Researchers at ETH Zurich and the Institute of Chemistry of Organometallic Compounds have come up with a new fuel cell concept.

It’s known that an active catalyst can form and change progressively while a chemical reaction is taking place. As a result, various catalysts specific to the individual reaction steps are formed from the metal catalyst complex.  But until now the researchers needed to use a “sacrificial molecule”, which “absorbs” the hydrogen molecule created early in the reaction.

The inspirational idea to bypass this problem occurred to ETH Zurich professor Hansjörg Grützmacher and his Italian colleague Claudio Bianchini while they were picking olives in Tuscany: an electrode, the anode, could be used instead of the sacrificial molecule to absorb the charges from the reaction and to convert them directly into electricity.

In the team’s new device an alcohol such as ethanol is converted into a corresponding aldehyde, and in the next step it is turned into the corresponding carboxylic acid, e.g. acetic acid. Even more interesting, the use of this special catalyst enables not only alcohols but also sugars such as glucose to be transformed. The raw materials, i.e. the alcohols used, can be natural fermentation products or by-products from bio-diesel manufacture.  That’s a long list for one fuel cell idea.

Fuel Cell Ethanol to Acetate and Electricity. Click image for more info.

The electrical generation operating principle of the new organometallic fuel cell is entirely different from previous types. It is based on a special molecular complex containing the very expensive metal rhodium. This complex is molecularly embedded in the anode material. The anode of a fuel cell absorbs liberated charges and transfers them to the cathode, which releases them again. This process generates an electric current. The special feature of the organometallic fuel cell is that the molecular complex in the anode acts as a catalyst and its function can easily be optimized. The anode’s support material is carbon powder, to which the molecular complex is applied as a fine dispersion.  Its like a ‘refillable battery’ oncept.

Professor Grützmacher points out, ”This fuel cell won’t solve the world’s energy problems.  But I think the fact that it can be used to make industrial chemicals from renewable raw materials with no waste products is an enormous step forward.”  Actually it’s quite an achievement.   Here is a self-starting fuel cell running at room temperature generating current and the waste is an industrial chemical feedstock. It sets up a production of chemicals with no waste and produces electricity as a side effect.  This is not a small idea.  Details are published in the Angewandte Chemie International Edition.

Grützmacher ETA Zurich Fuel Cell. Click image for the largest view.

The lab unit is a rectangular device made of transparent plastic, a little bigger than a fist. There is a rectangular recess on the front and two connections protrude from the top, one gold-colored, and the other silver. Two oversized-looking clamps hold together the two halves that make up the device.

Grützmacher thinks the organometallic fuel cell has great potential; for example, 1,2-propanediol, a dialcohol obtained from renewable raw materials, could be converted very selectively into lactic acid. Lactic acid is produced industrially on a large scale for use in the manufacture of biodegradable polymers. Today there is a major problem, for every ton of lactic acid most processes create approximately one ton of calcium sulphate, which requires expensive disposal. In contrast, the team’s fuel cell leaves no residue when it converts the raw material.

Grützmacher envisages other applications. The organometallic fuel cell could be miniaturized to power heart pacemakers. It could also contribute to reducing the metal demand of catalysts that often use rare earths or noble metals such as platinum.

Grützmacher explains, “If we succeed in constructing a catalyst molecularly, that would considerably improve the material efficiency,” the aim is to develop a fuel cell whose electrodes manage without metals, or at least use only abundant metals. Candidates include manganese, iron or cobalt, for example. Up to now the researchers have used rhodium in the organometallic fuel cells. Although this metal is often used in present-day catalysts, its availability is limited and the price is high.

On the other hand the organometallic fuel cell chemical reactions proceed more slowly than in a solution tank because, due to the way a fuel cell is constructed, they only take place on surfaces.  That explains the relatively low power output and why the fuel cell manufacture of larger quantities of chemicals will take longer than manufacturing in the conventional way.

Yet that olive-picking outing has had a big payoff with a wide array of new questions and routes to further research.  This could be a marker on the road to a cheap biofuel powered fuel cell.


6 Comments so far

  1. Tweets that mention Chemical Process Guys Find An Ethanol Fuel Cell Technology | New Energy and Fuel -- on January 6, 2011 6:21 AM

    […] This post was mentioned on Twitter by Consilium Advisers. Consilium Advisers said: Chemical Process Guys Find An Ethanol Fuel Cell Technology: (Source: New Energy and Fuel) Researchers at ETH Zur… […]

  2. Matt Musson on January 7, 2011 12:03 PM

    An interesting idea. It underscores the need to evaluate alternative fuels not just for their primary energy potential but also for their byproducts.

    Distilling gasoline for oil would actually a losing proposition – except for all the valuable byproducts that are produced.

  3. dental hygiene on January 9, 2011 9:52 PM

    Couldnt agree more with that, very attractive article

  4. willG on January 12, 2011 10:25 AM

    Re products that work in Fuelcells.If Scientific American is right and peakOil is 2014, then as of today BigOil has almost won since I dont see a viable alternative which is on the market which will power my fuel cell. BigOil has coached any government with money to send a little any direction to help products they know will not work. There is one working green fuel which will work in fuel cells but is not on the market yet. It is working in protostage but the company cant find backers. I want to buy a machine and they reply back that as soon as they are financed, they will sell machines.
    One independent financial guy I spoke with told me most investors will stay away in case BigOil decides to cancel them. If you know of a strong investor not afraid of BigOil`s antics please have them look at

  5. Mercurial 2011 on February 5, 2011 9:42 PM

    You must participate in a contest for among the best blogs on the web. I’ll suggest this web site!

  6. Arthur NOGUEIRA on May 29, 2012 6:11 AM

    Can isobutanol be used in a fuel cell?

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