http://www.global-greenhouse-warming.com/support-files/wood_gas_generator.pdf
Warning - PDF download - may take a bit.
Another - again PDF 139 pages
http://www.global-greenhouse-warming.com/support-files/wood_gas_generator.pdf
http://en.wikipedia.org/wiki/Wood_gas_generator
http://www.crest.org/discussiongroups/resources/
http://www.crest.org/discussiongroups/resources/stoves/Reed/Turbo2.htm
read up on these before... Some wood stoves claim to gasify the wood to get all the energy out of it... Interesting claims
That is the way pellet stoves work - you can see the flame above the pellets in some. You will note that when wood burns the flame is slightly above it as the gasses burn.