Overview of thermal energy storage technologies and applications

by Dr Peter Klein CSIR

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Agenda

1. Why thermal energy storage

2. Description of thermal energy storage technologies

3. Identification of applications

4. Thermal storage testing laboratory

5. Conclusions

3

Importance of energy storage Increasing penetration of variable renewable energy generators requires flexibility

1Based on draft Integrated Resource Plan 2018

0

20

40

60

80

100

32%

16% 17%

19%

[GW]

13%

23%

2020 2030 IRP1

2030 IRP3

12%

18%

2040 IRP1

2050 IRP3

29%

2040 IRP3

21%

34%

2050 IRP1

29%

4%3%

Installed capacity Energy mix

Solar PV

Wind

0

50

100

150

200

250

[TWh]

2040 IRP1

36%8% 7%

1%

28%

3%

2020

13%

2030 IRP1

14%

2030 IRP3

15%

13%

25%

2040 IRP3

20%

42%

2050 IRP1

16%

2050 IRP3

Solar PV

Wind

Percentages indicate fraction of total generation installed capacity and energy mix

4

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

Thursday

Day of the week

GW

Wednesday SundayMonday Tuesday Friday Saturday

Future energy system will be built around variability of solar PV & windActual scaled RSA demand & simulated 15-minute solar PV/wind power supply for week from 15-21 Aug ‘11

Excess Solar PV/Wind

Residual Load (flexible power)

Useful Solar PV

Useful Wind

Sources: CSIR analysis

Electricity Demand

5

Value of a Flexible Energy System0% load flexible

Exce

ss

Def

icit

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

Flexible Gas (CCGT) Peaking Gas (OCGT)

Energy curtailed

In order of 15% of generated energy curtailed in models

Friday

Day of the week

GW

Monday Tuesday Wednesday SundaySaturdayThursday

6

Exce

ss

Def

icit

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

GW

SundaySaturdayFridayThursdayWednesdayTuesdayMonday

Day of the week

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

30No Flexible Load

Value of a Flexible Energy System25% load flexible – energy balanced intraday

7

Value of an Integrated Energy System25% load flexible – energy balanced intraweek

No Flexible Load

Exce

ss

Def

icit

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

GW

SundaySaturdayFridayThursdayWednesdayTuesdayMonday

Day of the week

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

8

So why use thermal energy storage for flexibility?Thermal energy is the dominant energy end-use

Power-to-Heat/Cold

• Solar Thermal (CSP)• Waste Heat Recovery• Biomass• Heat/Cold from Ambient• Absorption Chillers

Thermal Battery (TES)

Energy End-Use

Advantages of TES• Low cost• Low tech• Potential for seasonal storage and high energy storage densities (thermochemical)• High storage efficiencies• Scalable and modular• Wide operating conditions• Deployed at GWh scale or residential• Can size power and energy independently

Concept preferably requires thermal energy for end-use

9

So why use thermal energy storage for flexibility?Thermal energy is the dominant energy end-use

=92% =77% =71%

37% Final Energy Consumption2

6% Final Energy Consumption2

22% Final Energy Consumption2

1Based on DoE calculations in draft Integrated Energy Plan 20162Based on IEA Energy Balances for 2015

10

Chemicals

Iron and Steel

13%

87%

Thermal Non-Thermal

65%

35%

Non-ferrous metals

Other manufacturing

33%

67%

46%54%

Gold mining

Platinum mining

21%

79%

21%

79%

Based on DoE calculations in draft Integrated Energy Plan 2012

End-use of electricity in industry in South Africa

11

Integrating thermal storage into industry

12

Thermal Energy Storage

Thermal

Sensible Heat

Liquids Solids

Latent Heat

Solid-Liquid Liquid-Gas Solid-Solid

Chemical

Solid-Gas Reactions

Liquid-Gas Reactions

Gas-Gas Reactions

Overview of Thermal Energy Storage Technologies

13

Energy stored if no phase change

Charging

Discharging

Sensible heat TESLatent heat TES

PCM

Comparison of sensible and latent heat storage

technologies

Energy Stored Discharge Temperature

14

Sensible heat storage overview

L. Heller, Literature Review on Heat Transfer Fluids, STERG Report, 2013.

W. B. Stine and M. Geyer, “Power from the sun. Retrieved April 15, 2011, from http://www.powerfromthesun.net/book.html,” 2001.

