Personal Observation: Fuel cells are a type of battery, and could easily displace other types of batteries Pt. 1
Some months ago, I had a discussion with a pro-BEV† fan. The subject was over future battery technology, in particular the potential of metal-air batteries. Now, I'm sure the guy was totally confident that BEVs are "the future," and that fuel cells couldn't possibly play anything but a minor role in this. One reason he was so confidence was that metal-air batteries potentially offered such a massive leap forward over what is possible with current batteries. He basically said something to the effect that "if we had batteries with over 1000 watt-hours per kilogram, it would totally changed the world!" I'm pretty sure he wrote that with a gleeful face, because in his mind this was an unbeatable argument against hydrogen fuel cells.
Unfortunately, he made a rather serious error in his analysis. Because you see, hydrogen fuel cells are metal-air batteries. More precisely, they're a type of flow battery that involve hydrogen and air, and the hydrogen playing the role of the metal. Since hydrogen is the lightest element, this also happens to have the highest theoretical energy density of any battery type too (around 40,000 watt-hours per kilogram). Even going with practical designs that exist today, we're still well past 1000 watt-hours per kilogram. Or in other words, the revolutionary battery that will change the world already exists and has existed for decades. It's just something BEV fans have totally dismissed this entire time.
So once you realize that there's no difference between what we consider to be batteries and fuel cells, you should also realize that there's no reason for fuel cells to have any kind of unavoidable disadvantage. We've heard a litany of supposed "facts" about the limitations of fuel cell technology, but absolutely none of them have to exist. Everything you can do with li-ion batteries, such as home recharging or fast accelerating cars, can also be done using fuel cells instead. It's just a matter of thinking about the problem as if fuel cells are a kind of electrochemical system and not some exotic combustion process.
Of course, you do tend to hear some of the truly Luddite nonsense about hydrogen, like that hydrogen will always explode like the "Hindenburg" or that fuel cells are ridiculously complicated. None of that is remotely true, as hydrogen is extremely safe if handled properly and fuel cells are very straightforward devices. There's no point in even bothering to answer all of those dumb questions, and the simplest solution is usually to just call them for what they are: Luddites, naysayers, old-fashioned fogeys, or people stuck in the past.
The only argument of that nature that maybe holds water is the argument that fuel cells are somehow "inefficient." Their position is that in the future, we'll naturally gravitate towards the most efficient solution for all things. If fuel cells are less efficient than lithium-ion batteries, then the conclusion is that they can't be the part of the future. This of course ignores two problems: The first is that there are many definitions of efficiency and energy efficiency is just one of them. With hydrogen, you ultimately end up using just using water and air, whereas with nearly anything else you'll require a vast increase in mining metals that aren't nearly as plentiful. A solution that uses extremely plentiful materials is going to be much more efficient than anything that uses rarer materials under that metric.
The second point is that since fuel cells technically are batteries, they aren't really limited in energy efficiency either. Sure, given the current state of fuel cell technology there are limitations. But these limitations don't need to exist in the long-term. In fact, according to this paper, the theoretical limit of fuel cell efficiency is 100%, or basically the same as any other type of battery. You might have heard other sources like Wikipedia‡ claim that it is less than this, but those claims are based on fundamental misunderstandings. Many people, including even well-educated ones like physicists, have made the false conclusion that fuel cells are a kind of combustion engine. As a result, they've generated all sorts of invalid figures like 83%, or 85-90%, or 94% or whatever. None of them are correct. It's 100% and that's the clear-cut answer.
† For clarity's sake, "BEVs" refers to lithium-ion powered cars unless I state otherwise.
‡ Wikipedia's articles on fuel cells and related subjects are total garbage. Not only are they biased, they have made factual errors regarding fundamental physics. Someone really need to bring these issues up with the editors at Wikipedia and force them to fix those errors.
