Rust isn't much fun to deal with. It's the product of a process called oxidation and happens when iron and oxygen react in the presence of water. Anyone who has had to scrub rust off of an old bike or try to open an ancient metal gate knows that it can be a real pain. But it might also be a way for us to finally realize the potential of hydrogen fuel cells.
First, let's have a quick refresher on our interest in hydrogen as a fuel. Back in 2003, then-U.S. President George W. Bush launched a hydrogen economy initiative. The goal was to develop hydrogen fuel cell technology and infrastructure. A hydrogen fuel cell produces power through a guided chemical reaction between hydrogen and oxygen, producing only electricity, heat and water as a result. But there were (and are) a few challenges to making this happen, namely:
- Fuel cells are still rather large and heavy, adding to a vehicle's weight and therefore requiring the vehicle's electric motor to work even harder to move the car.
- Hydrogen fuel cells require rare elements, like platinum, for catalysts and ionic membranes, making them very expensive.
- Building out a new fuel infrastructure for a country the size of America will cost billions of dollars.
- Despite hydrogen being the most plentiful element in our galaxy, it's hard for us to come by it.
That last problem is a doozy -- hydrogen is a friendly type of element. It'll pal up with lots of other elements, like carbon or oxygen. So while there's plenty of hydrogen on Earth, much of it is locked into molecules with other stuff. We can break those molecular bonds and free up hydrogen but that requires energy. If we spend more energy capturing hydrogen than the hydrogen itself can provide us, that's a losing proposition.
Enter our old buddy, rust. I read over at Science Daily about some engineers who are using the nanostructure of rust particles to develop photoelectrochemical cells (PECs), which can harness the power of solar energy to break the molecular bonds of water. Breaking those bonds gives us hydrogen and oxygen, the very same ingredients we need to make a fuel cell work. Essentially, we convert the solar energy to electricity and use that to break down those molecular bonds in a process called electrolysis.
By offloading the energy requirement to the sun, we don't have to worry about spending more energy than we get out of the deal. And by designing electrodes using the nanostructure of rust as a sort of nano-architectural blueprint, we can harness that solar energy more efficiently and produce hydrogen at a lower cost than what we can manage with older methods.
How the engineers came up with the idea to use rust in the first place is beyond me. And it may turn out that there are other nanostructure designs that are even more efficient. But for now, I'm just going to hope that this means the hydrogen economy we dreamed about a decade ago is that much closer to becoming a reality.