The discovery of an unstable form of lithium borohydride at the European Synchrotron Radiation Facility (ESRF) may take research into hydrogen-fuelled cars a step further, states a paper just published in the weekly peer-reviewed chemistry journal Angewandte Chemie. Researchers are currently studying a number of compounds that could be of interest to hydrogen technology, but none of them have been found to be suitable for practical application.
In order for hydrogen technology to work, one of the things needed is a material that can store great amounts of hydrogen and at the same time release it easily. However, none of the materials under consideration by science has so far been proven to unite both of these features.
This is also true of all forms of lithium borohydride known before the ESRF discovery: While lithium borohydride (LiBH4) is promising as a medium for hydrogen storage because of its high weight content of hydrogen (18%), it only releases this hydrogen at high temperatures exceeding 300° Celsius, a considerable drawback.
The new form of the compound, on the other hand, is unstable, so that it is likely to let the hydrogen go more easily, i.e. at lower temperatures. 'This one is really unexpected and very encouraging,' says Dr Yaroslav Filinchuk, one of the authors of the paper.
During the experiment, the researchers applied pressures of up to 200,000 bar to the samples, an impressive figure as this is about 80 times the pressure exerted on the Earth's crust by Mount Everest, but still no record. The new form of LiBH4, however, 'becomes even more attractive considering the fact it appears already at 10,000 bar, the pressure used by pharmaceutical companies to compress pellets,' explains Dr Filinchuk. Now, the research team will have to find a way to conserve the pressurised form of the compound under ambient conditions and study its storage properties in more detail.
Facing climate change and the rapid decline of fossil fuel resources, clean hydrogen energy by some is seen as the future alternative to petrol: Five kilograms of hydrogen would take a car the same distance as 20 litres of petrol, supporters of hydrogen technology advocate. Critics, on the other hand, claim that hydrogen is not economically feasible to use for transportation, nor will its use reduce global warming, because of the cost and greenhouse gases generated during production, the low energy content per volume and weight of the container, the cost of fuel cells, and the cost of the infrastructure.