From the ancient civilization of Egypt up to the present, Egyptian farmers have been cultivating cotton crops in the Nile Valley and in the Nile Delta. After the harvest operation, the cotton crop residues comprising cotton stalks are collected and transported for storage on the fields and the roofs of houses. In former times the farmer’s family used these residues throughout the year as a domestic energy resource for the traditional mud oven for cooking and baking.

These residues are an overwintering site for insects such as the pink bollworm. This worm attacks the cotton and nearby crops causing serious economic losses due to quantitative and qualitative crop damage affecting about 20% of the crop per year. This infestation by the harmful insects must be stopped. Because of this, the Ministry of Agriculture in Egypt obligated the farmers to burn the cotton residues on the fields immediately after the harvest operations. This resulted in huge emissions of harmful gases in rural areas, which also affected the nearby urban centres including Cairo. As a counter measure, the Ministry of the Environment issued a law forbidding the farmers to burn the residues. This confusion in laws has led to illegal burning and storage of these residues.

A new technology for handling cotton stalks in Egypt is required as a solution for this problem. Briquettes appear to be an advantageous solution for handling cotton stalk residues. Through this process an easily storable, pest-controlled and environmentally friendly biofuel can be produced. It serves as a complementary domestic biofuel and reduces the dependency of the farmer’s family on fossil fuels. These investigations were carried out to clarify the fundamentals for such a technology.

Because their properties are similar to those of cotton stalks, poplar branches, hemp shives and rye straw were used as substitute materials. These materials were pressed in a mechanical laboratory press machine. Three cylindrical stamps with diameters of 30, 42.5, and 60 mm were used to press the materials. Five different moisture contents of about 0%, 5%, 10%, 15%, and 20% were chosen to press these materials. The materials used were also pressed in a commercial press machine to study the features in this type of machines.

The briquette density was measured, its stability was examined, and its durability was also tested. The materials used were also burned and analysed chemically in order to evaluate their use as environmentally friendly fuel.

The results show that there is a correlation between the pressure and the briquette density. There is also a correlation between the pressure and the radial compressive strength of the briquette.

Particle size has a limited effect on the briquette density. Small particles (x₅₀ < 3 mm) produce briquettes of a higher density than coarser particles.

The optimal moisture content for briquetting the used materials is about 10%. Cotton stalks in Egypt reach this range of moisture content after one-week field storage in October (harvest month). This means that these residues can briquetted directly on the field one week after the harvest by a suitable type of briquetting machine without incurring any additional costs for drying.

The temperature has a major influence on the elimination of the Pink Bollworm. 70 °C for at least 2 minutes is required in order to kill these worms and their eggs or larvae. Decreasing the temperature will increase the time needed for this process.

The experimental materials including cotton stalks are well suited for combustion. The ecologically and firing-relevant material content, the ash content and the heating values lie within the ranges of usual solid biofuels. The combustion of briquettes is more regular than the combustion of loose materials. This is because of the high density of the briquettes.

Briquetting of cotton stalks is 5% more costly, than the use of kerosene as an energy sources in households. These higher costs of briquetting cotton stalks (5%) will be more than returned to the farmer the form of a clean environment. In addition, the extermination of the cotton pink bollworm through briquetting will increase the crop production by about 20%. This is equivalent to the losses because of this worm.

It can be stated that stable briquettes without binding materials can be produced from cotton stalks in Egypt depending on the material, sufficient pressure, and suitable moisture content. This application of briquette technology can solve the phytosanitary, environmental and storage problems of cotton stalks. The confusion in cotton stalk disposal laws in Egypt would also be overcome. Then farmers’ households could cover their needs for fossil fuels for cooking and baking by using a renewable and environmentally friendly source of energy.