If you were a city, would you want to be the first to implement an unproven technology whether it's hydrogen streetcars or super fast charging streetcars? I know that makes it tough for innovation but it seems like a lot of risks and on a political level it means career death if the program crashes. That being said, there are lots of interesting ideas out there that might deserve a look. In addition to the two above, the inductive motor looks interesting as well.
One thing though, I really really don't get the hate of overhead wires. They have been proven since 1888 and create no point source emissions. Get over your personal aesthetic people. If you were so concerned with wires, you should also be concerned with that smog stuff as well. As I've said before, it may look bad to you, but my lungs don't care.
On a similar note, some Railroads are considering electrification as well as allowing corridors to be used for wind power transmission. This idea has been around for a while and I'm glad they are finally catching on.