Researchers from Université Félix Houphouët-Boigny in Côte d’Ivoire, together with their colleagues from France’s Arts et Métiers ParisTech, have developed a design for an industrial-scale plant that could produce solid biofuel from cashew shells. Their work shows that this type of agricultural waste, which was previously considered useless and was burned on-site, can be transformed into a valuable energy resource and pose a viable alternative to charcoal, which remains the primary fuel for most African households and a major source of carbon dioxide emissions.
As part of their study, the scientists designed a plant that would produce 8,000 tons of fuel per year in the capital of Côte d’Ivoire, Yamoussoukro. The basic process is quite simple. Cashew shells are subjected to thermal treatment, during which they break down into biochar, bio-oil and gases. Next, the biochar is crushed and sugarcane molasses is added as a binder, after which the resulting mass is pressed into briquettes and dried. The result is a compact fuel with a high calorific value, which is easy to store and transport. Furthermore, the plant can annually produce some 4,000 tons of bio-oil, a byproduct that will be either sold or utilized to meet the plant’s own energy needs.
Calculations demonstrate that the project will be highly profitable. One kilogram of fuel costs only €0.17, and it can be sold at the price of charcoal, €0.31. With this difference, the annual net profit will reach about €2 million, and the full payback period will be shorter than four years.
The researchers also conducted a sensitivity analysis to assess the project’s resilience to inflation and economic instability. They found that even with a 50% increase in costs for raw materials, electricity and labor, the plant will maintain a positive profitability. Transportation costs and taxes will not have a significant impact on the overall economic indicators of the plant either.
Therefore, the researchers conclude, cashew processing waste has the potential to become a national resource in Côte d’Ivoire. This is why they are promoting the idea of including this project in the country’s national renewable energy development programs.
