Any commercially available BioChar Retorts I can put in my house?

Does anyone know of a commercially available biochar retort I can put in my basement without burning my house down?
I live in relatively mild Northern California, but I would like a backup to the solar thermal when the clouds roll in.
I would just use it when needed for heat, but I could make biochar and use the excess heat for the house and domestic hot water.
It can't be something welded out of oil drums, it needs to be something safe and preferable attractive.
I would also talk to someone who professionally builds them.

Thanks,
Patrick