Plasma technology turns coffee into renewable fuel

Coffee grounds have long been considered a great potential source of green energy, but their large-scale use has so far encountered a serious technical obstacle. The main problem is their high moisture content. Traditional processes for converting them into fuel require extensive pre-drying, which consumes so much energy that the entire process is financially unviable.

Researchers from the South Korean Institute of Geosciences and Mineral Resources (KIGAM) have successfully solved this problem with a new process, which they have presented in the scientific journal Chemical Engineering Journal. The key to the success is a technology called flame plasma pyrolysis. This system allows the direct processing of biomass, which contains about 55 percent moisture, under atmospheric pressure. The device uses plasma flames with temperatures between 800 °C and 900 °C, which are created by the combustion of liquefied petroleum gas and compressed air.

Due to the extremely high heat, the moisture inside the coffee particles evaporates instantly. The resulting pressure causes microscopic explosions. These explosions accelerate carbonization and create an extremely porous structure of the material. Moisture is no longer an obstacle, but becomes an activation medium that accelerates chemical reactions and improves the final quality of the final product or fuel.

Under optimized conditions, the entire conversion takes only 90 seconds, and the mass of the material is reduced by 83.3 percent. The obtained fuel, due to its high porosity and calorific value, is suitable for both high-quality solid renewable fuel and advanced carbon materials in industry.

The advantage of this compact device is that it is also ideal for decentralized systems. Instead of expensively transporting heavy, wet waste to large processing centers, these plasma units could be placed directly next to larger waste sources, such as industrial roasters or collection centers. In addition to coffee, FPP technology is also suitable for other types of organic waste with a high moisture content, including food waste and agricultural residues.

It is worth noting that the plasma system still requires fossil fuels to operate. Therefore, in practice, the overall carbon footprint and energy balance will need to be accurately calculated to confirm the long-term sustainability of the project.