Technologies for hydrogen liquefactionDavid Berstad, SINTEF Energi AS

Gasskonferansen, Trondheim, 11. april

Presentation outline

• Properties of hydrogen

• Brief history of hydrogen liquefaction

•Hydrogen liquefiers, current use and capacities

•Description of state-of-the-art liquefaction technology

•Outlook – potential for short- and long-term

improvements for hydrogen liquefaction processes

2

Hydrogen (H2) properties

• Molar mass: 2.016 kg/kmol

• Normal boiling point: ≈ 20.3 K (≈ -253 °C)

• Critial pressure: ≈ 13 bar

• Critical temperature: ≈ 33 K (≈ -240 °C)

• Normal liquid density: ≈ 71 kg/m3

• Lower heating value: 120 MJ/kg (33.3 kWh/kg)

• Higher heating value: 142 MJ/kg (39.4 kWh/kg)

3

Some liquid-hydrogen-related historic events

• 1898: First successful liquefaction by J. Dewar (UK)

• 1952: 0.6 t/d liquefier built (NBS-AEC Cryogenic Engineering Laboratory,

Boulder, Colorado)

• Mid/late 1950s: Liquid hydrogen demand for space rocket propulsion

• 0.8 t/d + 3.4 t/d + 27 t/d (Built by Air Products in West Palm Beach, Florida)

• 1987: Europe's largest hydrogen liquefaction plant built

• 10 t/d (Build by Air Liquide in Waziers, France)

• Liquid hydrogen needed for development of the Ariane 5 space launch vehicle

4

Current applications for liquid hydrogen

• Aerospace industry

• Chemical industries

• Electronic/semiconductor industry

• Health care industries

• Metallurgical industries

• Fuel cell manufacturers

• Glass production

• Food and beverage industry5

LH2

LH2

Rough liquefier capacities in selected regions

6

Japan:≈ 30 t/d

Europe:≈ 20 t/d

America:< 300 t/d

Purpose of liquefaction

• Enabling high-density storage and transport at low pressure

• Transport and storage economics analogous to LNG vs. CNG

7

1

10

100

1000

0 50 100 150 200 250 300 350

Den

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Pressure of compressed gas [bar]

Hydrogen

Methane

Importance of high hydrogen liquefier efficiency

Ratio between liquefaction power (electric) and energy

content (heating value) of the liquefied gas

8

0%

5%

10%

15%

20%

25%

30%

35%

25% 30% 35% 40% 45% 50% 55% 60%

Liq

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/ E

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Exergy efficiency of liquefaction process

Hydrogen, LHV

Hydrogen, HHV

Methane, LHV

Methane, HHV

State of the art (5–10 ton per day)

Snøhvit LNG (15 000 ton per day)

Large potential for improving hydrogen liquefier efficiency by

scaling up train capacity!

Methane

Current liquid hydrogen storage capacity

9

Image source:• https://www.nasa.gov/content/liquid-hydrogen-

the-fuel-of-choice-for-space-exploration• Kawasaki Heavy Industries

≈ 12 m≈ 20 m

NASA, USA3 800 m3

270 t

JAXA, Japan540 m3

38 t

LH2 truck< 50 m3

< 3.5 t

Large-scale liquid hydrogen storage

10

≈ 45 m

≈ 12 m≈ 20 m

NASA, USA3 800 m3

270 t

JAXA, Japan540 m3

38 t

40 000 m3

2 800 t50 000 m3

3 500 t

LH2 truck< 50 m3

< 3.5 t

Existing

Image source: Kawasaki Heavy Industries

Hydrogen liquefier feed and product conditions

• Hydrogen feed pressure: typically 15–20 bar (critical pressure is

approximately 13 bar)

• Hydrogen purity requirement: Generally 10–100 ppm, depending on

impurity composition

• Internal adsorbers at low temperature in the liquefier reduces the

impurities concentration to < 1 ppm before final liquefaction stages

• Final liquid hydrogen state:

• Typically saturated or subcooled liquid at 1.2–1.5 bar

• Para-hydrogen content > 95 %11

State of the art for hydrogen liquefaction

• Current "large-scale" plants

• Capacity of typically 5–15 ton per day

• Hydrogen Claude cycles using liquid nitrogen for precooling

• Typically 10–12 kWh/kg specific liquefaction power

• Smaller plants

• Capacity typically below 2–3 ton per day

• Helium Brayton cycles with liquid nitrogen precooling gives the best overall

economy

• Lower capacities can also be delivered, down to approximately 0.15 ton per day

• Small capacities are more sensitive to CAPEX and less to OPEX12

13

H2 fe

ed

-193°C

-180°C

30°C

LN2

-242°C

-243°C –

-251°C

-252°C

20 bar

1.2–1.5 bar

20–25

bar

3–5 bar

1.2–

1.3 bar

State of the art for hydrogen liquefaction

• Hydrogen Claude cycle

• Liquid nitrogen pre-cooling to ≈ 80 K

• Hydrogen purification in adsorbers after

LN2 pre-cooling

• Adiabatic ortho-para conversion after

LN2 pre-cooling

• Further continuous ortho-para

conversion internally in heat exchangers

• Final liquefaction by expansion through

an ejector, also recompressing boiloff

gas from storage

Hydrogen Claude refrigeration cycle

LN2 precooling cycle

Hyd

rogen

14

H2 fe

ed

-193°C

-180°C

30°C

LN2

-242°C

-243°C –

-251°C

-252°C

20 bar

1.2–1.5 bar

20–25

bar

3–5 bar

1.2–

1.3 bar

State of the art for hydrogen liquefaction

Oil-free hydrogen piston compressors

• 2-stage low-pressure compressor

• 2-stage high-pressure compressor

Plate-fin heat exchangers filled with catalyst

grains on the hydrogen feed side for ortho-

para conversion

Open liquid nitrogen pre-cooling process

• Supplied from adjacent air separation

unit or other source

Capacity control: Smooth load control

between roughly 40 % and 100 % load

Hydrogen Claude refrigeration cycle

LN2 precooling cycle

Hyd

rogen

15

H2 fe

ed

-193°C

-180°C

30°C

LN2

-242°C

-243°C –

-251°C

-252°C

20 bar

1.2–1.5 bar

20–25

bar

3–5 bar

1.2–

1.3 bar

State of the art for hydrogen liquefaction

Cryogenic expanders

• Radial hydrogen turboexpanders

• Oil or gas bearings (or magnetic)

