1

Troy A. Semelsberger Los Alamos National Laboratory

Hydrogen Storage Summit Jan 27-29, 2015

Denver, CO

Chemical Hydrogen Storage Materials

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Objectives

1. Assess chemical hydrogen storage materials that can exceed 700 bar compressed hydrogen tanks

2. Status (state-of-the-art) of chemical hydrogen storage materials

3. Identify key material characteristics

4. Identify obstacles, challenges and risks for the successful deployment of chemical hydrogen materials in a practical on-board hydrogen storage and delivery system

5. Ask the hard questions

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Presentation Caveats

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• Presentation focused solely on the onboard storage of hydrogen for light duty automotive applications

• All DOE targets are equally weighted

• All DOE targets must be met concurrently

• Focused on the general class of chemical hydrogen storage materials

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Introduction and Overview

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5

Introduction and Overview

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According to Toyota and Hyundai— fill-time, volumetric capacity and gravimetric capacity are not show-stoppers

to commercialization

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0

20

40

60

80

100

Start Time to Full Flow (20°C)

Fill Time (5 kg H2)

Start Time to Full Flow (-20°C)

Transient Response

Fuel Purity

Wells-to-Power Plant Efficency

Loss of Useable H2

Fuel Cost

Cycle Life (1/4 - full)

Volumetric Density

Onboard Efficiency

System Cost

Min. Full Flow Rate

Max. Delivery Pressure

Min. Operating Temp.

Max. Operating Temp.

Min. Delivery Pressure

Max Delivery Temp.

Min. Delivery Temp. Gravimetric Density

2017 Ultimate

6* Estimated fill times for Toyota FCHV ~ 5 min (5.8 kg H2?), Hyundai Tucson ~ 10 min ( 5.8 kg H2)

700 bar Compressed Hydrogen-Commercialized Technology

*

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HSECoE Chemical Hydrogen Storage Baseline System

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Hydrogen Purification System

(FT-2)

Fuel Cell

Reactor (RX-1)

Volume Displacement Tank (TNK-1)

Phase Separator Ballast Tank

(PS-1)

Fill Station Fill & Drain

Ports

P S

PS

T

P

Rupture Disk @ 2 bar (INS-01)

L

Flapper Doors

½" P

last

ic

½" P

last

ic

3/8” SS

Reactor Heater (H-1)

3/8” SS

PRV @ 5 bar (V-4)

INS-08

INS-07

PRV @ 30 bar (V-2)

T

INS-06

INS-04

V-5

INS-09

INS-10

V-3

INS-11

3/8" SS

½” S

S

3/8" Al

3/8" Al

T

INS-05

Rupture Disk @ 2 bar (INS-03)

L

INS-02

½" Plastic

Pusher Fan Motor (M-5)

Gas & Liquid Radiators (RD-1/2)

T

V-1

MM

S

C

3/8"

Al

3/8” SS

C

Feed Pump (P-1)

Recycle Pump (P-2)

Ballast Tank (TNK-2)

Baseline system developed for fluid-phase chemical hydrogen storage materials; neat liquids, non-settling homogeneous slurries, and solutions

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8

7.8 wt. % Chemical Hydrogen Storage Material

2017 Ultimate

0

20

40

60

80

100

Start Time to Full Flow (20°C)

Fill Time (5 kg H2)

Start Time to Full Flow (-20°C)

Transient Response

Fuel Purity

Wells-to-Power Plant Efficency

Loss of Useable H2

Fuel Cost

Cycle Life (1/4 - full)

Volumetric Density

Onboard Efficiency

System Cost

Min. Full Flow Rate

Max. Delivery Pressure

Min. Operating Temp.

Max. Operating Temp.

Min. Delivery Pressure

Max Delivery Temp.

Min. Delivery Temp. Gravimetric Density

ECoE estimates based on a neat liquid with 7.8 wt. % usable H2 and idealized system design of mass 30.6 kg and 35 L

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9

700 bar H2 vs. 7.8 wt.% Chemical Hydrogen (ultimate targets)

7.8 wt. % CH liquid 700 bar Comp H2

0

20

40

60

80

100

Start Time to Full Flow (20°C)

Fill Time (5 kg H2)

Start Time to Full Flow (-20°C)

Transient Response

Fuel Purity

Wells-to-Power Plant Efficency

Loss of Useable H2

Fuel Cost

Cycle Life (1/4 - full) Volumetric Density

Onboard Efficiency

System Cost

Min. Full Flow Rate

Max. Delivery Pressure

Min. Operating Temp.

