Thermal Energy Storage in Solar Thermal Power Plants

Thermal Energy Storage (TES)

Technologies

Applications – Ice cream

cart to Power Gen

Materials -pebbles, Metals,

Molten salt, Paraffin Wax

TES –

Storage of energy in the form

of Latent or Sensible heat of

a material for a later use

WIDE

TES in Power Generation Applications –Concentrated Solar Plants (CSP)

Solar Field

Power BlockTES

Primary UsePower

ApplicationsCSP

Material75%

InstallationsMolten Salt

Parts of a typical Parabolic

Trough CSP with TES

Molten Salt Storage –Big installation base already

Storage – Base load Solar plants possible, Gema Solar 15 hours storage

Molten Salt Storage

2.5 GW ~13 GWh

Electrochemical storage

1.9 GW Small Durations

MOLTEN SALT – Ideal for CSP TES

Thermal Energy Storage (TES) TypesDirect and Indirect

TES

Direct Indirect

• No separate working

fluid for heating &

storage

• Mostly used with

Solar Tower

• E.g.: Solar Electric

Generating Station I,

Gema Solar etc.

• Higher operating

temp upto 5500 c

• Separate working

fluid for heating

(HTF) and storage

(molten salt)

• Mostly used with

Parabolic Trough

• E.g. : Arenales,

Andasol-I, Andasol-II

• Lower operating

temp upto 3800 cRef: NREL,IRENA

Working Principle of Parabolic Trough plant and and need for storage

© Solarmillenium

Cold Tank

Power Block

Heat

ExchangerHeat

Xchngr

Solar Field

380o C

390o C

285o C

385o C

290o C

290o C

Hot Tank

390o C

DD

Parabolic Trough Type Solar Power Plant – Storing Heat in the Molten Salt

© Solarmillenium

Cold Tank

Power Block

Heat

ExchangerHeat

Xchngr

Solar Field

380o C

390o C

290o C

285o C

390o C

290o C

385o CHot Tank

DD

Parabolic Trough Type Solar Power Plant – Recovering Heat from Molten Salt

Cold Tank

Power Block

Heat

ExchangerHeat

Xchngr

Solar Field

380o C

390o C

285o C

390o C

290o C

385o CHot Tank

DD

Molten Salt – Direct storage systems Generally used with Solar Tower - CSP

Solar Tower

Heliostats

Central

Receiver

Hot Tank

Solar Tower - CSP plants Molten Salt – Direct storage systems

Cold Tank

Power Block

Heat

Exchanger

Solar Tower

Upto 560o C

Hot Tank

Plant Configuration

• Technology: Parabolic trough

• Electricity Generation: 150 GWh/yr

• PT Loops : 156

• Turbine Capacity (Gross): 50 MW

• Storage – 7 Hrs Full load

Thermal Storage

• EPC - Flagsol

• Molten Salt - 28,500 tons (BASF)

• Tank Height - 14 m

• Tank diameter – 38.5m

• Temp loss per day – 1o

C

Steag 50 MW CSP Plant with 7 Hrs storageMain Parameters

Molten Salt Indirect storage : Costing Breakup