the demand for energy storage in regenerative energy systems

The demand for energy storage in regenerative energy systems

First International Renewable Energy Storage Conference (IRES I)

Gelsenkirchen, October, 30th/31st 2006

Electrochemical Energy Conversion and Storage Systems GroupInstitute for Power Electronics and Electrical Drives (ISEA)

RWTH Aachen University / Germany

Dirk Uwe Sauer

No 230.10.2006Prof. Dr. Dirk Uwe Sauer Demand for energy storage in regenerative energy systems

Power generation and consumption must be in equilibrium at any time

This results in a shut down of appliances or grid segments.

Imbalance amongst power generation and consumption immediately results in a drop of voltage or in overvoltage.


Blackout in Italy during night (28.09.2003, 4:00 a.m.)

Source: IAEW, Prof. Haubrich


Power generation and consumption must be in equilibrium at any time

Imbalance among power generation and consumption immediately results in a drop of voltage drop or in overvoltage.

This results in a shut down of appliances or grid segments.

Storage systems with very fast response time,

high power capability and

sufficient energy reserve

are required.


Actual electricity rates (Energy Stock Exchange), Germany 2001

Time / Days

Tim

e / H

ours

Eur

o C

ent /

kW

h

2,5

5,0

7,5

10,0

12,5

15,0

17,5

20,0

25,0

Source: Fritz Crotogino, KBB Hannover


Definition of a storage system

Power generation from renewable energies

Transmission lines vs. storage systems

Autonomous power supply systems

Demand for heat storage systems

Storage technologies

Power and energy sizing for various applications and storage technologies

Conclusions

Outline


Definition of a storage system for electrical energy

charging of storage discharging of storage

converter.

electricalenergy

definescharging power

energystorage

definesenergy capacity

converter

definesdischarging power

electricalenergy

Compressed air storage:

compressor cavern, heat storage turbine

integrated deviceBatteries / Supercaps:

Pumped hydro: pump water basin turbine

Hydrogen storagesystem:

electrolyser hydrogen storage fuel cell, turbine


Energy generation from solar radiation and wind are highly fluctuating

Balancing either by flexible thermal or hydro power plants, or by storage systems.

% o

f ins

talle

dra

ted

capa

city

1 hour

PV

wind power% o

f ins

talle

dra

ted

capa

city

PV

1 week%

of i

nsta

lled

rate

d ca

paci

ty

wind power

% o

f ins

talle

dra

ted

capa

city

Figures: IAEW, Prof. H

aubrich


Fluctuations of a large number of power generators level out on a minute basis

Distributed photovoltaic systems balance the power output and makes fluctuating power generators predictable.

12 24 36 48 60 720hours

100

80

60

40

20

0

100 systems1 system

source: E. Wiem

ken, from W

BGU

report


0

2.000

4.000

6.000

8.000

10.000

12.000

14.000

16.000

1. Jan. 1. Feb. 1. Mrz. 1. Apr. 1. Mai. 1. Jun. 1. Jul. 1. Aug. 1. Sep. 1. Okt. 1. Nov. 1. Dez.0

2.000

4.000

6.000

8.000

10.000

12.000

14.000

16.000

1. Jan. 1. Feb. 1. Mrz. 1. Apr. 1. Mai. 1. Jun. 1. Jul. 1. Aug. 1. Sep. 1. Okt. 1. Nov. 1. Dez.Jan Feb März Apr Mai Juni Juli Aug Sep Okt Nov Dez

Leis

tung

MW installierte Windkraftleistung

Windeinspeisung

Pow

er

Mar May June July Oct Dec

XX

On an annual basis the fluctuations remain highFigures: IAEW

, Prof. Haubrich

average power

generated wind power

installed wind power

Power generation from wind generators in Germany in 2003


Increasing renewable energy penetration

Source: WBGU (in German)

German Advisory Council onGlobal Change (WBGU)http://www.wbgu.de/

prim

ary

ener

gy [E

J/a]

geothermal energyother renewables

Solar thermal power plant technologies(only heat)

solar power (photo-voltaics and solar-thermal power plants)

wind powerbiomass energy(modern)biomass energy(traditional)hydropowernuclear energynatural gascoaloil


Wind energy is not a decentralised energy source

In Germany, wind energy is localised mainly in the northern part near the coast lines.Future off-shore wind parks will result in up to several 10 GW of installedpower in the North Sea.

source: IAEW, Prof. Haubrich


10

20-150,1

1

100

-20 -10 -5 0 5 10 %ΔPWEA / Pinst,WEA

p

2h1h15 min

Gradients in the cumulative power generation from wind turbines are small

Probability of variations in the cumulative output of all wind generators in Germany within 15 min, 1 hour or 2 hours.

source: ISET Kassel

Variation must be compensated by thermal or hydro power plants and storage systems.


