Rare metals could make hydrogen-powered cars more efficient

Steve Dent

Despite being much faster to fuel up than EVs, hydrogen fuel cell-powered cars have largely failed to make an impact. There are various reasons for that like the crazy expensive infrastructure and hydrogen's explosiveness, but the main one is that from well to wheels, hydrogen cars are much less efficient than EVs. Now, researchers from Spain and Norway have unveiled a new method to convert methane to hydrogen with almost no loss of energy, perhaps making the vehicles (slightly) more feasible.

The system builds on a hydrogen production process called steam reforming. During the process used today, 700 to 1,000 degree Celcius steam reacts with methane (natural gas) under high pressure in the presence of a catalyst like nickel or platinum, producing H2, water and CO2. The problem is that only 65-75 percent of the methane's energy is captured as hydrogen and the process still releases significant amounts of CO2 -- about half of what your car produces when burning gasoline.

By adding a ceramic membrane to that process, the researchers were able to generate hydrogen from natural gas in one step "with near zero energy loss," they said. The membrane is made from barium, zirconia, yttrium and other rare elements, and the trick is to apply an electrical voltage difference across its surface. When you do that, the steam and methane mix will transit to the other side as protons, creating ionized hydrogen.

The end result is concentrated, impurity-free hydrogen that's already compressed electrochemically at up to 50 bar (750 psi). With not much more treatment, it's then ready to be used in a fuel-cell vehicle or for industrial purposes. The team didn't mention how pollutive the process would be, but if less methane is required to make the same amount of hydrogen, it should produce less CO2. The system retains about 88 percent of the methane's energy, so "zero energy loss" is actually about a 12 percent loss.

They also note that the process scales down well, meaning you could produce hydrogen from your own natural gas lines using a small generator. That would let you refuel a hydrogen car at home, much as you can with an EV, reducing the need for complex H2 fueling infrastructure.

CoorsTek says that the well-to-wheel efficiency is 41 percent, and uses a spiffy infographic to show that's better than hybrids, gas cars and even EVs. That assumes, however, that your electricity is produced in a relatively inefficient way. It also notes that CO2 emissions for a car powered by the hydrogen would be a third less than an internal combustion engine and even slightly lower than an EV. That's not the case in nations that are powered mostly by renewable and nuclear energy, where the overall pollution from EVs would be much lower than any other vehicle.

Hyperbole aside, the development could still have tremendous value. CoorsTek notes that hydrogen use for transportation is a pittance compared to the hundreds of tons used by fertilizer manufacturers and other industries. Any improvement in reforming, then, could substantially reduce greenhouse gas emissions. Furthermore, on a larger scale, it would be feasible to capture and store the CO2 underground, as it's completely separated from the hydrogen.

On the other hand, there's a reason that oil companies support hydrogen cars and not EVs. Hydrogen fuel cells still consume a substantial amount of fossil fuels because of methane reforming, and at this point, the planet can't absorb a lot more greenhouse gases.

CoorsTek

  • This article originally appeared on Engadget.