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Bavarian Center for Applied Energy Research

- ZAE Bayern -

Andreas Hauer

Thermal Energy Storage –Technologies & Applications

Energy Storage –

Basic Definitions

Definitions „Energy Storage“

What is energy storage?

An energy storage system can take up energy and deliver it at a later point in time. The storage process itself consists of three stages: The charging, the storage and thedischarging. After the discharging step the storage can be charged again.

Charging Storage Discharging

HeatInput

ChargingProcess

Storage DischargingProcess

User

Ambience

Energy is supplied as heat,

is stored in some way,

is supplied as heat to a user.

Thermal Energy Storage Process

HeatOutput

T

S

Ta

T

S

Ta

T

S

Ta

T

S

Ta

Heat from heat source

Heat to storage

Heat to user Heat to ambience

Energy is conserved Exergy is „consumed“!

Conversion of heat in a storage process

Q = T * S

T

S

T

S

T

S

Ta Ta TaTa

T

SHeat from heat source

Heat to storage

Heat to user Heat to ambience

Temperature (quality of energy stored) can rise!

Conversion of heat in a storage process

Energy is conserved Exergy is „consumed“!

Motivation for the Storage of

Thermal Energy

Final Energy Demand (Germany)

Final Energy Demand (Germany)

The Role of Thermal Energy Storage

IEA Energy Storage Technology Roadmap

Roadmap Key Findings

• Storage can support energy system decarbonisation

• Some technologies already competitive, others (particularly electricity storage) still too expensive

• Additional R&D still needed to reduce costs

• Optimal role for storage varies widely across regions

• Power markets are ill-equipped to compensate storage for suite of services they can provide

• Thermal energy storage systems could make better use of wasted heat

The Role of Thermal Energy Storage

The Power of Transformation - Wind, Sun and the Economics of Flexible Power Systems

• DSI (in particular distributed thermal storage) showed significant promise, as suggested by its superior cost-benefit performance compared to other flexibility options. However, a degree of uncertainty exists regarding its full potential in real-life applications.

• Cost-benefit profiles …..

• The cost-effectiveness of distributed thermal storage points to the importance of coupling the electricity sector with other sectors of the energy system to achieve cost-effective VRE integration.

• In addition to coupling the heat and electricity…

Technologies for Thermal Energy Storage

Thermal Energy Storage

Thermal Energy Storage Technologies:

• Storage of Sensible Heat

• Thermochemical Heat Storage

• Storage of Latent Heat

∆T

Temperature

Ther

mal

En

ergy

(Sto

red

)

∆QWater∆QPCM

Melting Temperature

Tm

Sensible / Latent Heat Storage

++ heatheat

DISCHARGEDISCHARGE

CHARGECHARGE

STORESTORE

+ + heatheat

++ heatheat

DISCHARGEDISCHARGE

CHARGECHARGE

STORESTORE

+ + heatheat

Chemical Reactions:

Example:

© ECN

Thermochemical Storage

AB + Heat A+B Charging: Heat Engine

c=1-Tamb/Tchar

Discharging: Heat Pump

d= 1/(1-Tamb/Tdischar)

Applications for Thermal Energy Storage

Integration of Renewable Electricity

• Grid Stability

Frequency regulation

Voltage support

T&D congestion relief

Black start• Grid balancing

Fast power reserve

Peak Shaving

Self-consumption, Off-grid• Demand Side Integration

Dispatchable Load Power-to-Gas Power-to-Heat

Integration of Renewable Thermal Energy

• Concentrated Solar Power

• Solar-thermal Process Heat

• Solar-thermal Heating & Cooling

Industral Processes

• Waste Heat Utlization

• Recuperation of Mech. Energy

Buildings

• Heating & Cooling

Day/Night-Balancing

Summer/Winter-Balancing

Electricity Production

• Fossil Thermal Power Plants

• Heat Utilization of CHP

• …

Mobility• Propulsion• Heating / Air Conditioning

Renewable Energies Energy Efficiency

Integration of Renewable Electricity

• Grid Stability

Frequency regulation

Voltage support

T&D congestion relief

Black start• Grid balancing

Fast power reserve

Peak Shaving

Self-consumption, Off-grid• Demand Side Integration

Dispatchable Load Power-to-Gas Power-to-Heat

Integration of Renewable Thermal Energy

• Concentrated Solar Power

• Solar-thermal Process Heat

• Solar-thermal Heating & Cooling

Industral Processes

• Waste Heat Utlization

• Recuperation of Mech. Energy

Buildings

• Heating & Cooling

Day/Night-Balancing

Summer/Winter-Balancing

Electricity Production

• Fossil Thermal Power Plants

• Heat Utilization of CHP

• …

Mobility• Propulsion• Heating / Air Conditioning

EES – TES – EES/TES/CES

Renewable Energies Energy Efficiency

Thermal Energy Storage and Power Generation

© Solar Millennium

Molten Salt Storage forConcentrated Solar Power

High-Temperature ConcreteStorage for Electricty

Generation

© DLR

Seasonal Storage of Solar Thermal Energy

Hot Water Storage at Ackermannbogen, München

Solar Community & Borehole UTES at Drake

Landing, Canada

© ZAE Bayern

© Solarthermalworld

Waste Heat Utilization / Process Heat

Waste Heat Utilization in a Iron Foundry by a Combined Oil & Rock Storage

Mobile Sorption Storage forWaste Heat from an

Incineration Plant

© ZAE Bayern

© ZAE Bayern

„Passive Cooling“

„Phase Change Slurries“

Open „Desiccant“-Systems

Buildings: Air Conditioning & Cooling

Hot Water Storages

Subcooled PCM

Buildings: Heating & Domestic Hot Water

Chemical Reaction: Magnesium-Chloride

Thermal Energy Storage and CombinedHeat & Power

© ASUE e.V. / SenerTec Kraft-Wärme-

Energiesysteme GmbH

© DLR & STEAG New Energies GmbH

Latent Heat Storage forCombined Heat and Power

Plant

CHP with Hot Water bufferStorage

Leveled Playing Field!

• No Subsidies necessary!

• Flexibility has to be remunerated!

Japan:

Ice Storage for

Air Conditioning

due to high electricity

Fees at peak hours

Thermal Energy Storagein Economic Suitable Application

Conclusions:

Thermal Energy Storage

A number of different applications for the impovement of energyefficiency or the integration of renwable energy can be approached bythermal energy storage

The chosen thermal energy storage technology has to matchthe actual application

Thermal energy storages can help integrating renewableelectricity, in particular for cooling applications!

Different thermal energy storage technologies are

available or subject to R&D activities

Conclusions

© Bayerisches Zentrum für Angewandte Energieforschung e. V.

Alle Rechte vorbehalten, auch bezüglich jeder Verfügung, Verwertung, Reproduktion, Bearbeitung und Weitergabe sowie für den Fall von Schutzrechtanmeldungen.

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