Burning with an energy density three times greater than fossil fuels but without producing carbon dioxide, hydrogen has obvious environmental credentials. Until now, hydrogen's rollout as a next-generation clean energy source has been hampered by the question of how to store it: as the lightest element, it needs to be kept at high density.
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A European and South Korean research project harnessing nanotechnology developed novel materials to store the hydrogen, offering the hope that its use can become more widespread.
The project, NANOHy, produced theoretical modelling, synthesis, characterisation and testing of novel nanocomposite materials for hydrogen storage. It combined the latest developments in metal hydrides - metals bonded to hydrogen to form a new compound - with novel concepts for tailoring material properties.
“With the results of NANOHy the development of hydrogen storage materials made a step forward,” says NANOHy’s coordinator, Maximilian Fichtner from the Karlsruhe Institute of Technology (KIT), Germany. “Our breakthrough in the field of nanoscale energy materials was an important piece of the puzzle. However, the general problem of providing efficient and safe storage of hydrogen in pressurized, liquid, or solid form remains to be solved,” he adds.
The experimental work focused on the synthesis of the starting materials, namely the nanocarbons that serve as scaffolds and complex hydrides that are integrated into the scaffolds in order to form nanocomposites. The synthesis procedures worked for both materials, and in total several 100g of carbon templates (or frameworks for the structure), and about 100g of complex hydrides were produced.
The project team worked on developing intriguing concepts at the nanoscale, including self-assembled polymer layers, which are layers that form automatically at the surface of a particle through electrostatic forces. Fichtner says the project also stimulated other research groups and led to follow-up activities in this exciting area. “We found that research can be transferred to other areas such as the development of battery materials where it has become an increasing issue to develop materials with higher storage capacities, better safety and improved life cycle,” he says.
One of the project partners, Young Whan Cho from the South Korean Institute of Science and Technology (KIST), helped the project team by offering complementary research on nanotechnology structural concepts. Young says that, although there are still hurdles to be overcome before the research can be commercialised, NANOHy met most of its goals. “If we develop a reliable and economical hydrogen storage technology, the commercialisation of carbon-free fuel cell cars could become a reality in the near future,” he explains. “That would mean the cost of the electricity distribution from renewable energy sources will be significantly reduced,” he adds.
More broadly, the research has led to a better understanding of hydrogen storage materials at nanoscale. “We know now how to prepare such systems, how to research them and how a selected system behaves in a laboratory tank,” says Fichtner. “Nanoscale systems are – in general – present in almost every part of our daily life and it is expected that energy storage systems will be based on nanoscale materials due to their improved properties,” concludes Fichtner.