15

Latent heat storage overview

Hoshi, Akira, et al. "Screening of high melting point phase change materials (PCM) in solar thermal concentrating technology based on CLFR." Solar

Energy 79.3 (2005): 332-339.

16

Latent heat storage: Ice storage for HVAC

https://www.energy-storage.news

Southern California Edison – 25.6MW of peak ice storage capacity 1800 behind the

meter ice batteries, as part of 250 MW energy storage requirement

17

0

1 000

2 000

3 000

4 000

5 000

6 000

0 2 4 6 8 10 12 14 16 18 20 22 24

Load [kW]

0

200

400

600

800

1 000

1 200

GHI [W/m2]

0

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35

40

0 2 4 6 8 10 12 14 16 18 20 22 24

Temp. [C]

0

5

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40

0 2 4 6 8 10 12 14 16 18 20 22 24

Temp. [C]

GHI and Temperature Load and Temperature

Alignment between Solar supply, load and temperature

as measured in summer at CSIR campus

18

Charging (endothermic) Discharging (exothermic)

Thermochemical heat storage overview

19

Example of adsorption storage system

20

Comparison of Thermal Energy Storage Energy Densities

21

Power-to-HeatWaste Heat Recovery Passive Applications

CSIR Energy Centre Thermal Storage ResearchKey roles identified for Thermal Storage

Concentrating Solar Power

Utilise low cost thermal storage to shift thermal loads in time

Based on US DOE, Energy Storage Database (2017)

22

Power-to-HeatWaste Heat Recovery

Key roles identified for Thermal Storage

Waste heat recovery

• Smooth loads• Batch-wise processes• Increase efficiency• Increase capacity factor• Supply for peak loads• Improve industrial efficiency

Electricity

E

Thermal Storage

Heat

H

• Couple electricity and heat sectors

• Primarily from PV and wind• Utilise low cost TES to add

flexibility• Many existing loads can be

made flexible at low cost

23

Waste Heat Recovery Pilot Project (WHR) under YREF grantHow can thermal storage be integrated into WHR systems + SMME development

Waste heat from high temperature kilns >1000 oC Drying moulds at 60 oC

Partnership with NCPC combining energy audit with research and development fornon standard WHR solutions

24

Waste Heat Recovery Boosted by TESAddition of TES adds 33% to average power

Slide from Romagnoli, A. “Waste heat recovery in industrial processes via thermal

energy storage” National Energy Efficiency Conference 2015

25

Passive ApplicationsConcentrating Solar

Power

Key roles identified for Thermal Storage

• Typically 2 tank molten salt• Generate electricity• Commercially mature (1.1GWh)• Opportunities for cost reductions

with low cost materials (e.g. rocks)• Cost competitive issue with

PV+battery

• Provide passive cooling in buildings HVAC• Integrate thermal storage into building envelope• Eliminate need for active cooling

26

Thermal Storage Laboratory: Excellent integration opportunity between Energy Materials and Energy Storage

Low technology solutionsShort time to market

B. Zalba, J. M. Marin, L. F. Cabeza and H. Mehling, “Review on thermal energy storage with change: materials, heat

transfer analysis and applications,” Applied Thermal Engineering, vol. 23, pp. 251-283, 2003

27

Conclusions

1. Thermal energy is the largest end-use of energy in South Africa

2. A range of TES technologies exist which can be incorporated to add grid flexibility at low cost

3. In the near term TES for waste heat recovery presents an interesting opportunity

4. CSIR Energy Centre is looking to develop new materials and heat exchange designs for TES

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Thank you