Dead trees or charcoal is generally used as a reductant in the production of pure silicon for use in industry what other reductants could be used?
On a small scale, hydrogen gas is certainly an option. Here is a paper: Reduction Kinetics of Metal Oxides by Hydrogen. High temperatures induce the formation of monoatomic hydrogen as the active agent.
However, on a practical note, explosive mixtures of hydrogen with air exist over a wide range (Wikipedia has a good discussion on this topic), so this path is clearly not without danger.
[EDIT] To address a question on trials, not that am aware of, however, here is an interesting experiment one may conduct at a seemingly much lower temperature that is likely safe. For reducing, it is known that in situ creation of the hydrogen atom radical (cited as the major reducing species by Buxton, see Eq 3 on page 2 here). Suggestively, the chemisorption of the hydrogen radical on the surface of metals like Zn, Al and Mg (albeit, effective for a limited lifespan) may be an interesting trial path.
So, as an experiment, proceed to imbue the surface of Mg or Al metal with the hydrogen atom radical (from the traditional nascent hydrogen generation methods based on say Al/NaOH). Place the SiO2 on the imbued metal surface and heat.
As to the reaction mechanics, the •H radical functional behaves based on the equation:
$\ce{ e- + H+ &lt;=&gt; •H }$
where this seemingly reversible formation reaction apparently acts as (e-,H+) pair on ions. For an example, citing a work in Hydrometallurgy 2008: Proceedings of the Sixth International Symposium on p. 818, a suggested commercial reductive leaching equation, to quote:
$\ce{PbS + 2 •H = Pb + H2S (5) }$
Now, could a related reaction path exist with SiO2 at a much lower temperature? To answer, this suggested trial could be quite interesting.