Rajnish Kumarrajnish@iitm.ac.in

Hydrogen Liquefaction & Storage Symposium26 – 27 September, 2019

University of Western Australia, Perth

Hydrogen hydrates for storage and release of molecular hydrogen

Are we heading towards a hydrogen economy?

1800(Post industrial revolution)

27 kg of C

21 kg of C

14 kg of C

2005

Wood, muscles power

20xx19600*

per G

J of

ener

gy o

btai

ned

Coal

Oil

Natural gas

H2

10/1/2019 Prof. Rajnish Kumar, IIT-Madras, Chennai 2

Storage of Molecular Hydrogen in Hydrates

Concentration of THF (mol%)

0 1 2 3 4 5 6

wt%

of H

2

2

3

4

Region I

Region II Region III

Region I

Region II

Region III

Image sourced from open literature.

Structure I (sI) ! 2S.6L.46H2O512 (S) 51262 (L)

r ≈ 3.95A r ≈ 4.33A

Structure II (sII) ! 16S.8L.136H2O512 (S) 51264 (L)

r ≈ 3.91A r ≈ 4.73A

Structure H (sH) ! 3S.2M.1L.34H2O512 (S) 435663 (M) 51268 (L)

r ≈ 3.91 A r ≈ 4.06Ar ≈ 5.71A

Hydrates normally forms 3 distinct structures

H2THF

0 2 4 6

15.0

15.1

15.2

Pre

ssu

re (

ba

r)

0 4 8 12 1635.1

35.2

35.3

35.4

35.5

35.6

Pre

ssu

re (

ba

r)

0 4 8 12 16

56.2

56.3

56.4

56.5

56.6

56.7

Pre

ssure

(b

ar)

0 2 4

81.6

81.7

81.8

81.9

0 2 4 6

69.3

69.4

69.5

69.6

Pre

ssu

re (

ba

r)

Pre

ssu

re (

bar)

Time (hrs)0 4 8 12 16

93.7

93.8

93.9

94.0

94.1

94.2

Pre

ssu

re (

bar)

Time (hrs)

H2 saturation in hydrate phase is a slow process, sometime it takes up to 8 -10 h for complete saturation at hydrate forming pressure

Gas uptake profile of H2 in 5% THF hydrate at –11oC and pressure up to 95 bar.

Maximum 1.2 wt % hydrogen in the hydrate phase at 135 bar and –11oC

0 2 4 6 8 10 12 14

0.0

0.2

0.4

0.6

0.8

1.0

1.2

wt%

H2

Pressure (MPa)

5.7% THF, -12oC

2.7% THF, -12oC

1.0% THF, -12oC

5.7% THF, -1oC

12 10 8 6 4 2 0

-200

0

200

400

600

800

1000

1200

1400

Inte

nsi

ty

PPM

H2 hydrate 5 minutes 40 minutes 2 Hrs 4 Hrs 20 Hrs

T=-11oC, P=140 bar, 5.0 mol% TDF/D2O hydrate

Almost 50% conversion in 30 mins Minimum H2 occupancy=1.2 wt% (Without accounting for para hydrogen)

In-situ NMR

10 0

0

200

400

600

800

1000

Inte

nsi

ty

PPM

Hydrate Gas+Hydrate (240 min) Gas + Hydrate (5 min) No Gas

H2 occupancy, 1.21 wt% with 2.6% TDF/D2O hydrate

4080 4100 4120 4140 4160 4180

Para enriched H2 gas at room temperature,

O/P ratio = 1.5

Inte

nsi

ty (

a.u

.)

Wavenumber (cm-1)

H2 gas, ortho to para ratio = 5.3

400 600

Para enriched H2 gas, Ortho to Para ratio = 1.1

Inte

nsi

ty (

a.u

.)

Wavenumber (cm-1)

H2 gas, Ortho to Para ratio = 2.75

ParaPara

Raman spectroscopy shows unique peaks for ortho and para hydrogen (gas phase)

Do we have a take home message?

• Preliminary results suggests that storage capacity is in the range of 1.2%-1.4% (by weight) at moderate synthesis pressure and sub zero temperature.

• Is it possible that some of the large cages are occupied by a cluster of 2 hydrogen molecules or large cages have 4 hydrogen molecules?

• Hydrogen storage capacity at low temperature should be explored …

H2 hydrate formation at low temperature and low pressure

Peak position and peak width for H2 hydrate (?)

4080 4100 4120 4140 4160 4180

In

ten

sity

(a

.u.)

