Infrasound in the Production of Biochar

This project studies the application of infrasound in the pyrolysis process for biochar production.Biochar is a charcoal-like material rich in carbon, which is derived from biomass under low-oxygenconditions. Biochar has many uses, such as carbon capture, pollution removal through adsorption,and in renewable energy systems. However, the limited heat transfer and efficiency of the processpresents a challenge for mass production. Infrasound, which describes sound waves below 20 Hz,has shown potential in enhancing the natural convection and heat transfer during the combustionprocess. This report presents a combination of literature studies and two experiments which investi-gate whether infrasound can improve the efficiency of biochar production. During the first lab, theimpact of the infrasound on the heat distribution in biomass was studied, using a controlled setup tomeasure the temperature differences. The results revealed a significant improvement in convectiveheat transfer when infrasound was applied to the setup. The second lab studied biochar productionwith varying biomass quantities and infrasound amplitudes with the help of a grill with built-in infra-sound speakers. The results from the second lab showed that higher infrasound amplitudes generallyresulted in increased combustion, although safety became a concern at higher temperatures and el-evated amplitudes of infrasound. Further analysis of the produced biochar, with X-ray diffractionand scanning electron microscopy, provided insights regarding its chemical composition as well as itsporosity. This report also presents the results from a literature study on the use of different materialsand the effect each of them has on the pyrolysis process. Woody biomass containing lignin resultsin a high biochar yield, rendering recycled wood panels a promising alternative material. Anotherpromising method is co-pyrolysis, with plastic as a main component along with other organic feed-stocks. A negative side effect from both these methods is the release of toxic volatile gases. Plasticwas shown to have a positive effect on the biochar yield, with improved quality at a low plastic ratioand with a temperature of 300 °C.