Whenever I read a headline or subtitle along the lines of one that got my attention over the weekend, I assume there's more to the story than meets the eye. "Professor says Energy Department ‘egos’ blocking hydrogen breakthrough". Shocking, if true. A professor at Purdue University has developed a process for producing hydrogen from aluminum and water, thereby avoiding many of the obstacles that stand in the way of widespread adoption of hydrogen as a clean transportation fuel. He even seems to realize that economics might determine whether his system can replace gasoline, at least in terms of the relative costs of aluminum and petroleum products at the pump. Unfortunately, if he has considered larger issues, such as creating an entire infrastructure for delivering what would eventually be over a billion tons of aluminum per year to service stations, or whether there might be a better use for the zero-emission electricity necessary to recycle the resulting aluminum oxide back into metal and ship it around the country for re-use in making zero-emission hydrogen, it isn't apparent from this MSNBC article.
Professor Woodall is certainly correct that producing, storing and delivering large quantities of hydrogen are key challenges on the way to a hydrogen economy for transportation. However, he is hardly the first person to have considered using metals or alloys for storing or generating hydrogen or other energy carriers onboard vehicles. In combination with a hydrogen fuel cell, his system is comparable to the Zinc-air "fuel cell" or battery, which generates onboard electricity from metallic zinc pellets and then recycles them at a central location. That concept seems somewhat further advanced, but it is not yet commercial, either.
All these approaches run afoul of a problem common to hydrogen and other alternative fuels that are energy carriers, but not energy sources. The closed loop of aluminum metal/aluminum oxide/aluminum metal that Professor Woodall is proposing needs an external energy source. In fact, the laws of Thermodynamics require that the energy necessary to turn the oxide back into metal must be greater than the energy that can be captured from putting the resulting hydrogen into a fuel cell. In order for this system to work, we must have either large numbers of new, non-polluting power plants, or burn additional fuel in the spare off-peak capacity of existing coal or natural gas-fired power plants, with resulting emissions. It might still be worth doing, if the overall system efficiency--including the enormous energy cost of retrieving and transporting all that aluminum--and emissions were better than fueling cars with natural gas directly, or with ethanol derived in large part from natural gas and coal, or using the electricity to recharge the batteries of plug-in hybrids or EVs. It would not be worth doing if the hydrogen were burned in internal combustion engines, as I've explained previously.
What I find distinctly unhelpful here is the professor's apparent attitude. The world is full of engineers so convinced of the logic and beauty of their ideas, that they cannot grasp that there might be some perfectly good reason why the rest of the world doesn't see things their way. My wife can attest that I occasionally fall into that trap myself. But if there was ever a "better mousetrap" season for good energy ideas, this is it. Since the idea has been taken up by a startup company, their success, rather than the queue for DOE funding, ought to be the acid test of the practicality of the professor's invention. If aluminum pellets are a viable competitor for gasoline, savvy investors will figure that out before the rest of us even hear about it.
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