ON PAPER, HYDROGEN appears like a dream gas. Coal, oil and pure gasoline generate planet-warming carbon dioxide when burned. Hydrogen produces pure water. Hydrogen crams extra power into much less area than batteries do (although, admittedly, lower than petrol or diesel do). And an empty tank may be refilled with hydrogen a lot quicker than an empty battery may be refilled with electrical energy.
In follow, issues are trickier. Storing significant portions of hydrogen gasoline requires compressing it a number of hundred-fold. Liquefying it’s another choice, however one which requires cooling the stuff to -253°C. Both course of requires rugged tanks. Over time, hydrogen gasoline can infiltrate metals, weakening them and probably inflicting cracks. Tanks should be constructed from particular supplies designed to withstand this breakdown.
There could also be a greater means. Researchers on the Fraunhofer Institute for Manufacturing Know-how and Superior Supplies in Germany, led by Marcus Vogt, assume that supplying hydrogen as goop slightly than gasoline affords a means round a few of its limitations. They’ve been experimenting with a chemical compound that may be pumped right into a cartridge after which persuaded to surrender its hydrogen on demand.
Their invention, which they dub “Powerpaste”, bears a passing resemblance to toothpaste. Its principal ingredient is magnesium hydride, a compound that, when launched to water, reacts with it to type hydrogen and magnesium hydroxide (a substance extra acquainted as milk of magnesia, a stomach-settling antacid). The escaped hydrogen can then be diverted right into a gas cell, the place it reacts with oxygen from the air to generate electrical energy. The magnesium hydroxide waste is emptied from the reactor routinely.
Dr Vogt’s scheme affords a number of benefits over batteries, petrol and extra standard methods of dealing with hydrogen. One is the storage of extra power per litre, and per kilogram, than both batteries or petrol can handle. A second is ease of refilling, which is solely a matter of swapping an empty cartridge of paste for a full one, and topping up the water, which is saved in a separate tank. A 3rd benefit is that, not like a battery, the paste doesn’t steadily lose its saved power whether it is left on the shelf.
Furthermore, the paste itself is non-toxic, as are the response’s by-products. However there are many subtleties to work via. Left to its personal units, magnesium hydroxide reacts solely slowly with water as a result of the response kinds a barrier on the fabric’s floor that inhibits additional chemistry. To beat this, Dr Vogt and his group have discovered a chemical additive that significantly accelerates the response. They’ve additionally discovered a means to make sure that the response may be managed exactly sufficient to produce solely as a lot hydrogen as is required at any given second.
The paste is unlikely to up-end the clean-car business, the place battery-powered automobiles have already established themselves because the dominant know-how. However Dr Vogt nonetheless hopes that his invention might discover niches. One early use could possibly be in small automobiles resembling scooters, or in flying drones the place weight is at a premium. It’s onerous to scale down the kinds of professional quality tanks wanted to retailer elemental hydrogen, he says. Powerpaste might thus allow longer ranges for scooters, and flight instances for drones measured in hours slightly than minutes. Miniature stoves aimed toward campers are one other concept.
A pilot plant in Brunswick, a metropolis in Decrease Saxony, will be capable of produce 4 tonnes of the stuff per yr when it’s completed later this yr. And heavier-duty makes use of are actually potential, if that’s what clients would really like. Dr Vogt has already constructed a small demonstration unit for the German military. ■
This text appeared within the Science & know-how part of the print version beneath the headline “Toothpaste in your tank”
