By David Booth
One of the big reasons fuel cell-powered vehicles — (not so) affectionately called “fool cells” by Tesla’s Lord Elon — haven’t caught on is simple distrust. A testament that mankind can occasionally learn from its past — especially if something goes boom! — the crash of the Hindenburg 83 long years ago still haunts us all.
Worries that their car might suddenly turn into a fireball is a major concern for the mainstream commuter looking for an emissions-free alternative to the internal-combustion engine. Oh, engineers and policy wonks will rhyme off distribution costs and the massive amount of electricity that hydrolysis requires as the biggest impediments to widespread hydrogen usage, but for the man on the street, it is those horrific images of the giant airship’s seemingly spontaneous combustion that remains hydrogen’s public face forward. The idea of hydrogen as savage and minacious will be forever etched into our consciousness. Even if, were we to really examine its relative risk, we’d probably find gasoline is actually more dangerous.
But what if hydrogen gas could be made safe — safe enough, in fact, you could leave it in your garage? Hell, on your Roche Bobois coffee table in your favourite room in the house if you really wanted? What if, in fact, the hydrogen in question wasn’t even a gas?
I know what you’re thinking. You don’t need to know a periodic table from a kitchen dining set to know hydrogen has to be pretty darned cold — -252.87 C, in point of fact, colder than nitrogen — to be rendered liquid. That’s -423.17 F, by the way, just in case you’re still stuck in Imperial for the truly big numbers.
Nonetheless, a company in Dresden — Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM — has seemingly found a way to make hydrogen as inert as the “slime” your three-year-old plays with. In fact, it looks and feels pretty much like a “stress-relief sludge toy” that captures the mind of any toddler facing the pressures of, well, learning to crawl. Officially, it’s called Hydrogen Powerpaste, but it looks like the goop you use to caulk bathtubs. And, because I know the question was on the tip of your tongue, the company says it’s completely stable until at least 250 C and will happily sit in a fuel tank for extended periods of time without decomposing.
As for how it generates electricity, the engineers at Fraunhofer say they extrude the magnesium hydride slush into a chamber where it is mixed with water and, presto, it creates hydrogen, which feeds a fuel cell that, in turn, provides the electricity to power an electric motor. The magnesium hydride and water are housed in different tanks until they are ready to be mixed and the goop itself supplies a little less than half the hydrogen — MgH2 is, in fact, 7.66 per cent, by weight, hydrogen — while the water, H20, of course, is 11.1 per cent hydrogen. According to the researchers, depending on the relative size of the tanks, some fill-ups might be as simple as taking a garden hose to your filler cap.
The challenges, as with all technologies in their infancy, are huge. For one thing, the system is actually being developed for e-scooters because, well, Vespas and motorcycles have an acute problem with battery range. To wit: While it’s fairly easy to fit the 400 or 500 kilograms of a long-range 100-kilowatt-hour battery into the chassis of a car, it’s extremely difficult — that should be read “impossible” — to do so for a motorcycle powered by current lithium-ion technology.
Indeed, today’s full-sized electric motorcycles can barely eke out 125 kilometres at highway speeds. Fraunhofer claims its Powerpaste is some 10 times as energy-dense as lithium-ion, and that it also has greater energy storage ability than gaseous hydrogen stored at 10,000 psi. In fact, says Fraunhofer, Powerpaste boasts range on par with — “or even greater than” — gasoline.
The limitations of Powerpaste are obvious. How does one pump such a sludge into a tank and, more importantly, what the heck does one do with it once it’s depleted as a source of hydrogen? Can the spent magnesium actually be recycled for re-use as a fuel? For its part, Fraunhofer sees the magnesium hydride housed in replaceable containers — sort of like the replaceable batteries Taiwanese electric scooter manufacturer Gogoro is touting. But, while that might be manageable for a lightweight two-wheeler, it sounds impractical for a full-sized automobile (although not nearly as idiotic as the battery-swapping proposed by Israel’s Better Place).
And then there’s the energy required to produce the goop. Will the energy in/energy out equation be comparable to current battery-powered cars — on a well-to-wheels basis — or closer to current hydrogen production techniques? Will the convenience of refuelling outweigh the premium charged?
The company does claim, however, that the infrastructure needed won’t be nearly as expensive as gaseous hydrogen — it’s claiming tens of thousands of dollars for a charging station rather than millions — and that it will be more easily transported. The company also says it’s even cheap to transport, since no costly high-pressure tanks are required, nor is refrigeration needed to keep liquid hydrogen hyper-cold — perhaps Powerpaste would actually be cheaper than conventional hydrogen.
Perhaps more important, however, is that Fraunhofer’s research has changed the paradigm surrounding hydrogen as a fuel. It speaks to a hydrogen-fuelled future unencumbered by the limitations of the past. Even if Fraunhofer’s system doesn’t work, we are no longer looking at hydrogen as a cumbersome, difficult-to-manage gas that could explode with the slightest of sparks (the Hindenburg catastrophe was, of course, blamed on plain old static electricity). Regardless of whether this Powerpaste experiment is successful, it does show the hydrogen that fuels the future could be as innocuous as a gooey slime that your kids play with. Fraunhofer’s researchers certainly think the potential is huge; they’re building a pilot plant that will produce four tons of magnesium hydride by the end of the year.
