner, A. Thess

German Aerospace Center (DLR), Cologne, Germany

> Grand Renewable Energy 2014 > Matthias Schmidt • Operation Modes of a High Temperature Thermochemical Heat Storage System in kW-Scale > 28th July to 1st Aug 2014

www.DLR.de • Slide 1

High Temperature Thermochemical Energy StorageApplications

- Decoupling of solar radiation from eletricityproduction

- Flexibility of conventional power plants

- Reutilization of industrial waste heat


www.DLR.de • Folie 2

High Temperature Thermochemical Energy StorageLimestone as a promising storage material

- Cheap raw material (70$ per ton)

- Environmental friendly and nontoxic

- Production in industrial scale

- Additional chemical potential with the reaction with water vapor



Thermochemical Energy StorageReaction System CaO/ Ca(OH)2



CaO(s) + H2O(g) ⇌ Ca(OH)2(s) + ∆H

charging step - endothermal

0,001

0,01

0,1

1

10

1,0 1,1 1,2 1,3 1,4 1,5 1,6 1,7

p gas

[bar

]

Temperatur 1000 / T [1/K]

CaO(s)

Ca(OH)2(s)

636727 560 496 441 394 352 315

Temperature [°C]

H2O(g)

discharging step - exothermal

0,001

0,01

0,1

1

10

1,0 1,1 1,2 1,3 1,4 1,5 1,6 1,7

p gas

[bar

]

Temperatur 1000 / T [1/K]

Thermochemical Energy StorageReaction System CaO/ Ca(OH)2

- Very high energy density – 0,4 kWh/kg- Adjustability of charge and discharge temperature- Possibility to transform heat- Loss free storage of chemical potential



CaO(s) + H2O(g) ⇌ Ca(OH)2(s) + ∆H

storage Ca(OH)2(s)

CaO(s)

636727 560 496 441 394 352 315

Temperature [°C]

H2O(g)

Material Properties - CaO/Ca(OH)2

Chemical properties:

Thermophysical properties:



F.Schaube et al. (2012).A thermodynamic and kinetic study of the de- and rehydration of Ca(OH)2 at high H2O partial pressures for thermo-chemical heat storage. Thermochimica Acta 538(2012) 9 - 20

C. Roßkopf et. al (2014) Investigation of Nano Coated CaO Ca(OH)2 Cycled in Thermochemical in a Thermochemical Heat Storage, submitted

Pilot Reactor - 10kW, 25kg Ca(OH)2plate heat exchanger



HTF HTF

ReactionBed

Heat Flux

Heat Conduction

vReaction Bed

Pilot Reactor - 10kW, 25kg Ca(OH)2plate heat exchanger



HTF HTF

ReactionBed

Heat Flux

Heat Conduction

vReaction Bed

CaO(s) + H2O(g) ⇌ Ca(OH)2(s) + ∆H

510°C

Charging ModeDehydration of Ca(OH)2 at 100mbar vapor pressure



0

0,2

0,4

0,6

0,8

1

1,2

400

420

440

460

480

500

520

0 50 100 150 200 250 300 350 400 450

Pres

sure

[bar

]

Tem

pera

ture

[°C

]

Time [min]

T_air_in

T_R_03

T_R_05

T_R_11

T_R_12

T_air_out

p_reactor

Discharging Modehydration of CaO at 1 bar vapor



300

350

400

450

500

550

0,00 20,00 40,00 60,00 80,00 100,00 120,00 140,00 160,00 180,00

Tem

pera

ture

[°C

]

time [min]

T_air_inlet

T_R_01

T_R_05

T_R_11

T_R_13

Heat Generation ModeHydration of CaO, starting temperature of 350°C

www.DLR.de • Chart 11

0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

0,80

0,90

1,00

330

350

370

390

410

430

450

470

490

0,00 50,00 100,00 150,00 200,00 250,00

Con

vers

ion

Tem

pera

ture

[°C

]

time [min]

T_air_inlet

T_air_outlet

Conversion


Next StepsSeparation of Power and Capacity



Pro

cess

inte

grat

ion:

HTF

HTF

Capacity ~ A_hex ~ $$$

Pro

cess

inte

grat

ion:

Capacity

P_reactor ~ $

Next StepsSeparation of Power and Capacity – Pilot Plant in 2015



Capacity: 100 kWh~ 250 kg Ca(OH)2

Reactor: 10 kW~ 25 kg/h

Summary

- Thermochemical energy storage with CaO/ Ca(OH)2demonstrated in kW scale

- Peak power of 8 kW

- Charging at 450°C

- Discharging at 490°C and 545°C

- Demonstration of moving bed pilot plant scheduled for beginning of 2015



[email protected]

German Aerospace Center (DLR), Cologne, GermanyInstitute of Technical ThermodynamicsThermo-chemical Systems

high temperature thermochemical energy storage: operation … · 2014. 8. 27. · plate heat...

Documents