Energy Storage – Definitions, Properties and Economics

Andreas Hauer

Latin America Public-Private Partnerships Workshop on Energy Storage for Sustainable Development April 16-17, 2015 Rio de Janeiro, Brazil

Content

• Basic Definitions• Properties• Economics • Market• Conclusions

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 the discharging. After the discharging step the storage can be charged again.

Charging Storage Discharging

Definitions „Energy Storage“

What is actually stored?

The form of energy (electricity, heat, cold, mechanical energy, chemical energy), which is taken up by an energy storage system, is usually the one, which is delivered. However, in many cases the charged type of energy has to be transformed for the storage (e.g. pumped hydro storage or batteries). It is re-transformed for the discharging. In some energy storage systems the transformed energy type is delivered (e.g. Power-to-Gas or Power-to-Heat).

h

Relation between energy storage systems and their applications

The technical and economical requirements for an energy storage system are determined by its actual application within the energy system. Therefore any evaluation and comparison of energy storage technologies is only possible with respect to this application.

The application determines the technical requirements (e.g. type of energy, storage capacity, charging/discharging power,…) as well as the economical environment (e.g. expected pay-back time, price for delivered energy,…).

Definitions „Energy Storage“

Electrolysis Hydrogen

Constant Supply Fluctuating Supply

Matching Supply and Demand

„Storage of Power“ „Storage of Energy“

e.g. Power Reserve e.g. Peak Shaving / Dispatchable Load

Difference between Power & Energy

Pow

er

Pow

er

Seconds - Minutes Hours – Days

Energy Storage – Properties

– Storage Capacity (kWh/kg, kWh/m³)

– Charging / Discharging Power (W/kg, W/m³)

– Storage Efficiency

– Storage Period (Time)

– Cost (€/kWh, €/kW)

– Competing Technologies

Phys. / Chem. Effect, Storage Material, Operation Conditions

Storage Design & Engineering, Transport Phenomena,…

Losses (Storage Period, Transformations)

Hours, Days, Months, Years

Investment, Number of Storage Cycles

Properties of an Energy Storage System

Transmission System, Smart Grids, Demand Side Management, Electricity Production

Storage

technology

Storage Mechanism

Power CapacityStorage Period

Density Efficiency Lifetime Cost

MW MWh time kWh/ton kWh/m3 % # cycles $/kW $/kWh¢/kWh-

delivered

Lithium Ion

(Li Ion)

Electro-chemical

< 1,7 < 22 day - month 84 - 160 190 - 375 0,89 - 0,982960 -5440

1230 - 3770

620 - 2760

17 - 102

Sodium Sulfur (NAS) battery

Electro-chemical

1 - 60 7 - 450 day 99 - 150 156 - 255 0,75 - 0,861620 - 4500

260 - 2560

210 - 920 9 - 55

Lead Acid

battery

Electro-chemical

0.1 - 30 < 30 day - month 22 - 34 25 - 65 0,65 - 0,85160 - 1060

350 - 850130 - 1100

21 - 102

Redox/Flow battery

Electro-chemical

< 7 < 10 day - month 18 - 28 21 - 34 0,72 - 0,851510 - 2780

650 - 2730

120 - 1600

5 - 88

Compressed air energy storage (CAES)

Mechanical 2 - 300 14 - 2050 day -2 - 7 at

20 - 80 bar0,4 - 0,75

8620 - 17100

15 - 2050 30 - 100 2 - 35

Pumped hydro energy storage (PHES)

Mechanical450 - 2500

8000 - 190000

day - month0,27 at 100m

0,27 at 100m

0,63 - 0,8512800 - 33000

540 - 2790

40 - 160 0,1 - 18

Hydrogen Chemical varies varies indefinite 340002,7 - 160 at 1 - 700 bar

0,22 - 0,50 1384 - 1408

- 25 - 64

Methane Chemical varies varies indefinite 16000 10 at 1 bar 0,24 - 0,42 1 - - 16 - 44

Sensible

storage - WaterThermal < 10 < 100 hour - year 10 - 50 < 60 0,5 -0,9 ~5000 - 0,1- 13 0,01

Phase change materials (PCM)

Thermal < 10 < 10 hour - week 50 - 150 < 120 0,75 - 0,9 ~5000 - 13 - 65 1,3 - 6

Thermochemical storage (TCS)

