In western Africa, the shea tree produces a fruit which contain oil-rich kernels. For many years, AAK has imported shea kernels from West Africa to Denmark where the high-quality oil is extracted.
The AAK vision
A by-product of shea oil extraction is a solid fiber material called shea meal that has no nutritional value. The AAK site in Aarhus, Denmark has long held aspirations to burn shea meal as a single fuel source used to power the processing and refining of shea oil. However, certain properties of shea meal have made it difficult to achieve this vision in the past.
Tests and trials
Many European power plants have purchased our shea meal and attempted to burn it as a single fuel source, but none have succeeded, in part because the ash and the flue gas emissions from the shea meal are very different from wood and other solid fuels. Therefore, shea meal is generally mixed with wood pellets, straw and coal to be burned for fuel.
In 2012, we became aware that a supplier had progressed on the combustion of difficult fuel sources. Together with this supplier, we conducted extensive tests using a small 500 kW combustion chamber in which shea meal was burned.
These experiments indicated that shea meal could be used as a single fuel source in an effective and efficient manner. Based on these findings, we decided to apply the technology at an industrial scale. In 2015, a 5 MW steam boiler was ordered, and a joint development project was initiated with the supplier.
Results from 2019
After several trials and rebuilds, the 5 MW boiler has been connected to our steam supply system, and production in Aarhus is now partially powered by energy produced from shea meal. During 2019, this initiative has led to a 7 percent reduction of our greenhouse gas emissions in Denmark compared to 2018 – a great achievement based on the efforts of our dedicated employees in Aarhus.
"As the largest processor of shea kernels globally, AAK Denmark has full focus on sustainable production. By applying the best available technology to increase the efficiency, recycling and bio-conversion of our energy, we can stay at the forefront of sustainable production", says Palle Jensen, Site Manager AAK Denmark.
As we gain experience in burning shea meal as a single fuel source and seek to optimize the boiler's energy output, we will continue to evaluate if this technology and the materials we have chosen are viable in the long-term perspective.