Concentration of power generation results in overloads in transmission lines

High voltage transmission lines in Germany. Red segments are overloaded due to wind power generation in the northern part of Germany.source: IAEW, Prof. Haubrich

Problem can be solved bybuilding new transmission linesinstallation of storage systems close to the power generators

Storage systems allow for a more uniform load on the transmission lines.Storage systems supersede high investments in back-up thermal power plants.


Power transmission - an alternative to level power generation from renewable sources ?

This requires very large power transmission capacities throughout Europe or world-wide.

Expensive and not available today.

source: V. Quaschning, from WBGU report

month

Cape Town

Algiers

Berlin

mon

thly

ave

rage

of s

olar

radi

atio

n

Moscow Berlin Lisbon

time [MEZ]

sola

r rad

iatio

n


Energy storage vs. energy transport

Transmission lines are the backbone of European power supply infrastructure.

Transmission linesefficiency high (HVDC ~ 5% losses/ 1000km)expensive, especially in sparsely populated areasrequires world-wide co-operation, susceptible to international crisesplanning takes more than a decadetransport capacity limited (~ 1 GW)

Storage systemsefficiency depends on technology (40 - 80% round trip)very flexible in power and energy capacityreduce dependency on third party countriesexpensiveessential in remote power supplies

Pro and cons for energy storage and power transmission lines:


Not all renewable energies are volatile by nature

Wind power, photovoltaics and solar thermal power plants depend very much on the actual local weather conditions.

Other renewables can be used perfectly for the control of grids, load levelling and reserve power:

biomass (solid or gas)

geothermal energy

hydro power

tidal energy

Future energy systems will be always a mix from various technologies including storage systems.


Autonomous power supply systems -remote houses

pictures: Fraunhofer ISE


Autonomous power supply systems -technical applications


pict

ures

: Fra

unho

fer I

SE


Autonomous power supply systems -design of PV-battery and PV-hybrid systems

Hybrid system: several generators supplementing each other (here: PV, wind and motor generator)

motor gen.

MGAC/DC∼

=

direct current bus bar (DC)

PV-Gen.

Battery

DC-loads

alternating current bus bar (AC)

DC/AC=

∼AC-loads

wind gen.

WG

chargecontrollerPV gen.


Autonomous power supply systems -rural electrification



Rural electrification - solar home systems and village power systems (mini-grids)

Distributed storage in each house (solar home systems) or in a central power supply station (mini-grid)

School, hospital,assembly hall

Central powersupply station

productiveapplications

school, hospital,assembly hall


Demand for heat storage

Solar thermal power plants

Solar thermal collector systems for residential houses or settlements

Combined heat and power co-generation


Solar thermal power plant with heat storage

Source:Ciemat, Plata Forma Solar, Dr. Romero


Concept for a seasonal heat storage in a settlement

Source:Ruhr-Universität Bochum, Prof. Unger

central heat stationflat collectors

heat distributioncollector network

gasgas

burner

cold water intake

seasonal heat storage


Combined heat and power co-generation

Source:DEFU, H. Weldingh

Source:Buderusheat storage


Demand for heat storage

Solar thermal power plants:to extend the operation time, to evenly supply power, and to increase the dispatchability

Solar thermal collector systems for residential houses or settlements:

to supply heat during nights, periods of bad weather conditions,or during winter months

Combined heat and power co-generation:to decouple heat and power consumption in industrial applications or distributed power generation


