GreenGen TLUD / retort stoves from Vietnam

http://www.greengenstove.com/index.php/en/component/content/article/12-intro/48-intro-e2
GreenGen Stove: is a TLUD (top lit up-draft) can save 50%-70% wood compare to traditional stoves. 
GreenGen Stove: is designed to use with optional Biomass Boxes. Lose biomass such as rice husk, straw, garden leaves,... can be put in biomass box(es) for cooking. Depending on avalablity of the biomass, users can have flexible choice of using wood only or in combination with 1 or 2 biomass boxes.

GreenGen Stove create Biochar: the biomass boxes create biochar as a byproduct at the end of the cooking process. The harvested Biochar can be used as soil enrichment or to make char briquette to cook again.