a future energy chain based on liquefied hydrogen

8/8/2019 A Future Energy Chain Based on Liquefied Hydrogen

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1SINTEF Energy Research

A future energy chain based onliquefied hydrogen

David Berstad, Jacob Stang, Petter Neks

SINTEF Energy Research

Trondheim

Hydrogen and Fuel Cells in the Nordic Countries, Oslo, 2009


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Outline

Background: options for energy chains based on bulktransport and distribution of hydrogen

Importance of making efficient, large-scale liquefiers incase of liquid hydrogen bulk distribution

Our contribution: design of a large-scale hydrogen

liquefier concept based on mixed-refrigerant (MR)technology to enhance liquefaction efficiency

Currently proven viable in LNG production

Investigation of the application of MR technology in the field ofhydrogen liquefaction


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Background

Depending on degree of market penetration, centralhydrogen production with bulk distribution to retail sites is

a possible scenario for the early stages of the hydrogeneconomy1,2

Options for bulk transportation:

Compressed gaseous hydrogen (CGH2) Very high pressure, ambient temperature

Liquefied hydrogen (LH2)

Saturated liquid at near-atmospheric pressure Liquefaction processes are very energy-intensive

1 Kramer G.J., Huijsmans J.P.P. and Austgen D.M. Clean and green hydrogen. 16th World hydrogen energy conference, 2006.

2 Tzimas E., Castello P. and Peteves S. The evolution of size and cost of a hydrogen delivery infrastructure in Europe in themedium and long term. International Journal of Hydrogen Energy Volume 32(1011), 2007, 13691380.


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Hydrogen energy chain options

Hydrogenliquefier

LH2storage LH2 transport truck

CGH2 transport truck

CGH2 storage

Conversion from primaryenergy source:

Gasificaton (Coal, biomass) Reforming (Natural gas)

Electrolysis (Electricity)

Conditioning

Compression

Retail sites

Retail sites


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Hydrogen transport typical values

Capacity: 0.30.6 t

Transport pressure: 200700 bar

CGH2 transport truck

LH2 truck transport has typically 610 times the capacity of that of CGH2 CGH2 vessels are not emptied completely as a certain pressure level must be

maintained in the vessels (cushion gas)

LH2 transport truck

Capacity: 0.44 t

Transport pressure: 11.3 bar



Hydrogen transport typical values

8.4% of total weight

1.3% of total weight

Pictures from: Wolf J. LH2 makes you mobile. Linde Reportson science and technology, 2003, 1, 3035.



Retail sites operations

Flexibility With close to equal overall cost, LH2-baseddistribution enables delivery of hydrogen in any form with

low energy consumption at retail-side filling stations

CGH2 does not offer this flexibility without on-siterefrigeration

Large scale centralized liquefactionLarge scale centralized liquefaction

with carbon capture and sequestrationwith carbon capture and sequestration

LiquidLiquid HydrogenTruckedHydrogenTrucked

(or shipped in)(or shipped in)

Storage in structuresStorage in structures

(partly cooled and(partly cooled and

partly pressurized)partly pressurized)

CompressedCompressed

(pressurized during(pressurized during

gasification)gasification)

LiquidLiquid

Hydrogen refueling stationHydrogen refueling station

storage as LHstorage as LH22

Large scale centralized liquefactionLarge scale centralized liquefaction

with carbon capture and sequestrationwith carbon capture and sequestration

LiquidLiquid HydrogenTruckedHydrogenTrucked

(or shipped in)(or shipped in)

Storage in structuresStorage in structures

(partly cooled and(partly cooled and

partly pressurized)partly pressurized)

CompressedCompressed

(pressurized during(pressurized during

gasification)gasification)

LiquidLiquid

Hydrogen refueling stationHydrogen refueling station

storage as LHstorage as LH22



Previous ShellLinde well-to-wheel study1

Early-phase scenario: reforming of methane, CO2 capture andbulk transportation of hydrogen from production site to retail site

Liquid hydrogen (LH2) vs. compressed gaseous hydrogen

(CGH2)

1 Kramer G.J., Huijsmans J.P.P. and Austgen D.M. Clean and green hydrogen. 16th World hydrogen energy conference, 2006

Assumed specific liquefaction powerfor LH

2: 10 kWh/kg

LH2

Average distribution distance: 75 km

Production volume: 100 tonnes/day

Number of retail sites: 100

LH2 transport capacity: 3500 kg/truck

CGH2 transport capacity: 350 kg/truck



Transition from current LH2 production

Existing liquefiers Envisioned future liquefiers

Market LH2 mainly for specific industrialpurposes

LH2 as an energy commodity

Plant capacity 4.4 tonnes/day (Ingolstadt, 1992)1

5.0 tonnes/day (Leuna, 2007)2Significant scale-up in capacity(30100 tonnes/day or more)