Max. Operating Temp.

Min. Delivery Pressure

Max Delivery Temp.

Min. Delivery Temp. Gravimetric Density

*

* Estimated fill times for Toyota FCHV ~ 5 min (5.8 kg H2?), Hyundai Tucson ~ 10 min ( 5.8 kg H2)

ECoE estimates based on a neat liquid with 7.8 wt. % usable H2 and idealized system design of mass 30.6 kg and 35 L

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10

700 bar H2 vs. 6.0 wt. % Chemical Hydrogen (ultimate targets)

6 wt.% CH Liquid 700 bar H2

0

20

40

60

80

100

Start Time to Full Flow (20°C)

Fill Time (5 kg H2)

Start Time to Full Flow (-20°C)

Transient Response

Fuel Purity

Wells-to-Power Plant Efficency

Loss of Useable H2

Fuel Cost

Cycle Life (1/4 - full) Volumetric Density

Onboard Efficiency

System Cost

Min. Full Flow Rate

Max. Delivery Pressure

Min. Operating Temp.

Max. Operating Temp.

Min. Delivery Pressure

Max Delivery Temp.

Min. Delivery Temp. Gravimetric Density

*

* Estimated fill times for Toyota FCHV ~ 5 min (5.8 kg H2?), Hyundai Tucson ~ 10 min ( 5.8 kg H2)

ECoE estimates based on a neat and idealized system design of mass 30.6 kg and 35 L

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Well-to-Wheels Energy Breakdown WTW Energy Breakdown kWh/kg‐H2

700 bar Gas 2020

CcH2 Liq. H2 2020

Liquid AB 2020

Liquid Alane 2020

Absorbent 2020

Plant Gate 50.3 50.3 50.3 50.3 50.3 Regen 0.0 0.0 143.0 67.8 0.0

Liquefaction 0.0 17.5 0.0 0.0 0.0 Terminal 4.5 3.2 0.3 0.2 10.4

Transport (Trailer) 0.6 0.1 0.3 0.3 0.3 Station 3.6 0.6 0.0 0.0 13.0

Vehicle Storage Parasitics 0.0 0.0 8.1 16.2 9.5

Total 59.0 71.8 202.0 134.8 83.5

11M. Paster, et. al. Liquid Carrier and Adsorbent Systems WTW Analyses for the HSECoE, February 2013

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Well-to-Wheels Cost Breakdown

12M. Paster, et. al. Liquid Carrier and Adsorbent Systems WTW Analyses for the HSECoE, February 2013

WTW Cost Breakdown

700 bar Gas 2020

CcH2 Liq. H2 2020

Liquid AB 2020

Liquid Alane 2020

Absorbent 2020

Pl ant Gate $1.95 1.95 1.95 1.95 1.95 Re ge n $0.00 $0.00 $10.46 $4.00 $0.00

Lique f action $0.00 $0.96 $0.00 $0.00 $0.00 Te rminal $0.52 $0.40 $0.08 $0.07 $0.84

Transport ( Trai l e r) $0.50 $0.12 $0.23 $0.24 $0.51 Station $0.93 $1.07 $0.68 $0.68 $2.01

Ve hicl e Storage Parasitics $0.00 $0.00 $0.56 $0.95 $0.68

Total $3.91 $4.50 $13.96 $7.88 $6.00

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Compressed Hydrogen Pathway

2

4

2H Source H O

Biomass CH

Com

pres

sed

H2

Notables: No regeneration schemes necessary Unidirectional processing pathway

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Chemical Hydrogen Processing Pathway

2

4

2H Source H O

Biomass CH

Notables: Bidirectional processing pathway Added complexity and processing steps

……energy consuming and costly

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Chemical Hydrogen Processing Pathway

¿Bidirectional processing pathway?

OR ¿Unidirectional?

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Chemical Hydrogen Processing Pathway ¿Unidirectional?

2

4

2H Source H O

Biomass CH

2

4

C Source CO

Biomass CH Coal

DME MeOH FT Diesel FT Gasoline EtOH

Car

bon

Base

d C

hem

ical

H

ydro

gen

Ref

orm

ing

……. for example

¿ non-carbon based analogs?

