Essentially any cellulose can be pelletized. Grind it up a bit, add a sprinkle of water to dampen it, and shove it through a pellet mill. Then burn it in a pellet stove (if it isn't so saturated with flame retardants or toxic metallic inks that it wouldn't burn even with forced air, or would rot out the stove or poison the neighbors.)
I've been looking for a small pellet mill, to pelletize waste paper, cardboard, weeds, and the leftover stems/leaves/etc. of garden plants. (I already have a paper shredder and an electric-motor-powered wood chipper with a hammer-mill for brush, which should do a good job of breaking stuff up to a suitable size for a pellet mill.) But so far all the small mills I've seen are running about 4 to 5 grand. At the townhouse we burn a tad over a ton per year for heating and the garbage collection service doesn't charge for paper and yard waste. So at $300ish per ton for high-grade commercial pellets (and transport) it makes no sense to buy one of those mills.
(Might work out at the retirement place, which has more of a heating load even with the solar windows. But we can't switch over from propane until we're moved over there to babysit a pellet stove.)