NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Hybrid Hydrogen

Energy Storage

Michael Penev

May 22, 2013

All-Energy 2013

Aberdeen, UK

2

Talk Overview

Key Components of H2 Storage

Case Study of Islanded Hybrid-H2 Storage

Concept of Power to Gas Energy Storage

3

What is an Electrolyzer?

Electrolyzers can respond instantaneously to power fluctuations, thus

offering high frequency dispatchability

For every cubic foot of H2 produced, half cubic foot of O2 is produced.

H2 and O2 are produced at high purity

DC Power

Water

Hydrogen

Oxygen

H2O + electricity H2 + ½ O2

Ideal energy = 39 kWh/kg H2, HHV

4

Electrolyzer Types

Capacity (kW) Efficiency HHV

Alkaline 1 – 2,300 72%

PEM 1 – 130 60%

Solid Oxide pilot scale only 82%

Alkaline technology is commercially available.

Proton Exchange Membrane (PEM) systems are available in smaller

capacities, but offer long term performance and cost benefits.

Solid Oxide Electrolyzers (SOEC) are in development and will offer very

high efficiency and low cost.

All electrolyzer costs are approximately $1000 per kW in MW-scale context.

References:

Alkaline: NEL-Hydrogen system specifications

PEM: Proton On-Site system specifications

Solid Oxide: NREL/DOE internal systems analysis and cost estimations, 2011

5

Norsk Hydro’s 30,000 Nm3/h (~150 MW)

Electrolyzer Plant (1948 - 1990)

Reference: Knut Harg, Hydro Oil & Energy, Hydrogen Technologies

NAS – Hydrogen Resource Committee, April 19, 2007

Connected to a hydroelectric plant, generating about 70,000 kg/day

Alkaline Electrolyzers – Largest Installations

6

Hydrogen Storage Types

Storage Type H2 Storage cost $/kWh* • Terrestrial compressed tank** $ 45

• Deep-ocean gas storage*** $ 10

• Liquid hydrogen storage ** $ 2.5

• Geologic storage (porous rock formations) $ 0.50

• Dry-mined salt caverns $ 0.25

• Solution-mined salt caverns $ 0.05

* using 20 kWh/kg H2 (51% HHV efficiency)

** using H2A components model cost estimates

*** NREL cost estimate

Reference: Crotogino, F.; Huebner, S. (2008). “Energy Storage in Salt Caverns: Developments and Concrete Projects for Adiabatic Compressed

Air and for Hydrogen Storage.” Solution Mining Research Institute Spring 2008 Technical Conference, Porto, Portugal, April 28–29, 2008.

Deep ocean gas storage: NREL internal cost estimation, 2010

7

Power Generation Equipment

Generator Type Scale MW Cost $/kW Efficiency (HHV) Combine cycle (CC) plant 50 - 550 $550-720 51%

Oxy-combustion CC 50 - 550 $550-720* 62%

PEM Fuel Cells 0.1 -1.0 $2,500-5,000 40%

SOFC Fuel Cells 0.01 - TBD $4,500 61%

Only PEM Fuel Cells have been demonstrated for H2 to power for grid support.

* Oxy-combustion plant is assumed to have the same per-kW cost as CC. Oxy-

combustion has many simplifying aspects over air-combustion CC.

References:

Combine Cycle: “Cost and Performance Baseline for Fossil Energy Plants”, DOE/NETL, 2010

http://www.netl.doe.gov/energy-analyses/pubs/BitBase_FinRep_Rev2.pdf

Attachment:

http://www.netl.doe.gov/KMD/cds/disk50/NGCC%20Plant%20Case_FClass_051607.pdf

Oxy-combustion reference: Masafumi Fukuda and Yoshikazu Dozono, “Double Reheat Rankine Cycle for Hydrogen-Combustion Turbine Power

Plants”, Toshiba Corporation, Journal of Propulsion and Power, Vol. 16, No. 4, July-August 2000, Page 562

Solid Oxide: NREL/DOE internal systems analysis and cost estimations, 2011

PEM Fuel Cells: Personal communication with Kevin Bell from Ballard Power.

8

Talk Overview

Key Components of H2 Storage

Case Study of Islanded Hybrid-H2 Storage

Concept of Power to Gas Energy Storage

9

100% Hybrid Renewable Storage

Demand

Renewable Electricity

Battery

Inverter

DC

BU

S

Electrolyzer

Power Generator

Hydrogen Storage

Diurnal operation

Turns on when battery < ~70% state of charge

10

30,000 ft View of Storage Pros & Cons

Note: hybrid energy storage offers

spill over capability for displacing

transportation emissions via fuel cell

vehicles

Energy storage

system type

Round-trip

efficiency

Bulk-energy

storage cost

(non-diurnal)

Ability to be

refueled?

Batteries only 80% $700-$800/kWh No

H2 only 30%-50% $0.05-$45/kWh Yes

H2 & batteries (hybrid) 40%-70% $0.05-$45/kWh Yes

11

Example Island Installation (Wind & Solar Resource)

12

Demand Mismatch (measured data)

Hourly

electricity

demand

Hourly energy

output per

turbine (kW)

Large gaps in wind power

Note: Solar power

was used as well. It

was relatively

constant throughout

the year.

