Is PowerPaste The Key To The Hydrogen Revolution?

Hydrogen — it’s the clean energy option that refuses to go away. The Japanese government has been aggressively promoting it for years, setting back the battery electric plans of Honda and Toyota by a decade or more. It’s the ultimate example of the difference between theory and reality. On one hand, hydrogen fuel cells make electricity to power electric vehicles with no emissions other than water and heat. So far so good.

On the other hand, storing hydrogen is like herding cats. It wants to escape from any crack or crevice it can find. To transport it requires high pressure tanks capable of withstanding 700 bar — that’s 700 times atmospheric pressure. Such tanks are heavy and bulky, which is hardly ideal when it comes to fitting them into the chassis of a vehicle.

Then there is the fact that hydrogen fueling stations are virtually nonexistent and super expensive to build. So even if you own a hydrogen fuel cell car, you can’t go very far because you need to have enough hydrogen to get back home to your local refueling station. Factor in that most hydrogen today comes from reforming natural gas derived from fracking and you have a reality that makes hydrogen powered transportation seem like a pipe dream.

PowerPaste To The Rescue

Until now. Those clever folks at the Fraunhofer in Germany announced this month that researchers at its Institute for Manufacturing Technology and Advanced Materials in Dresden have developed PowerPaste, a safe way of storing hydrogen in a chemical form — magnesium hydride — that is easy to transport and replenish without the need for an expensive network of filling stations. “PowerPaste stores hydrogen in a chemical form at room temperature and atmospheric pressure to be then released on demand,” explains Dr. Marcus Vogt, a research associate at Fraunhofer IFAM.

PowerPaste. Image credit: Fraunhofer IFAM

Here’s how Fraunhofer describes its new miracle substance. “The starting material of PowerPaste is magnesium, one of the most abundant elements and, therefore, an easily available raw material. Magnesium powder is combined with hydrogen to form magnesium hydride in a process conducted at 350 °C and five to six times atmospheric pressure. An ester and a metal salt are then added in order to form the finished product.

“Onboard the vehicle, it is released from a cartridge by means of a plunger. When water is added from an onboard tank, the ensuing reaction generates hydrogen gas in a quantity dynamically adjusted to the actual requirements of the fuel cell. In fact, only half of the hydrogen originates from the PowerPaste. The rest comes from the added water.

“’PowerPaste thus has a huge energy storage density,’ says Vogt. ‘It is substantially higher than that of a 700 bar high-pressure tank. And compared to batteries, it has ten times the energy storage density.’ This means that PowerPaste offers a range comparable to — or even greater than — gasoline. And it also provides a higher range than compressed hydrogen at a pressure of 700 bar.”

Energy Density Vs. Energy Efficiency

That last part is important. For all its faults, gasoline is much more energy dense than any batteries available today. According to the American Physical Society, “Gasoline energy density is 47.5 MJ/kg and 34.6 MJ/liter. The gasoline in a fully fueled car has the same energy content as a thousand sticks of dynamite. A lithium-ion battery pack has about 0.3 MJ/kg and about 0.4 MJ/liter (Chevy VOLT). Gasoline thus has about 100 times the energy density of a lithium-ion battery.”

But when you factor in efficiency, the equation changes. “This difference in energy density is partially mitigated by the very high efficiency of an electric motor in converting the energy stored in the battery to making the car move — it is typically 60-80 percent efficient. The efficiency of an internal combustion engine in converting the energy stored in gasoline to making the car move is typically 15 percent (EPA 2012). With the ratio about 5, a battery with an energy storage density 1/5 of that of gasoline would have the same range as a gasoline powered car.” Does that mean a fuel cell car designed to run on PowerPaste will have the energy density advantages of a gasoline powered car and the efficiency of a battery electric car? If so, that could be the best of both worlds.

For Hydrogen, Just Add Water

Think of PowerPaste like the goop inside the tubes of caulk or adhesive at your local hardware store. Put it inside a device similar to a caulking gun, squeeze out some PowerPaste, add water and easy on down, ease on down the road. When the need arises, fit a new tube of PowerPaste, fill the water tank (shades of the early days of motoring when steam cars were all the rage!) and you’re good to go.

Fraunhofer goes on to say that unlike gaseous hydrogen, PowerPaste does not require a costly infrastructure. “This makes it ideal for areas lacking such an infrastructure. In places where there are no hydrogen stations, regular filling stations could therefore sell POWERPASTE in cartridges or canisters instead. The paste is fluid and pumpable. It can therefore be supplied by a standard filling line, using relatively inexpensive equipment. Initially, filling stations could supply smaller quantities of POWERPASTE – from a metal drum, for example – and then expand in line with demand.

“This would require capital expenditure of several tens of thousands of euros. By way of comparison, a filling station to pump hydrogen at high pressure currently costs between one and two million euros for each fuel pump. POWERPASTE is also cheap to transport, since no costly high-pressure tanks are involved nor the use of extremely cold liquid hydrogen.” As an added benefit, PowerPaste is stable up to 250º C.

Pilot Production This Year

Fraunhofer says a pilot PowerPaste production plant will begin operations this year with an annual capacity of four tons. Well, talk about your drop in the bucket! That’s barely enough to power a small fleet of Citroen AMI microcars for a year. So is this announcement just a dollop of feel good in a sea of bad news about fossil fuels? Maybe. And then again, maybe not. Some of us can remember when LEDs were so dim no one could imaging them ever having any practical uses. That wasn’t all that long ago, in fact.

The real question is, where is the hydrogen going to come from that will be combined with all that magnesium powder, esters, and metal salts? The answer for most futurists is excess renewable electricity, which is expected to be available in great abundance as wind and solar power continues to ramp up. But we are nowhere near that point yet. For the moment, PowerPaste is more a curiosity than a panacea for the evils of burning fossil fuels. Then again, gasoline used to be sold in small containers in pharmacies, which goes to show you never can tell what the future has in store for us.

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