I'm assuming you mean on demand? However - Hay bales spontaneuously combust, I'm guessing the same could be true of bales of newspaper.
http://www.psla.umd.edu/extension/publications/haycombustionp1c.pdf
Hay that was too wet from rain or dew or that was not allowed to dry sufficiently in the field will
go through a curing process (sometimes referred to as a sweat) in storage. During the curing process,
heat is produced. This heat buildup is caused from live plant tissue respiration coupled with bacteria and
mold activity. Plant respiration converts plant sugars to water and carbon dioxide, increases neutral
detergent fiber (NDF) and acid detergent fiber (ADF) and decreases the net energy content of the hay.
Plant respiration slows as moisture content decreases but does not stop until plant moisture is 20% or
less. Mold organisms grow in hay having 20 to 35% moisture content. As with plant respiration, molds
likewise consume plant sugars, producing water and carbon dioxide, causing loss of dry matter,
digestible nutrients and net energy. The production of water through plant and mold organism
respiration can actually increase the moisture content of hay in storage (sweating) if the moisture is not
able to escape from the bale, mow (the pile of hay in the part of a barn where hay is stored), or stack.
Plant and mold respiration also generate heat. If the hay heats to 100°F or higher, browning
reactions begin (also called carmelization). In these reactions, proteins and amino acids combine with
plant sugars to form a brown polymer resembling lignin. This results in increased levels of ADF and of
acid detergent insoluble protein (bound protein) and reduced digestibility and net energy (Table 1).
Browning reactions release heat, and when coupled with heating from mold growth, result in an upward
spiral in temperatures of the hay mass. If the water generated by plant and mold organism respiration is
not able to escape from the bale, mow or stack, then what initially may have been a relatively small wet
spot becomes bigger and bigger as the heating drives moisture into hay surrounding the spot.
...
...
Although most problems with spontaneous combustion begin occurring within two weeks after
hay has been placed in storage, combustion is possible for two months. Growers, especially those who
know that the hay was a little too wet or green when it went into storage, should start checking for
temperature rises within two days following storage and monitor on a daily basis for at least 10 days to
two weeks. Depending upon storage conditions and initial moisture content of the hay, it may be
necessary to continue monitoring for up to two months. But generally, any problems that result from
storing hay with an excessive moisture content are most likely to occur during the first month of storage.
