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Hydrogen Gas Stored as a Liquid and Back Again
June 3, 2014 | Leave a Comment
The new technology has another application – the technology could be used with atmospheric carbon dioxide to synthesize a number of useful chemical products.
For many lay people hydrogen is often thought to be the fuel of the future. The basic problem is storage. Being the smallest atom it is a devil to contain, and must be stored and transported under pressure in specialized and expensive containers. It burns with oxygen at an incredible rate. A confined burn would seem like an explosion, an open air burn would resemble a blow torch.
Therefore hydrogen has issues in terms of safety, logistics, and profitability that could significantly limit its wider use. The risks are significant and the dangers exceed more common chemicals such as the smokeless power used in small firearms. To background that, smokeless powder ignited in the opens sizzles, and not very merrily at that, rather than burns at explosive rates. To get it to burn fast enough to work in a firearm smokeless powder must be confined and ignited virtually simultaneously. Small arms ammunition can be mailed and sent via UPS and others. Hydrogen requires those specialized open air trucks used for transporting gases under pressure. Hydrogen is a very volatile chemical.
Hydrogen storage and transport poses significant challenges to engineer safe and practical use.
The EPFL scientists researched and have developed a simple system based on two chemical reactions. The first reaction transforms hydrogen into formic acid, a liquid that is easy to store and less flammable than gasoline, while the second reaction does the reverse and restores the hydrogen.
Team leader Gabor Laurenczy’s group has already developed a process for transforming formic acid into hydrogen gas. The method was the subject of several articles, one of which appeared in Science, and it is already currently under industrial development.
But a complete and coherent system would also require the inverse process: the transforming of hydrogen into formic acid. The new process has now been designed, completing the cycle, thanks to the financial support of EOS Holding.
The scientists in Laurenczy’s team have described the process in a Nature Communications article. The new process synthesizes formic acid in a single step, starting with hydrogen and atmospheric CO2.
Today’s conventional methods to accomplish this involve several steps, which are complicated to carry out and generate undesirable chemical byproducts.
EPFL process of two chemical reactions – hydrogen to formic acid and back to hydrogen – are catalytic with the advantage is that nothing is lost in the transformation, and the process can thus be used in constructing sustainable devices.
With their two catalytic reactions in hand, the researchers now possess all the technology they need to build a complete, integrated device. Laurenczy envisions small energy storage units in which the current from photovoltaic cells produces hydrogen by electrolysis, which is then transformed and stored as formic acid, and finally transformed back into hydrogen to produce electricity at night-time. “Our procedure is simple enough that it can be implemented at the domestic level,” he says.
If Laurency is right hydrogen fueling could finally be a very disruptive technology.
Formic acid is the basis of numerous organic syntheses. Its a an important building block in chemical production. There may even be a market someday for home produced formic acid.
That brings us back to the process used to sequester CO2. Laurenczy explains: “We are killing two birds with one stone: we could sequester part of the 35 gigatons of CO2 that are emitted into the atmosphere every year, and also use it to synthesize materials.”
With nothing other than a press release the EPFL folks sure stirred things up. With the back end of the process already in commercial development, it does sound good. We’re still a long way to putting a kit on every roof. The hydrogen fuel cell folks need to get economical product ready for sun to power to get under way in a mass market.
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