firewood is a loser, run the numbers

lets assume you have a wooded lot nearby and the wood is free

now you must go cut down the trees, cut up the trees, haul the logs
home, split the logs, stack the split firewood, later stack it by
house, carry it indoors and burn, haul out ashes.

thats a LOT of work, and not real convenient

now take all the hours worked and get minimum wage job, after taxes
your probabl;y stilll ahead working the job

and that assuming the firewood source is closeby and free......

add in splitter, chainsaw, vehicle for hauling wood and fuel to run
vehicle....