Towards a greener, sustainable energy with hydrogen?
Scientists on the Bordeaux campus, together with industrial partners, are developing various projects on the production and use of hydrogen in order to offer new technological solutions in the area of energy.
"Obtaining electrical energy that is more respectful of the environment from chemical energy? It is quite achievable with hydrogen, oxygen and a fuel cell", states Fabrice Mauvy, Professor of Solid-State Chemistry and Electrochemistry at the University of Bordeaux Institute of Technology, in the Institute for Solid State Chemistry Bordeaux (ICMCB – CNRS, Bordeaux INP and University of Bordeaux). The principle of the fuel cell, or hydrogen fuel cell is non-polluting and based on a simple reaction: hydrogen + oxygen → electricity + water.
"In reality, a fuel cell is not a battery: it does not contain energy. It has to be supplied with a gas but there is no combustion!" This gas is hydrogen, but very little is available in the natural state and it has to be manufactured. "Currently, 95% of global production of dihydrogen H2 is obtained from fossil fuels, this is "grey"hydrogen. "Green" hydrogen is manufactured from renewable energy sources", explains the lecturer-researcher. To then produce electricity, we use the fuel cell which operates to convert the chemical energy of hydrogen into electrical energy.
The battery that isn't a battery
"A great step forward was made in the field of materials when we were able to transfer one electron between two different solids. If we were capable of doing as well with ions, we could then store and produce electrical energy with much better yields" says Fabrice Mauvy. So researchers at the ICMCB are developing materials for hydrogen fuel cells that ensure good transfer of ions and electrons in order to obtain a yield that is sufficiently competitive in comparison with combustion systems (petrol in particular).
Within this context, the scientists have linked up with the company Hydrogène de France (HDF), which is located in Lormont and specializes in massive energy storage, to develop the European Cleargen project with other European partners. "The idea was to use the surplus hydrogen produced on the site of a petrol refinery (which up until now has been burned in flares) to produce megawatt-scale electricity."
Located on the Martinique site of the Société Anonyme de la Raffinerie des Antilles (SARA), this fuel cell allows a guaranteed production of electricity to be obtained. "This represents significant economic value, particularly on an island without a power station, faced with grid fluctuations and an intermittent energy supply", explains Fabrice Mauvy. And it works! I must admit that I had not imagined that one of the first profitable projects in the history of the fuel cell would take place in a refinery!"
The fuel cell also finds applications in smaller, more compact forms, such as in electrically assisted bicycles (EAB). Following a request made by the City of Bordeaux in 2015, ICMCB researchers developed three electrified bicycles with colleagues in the Integration: from Material to Systems Laboratory (IMS - CNRS, Bordeaux INP and University of Bordeaux) and the TechnoshopCoh@bit of the University of BordeauxInstitute of Technology. With a fuel cell located in the bottom bracket and a bottle of hydrogen attached to the frame, these green energy bicycles have been well received by the public. However, as fuel cell autonomy is linked to the size of the hydrogen "reservoir", their generalized adoption has come up against the shortage of hydrogen stations in France. "Hence the idea of designing an electrically assisted bike capable of producing hydrogen itself on demand", says the lecturer-researcher.
A green, autonomous electric bicycle
"With the innovative HELP project (Hydrogen Energy at Low Pressure) funded by Aquitaine Science Transfert, we have developed a mini-reactor that produceshydrogen from a tablet of magnesium and water." The effervescent reaction of the magnesium in water releases hydrogen, so supplying a fuel cell. Result: a green, autonomous electrically assisted bike. "Unlike lithium for example, there are abundant supplies of magnesium in the oceans and on land which are non-toxic. The system is light,low cost, and it is no longer necessary to store hydrogen in bottles”, details Fabrice Mauvy.
"On the other hand, during the reaction the magnesium becomes covered with a layer of magnesium hydroxide, which blocks the production of gas and gives only a low yield." Patented in 2015, the Bordeaux researchers have worked on a catalyzer which destroys this layer and accelerates the reaction. "Now we have a magnesium-hydrogen conversion yield of99%! With this process, there is a significant flow of hydrogen and initiating the process takes only a few seconds". The proof of concept is validated and the scientists hope that a manufacturer will take up the license for this technology.
The scientific team is also studying other processes, particularly recycling the residue of the reaction produced by magnesium and water. They are also trying to produce high-pressure hydrogen directly, by compressing it chemically, this would then allow large quantities to be available.
All of these innovative hydrogen projects, most of which involve collaborations with manufacturers, have numerous stationary applications as well as in transport systems (automobile, aeronautics, rail transport...). "Elected representatives are interested in these hydrogen projects which is very encouraging", announces the researcher. "Today, fuel cells are starting to exhibit good electrochemical performance. The problem with achieving better market penetration is still durability. This is why we continue to suggest materials which will increase product lifetime but do not penalize performance".
Professor at the Institute of Technology / Researcher at ICMCB