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Values denote maximum theoretical wt. % H2 (i.e., all hydrogen removed)Chemical Hydrogen Status M

ater

ial V

olum

etric

H D

ensi

ty (k

g H

/m 3 )

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160

140

120

100

80

60

40

20

0

H2

(700 bar,RT, wt.%= 100)

Alane

Ultimate Material Targets

N-ethylcarbazole

Cyclohexane

Decalin

2017

Mat

eria

l Tar

gets

Ca(AlH4)2 M

g(Al

H4 ) 2

KAlH4

NaBH4

LiAl

H4

KBH4

NaAlH4

Mg2H2

Mg2NiH4

LaNi5H6

BaReH9

Mg2FeH6

MOFs

Aerogels SWNT

MeOH

H2O

CH4 (liq)

Hardwood Timber

MeOH-SR

Bituminous Coal

Anthracite Coal

EtOH

DM

EDM

E-S

R

EtOH-SR MeOH-SR

Hydrazine

LiBH4

NH

3 (liq

) Gasoline

Diesel

Al(BH4)3

NH3BH3

CH4 (gas @ RT)

2017 Material Targets

Material targets derived from the idealized fluid-phase system design

0 5 10 15 20 25

Material wt % H2 17

1818

Chemical Hydrogen Materials

Chemical hydrogen storage materials have the highest potential in meeting the gravimetric and volumetric targets, but thermodynamics and kinetics are preventing their realization

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calin

Ca(

Mg(

AlH

4) 2

H4

NaAl

s

H Timbe

Bitu oal

oal

Li

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State-of-the-Art

0 5 10 15 20 25

0

20

40

60

80

100

120

140

160

Mg2H2

H2

(700 bar,RT, wt.%= 100)

Alane

Ultimate Material Targets

N-ethylcarbazole

Cyclohexane

De

AlH4)2

KAl

NaBH4

LiAl

H4

KBH4

H4

Mg2NiH4

LaNi5H6

BaReH9

Mg2FeH6

MOF

Aerogels SWNT

MeOH

H2O

CH4 (liq)

ardwood r

MeOH-SR

minous C

Anthracite C

EtOH

DM

EDM

E-SR

EtOH-SR MeOH-SR

Hydrazine

BH4

NH

3 (liq

) Gasoline

Diesel

Al(BH4)3

NH3BH3

Mat

eria

l Vol

umet

ric H

2 Den

sity

(kg

H2 /m

3 )

Material wt % H2

CH4 (gas @ RT)

2017 Material Targets

C-B

-N C

ompo

unds

(~9.

5 w

t.% m

ax)

C-H

Com

poun

ds (~

7.2

wt.%

max

)

B-N

Com

poun

ds (~

19.6

wt.%

max

)

C-H Compounds: reversible conjugated diene systems (7.2 wt. % theoretical, 7.2 wt. % observed) C-B-N Compounds: reversible CBN backbones (9.5 wt. % theoretical, ~4.5 wt. % observed) B-N Compounds: 19.6 wt.% theoretical, ~15.5 wt. % observed)

Values denote maximum theoretical wt. % H2 (i.e., all hydrogen removed) Material targets derived from the idealized fluid-phase system design

2020

Notable Shortcomings-in general

• Dehydrogenation kinetics • Shelf-life • Phase or phase change • Vapor pressure • Gravimetric capacity • Regeneration efficiencies • Fuel cost • Noble metal catalysis • Impurities • Durability and operability

Chemical Hydrogen

• Gravimetric capacity • Volumetric capacity • Fill time • High pressure

700 bar Hydrogen

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Key Material Properties

• Neat liquids with >7.8 wt. % H2 • Solid, slurry or solution phase compositions are highly improbable

…….if not impossible

• Maintaining fluid phase through dehydrogenation

• Very low/negligible vapor pressure (e.g., ionic liquids)

• Suitable dehydrogenation kinetics with high conversions • fast kinetics (> 0.4 moles H2/s, T = 125-200°C) • high hydrogen selectivities (SH2 > 0.997) • extended shelf-life greater than 60 days @ 60°C, X < 7.2%)

• Melting points: Tmpt < -40°C

• Energy efficient regeneration routes (WTPP > 66.6%) …….likely to be less efficient than compressed hydrogen

• Fuel cost …….likely to cost more than hydrogen

• Fuel Cell Impurities (i.e., reaction selectivity) • recycle vs. replenish

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Summary: Material Property Guidelines Parameter Symbol Units Range* Assumptions