Wavenumber (cm-1)

H2+THF@100 bar

H2 hydrate @ 180 bar

Spectra has been normalized, for similar noise level

140 bar

Low temperature methane hydrate and carbon dioxide hydrate

12

PNAS, 116(5), 1526-1531

Literature suggests that formation of H2-NH3hydrate would be possible at low temperature

The activation of ice surfaces by ammonia at low temperatures is a well known phenomenon. Presence of ammonia is critical in forming clathrate at a very low temperature region where methane by itself may not form a clathrate hydrate. It was experimentally proved that presence of ammonia and methane give a clathrate hydrate that is much more stable Synergistic behaviour of ammonia and methane could be first extended to ammonia-methane-hydrogen hydrate and then to hydrogen – ammonia

13

Shin et al., 2013

Why Study Clathrate Hydrate?

• Understanding the hydrate at molecular level and measuring the right temperature and pressure zone where these hydrates can exist.

• Understanding the mechanism of hydrate formation and decomposition

• Potentially a sustainable energy source

• Safety in deep oil drilling operations

• Other technological applications and energy solutions like gas separation, methane storage and transportation

10/1/2019 Dr. Rajnish Kumar, NCL - Pune 14

Gas Hydrate

As a source of methane /natural gas

As a means to develop technology

Permafrost-associatednatural gas hydrate

Deepwater marine natural gas hydrate Gas storage Gas separation Desalination Refrigeration

Hydrogen storage

Natural gas storage & transportation

Methane separation

CO2 separation (CCS)

CH4 + CO2/H2S

CH4 + O2/N2

CH4 + C2H6 + C3H8CO2 + H2

N2 + CO2

Natural gas production

Flow Assurance

Bench Scale High Pressure Continuous Setup for Studying Methane Decomposition Kinetics at sub-Sea

Environment in Presence of Identified Additives

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Use of additives in the circulating water stream to enhance hydrate dissociation kinetics

(a) (b)

(c)

Gas bubbles on top of the waterflooded hydrate bearing sedimentindicating the release of methanegas as a result of dissociation ofmethane gas hydrates.

(a) Hydrate formation sediment prior to the start of the experiment .(b) Hydrate bearing sediment after water flooding.(c) Presence of gas bubbles indicating release of gas as a result of dissociation of gas hydrates.

Use of additive along with thermal stimulation/depressurizationcan significantly enhance the hydrate decomposition kinetics

0.0 0.1 0.2 0.3 0.4 0.50.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

No

rmali

se

d m

ole

s

(ga

s r

ele

ase

d)

Time(h)

A1 A2 A3 A4 A5 A6 A7 Pure Water A8 A9 A10 A11 A12

0.0 0.1 0.2 0.3 0.4 0.5 0.60.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

No

rmali

sed

mo

les

(gas

re

lea

se

d)

Time(h)

A1 A2 A3 A4 A5 A6 Pure Water(283K) A7 A8 A9 Pure Water(293K)

10/1/2019 Prof. Rajnish Kumar, IIT Madras 17

Sustainable production of methane by molecular replacement

" Thermodynamic feasibility

" Kinetics of replacement

" Structure stability &Thermodynamic stability

10/1/2019 18Prof. Rajnish Kumar, IIT Madras

AcknowledgementsFunding Partners (Gas Hydrate Research)• Department of Science and Technology (DST)• CSIR – 12th five year plan (Tapcoal)• Gas Authority of India Limited (GAIL)(Process Development)• Department of Bio-Technology (DBT)

Scientific Partners (Gas Hydrate Research)• Dr. Praveen Linga (NUS, Singapore)• Dr. T. Pradeep (IIT Madras)• Dr. John Ripmeester (NRC, Canada)• Prof. Peter Englezos (UBC, Canada)

Students who worked in the lab

1. Vikesh S. Baghel (M.E, now with Halliburton)2. Asheesh Kumar (PhD, Now with University of Western Australia)3. Nilesh Choudhary (PhD, now with KAUST)4. Gaurav Bhattacharya (PhD, Now with NUS, Singapore)5. Subhadip Das (PhD, now with LPU, India)6. Amit Arora (PhD, now with IIT – Roorkee)7. Namrata Gaikwad (PhD Student)8. Kavya (PhD Student)9. Kishore, Sheshan & Ravinder, (M.Tech Students)10. Omkar & Pragati (Postdocs in the group)

10/1/2019 20Prof. Rajnish Kumar, IIT-Madras, Chennai

10/1/2019 Prof. Rajnish Kumar, IIT Madras 21

Thank You!