Optical measurements of carbon based solid fuels: Biomass and coal from single particle to group combustion

Climate change is one of today's most pressing global issues, requiring industries to drastically cut greenhouse gas emissions while maintaining technological and economic progress. The main cause is the greenhouse effect driven by human-made emissions, especially carbon dioxide, leading to rising global temperatures, sea level rise, extreme wildfires, and biodiversity loss.Energy production from fossil fuels remains the largest source of CO¿ emissions worldwide, including in Germany and Europe. However, advanced combustion technologies-particularly oxy-fuel combustion-offer promising solutions by enabling the separation and storage of CO¿. When combined with carbon capture and storage (CCS), even negative CO¿ emissions may be achieved through biomass combustion.This research aims to study and characterize the combustion behavior of single and multiple fuel particles under oxy-fuel conditions, focusing on both fossil and biogenic fuels. A special emphasis is placed on pine needles as a potential biomass source and their role in wildfire dynamics.The study is divided into three parts:¿ Fundamentals and Methods: Overview of solid fuel combustion in oxy-fuel atmospheres, experimental setup, and optical measurement techniques.¿ Experimental Results: Comparison between single-particle and group combustion, and between biogenic and fossil fuels, highlighting key variables influencing the transition between these combustion modes.¿ Application to Pine Needles: Investigation of raw and torrefied pine needles in a different reactor to evaluate their energy potential and relevance to wildfire prevention.Overall, the findings provide new insights into the combustion processes of solid fuels in oxy-fuel conditions and advance the understanding of particle interactions, contributing to both cleaner energy generation and wildfire mitigation strategies.