• Dynamic gas bearings are most

reliable and the current frontier.

Installed in all recent liquefiers in

Japan

• Typically 10–50 kW, up to > 85%

isentropic efficiency

• Oil or gas brakes to dissipate shaft

power

Hydrogen Claude refrigeration cycle

LN2 precooling cycle

Hyd

rogen

Courtesy of Linde Kryotechnik AG.S. Bischoff, L. Decker. First operating results of a dynamic gas bearingTurbine in an industrial hydrogen liquefier. AIP Conference Proceedings 1218, 887 (2010)

• High-efficiency hydrocarbon-based mixed refrigerant pre-cooling processes

• PRICO-type, Kleemenko-type, or cascade-type processes are possible

• Higher degree of process integration Lower losses in heat exchangers

• Larger and more efficient compression and expansion machinery

• Possibility of power recovery from cryogenic expanders instead of dissipating

the shaft power with brakes

• Lower relative boil-off rate from liquid hydrogen storage

• Long-term: Possibly new refrigerant mixtures, e.g. He/Ne or H2/Ne to enable

the use of turbocompressors instead of piston compressors16

Scaling up liquefier train capacity enables…

0

1

2

3

4

-260 -250 -240 -230 -220 -210 -200 -190 -180 -170 -160

Re

lati

ve e

xerg

y lo

ss

kW e

xerg

y /

kW h

eat

tra

nsf

err

ed

]

Hot side temperature {°C]

ΔT between hot and cold side [°C]

ΔT 5 °C

ΔT 4 °C

ΔT 3 °C

ΔT 2 °C

ΔT 1 °C

Very tigh heat integration needed to curb thermodynamic losses

17

QΔT

Hot side

Cold side

18

Composite Curves for a block with 100 ton hydrogen per day capacity

Very tigh heat integration needed to curb thermodynamic losses

020406080

100120140160180200220240260280300

0 5 10 15 20 25 30 35 40 45

Tem

per

atu

re [

K]

Duty [MW]

19

Composite Curves for a block with 100 ton hydrogen per day capacity

Very tigh heat integration needed to curb thermodynamic losses

0

1

2

3

4

5

6

7

8

9

020406080

100120140160180200220240260280300

0 5 10 15 20 25 30 35 40 45

Tem

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K]

Tem

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Targeted liquefier efficiency improvement

Up to 50 % reduction of power requirement has been identified by several projects1,2

20

10%

15%

20%

25%

30%

35%

25% 30% 35% 40% 45% 50% 55% 60%

Liq

uef

acti

on

po

wer

/ E

ner

gy c

on

ten

t

Exergy efficiency of liquefaction process

Hydrogen, LHV

Hydrogen, HHV

Target for scaled-up process (> 50 ton per day)

State of the art (5–10 ton per day)10–12 kWh/kg

1 www.idealhy.eu2 Cardella U., Decker L., Klein H. Large-Scale Hydrogen Liquefaction. Economic viability. ICEC 26 - ICMC 2016 conference

21Courtesy of Linde Kryotechnik AG.Cardella U., Decker L., Klein H. Large-Scale Hydrogen Liquefaction. Economic viability. ICEC 26 - ICMC 2016 conference

Targeted liquefier efficiency improvement

Targeted specific cost improvement

22

Courtesy of Linde Kryotechnik AG.U. Cardella, L. Decker, H. Klein. Roadmap to economically viable hydrogen liquefaction, International Journal of Hydrogen Energy, Volume 42, Issue 19, 2017, Pages 13329-13338.

More than 50 % specific

liquefaction cost is targeted

from scaling-up, which enables

reductions in both specific

CAPEX and specific OPEX.

23

Acknowledgements

This publication is based on results from the research project Hyper,

performed under the ENERGIX programme. The authors acknowledge

the following parties for financial support: Statoil, Shell, Kawasaki Heavy

Industries, Linde Kryotechnik, Mitsubishi Corporation, Nel Hydrogen and

the Research Council of Norway (255107/E20).

Teknologi for et bedre samfunn

Conversion of ortho-H2 to para-H2

• Hydrogen exists in two different spin isomers and thus energy levels

• At ambient temperature, an equilibrium hydrogen mixture consists of:

• 75 % ortho-hydrogen – higher energy level, parallel spin

• 25 % para-hydrogen – lower energy level, antiparallel spin

• In liquid state, the equilibrium composition is close to 100 % para-H2

• Without conversion during liquefaction, almost 20 % of the liquid would

evaporate within the first 24 hours of storage, due to spontaneous conversion

• The heat of spontaneous conversion is higher than the heat of

evaporation at liquid storage conditions25

Purpose of liquefaction

• Enabling high-density storage and transport at low pressure

• Transport and storage economics analogous to LNG vs. CNG

26

0%

10%

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Pressure of compressed gas [bar]

Methane

Hydrogen