13

Optimization Methodology

Gradient descent minimization of levelized cost of electricity (LCOE)

Optimization parameters (using HOMER model):

1. Size of solar panels

2. Number of wind turbines

3. Number of batteries

4. Capacity of power electronics

5. Size of fuel cell

6. Size of electrolyzer

7. Size of hydrogen storage

concept illustration of gradient descent from wikipedia

- $5,500 /kW, no tracking

- $4,400 /kW, 1.8 MW each

- $745 / kWh, Xtreme Power DPR 1500

- $609 /kW, rectifier & inverter

- $4,000 /kW, 40% HHV efficiency PEM

- $1,000 /kW, 70% HHV efficiency Alkaline

- $700/kg, Terrestrial, steel tank

Note: only “off-the-shelf” technologies were used

for this analysis.

Reference: Xtreme Power Battery: system specifications from Xtreme Power

14

Energy Storage State of Charge

-

500

1,000

1,500

2,000

2,500

0 1000 2000 3000 4000 5000 6000 7000 8000

Hydrogen storage energy content(MWh)

Battery energy content(MWh)

Ene

rgy

Sto

rage

Co

nte

nt

(MW

h)

Hour of the year

-

5

10

5000 5100 5200

Solar

Wind

Battery

Fuel Cell

Cumulative Energy to Load (MWH/year)

15

Energy Storage State of Charge

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

6

12

18

24

Ho

ur

of

Day

Battery Energy Content

Day of Year

1,600

2,400

3,200

4,000

4,800

5,600

6,400

7,200

8,000

8,800

9,600

kWh

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

6

12

18

24

Ho

ur

of

Day

Stored Hydrogen

Day of Year

0

16,000

32,000

48,000

64,000

80,000

96,000

112,000

128,000

144,000

160,000

kg

Stored energy in batteries (MWh)

Stored hydrogen (MWh) MWh

2,400

2,160

1,920

1,680

1,440

1,200

960

720

480

240

-

MWh

9.6

8.8

8.0

7.2

6.4

5.6

4.8

4.0

3.2

2.4

1.6

Total batteries = 9 MWh, $6.8 million

Total H2 stored = 150,000 kg, $105 million

16

LCOE Vs. Renewables Fraction

$0.00

$0.05

$0.10

$0.15

$0.20

$0.25

$0.30

$0.35

$0.40

$0.45

0% 20% 40% 60% 80% 100%

LCO

E ($

/kW

h)

Renewable Fraction

100% renewable fraction solutions resulting LCOE: - 100% hydrogen = 0.51 $/kWh

- Hybrid hydrogen = 0.43 $/kWh

- 100% batteries = 3.56 $/kWh

17

Best-in-class: SOEC, Salt Cavern, Oxy-Combustion S

alt f

orm

ation

Hydro

gen

So

lution

Min

e

Oxygen

So

lution

Min

e

~1km

Plant components

- High – pressure electrolyzer (SOEC)

- Gas storage: solution mined salt dome

- H2/O2 turbine

18

SOEC, Salt Cavern, Oxy-Combustion

Alkaline PEM SOEC

Power Gen. Technology Component HHV efficiency 72% 60% 82%

Air-combustion CC 51% 37% 31% 42%

Oxy-combustion CC 62% 45% 37% 51%

PEM 40% 29% 24% 33%

SOFC 61% 44% 37% 50%

Hydrogen Production Technology

Best in class for this location long-term:

- Solid oxide electrolyzer (SOEC) $1,000/kW (not available)

- Salt cavern storage $0.08/kWh (not available today)*

- Oxy-combustion CC $720/kW (not available today)

- Levelized cost of electricity = 20.2 ¢/kWh Note: - ancillary service revenues can rival power production revenue

-

* Additional storage cost of O2 increases cost from $.05 kWh to $.08 per kWh.

19

SOEC, Salt Cavern, Oxy-Combustion

PVLin

FCDPR1500

ConverterElectr.

H2 Tank0

20,000,000

40,000,000

60,000,000

80,000,000

100,000,000

Net Present Cost ($)

Cash Flow Summary

PV1.8MW Linearized

Fuel Cell

Xtreme Power DPR 1500

Converter

Electrolyzer

Hydrogen Tank

Solar panels

Wind turbines

H2/O2 turbine

Batteries

Power electronics

Electrolyzer

Hydrogen storage

Net present value (millions of $)

20 40 60 80 100 0

NPV of Equipment Cost (including O&M)

20

Key Technologies

Oxy-combustion hydrogen turbines o Enables low-cost, high-round trip energy storage

o Engineering development required

o No scientific breakthroughs needed

Solid oxide electrolyzers, high-pressure o Enables low-cost, high-round trip energy storage

o Solid oxide materials are ideal for high-pressure operation

(low back-diffusion due to material impermeability)

o Science & engineering development required

o 1000’s of hours of operation have been demonstrated on modules

o High pressure operation has been demonstrated on stacks

21

Talk Overview

Key Components of H2 Storage

Case Study of Islanded Hybrid-H2 Storage

Concept of Power to Gas Energy Storage

22

Power to Gas Energy Storage

Battery D

C B

US

Electrolyzer

Natural gas pipelines can operate with 10% H2 (as much as 20% has been commercially demonstrated)

Natural Gas Pipeline

Inverter

RECs

$$$

$$$

ancillary

services

Transmission

Transportation Power Gen. Heating

Hyd

rog

en

23

Questions?