Heat vs. chemical vs. electrical energy storage

low exergy content, especially at low and medium temperaturesfair energy densitywater @ ΔT = 100K: 116 kWh/m3

phase change materials (latent heat) interestingice / water: 93 kWh/m3

water / vapour: 626 kWh/m3

transport always requires mass transport

Chemical storagehigher exergy contenthigher energy densitylithium-ion battery: 300 kWh/m3

liquid hydrogen: 2,400 kWh/m3

petrol: 10,000 kWh/m3

Electricity 100% exergyvery low energy densityelectrostatic field: ~10 kWh/m3

magnetic field: ~10 kWh/m3

transport without mass transport at speed of light, cables required

Heat storage


Various materials for heat and technologies for electricity storage

Heat storage materialswatersoil, concretephase change materials (medium and high temperature)zeolithestationary or mobile storage systemsthermo-chemical metal hydride alanat




Electricity storage technologiesdouble layer capacitorsflywheelssupra-conducting coilsconv. batteries (lead-acid, lithium, NiMH, NiCd, ...)high temperature batteries (NaS, NaNiCl, ...)redox-flow batterieszinc-bromine batteriescompresses airpumped hydrohydrogen storage systems


Technologies for Electrical Storage Systems

Pumped hydro

Pumped hydro

Superconductive coils

Superconductivecoils Flywheels FlywheelsCompressed air

Compressed air

Supercapacitors

Supercapacitors

Supercapacitor

Redox-Flow batteries

Redox-Flow batteries

HydrogenBatteries - lead-acid, lithium, NaNiCl, ...

Batteries - lead-acid, lithium, NaNiCl, ...

Hydrogen

Various storage technologiesare available or need further

development -but all need improved integration

into the grid or otherapplications




Electricity storage technologiesdouble layer capacitorsflywheelssupra-conducting coilsconv. batteries (lead-acid, lithium, NiMH, NiCd, ...)high temperature batteries (NaS, NaNiCl, ...)redox-flow batterieszinc-bromine batteriescompresses airpumped hydrohydrogen storage systems


Sizing of storage systems for different applications

spec

ific

pow

er [k

W/k

Wh]

installed storage capacity

typi

cal

disc

harg

e tim

e1 kW 100 kW 10 MW10 W

1

0.01

100

installed power

1 GW

100 GW

kWh MWh GWh TWh

10 ms

1 s

1 min

1 hour

½ day

1 week1 month

1 year

1

2 - solar home system3 - PV hybrid4 - village power supply5 - load levelling LV6 - load levelling MV

1 - PV battery system

7 - load levelling HV8 - stabilisation of wind t.10 - UPS

9 - single home storage

2 3 4

5 6 7

8

9

10


Operating range of different storage technologies

spec

ific

pow

er [k

W/k

Wh]


typi

cal

disc

harg

e tim

e1 kW 100 kW 10 MW10 W

1

0.01

100

installed power

1 GW

100 GW

kWh MWh GWh TWh

10 ms

1 s

1 min

1 hour

½ day

1 week1 month

1 year

II - supercaps, flywheelsIII - batteriesIV - redox-flow batteriesV - compressed airVI - pumped hydro

I - capacitors, inductors

VII - hydro storageVIII - hydrogen storage

I

III

IV

VII

II

V VIVIII


Matching among applications & storage technologies

spec

ific

pow

er [k

W/k

Wh]


typi

cal

disc

harg

e tim

e1 kW 100 kW 10 MW10 W

1

0.01

100

installed power

1 GW

100 GW

kWh MWh GWh TWh

10 ms

1 s

1 min

1 hour

½ day

1 week1 month

1 year


Conclusions IStorage technologies for a wide power and energy range are needed.

Existing storage technologies can match the requirements -for heat and for electricity.However, several challenges must be faced:

reduction of life cycle costs (increase of lifetime, decrease of investment costs) increase of energy densityincrease of efficiencyenvironmental compatibility (recycling, integration into the landscape, poisonous materials)


Conclusions IIEnergy systems with a high penetration of renewablesneed storage systems

to avoid shut downs of power generators if generation exceeds consumptionto minimise the need for additional transmission linesto avoid investments in power plants for peak power generationto make efficient use of combined heat and power plantsto transfer heat energy from summer to winter


The conference will show:

Storing energy in present and future energy systems with a high degree of renewable energy penetration is an essential demand.

Various technologies are available.

Further research, development and demonstration in parallel with developing renewable energy technologies is necessary.

Storage systems are a key technology for our future energy systems!


Children in Indonesia regarding curious the battery storage

systems of the power supply system of their village.

Bild

: Fra

unho

fer I

SE

Enjoy the conference, make contacts and see the

emerging and the mature technologies!

the demand for energy storage in regenerative energy systems

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