(6eh) Energy Storage in Clathrate Hydrates – Recent Advancements in Solidified Natural Gas (SNG) Technology

Hari Prakash Veluswamy

Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117 585

SNG (solidified natural gas) technology is a promising and potential technology for long-term and large-scale storage of methane (natural gas) in hydrates due to the plethora of benefits it offers in comparison to conventional methods of natural gas (NG) storage. The technology has the potential to store multi-fold volumes of natural gas in compact hydrate crystals offering the safest and environment friendly mode of NG storage. Energy recovery from SNG is very easy by simple thermal stimulation (low waste heat is sufficient) with the possibility of complete recovery of the stored gas. Few key existing challenges that impede the commercial deployment of SNG include the need for severe operating conditions (low temperature and high pressure requirement for hydrate formation), slow kinetics of hydrate formation and the stringent storage conditions (storage temperature of -20 deg C at atmospheric pressure based on the anomalous ‘self-preservation’ effect). Recently, we demonstrated the rapid hydrate formation kinetics in presence of methane and 5.6 mol% tetrahydrofuran (THF) in a simple unstirred reactor configuration at moderate pressures and near ambient temperature conditions. The feasibility of scale-up potential of this approach was also documented in our study. Molecular level characterization studies have revealed the characteristic two-step mixed hydrate formation process and a plausible mechanism for the rapid hydrate growth was formulated. Hydrates formed in presence of THF are very stable, thus storage is possible at temperatures even at 0 deg C at atmospheric pressures without depending on the ‘self-preservation’ effect.

PhD work:

My PhD thesis investigation was on energy storage in clathrate hydrates. This involved the research in storing energy rich gases like hydrogen and methane in the form of hydrates. My initial research focused on examining the challenging aspect of storing hydrogen in the form of hydrates. I have worked on different domains of hydrate research that include hydrate phase equilibrium studies, investigation of macroscopic kinetics of hydrate formation/dissociation and examining the morphology of hydrate crystals during formation and dissociation of hydrates. Next part of my PhD research involved storing methane via clathrate hydrates. I found out an effective method to form mixed methane hydrates rapidly at moderate conditions (closer to ambient temperature and low pressures) in a simple unstirred reactor configuration. Feasibility to scale up this method without significant reduction in the methane storage capacity was demonstrated through my research. The experimental data generated from my PhD research played a significant role in the award of a prestigious multi-million external grant by Energy Markets Authority (EMA), Singapore. This project had also won the highly commended research project award presented by Institution of Chemical Engineers (IChemE) Singapore in 2016.

Post-doctoral work:

Since the completion of my doctoral study, I am working as a lead in the project for developing the ‘Solidified Natural Gas (SNG) Technology for Energy Storage to Strengthen Energy Resilience in Singapore’ granted by EMA. The objective of this project is to develop a prototype to demonstrate the feasibility of hydrate based SNG technology for storing natural gas in the form of hydrate pellets. I investigate the storage and gas recovery aspects from hydrate pellets for the effective integration of SNG technology. I am also working on the design and fabrication of different units that aid in the realization of the SNG technology. I am also learning hydrate characterization techniques like Differential Scanning Calorimetry and In-situ Raman spectroscopy to understand the hydrate formation at molecular level.

Research Interests:

• Gas hydrates
  • Energy storage
  • Energy recovery from hydrates
  • Gas separation
• Flue gas desulphurization in power plants
• Integrated gasification combined cycle (IGCC)

Teaching Interests:

Unit operations of Chemical Engineering, Chemical process technology and calculations, Heat transfer operations and electives like Environmental engineering, Corrosion engineering, Petroleum refining and petrochemicals are the courses that I might be interested in teaching. During my PhD tenure, I have served as a grader for Design project and Heat & Mass transfer modules offered in the Department of Chemical and Biomolecular Engineering of National University of Singapore (NUS). I have served as an able mentor to seventeen undergraduate students during their final year project in our laboratory during my research tenure at NUS. I am proud to state that three of my mentees received Innovation and Research Merit Awards by NUS and five of them had received American Institute of Chemical Engineers (AIChE) - Singapore Local Section (SLS) award for their project work.

Awards:

• Highly commended Young Chemical Engineer in Research by IChemE Singapore in 2016
• Honorable mention in recognition of contributions to research during graduate study by American Institute of Chemical Engineers (AIChE) Singalore Local Section (SLS) 2016
• 2015 Applied Energy Award for highly cited review paper
• President's Graduate Fellowship (PGF) for the year 2014-15 by NUS

Selected Publications:

1. Veluswamy, H. P.; Kumar, A.; Seo, Y.; Lee, J. D.; Linga, P., A review of solidified natural gas (SNG) technology for gas storage via clathrate hydrates., 2018. Applied Energy, 216, 262-285.
2. Veluswamy, H. P., Wong, A. J. H., Babu, P., Kumar, R., Kulprathipanja, S., Rangsunvigit, P., & Linga, P., Rapid methane hydrate formation to develop a cost effective large scale energy storage system., 2016. Chemical Engineering Journal, 290, 161-173. [Highly cited paper]
3. Veluswamy, H.P., Kumar, R., Linga, P., Hydrogen storage in clathrate hydrates: current state of the art and future directions., 2014. Applied Energy, 122, 112-132. [Highly cited paper]
4. Veluswamy, H. P., Linga, P., Macroscopic kinetics of hydrate formation of mixed hydrates of hydrogen/tetrahydrofuran for hydrogen storage., 2013. International Journal of Hydrogen Energy, 38, 4587-4596.

Contact details: Tel: (65) 6601-1604; e-mail: chehpv@nus.edu.sg