Python-Based Process Modelling and Optimisation of Pyrolysis Valorisation of Palm Kernel Shells and Empty Fruit Bunches for Biochar Production: A Circular Economy Assessment

In the heart of Ghana's palm oil industry, a massive amount of waste is generated every day. For every ton of fruit harvested, the process leaves behind two distinct types of residue: hard, shell-like fragments from the nut and large, fibrous bunches that once held the fruit. Currently, most of this material is either left to rot in the open or burned, a practice that releases smoke and greenhouse gases into the atmosphere while wasting a valuable resource. Scientists have long known that these leftovers could be transformed into something useful through a process called pyrolysis. This is a method where biomass is heated in the absence of oxygen, breaking it down into a solid, carbon-rich material known as biochar, along with gases and oils. Biochar is a versatile substance; it can improve soil health, filter water, and lock away carbon that would otherwise warm the planet. However, turning this potential into a reliable reality requires knowing exactly how to run the process. The temperature and the length of time the material is heated are critical, but finding the perfect balance for these specific Ghanaian residues has been difficult without expensive and time-consuming trial-and-error experiments in a lab.

A team of researchers from Ghanaian universities has taken a different approach, using the power of computer modeling to solve this puzzle. Instead of burning thousands of tons of shells and bunches in a physical laboratory, they built a detailed digital simulation using Python, a popular programming language for scientific work. They created a virtual model that mimics how the different parts of the palm waste—cellulose, hemicellulose, and lignin—react when heated. By feeding this model data from existing scientific literature, they were able to predict how much biochar would be produced under various conditions. To ensure their predictions were robust, they ran thousands of simulated scenarios, introducing small, random variations in the composition of the waste and the operating conditions. This allowed them to see not just a single outcome, but a range of likely results, accounting for the natural inconsistencies found in real-world farming. They then used advanced mathematical techniques to search for the single best set of conditions that would maximize the amount of biochar produced while ensuring it met strict quality standards for carbon content.

The simulations revealed a clear and consistent path forward. The researchers found that the quality of the final product is the most important factor limiting the process. To produce premium-grade biochar that is suitable for high-value markets and carbon credit schemes, the material must contain at least 60 percent fixed carbon. This requirement forces the process to operate at a specific temperature, around 393 degrees Celsius. If the temperature is too low, the biochar is too impure; if it is too high, the solid material breaks down into gases, reducing the total amount of product. The model determined that at this optimal temperature, the palm kernel shells need to be heated for about 50 minutes, while the empty fruit bunches require a slightly longer time of 57 minutes. Under these precise conditions, the process yields a biochar output of 42.2 percent for the shells and 38.5 percent for the bunches. The analysis also highlighted that the amount of lignin in the waste is the biggest source of uncertainty; because lignin is the most heat-resistant part of the plant, variations in its content have the largest effect on how much final product is obtained.

When the researchers applied these findings to a typical palm oil mill in Ghana, the economic and environmental picture became strikingly clear. A standard mill processing ten tons of fruit bunches per hour generates enough waste to produce over 5,500 tons of biochar annually. This is not just a theoretical number; it represents a tangible shift from waste management to resource creation. The study calculated that by switching from open burning to this pyrolysis method, a single mill could prevent the release of approximately 31,854 tons of carbon dioxide equivalent every year. This benefit comes from two sources: the carbon that is permanently locked into the biochar and the emissions that are avoided by not burning the waste in the open. Financially, the outlook is equally promising. Even under conservative market assumptions where biochar sells for a modest price and carbon credits are low, the operation generates a net profit. In more favorable market scenarios, the annual revenue could reach over three million US dollars. The empty fruit bunches, which are more abundant than the shells, drive the majority of this economic value, making them the primary engine for a circular economy at the mill site.

The study concludes that this computational framework offers a reliable blueprint for commercializing biochar production from palm oil waste in West Africa. The researchers demonstrated that it is possible to identify the exact operating conditions needed for a profitable and environmentally beneficial process without needing to conduct exhaustive physical experiments first. The only major constraint is the need to maintain the high carbon quality required by international standards, which dictates the temperature and time. While the computer model provides a strong foundation, the authors note that future work should include pilot-scale tests in Ghana to confirm these results under local operating conditions and to analyze the full life cycle of the technology. For now, the simulation proves that what was once considered a nuisance waste product can be transformed into a valuable asset, turning a significant environmental liability into a source of clean energy, improved soil, and economic growth.