(568e) Bioenergy Production with Carbon Capture: An Optimization of Materials

Bioenergy with carbon capture and storage (BECCS) is a carbon negative process for energy production. BECCS has the potential to become a major process in the fight against climate change and has been increasingly recognized as such since its inception in 1998. One thing that is particularly intriguing about BECCS is that, in addition to producing energy while removing carbon from the atmosphere, it can produce solid carbon which can be easily stored and used for industrial applications. BECCS is a promising process with a low-energy demand.

We have used a design of experiments to quantify the energy production of biomass devolatilization coupled with the adsorption capacity of the resulting biochar. Tested factors include temperature, heating rate, particle size, fuel/biomass type, and gas atmosphere. There are many properties of biochar that can be affected by the temperature at which thermal decomposition occurs. As the temperature increases, we see a reduction in volatile matter due to dehydration and devolatilization. Most of the organic material is volatile, therefore increasing the temperature will evolve more potential energy, however, there is a trade-off between energy and carbon capture potential. Aside from the temperature, heating rate is also an important parameter because that can determine biochar yield. The higher the heating rate, the lower the biochar yield, but the better the CO2 adsorption capacity. Determining the optimal heating rate for the biomass is a goal of this study.

A design of experiments approach was utilized to determine specific adsorption capacity of CO₂. Specific capacities were in excess of 1.5 mmol CO₂ per gram of biochar for temperature cycles between 30°C and 80°C. Additionally, activation energies and exothermic peaks are determined via thermogravimetry and calorimetry. Scoping studies show a consistent activation energy curve as conversion increases to approximately 60%, where a peak indicates the devolatilization of most of the organic matter. We suspect that this presents the limit to energy production and shows the approximate peak of carbon capture potential for BECCS applications.