|Boiling Point No. 01 - Special Edition 1989 (ITDG, 1989, 28 p.)|
by Ahmed Abasaeed - National Council for Research, Sudan, Reproduced from VITA News April 1988
To supply its energy needs, Sudan depends heavily on biomass which in the form of wood and charcoal supplies about 80 percent of the total energy consumed in the country. More than 90 percent of this amount is used to meet households needs, ie cooking fuel. This heavy dependence on biomass has resulted in the depletion of forest reserves, which has led to fast rates of desertification, linear rates estimated at 10-20 km per year. In some parts of the country, desertification is becoming a real threat to people's lives and livelihoods.
Firewood is Cut Faster Than Trees Grow
The common practice of cutting trees to be used as fuelwood is no different in Sudan than in most African countries. People just go outside, cut wood, cook their food - usually in cookstoves with very low efficiency - and do the same thing day after day. Until recently, they never stopped to think what would happen when the trees were gone; it probably never occurred to them that the forests could disappear. All they knew was that they needed to cook food and that trees out there could supply them with the needed energy. Now more money has to be paid for wood. Now they know that trees are not being replaced at the same pace they are being cut.
Utilization of agricultural residues, eg cotton stalks, can play an important role in enhancing the energy situation in Sudan. Cotton stalks are currently wasted except for minor quantities that are used for cooking fuel. Some 800,000 tons are burned in the field as a sanitary measure to prevent the spread of cotton diseases to next season's crop. A number of projects have been started to utilize the stalks during the short period that they are available, with testing to ensure that the methods would not present a disease spreading problem. Carbonization, briquetting of carbonized stalks, briquetting of raw stalks and power generation using the stalks have been attempted. Of these, briquetting of carbonized stalks has almost reached the commercial stage.
The El Rahad Scheme is the second largest agricultural scheme in Sudan. Two field demonstrations of briquetting of carbonized cotton stalks used pneumatic and hydraulic briquettors respectively and cellulose fibre and starch as binding agents. During the demonstrations, a number of local people were trained in carbonization and briquetting of the stalks. Training on carbonization was especially important, because the process reduces the threat of disease and the carbonized stalks can be kept for as long as a farmer wants. The briquettes produced were distributed to about 200 families at the scheme and an acceptability survey asked users to compare the briquettes with wood charcoal. Responses to the survey showed that people preferred the briquettes over wood charcoal because they light faster, last longer and produce no smell or smoke. They also produce a heavier layer of ash than does wood charcoal, which was seen as a plus. Ash formation around the briquettes suits the Sudanese way of cooking, which requires long cooking times and high heat output. Ash forms an insulation layer around briquettes and reduces the combustion rate. The success of these demonstrations, coupled with the great enthusiasm expressed by farmers, have led the management of El Rahad scheme to enter into the briquetting business. They will install their first commercial unit this year.
This year as well SREP is conducting similar demonstrations at El Gazira scheme, the largest agricultural scheme, which cultivates an area of over 2.5 million feddans. (1 Feddan = 4200 m2). Carbonized cotton stalk briquettes could replace 11 percent of the current wood charcoal market. With the success of the El Gazira demonstration, we hope to disseminate this technology and extend it to include other agricultural residues, such as groundnut shells.