Burning coal is cheaper than most heating alternatives short of having the acreage of trees you can fell, cut and burn.
My idea for those that cannot get coal is to get as much spam mail as they can, shred everything and if possible add some sawdust and make your own presto logs.
Its actually quite feasible to turn ordinary combustible paper trash into compressed logs, it only has to be shredded and then mixed into a wet slurry, poured into some short 4” ABS tubes and set aside to dry, push out the logs so to speak.
Shredding can be done any number of ways from actually buying a leaf shredder or using a power mower, after any number of ways to get the paper, sawdust, cardboard etc chopped into smaller but not real small chunks put everything into a portable concrete mixer you can rent, if not a plastic garbage can and use a large paint mixer on a drill.
4 inch ABS pipe is real cheap,its not mandatory to use 4 inch it just costs more to get something bigger the more tube you have the better, I would say just off the top of my head because I have never done this just cut as many as you need 24” tubes, have a rubber cap on one end of all of them or a non-glued ABS cap, pour the oatmeal consistency slurry in the tubes for what length you desire, let dry, it may take some time to dry, maybe a week or longer.
The logs I think should easily push out because of shrinkage. Just remove the cap and using a ram rod of say another piece of smaller ABS or PVC with a cap to push, I cannot say how fragile they may be.
In my shop I would use a hydraulic press to make mine, make them more dense and to squeeze out moisture for faster curing.
I hope this was good advice to someone.
BTW...Presto Logs was a product of the old Pacific Lumber Co of Scotia Cal here in Humboldt County but they don't make them any longer. They may have sold the machines and name to someone else?