Minimum Material capacity (liquids) mat g H2 / g material ~ 0.078

• System mass (excludes media) = 30.6 kg (36.3 kg) • 5.6 kg of H2 stored • Liquid media (neat) • Media density = 1.0 g/mL

Minimum Material capacity (solutions) mat g H2 / g material ~ 0.098

• System mass (excludes media) = 30.6 kg (36.3 kg) • Solute mass fraction = 0.35 ~ 0.80 • Solution density = 1.0 g/mL

Minimum Material capacity (slurries) mat g H2 / g material ~ 0.112

• System mass (excludes media) = 30.6 kg (36.3 kg) • Non-settling homogeneous slurry • Slurry mass fraction = 0.35 ~ 0.70 • Slurry volume fraction = 0 ~ 0.5 • Slurry density = 1.0 g/mL

Kinetics: Activation Energy

Ea kcal / mol 28–36 • Vreactor ≤ 4 L • Shelf life ≥ 60 days • Reaction order, n = 0 – 1 Kinetics:

Preexponential Factor A 4 x 109 – 1 x 1016

Endothermic Heat of Reaction Hrxn kJ / mol H2 Hrxn ≤ +17

• On-board Efficiency = 90% • # Cold Startups = 4 • T = 150 °C with no heat recovery • neat liquid (Cp = 1.6 J/g K) • Reactor mass = 2.5 kg SS (5.0 kg SS)

Exothermic Heat of Reaction Hrxn kJ / mol H2 Hrxn ≥ -27 • Tmax = 250°C

• Recycle ratio @ 50%

Maximum Reactor Outlet Temperature

Toutlet °C 250 • Liquid Radiator = 2.08 kg • Gas Radiator = 0.3 kg • Ballast Tank = 2.6 kg

Impurities Concentration

yi ppm No a priori estimates

can be quantified • madsorbent ≤ 3.2 kg

Media H2 Density mat) (m)(mat) kg H2 / L ≥ 0.07 • HD polyethylene tank ≤ 6.2 kg

Regen Efficiency regen % ≥ 66.6% • On-board Efficiency = 90% • WTPP efficiency = 60%

Viscosity cP ≤ 1500 None

* (a) parameter values are based on a specific system design and component performance with fixed masses and volumes (b) values outside these ranges do not imply that a material is not capable of meeting the system performance targets (c) the material property ranges are subject to change as new or alternate technologies and/or new system designs are developed (d) the minimum material capacities are subject to change as the density of the composition changes due to reductions in the mass and volume of the storage tank or reductions in system mass are realized material values correlate to the idealized system design (i.e., system mass = 30.6 kg, excludes media and tank mass )

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The Tough Questions

¿ Assuming an ideal chemical hydrogen material with all of the required material properties, is that enough to supplant compressed hydrogen?

¿ Can chemical hydrogen storage materials ever be as efficient or better than hydrogen production?

¿ Can chemical hydrogen storage materials be cost competitive with hydrogen?

¿ What efficiency and cost are needed to favor chemical hydrogen over compressed hydrogen?

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Notable Shortcomings-in general ¿ What are the ultimate advantages of chemical hydrogen storage materials over 700 bar compressed hydrogen?

- Lower Pressure

- Gravimetric Capacity - Volumetric Capacity

Lower Pressure Volumetric Capacity Gravimetric Capacity

WTPP Efficiency Fuel Cost

Overall Simplicity

700 bar H2Chemical H2 ?

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Acknowledgements

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Ned Stetson and Jesse Adams

Fuel Cell Technologies Office

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Disclaimer • The material properties detailed in this presentation were prepared in order to provide general

guidance for chemical hydrogen storage researchers and therefore should not be taken as rigid constraints.

• The presented material properties were developed within the constraints of our system design, component sizing, assumptions, and system operating conditions. In addition, the ranges in material properties are not specific to a particular material, and therefore can be applied to the general class of chemical hydrogen storage media.

• Material property values just outside the material ranges presented do not imply that a material is not capable of meeting the system performance targets, but rather that the material will require further examination.

• The material property ranges are subject to change as new technologies and/or new system designs are developed.

• The minimum material capacities are subject to change if the density of the composition changes because of reductions in the mass and volume of the storage tank.

• Material properties that fall within the presented material properties do not establish commercial viability or commercial success.

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