The research marks a major development in our understanding of efficient hydrogen storage. It was led by Dr Valeska Ting from our Department of Chemical Engineering in conjunction with researchers from Rutherford Appleton Laboratory and collaborators in the USA and Germany.
Sustainable, low-carbon fuel
Hydrogen presents a significant opportunity as a sustainable, low-carbon alternative to fossil-based transport fuels. However, hydrogen is typically stored as a compressed gas in bulky high pressure tanks and these costly storage problems are a barrier to its use as a transport fuel of the future.
The research, which has been published in the prestigious journal ACS Nano, found that when hydrogen is stored in materials with optimally-sized sub-nanometer pores, it is able to be simultaneously compressed and stored at much higher densities than in conventional tanks. These materials include activated carbons, zeolites, metal-organic framework materials and certain porous polymers which act as ‘molecular sponges’.
Using inelastic neutron scattering, which is one of the few experimental techniques that can be used to obtain direct information on the state of the hydrogen inside a solid material, the team observed hydrogen gas with a solid-like behaviour, indicating hydrogen densities almost 1,000 times the density of gaseous hydrogen at ambient temperatures and pressures.
Dr Ting said: “Greater understanding of how the nanoscale structure of the storage material can influence gas storage capacities is expected to lead to more accurate evaluation methods for existing porous hydrogen storage materials. This, in turn, should have an impact on the design and evaluation of new hydrogen storage materials for future automotive applications.”
Shift in focus
These findings open the door to a shift in focus towards pore design with future research looking to exploit storing high density hydrogen in solid materials, rather than as a liquid or a gas.
Dr Tim Mays, Head of Department of Chemical Engineering and a co-author on the paper, added: ”This work is a key step in making hydrogen storage in porous materials a practical reality. As well as involving important collaborations, this has been a real team effort at Bath including contributions from Chemical Engineering student Antonio Noguera-Diaz, a recent graduate in the Department Dr Jessica Sharpe, and research officer Dr Nuno Bimbo. We are very grateful for research funding provided by the University, the Science and Technologies Facilities Council (STFC) and the Engineering and Physical Sciences Research Council (EPSRC) in the last case via hydrogen SUPERGEN projects.”
The full article is available at: http://pubs.acs.org/doi/abs/10.1021/acsnano.5b02623