Shannon explains the operation of this gasifier, a prototype for a carbon-neutral source of heat and energy. See all power labs if you want to build your own. All Power labs is also working with Engineers Without Borders , among the international groups responding to the Haitian earthquake, to make carbon-neutral brick ovens which can be built in poor countries.
If you want to see more of this urban excursion, I've uploaded a set on flickr.
Edit: Just walked next door and placed the Engineers without Borders info in Carlos' Door. Heh, that will teach him to ask me questions.