Thermal < 1 < 10 hour - week 120 -250 120 - 250 0,8 - 1 ~3500 - 10 - 130 1 - 5

Energy Storage Technology Properties

Energy Storage – Economics

Economics of an energy storage system depend on• investment cost of the energy storage system• number of storage cycles (per time), which limits the delivered

amount of energy

Economics

Spending = Investment Cost

Earning = delivered Energy = Storage Cycles

Charging St. 100.000 €Storage 100.000 €Discharg. St. 50.000 €Total Cost 250.000 €

4 MWh per cycle, charge/discharge power 1 MW, 2 cycles per day, 1 MWh = 50 € 700 x 200 € = 140.000 €/Jahr

© ZAE Bayern

≈ 10.000 €/kWh ≈ 250 €/kWh

≈ 100 €/kWh ≈ 2,0 €/kWh© ZAE Bayern

© ZAE Bayern

Economics

Economics of an energy storage system depend on• investment cost of the energy storage system• number of storage cycles (per time), which limits the delivered

amount of energy• price of the replaced energy (electricity, heat/cold, fuel,…)• „Benefit-Stacking“

Top-Down Approach or „Maximum Acceptable Storage Cost“

The maximum acceptable storage cost (price per storage capacity installed, €/kWh) can be easily calculated on the basis of• Expected pay-back time• Interest rate• Energy cost

Example: In the building sector a payback period of 15 to 20 years and an interest rate of 3% to 6% can be accepted. The price for energy is 0.06 – 0.10 €/kWh.

Enthusiast: payback 20-25 a, interest rate 1%, energy cost 0.12-0.16 €/kWhBuilding: payback 15-20 a, interest rate 5%, energy cost 0.06-0.10 €/kWhIndustry: payback < 5 a, interest rate 10%, energy cost 0.02-0.04 €/kWh

Top-Down Approach or „Maximum Acceptable Storage Cost“

Seasonal storage: 0.96 - 2.29 €/kWhcap

Storage

technology

Storage Mechanis

m

Power CapacityStorage Period

Density EfficiencyLifetim

eCost

MW MWh time kWh/ton kWh/m3 %#

cycles$/kW $/kWh

¢/kWh-deliver

edLithium Ion

(Li Ion)

Electro-chemical

< 1,7 < 22day -

month84 - 160 190 - 375 0,89 - 0,98

2960 -5440

1230 - 3770

620 - 2760

17 - 102

Sodium Sulfur (NAS) battery

Electro-chemical

1 - 60 7 - 450 day 99 - 150 156 - 255 0,75 - 0,861620 - 4500

260 - 2560

210 - 920

9 - 55

Lead Acid

battery

Electro-chemical

0.1 - 30

< 30day -

month22 - 34 25 - 65 0,65 - 0,85

160 - 1060

350 - 850

130 - 1100

21 - 102

Redox/Flow battery

Electro-chemical

< 7 < 10day -

month18 - 28 21 - 34 0,72 - 0,85

1510 - 2780

650 - 2730

120 - 1600

5 - 88

Compressed air energy storage (CAES)

Mechanical

2 - 300

14 - 2050 day -

2 - 7 at

20 - 80 bar

0,4 - 0,758620 - 17100

15 - 2050

30 - 100

2 - 35

Pumped hydro energy storage (PHES)

Mechanical

450 - 2500

8000 - 190000

day - month

0,27 at 100m

0,27 at 100m

0,63 - 0,8512800 - 33000

540 - 2790

40 - 160

0,1 - 18

Hydrogen Chemical varies varies indefinite 340002,7 - 160 at 1 - 700

bar0,22 - 0,50 1

384 - 1408

- 25 - 64

Methane Chemical varies varies indefinite 1600010 at 1

bar0,24 - 0,42 1 - - 16 - 44

Sensible

storage - Water

Thermal < 10 < 100hour - year

10 - 50 < 60 0,5 -0,9 ~5000 - 0,1- 13 0,01

Phase change materials (PCM)

Thermal < 10 < 10hour - week

50 - 150 < 120 0,75 - 0,9 ~5000 - 13 - 65 1,3 - 6

Thermochemical storage (TCS)

