Excuse me bumping the thread, but I thought I'd add to the discussion a bit. (I saw the thread, and just
had to reply!)
Your idea is actually pretty good! In fact, there are experts that are thinking of fairly similar ideas.
There's a group that goes by the name "Coalition for Sustainable Rail" that is working on an experiment to use biocoal as fuel for a steam locomotive. (The locomotive in question is former AT&SF 4-6-4 #3463.) They've done calculations, and they say that the locomotive could possibly reach 130 mph while burning biocoal! Whether this is realistic or not is questionable, but they do seem to be optimistic. (Link here:
http://csrail.org/) (News article from 2012 here:
https://wattsupwiththat.com/2012/05...m-engines-another-high-speed-rail-boondoggle/) They also have some other railroad related projects that are pretty interesting.
Torrefied biomass, or "biocoal", is biomass that has been exposed to heat in an oxygenless environment (usually in the form of a sealed container). The "charred" power that's left is then compressed into solid "chunks" (for lack of a better word). It's similar to charcoal, but the materials they're made of and their production processes are somewhat different. (I believe charcoal is exposed to a small amount of oxygen while being heated, but don't quote me on it.)
The advantage of using biocoal is that is burns as hot as coal and can be used in place of coal without converting the combustion chamber,
but burns as cleanly as wood and can be made using virtually any kind of biomass. There are several power plants that have been utilizing biocoal as half of their fuel source. (Burning coal 50% of the time, and biocoal the other 50%.)
Others have already talked about charcoal, so I won't bother.
Not to get too far off topic, but steam modernization has been in the works ever since diesel locomotives "took over", though it's been rather "behind the scenes". The late Livio Dante Porta probably contributed the most to this effort. Many people have been inspired by his work (including myself), and have been expanding on his principles. (I personally would absolutely LOVE to do this as a career, but the idea of going to a university unfortunately doesn't appeal to me.)
So, yeah, you're thinking in the right direction!