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Hydrogen : fuel of the future ?
At a time when global energy needs are increasing dramatically, along with the carbon footprint on our planet, many countries are turning to renewable energy as an alternative to fossil fuels. However, the vast majority of them leads to the production of electricity, a form of energy that is not always best suited to energy requirements (e.g. for transport) because it is not easy to store in the present state of our technology.
Molecular hydrogen H2 could provide a solution. Used with O2 oxygen in a fuel cell, it allows high efficiency electricity and heat generation, water being its only "waste". Conversely, in order to produce molecular hydrogen, no natural deposit of which exists, one can perform the electrolysis of water, a reaction that requires an electricity input, from a renewable source for example.
In both cases, electrochemists play an essential role. They must improve the performance of each component of the electrolyser or fuel cell in order to increase efficiency, allow miniaturisation and reduce costs. For example, finding alternatives to noble (hence rare and costly) metal electrodes by replacing them with modified electrodes made of organic materials. It also involves finding ways to store H2 in a more practical form than pressurised cylinders : the H2 molecule can be stored (as hydride) in the interstices of metal powders (150l of H2 in a 1/2l cylinder) and restored when it is needed.
The partnership between chemists from Orsay and small companies allowed the development of prototypes. A portable water electrolysis device thus allows the hydride tank of a small scooter equipped with a fuel cell to be recharged with hydrogen. A quarter of an hour to achieve three hours of battery life : better than current electric cars ! The fledgling hydrogen technology still requires further developments but we can bet it will be part of our daily life in the second half of the 21st century !
Institut de chimie moléculaire et des matériaux d’Orsay, CNRS-Université Paris 11
- L’Hydrogène au volant (extrait)
Réalisation : Luc Ronat - Production : CNRS Images (2010)
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