If timeline memory serves me correctly, it was in the mid 90s that I read and a newspaper article on hydrogen powered vehicles. ...
Hydrogen has a number of interesting aspects that make it quite attractive for propulsion. However, it has a number of problems associated that make it suitable only where the silly high costs of using it are appropriate, such as rocket fuel where the costs and waste are paid for by the apparently bottomless pockets of us taxpayers.
Problem 1: It is expensive to produce. There are only 2 common ways of producing it, electrolysis of water, and reduction of methane. As far as the water, well that's a big negative. You'll lose energy in making it, you'll lose energy in transportation and storage, and then you'll finally get it to a car. Where it gets burned and turned into water. Nice on the emissions (short loop) until you start to figure out where the energy came from to make it in the first place. Since wind and solar are a minuscule proportion of the energy on the grid, you're back to burning methane and coal, which I thought we were trying to get away from in the first place.
And converting methane? I don't recall all the details, but it seems to me that if you're grabbing hydrogen from methane, you're either going to have some heavier hydrocarbon output, or a magic machine that poops carbon bricks out the back (doesn't exist). So you still have a waste product to get rid of, unless you're going to *gasp*
burn it.
So now we're going to have a nice, efficient (just for fun) class 8 truck that runs on hydrogen. You're going to end up reducing the payload from 25 tons down to 15 tons due to the extra tanks and plant required to carry the CNG and convert it on the fly to hydrogen, and keep the waste for processing at the destination. Not happening.
Problem 2: Storage. Hydrogen molecules are so flipping small they actually run right through the sides of a metal tank. Seriously. You get a percentage loss for each day you try to store the stuff. Hence the notations above where the only ones to use liquid hydrogen are the rocket guys who have budgets measured in cubic dollars. That's also why the methane reduction ideas are the only ones seriously considered for us normal humans. But that still has a lot of problems not yet resolved.
Problem 3: Economics. The battery solutions are getting a lot more traction these days because everybody can use small batteries for all kinds of things including of course, those wonderful cell phones we all know and loathe. Scaling them up for all the cars in the world sounds nice, but there's 2 problems associated with that, which are of course the generation of the electricity to store in those expensive batteries, and the fact that there are only a very few sources of lithium in the world. It is expensive stuff, and unlike oil and gas, we don't seem to be finding lots more of it anywhere.
So, in short, the real problem with hydrogen is that there are real problems with hydrogen, they don't have convenient, nor cheap solutions, and so at this point, it is just too expensive and inconvenient to consider further.
The elephant in the room: CO2. Yes, this supposed evil greenhouse gas that will poison us all after it cooks us from rising temperatures. It is all because of human activity, right? WRONG!!
The truth on CO2 as a greenhouse gas is that the studies conveniently neglect to point out a few pertinent facts. The concentrations of CO2 vary only on the order of ppms at most. Usually measured in units of parts per BILLION. Barely measurable without lots and lots of expensive equipment. This is due to the simple fact that the biosphere on this planet works very well to keep the CO2 component in balance. That's it. No more to say. Another fact is that all the 'studies' that claim to predict global warming based on CO2 refuse to admit to the fact that they depend on models where the assumptions are most likely driven by the desired outcome rather than actual fact. In addition, the models aren't vetted except by other theoretical exercises. They all amount to self-obfuscating and self-testing prophecies that don't have a connection to the real world.
Final conclusions: With the comments above about magical thinking and getting solutions out of the hands of politicians, I am in full agreement. Really, if we let the marketplace make the decisions, the things that work will be the winners, and the things that don't will be brutally culled. That is why the capitalist marketplace is the most efficient of all the economic systems out there.
OK, so I'm off my soapbox. For now.
Cheers,
PH