24

BACKUP SLIDES

25

Hydrogen Storage (Terrestrial)

300 kg H2

storage in

ISO

containers, in

Pearl Harbor

Hickham

26

Power Generation (Fuel Cell)

1.1 MW Ballard Hydrogen Fuel Cell

@ Toyota Headquarters in CA

27

Toshiba Advanced H2/O2 Cycle

This cycle is a hybrid between a combustion and steam turbine.

Toshiba predicts 61.7% HHV or 72.8% LHV efficiency for this cycle.

28

Ongoing Efforts in Oxy-Combustion

• Siemens installation of oxygen-blown combustion turbine. • They experience efficiency gain of 10% on LHV basis over conventional systems. • This system is developed for CO2 sequestration.

29

Ongoing Efforts in O2 Turbines

30

Combine Cycle (CC) Turbine

Diagram as seen on: http://www.victorvilletwo.com/

Combine cycle plants are

commonly designed for

peaking power. Their fuel is

more expensive than base-

load coal plants.

Plant efficiency 55-58% LHV

31 31

CC Major Differences With H2/O2

Bottoming Steam Cycle is

Integrated

Efficiency of a combine cycle is greatly impeded by atmospheric N2

- Compression shaft energy is used to compress N2

- N2 strips heat from the process, without providing power

- N2 produces NOX in the combustor

- NOX reduction strategies reduce burner efficiency

Pre-cooler & compressor not

present with H2/O2

• No NOX formation. • Need steam recycle

H2

O2

Exhaust NOX clean-up would

be obsolete. Exhaust would be liquid H2O

32

Alkaline Electrolyzers

http://www.nel-hydrogen.com/

NEL-Hydrogen Electrolyzers – 2.3 MW per unit

33

Proton Exchange Membrane (PEM) Electrolyzers

Electrolyzer Unit

Power Electronics

http://www.protononsite.com/

60 kg/day electrolyzer from Proton OnSite:

34

Solid Oxide Electrolyzers (SOEC)

Steam 650°C

Electricity, DC

Oxygen

Hydrogen 800°C

SOEC has very high efficiency due to thermal weakening of H-O bonds.

http://www.versa-power.com/

35

SOEC, Deep Water Storage, Oxy-Combustion

Alkaline PEM SOEC

Power Gen. Technology Component HHV efficiency 72% 60% 82%

Air-combustion CC 51% 37% 31% 42%

Oxy-combustion CC 62% 45% 37% 51%

PEM 40% 29% 24% 33%

SOFC 61% 44% 37% 50%

Hydrogen Production Technology

Best in class for this location long-term:

- Solid oxide electrolyzer (SOEC) $1,000/kW (not available)

- Deep water storage, $15/kWh (not available today)*

- Oxy-combustion CC $720/kW (not available today)

- LCOE hybrid = 32¢/kWh

* Additional storage cost of O2 increases cost from $10 kWh to $15 per kWh.

36

NPV of Equipment Cost

PV Lin FC DPR1500 Converter Electr. H2 Tank0

20,000,000

40,000,000

60,000,000

80,000,000

100,000,000

Net

Pre

sen

t C

ost

($)

Cash Flow Summary

PV

1.8MW Linearized

Fuel Cell

Xtreme Pow er DPR 1500

Converter

Electrolyzer

Hydrogen Tank

SOEC, Deep Water Storage, Oxy-Combustion

37

Alkaline, Salt Cavern, Oxy-Combustion

Alkaline PEM SOEC

Power Gen. Technology Component HHV efficiency 72% 60% 82%

Air-combustion CC 51% 37% 31% 42%

Oxy-combustion CC 62% 45% 37% 51%

PEM 40% 29% 24% 33%

SOFC 61% 44% 37% 50%

Hydrogen Production Technology

Best in class for this location long-term:

- Alkaline electrolyzer $1,000/kW

- Salt cavern storage $0.08/kWh (not available today)*

- Oxy-combustion CC $720/kW (not available today)

- LCOE hybrid = 21.3 ¢/kWh

* Additional storage cost of O2 increases cost from $.05 kWh to $.08 per kWh.

38

NPV of Equipment Cost

Alkaline, Salt Cavern, Oxy-Combustion

PV Lin FC DPR1500 Converter Electr. H2 Tank0

30,000,000

60,000,000

90,000,000

120,000,000

Net

Pre

sen

t C

ost

($)

Cash Flow Summary

PV

1.8MW Linearized

Fuel Cell

Xtreme Pow er DPR 1500

Converter

Electrolyzer

Hydrogen Tank