| Boiling Point No. 17 - December 1988 |
We welcome reports or advance notices of stove meetings, workshops or other articles for publication in Boiling Point. (Please see pg for last copy dates. Distribution from Rugby is not less than 6 weeks later).
Annually, large quantities of biomass wastes like sawdust, rice husks and many others, are produced as a result of forestry activities, timber production and agro-industry processes.
At present, only limited quantities of these materials are used, despite the vast potential of biomass wastes as an energy source.
Two main reasons for this underutilization are:
1. Low bulk densities resulting in high storage and handling costs are severe economic constraints for utilization of these residues.
2. Combustion characteristics of the bulk material are a further constraint in many cases.
BRIQUETTES, densified biomass, formed under high pressure and temperature, with a bulk density of 5-7 times that of loose material, can significantly decrease transportation and storage costs and have a positive impact on the combustion characteristics.
So far, only few briquetting projects have been successfully implemented despite the promising potential for energy savings.
The economic viability of briquetting depends on the following energy equivalence: 2 kg biomass briquettes = 1 litre of fuel oil.
Otherwise unused waste materials are transformed to a convenient fuel for industrial or domestic use. The shortage of traditional fuels and deforestation rates in many developing countries calls attention to the need for efforts to alleviate this energy crisis.
In the developed world, briquetting technology can contribute to better waste management and reduction of waste through re-utilisation of residues.
State of the art
There are several manufacturers of briquetting equipment in Western Europe. These installations require large investments making operation not economical in many cases at present shortcomings make production of briquettes too expensive.
At Twente University, research was done on modelling of flow characteristics of solid materials in a conical screw extruder. Methodological design methods and optimisation of parameters have led to the design of a densification machine based on the screw extrusion principle.
With the proposed technology it is possible to produce high quality briquettes of all ligneous waste materials without adding binders. The lignine, forced from between the cells under high pressure (1000 bar) and temperature (250°C), acts as a binder. Attention was given to minimizing the constraints for application of various raw materials.
The briquettes are strong, shock resistant, remain coherent during storage and combustion, and can be carbonised. Keeping in mind the large potential for this technology in agricultural and timber producing regions, it was initially designed for developing countries, ea. the densification of rice husks in Thailand.
Twente University is now collaborating on the aglomeration project in Sudan and also in Thailand with a project to pyrolise rice husk briquettes after briquetting.
A further problem with briquetting biomass residues in the third world is that their source is often widely scattered and unrelated to the location of the briquette users. This results in high collection and distribution costs unless very small briquetting machines can be developed to serve local sources and users - 'small is beautiful '. Boiling Point No.16 contained a report of ITDG's work on briquetting and the "briquette burner" stove.
Sri Lanka International Stoves Training Seminar 4-16th September 1989 Sustainable Production
The Energy Conservation Unit of the Ceylon Electricity Board is collaborating with ITDG in the organisation of a Stoves Training Seminar in Sri Lanka.
The seminar aims to establish guidelines for a strategy for sustainable stove production and dissemination using the experience of the Sri Lankan Urban Stoves Programme. This will enable participants to draw up a proposal and an implementation plan for a stoves programme relevant to their situation.
Planners and managers of stove programmes will be invited to attend the seminar and applicants able to fund their own costs will be considered. The seminar will be jointly funded by the Overseas Development Administration and the Ministry of Power and Energy, Sri Lanka.
Kengo International Biomass Energy Course Nairobi, Kenya, June 1989
Since 1986, Kenya Energy and Environment Organization (KENGO) has received an overwhelming number of requests for training in Biomass Energy Technologies from organizations and agencies from all over the world.
In response to this, and as a follow-up to a 1986 International Biomass Energy Planning Meeting, KENGO and Kenyatta University organized a successful three-week International Biomass Energy Course in April 1988. Participants in this course came from Kenya, Uganda, Ethiopia, Rwanda and India. Other specialised courses have been organized for Uganda, Sudan and Madagascar.
Numerous requests continue to be received for similar training. In view of this, KENGO intends to hold another course in June 1989. The theme of the course will be "Biomass Energy Technologies for Community Development".