Thermal < 1 < 10hour - week

120 -250

120 - 250 0,8 - 1 ~3500 -10 - 130

1 - 5

Energy Storage Technologies

Diurnal storage: 16 - 38 €/kWhcap

Storage

technology

Storage Mechanis

m

Power CapacityStorage Period

Density EfficiencyLifetim

eCost

MW MWh time kWh/ton kWh/m3 %#

cycles$/kW $/kWh

¢/kWh-deliver

edLithium Ion

(Li Ion)

Electro-chemical

< 1,7 < 22day -

month84 - 160 190 - 375 0,89 - 0,98

2960 -5440

1230 - 3770

620 - 2760

17 - 102

Sodium Sulfur (NAS) battery

Electro-chemical

1 - 60 7 - 450 day 99 - 150 156 - 255 0,75 - 0,861620 - 4500

260 - 2560

210 - 920

9 - 55

Lead Acid

battery

Electro-chemical

0.1 - 30

< 30day -

month22 - 34 25 - 65 0,65 - 0,85

160 - 1060

350 - 850

130 - 1100

21 - 102

Redox/Flow battery

Electro-chemical

< 7 < 10day -

month18 - 28 21 - 34 0,72 - 0,85

1510 - 2780

650 - 2730

120 - 1600

5 - 88

Compressed air energy storage (CAES)

Mechanical

2 - 300

14 - 2050 day -

2 - 7 at

20 - 80 bar

0,4 - 0,758620 - 17100

15 - 2050

30 - 100

2 - 35

Pumped hydro energy storage (PHES)

Mechanical

450 - 2500

8000 - 190000

day - month

0,27 at 100m

0,27 at 100m

0,63 - 0,8512800 - 33000

540 - 2790

40 - 160

0,1 - 18

Hydrogen Chemical varies varies indefinite 340002,7 - 160 at 1 - 700

bar0,22 - 0,50 1

384 - 1408

- 25 - 64

Methane Chemical varies varies indefinite 1600010 at 1

bar0,24 - 0,42 1 - - 16 - 44

Sensible

storage - Water

Thermal < 10 < 100hour - year

10 - 50 < 60 0,5 -0,9 ~5000 - 0,1- 13 0,01

Phase change materials (PCM)

Thermal < 10 < 10hour - week

50 - 150 < 120 0,75 - 0,9 ~5000 - 13 - 65 1,3 - 6

Thermochemical storage (TCS)

Thermal < 1 < 10hour - week

120 -250

120 - 250 0,8 - 1 ~3500 -10 - 130

1 - 5

Energy Storage Technologies

Energy Storage – Market

Energy Storage Systems are clean!

Energy storage systems used for the integration of renewables or the increase of energy efficiency deliver CO2-neutral energy to their customers.Rising prices for CO2 certificates would support the economics of energy storage!

e.g. power reserve

Fair Market Entry!

• No subsidies & no „market-entry-programme“ needed!

• As soon as „flexibility“ will be adequately remunerated, energy storage systems are competitive!

• Energy storage systems are no „final consumer“ and do not have to pay the related fees!

Japan:Ice storage for

air conditioning due to high electricity

prices in peak hours

Conclusions

Energy Storage Process = Charging + Storage + Discharging

Energy storage can match supply & demand

Energy storage systems can either focus on the storage of energy or power

Energy storage systems will have an increasing market share, if their benefits will be adequately remunerated

The economics depend on the investment cost, the cycle number in an actual application (per time) and the price of the replaced energy

Conclusions

Thank you very much for your attention!

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storagecosts top− down=energy costs×cycles per year

storage annuity

User Energy costs / €·kWh-1 Storage annuity / %

min. max. min. max.

Industry 0.02 0.04 25 30

Building 0.06 0.10 7 10

Enthusiast 0.12 0.16 4 6

Method: Top-down approach

27

storagecosts top− down=energy costs×cycles per year

storage annuity

User Energy costs / €·kWh-1 Storage annuity / %

min. max. min. max.

Industry 0.02 0.04 25 30

Building 0.06 0.10 7 10

Enthusiast 0.12 0.16 4 6

Method: Top-down approach

28

storagecosts top− down=energy costs×cycles per year

storage annuity

User Energy costs / €·kWh-1 Storage annuity / %

min. max. min. max.

Industry 0.02 0.04 25 30

Building 0.06 0.10 7 10

Enthusiast 0.12 0.16 4 6

Method: Top-down approach

Method: Bottom-up approach

29

investment costs = TES material + storage container + charging / discharging device