Specificliquefaction powerconsumption

13.6 kWh/kg (Ingolstadt)1

11.9 kWh/kg (Leuna)2

(10 kWh/kg in Shell study)

Considerably lower due to higheremphasis on energy efficiency,scaling-up advantages andshifted cost structure

Operation Flexible operation to adjust todemand (Leuna: 40100% loadrange)

Large base-load plants with highefficiency at full load

1 Bracha M. et al. Large-scale hydrogen liquefaction in Germany. Int J Hydrogen Energy 19(1):5359, 1994.

2 Bracha M. and Decker L. Grosstechnische Wasserstoffverflssigung in Leuna. Deutsche Klte-Klima-Tagung, 2008.



Efficiency of hydrogen liquefiers

0

2

4

6

8

10

12

14

16

18

20 25 30 35 40 45 50 55 60

Overall exergy efficiency [%]

Specific

power[kWh/kg

LH2]

Plants in Germany

Recently proposedlarge-scale concepts

Berstad D., Stang J. and Neks P. Comparison criteria for large-scale hydrogen liquefaction processes. Int J Hydrogen Energy34(3):15608, 2009




0

2

4

6

8

10

12

14

16

18

20 25 30 35 40 45 50 55 60


Specific

power[kWh/kg

LH2]


1barH2feedpres

sure

21barH2 feedpressure





0

2

4

6

8

10

12

14

16

18

20 25 30 35 40 45 50 55 60


Specific

power[kWh/kg

LH2]


Comparison of efficiency basedon equal boundary conditions

1barH2feedpres

sure






0

2

4

6

8

10

12

14

16

18

20 25 30 35 40 45 50 55 60


Specific

power[kWh/kgLH2]


1barH2feedpres

sure




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Creating a reference case for our work

The concept by Prof. Quack1 (2001) is the most efficient conceptpublished we have therefore based our work on this concept and

using it as reference process Changed assumptions of the reference process to be more

conservative/realistic than in original configuration:

Assumed 21 bar feed pressure instead of 1 bar

Inter-cooler temperature in compressor trains: 310 K Implemented pressure drop in all heat exchangers and inter-coolers

Minimum temperature approach (Tmin) in heat exchangers:

Above 235 K: Tmin= 3 K

Below 235 K: Tmin= 2 K

Liquefaction capacity: 86 tonnes/day

Resulting exergy efficiency: 45.7%

1 Quack H. Conceptual design of a high efficiency large capacity hydrogen liquefier. Advances in Cryogenic Engineering47:255263, 2001


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Implementing mixed refrigerant pre-cooling in the reference case

310 K 220 K 20 K

Pre-compressionto 80 bar

75 K

LH2

Process (H2)

Utilities

235 K

2-stagepropane

cycle

1-stageethane

cycle

Reversed Helium/NeonBrayton cycle with internal

recuperation

Original referenceprocess

Modified processwith mixedrefrigerant (MR)

Mixed refrigerant pre-cooling cycle

26 K

Expansionto 1 bar

ReversedHelium/Neon

Brayton cycle withinternal

recuperation

Utilities in the different temperature intervals


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Liquefaction processmodified with MR pre-cooling


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Power figures and overall results


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LH2 related to LNG

Lower heating value:

LNG: ~13.6 kWh/kg (~49 MJ/kg)

LH2: 33.4 kWh/kg (120 MJ/kg) Reversible liquefaction power (specific):

LNG: 0.11 kWh/kg (Snhvit gas, Hammerfest conditions)

LH2: 2.89 kWh/kg (21 bar feed pressure, 300 K ambient temperature)

The Snhvit LNG plant:

Specific design power consumption: 0.23 kWh/kg1

Exergy efficiency: ~48%

The best-performance LH2 process with MR pre-cooling: Specific design power consumption: 6.17 kWh/kg

Exergy efficiency: ~47%

1 Heiersted R.S., Lillesund S., Nordhasli S., Owren G. and Tangvik K. The Snohvit Design Reflects A Sustainable EnvironmentalStrategy. Conference paper, LNG-14, Quatar, 2004.


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Conclusion

The LH2 processes employing MR pre-cooling show a specificpower consumption of 6.176.49 kWh/kg and exergy efficiencyof 44.646.9%

4050% reduction of power consumption, down from 12 to 67kWh/kg, will represent a radical improvement within large-scalehydrogen liquefaction and contribute to further enhancement ofthe competitiveness of LH2 as energy carrier in an hydrogen-

based energy chain As for LNG, MR pre-cooling may play an important role in the

efforts towards efficient large-scale liquefaction processes

High exergy efficiency is desired and may be obtainable forlarge-scale liquefiers with energy optimisation, extensiveprocess integration and high-efficiency compressors andexpanders


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Further work: continuation projectproposal


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Hydrogen liquefier rig for experimentalactivities


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Acknowledgements

Financial support

Scientific support

a future energy chain based on liquefied hydrogen

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