From a scale of use perspective, I was thinking of portability of a couple bags such as in the back of the pickup. Instant campfire just about anywhere I would want to make one, even if it isn't the cleanest burning option. Along those lines, it would be a stable fuel source scalable by transport mode for general combustion at least as good as other typically portable types. Once at a retreat location, I would plan on relying on whatever fuel source is in place. But just to get there, even a 5 or 10 lb bag of coal could be a significant advantage for bug out. What would be an equivalent btu/lb load in propane, butane, gasoline, etc., packaged in what form, and in what method would it be utilized?

I can see some other marginal advantages to coal as a portable fuel source.