Quoting "Prof. S.C. Bhattacharya" :

Dear all,

I would be happy to share some publications arising from the following
activities at the Asian Institute of Technology:
1. Sida funded Regional project: An information package (including
construction details) on biomass briquetting machines developed in a
number of Asian countries and design of natural- cross-draft gasifier stoves that can operate continuously is available. The briquetting machines developed
were improvements on standard screw-press heated die design. Cross-flow
gasifier stoves were designed for different sizes; these do not need any
blower and can operate continuously without any smoke.

• Technology Packages: Screw-press briquetting machines and briquette-fired stoves
• Technology Packages: Solar, Biomass and Hybrid Dryers

The briquetting and gasifier stove work I mentioned was carried out under a
Sida-sponsored project at the Asian Institute of Technology (AIT). The
project involved researchers from 12 national research institutes of six
Asian countries, e.g., Bangladesh, Cambodia, Lao PDR, Nepal, Philippines and
Vietnam. The findings of the project were disseminated through national
dissemination seminars in these countries; published "Technology packages"
were distributed widely in the region and are still available for
downloading from the project website. We organized technology transfer
workshops, in which a number of NGOs form the region were invited, on most
of the technologies developed.

(There is no restriction on distribution of the technology packages.)

Unfortunately, the link of the project is not working due to heavy flood in
Thailand; AIT appears to be still under 2 m of water.

2. GTZ funded project on Biocoal: We used the term "Biocoal" (rather than
"Biochar") for charcoal produced from solid organic residues such as
agricultural residues and waste wood. The findings of the project were
reported in a book titled "Biocoal Technology and Economics" by "Regional
Energy Resources Information Center (RERIC)" (email:enreric@ait.ac.th).

The chapters of the 495-page book were:

• 1. State of the art of biocoal technology,
• 2. Biocoal technology: A comparison of options and recommendations,
• 3. Carbonisation of sawdust briquettes,
• 4. Laboratory-scale batch carbonisation selected residues,
• 5. Cost and availability of selected residues in Thailand,
• 6. Characterisation of selected residues,
• 7.Biocoal: Market requirements and Opportunities in Thailand, and 8. Economics of biocoal production in Thailand.

A few copies of the book are still available with RERIC. A number of
chapters of the book were summarised as journal articles; I will be happy
to
share some of these with interested persons for their personal use and
research purpose.

Other technology packages and published papers of the Sida project can be downloaded from www.retsasia.ait.ac.th. The biomass/stove group may be interested the package on drying, which includes a hybrid drier using solar energy and bioenergy from a gasifier stove, heat output of which could be automatically controlled by using a thermostat.

I also coordinated another regional project (Asian Regional Research Programme in Energy, Environment and Climate, ARRPEEC) funded by Sida in three phases during 1995-2005. One of the 4 projects of ARRPEEC was on biomass. Dissemination booklets of ARRPEEC and some of the papers published can be downloaded from http://www.arrpeec.ait.ac.th

Mussie T. (Lecturer at Mekelle University, Ethiopia), October, 2011

This is a Natural Draft Gasifier stove, that is designed with a central column of air that is designed to burn more common Ethopian fuels, e.g. coffee husk and saw-dust (cow dung binder) briquettes in addition to more conventional wood chips.

the air column is drilled on the surface so as to let additional primary air radially into the fuel at different stages to compensate for air clotting that can occur when run with small sized fuel as you go up from along fuel column. This helps the flaming pyrolysis from being air starved due to interlocking of fuel particles. In addition to that, closely spaced holes of relatively larger size were made near the top of the central air column to supply more hot post‐pyrolysis secondary air. The presence of two hot secondary air admission points is meant to supply enough air while keeping the stove short with reduced heat loss.

Once the stove has enough fuel, it is typically started with wood chips, or an accelerant to help the briquettes light, and then in all of the trials it burned without smoke until the fuel tank was filled with charcoal (typically between 60 and 90 minutes later). This is a biochar-producing stove, the stove does not efficiently combust it. Friability and the composition of the char depended upon the feedstocks.

For an excellent analysis of the stove, and pictures of the biochar, please see the included Report: Results from Preliminary Experiments Conducted on Multi‐level
Primary Air Entry Gasifier Stove

Here is a report on the recent micro gasifier camp in Honduras from Timothy Longwell