What happened to hydrogen cars? I was expecting them to come out on top, but it seems electric charging stations are growing much faster than hydrogen refill stations.
Burning hydrogen is but one step in the whole "well to wheels" chain that's needed to get your car moving. That single step appears very appealing - it turns into water! - but all the other steps along the way are extremely difficult.
How much energy can a car have with a "full tank of hydrogen", and what would that tank look like? Remember, a bucket of gasoline contains more hydrogen than a bucket of liquid hydrogen, and the gas kan be reasonably safely kept in the bucket, but the hydrogen requires very special equipment.
How will you get the hydrogen into the car? Gas can be poured into the gas tank, how would you transfer liquid hydrogen safely? Remember, chain-smoking stressed out soccer moms with three screaming kids in the car have to be able to do this without blowing themselves up.
How will you get hydrogen to the gas stations? How will you manufacture the hydrogen? You can't mine it or collect it, so you would have to create it by splicing water, a process which consumes a lot of energy. Where will you get that energy from? And if you're going to use electricity anyway, how much of that energy is lost in the process?
What's the "well to wheels" efficiency of a hydrogen vehicle? I'm pretty sure it's smarter to just charge a battery in the vehicle directly, through the electricity network, rather than going the roundabout way of creating volatile hydrogen at special plants, transporting that hydrogen to gas stations, having equipment for allowing people to fill up their cars, and finally combust the hydrogen in the car to make it move.
So what happened? Someone did the math on the whole chain, instead of just handwaving the massive infrastructure problems away.
The benefit of hydrogen IMO is not needing to mine tons of potentially hazardous or toxic minerals to make giant swaths of batteries, not to mention that you can actually fill up the fuel tanks just like you would with gasoline, rather than needing to wait 30-60 minutes for a "supercharger", and the overall range of existing hydrogen vehicles is generally on par with or better than the range of gas-powered vehicles.
They've already "solved" most of the problems you mention; the "problems" are with scaling that sort of infrastructure. Scaling EV chargers is just much simpler.
Once the number of EV's get high enough, we can have recycling stations for them. Another benefit of having an Electric car is that you don't care about the source that produces the electricity. So tomorrow when cold fusion is feasible, we just build a bunch of them and power all our vehicles with the electricity that they produce.
However, I am interested in hydrogen as a fuel from a long term perspective. In the future when we have vehicles that need to run on other planets, presumably hydrogen will be the fuel; however I'm not sure those engines will be IC; maybe miniaturized jet engines? :)
edit: probably not, since jet engines need oxygen which may not be available on other planets
>Remember, a bucket of gasoline contains more hydrogen than a bucket of liquid hydrogen
I don't know what you mean by "contains more hydrogen", but if we look at the calorific value (energy per unit weight) then hydrogen has almost 3 times that of gasoline [1]
I meant it in the most literal sense possible. The density of liquid hydrogen is around 70kg/m^3, but the density of gasoline is around 700kg/m^3. This means the despite all the carbon atoms, there are still more hydrogen atoms in a bucket of gas than in a bucket of liquid hydrogen.
You are correct in that liquid hydrogen has more energy per weight than gas, but gas is ten times denser, so it has around three times more energy per volume, and both are important when it comes to designing a safe fuel container that fits in a car.
It does not occur naturally on earth, takes energy to make, takes energy to compress, is prone to exploding, and is only liquid at extremely low temperatures. Or that's what Musk keeps saying every time he's asked, I'm not sure what the general consensus is among scientists and engineers on the subject. As things stand right now it does not appear to be a useful fuel source for cars.
