Biomass and waste-to-energy
Biomass is a renewable and sustainable source of energy derived from organic materials such as:
- Woody biomass obtained from trees residues and forestry
- Crop residues from agriculture
- Energy crops (such as miscanthus or microalgae, dedicated to biomass energy production), and
- Organic waste from different sources, such as municipal solid waste, sewage sludge or other organic waste
The source of energy is considered renewable if the rate of consumption does not exceed the rate of replenishment.
Processes to convert the biomass or waste to energy include:
- Combustion, directly burning biomass or waste to produce heat or electricity
- Gasification, producing a mixture of carbon monoxide (CO) and hydrogen (H2), called syngas, that is used as a fuel gas.
- Anaerobic digestion, producing biogas, composed mostly of methane (CH4), and carbon dioxide (CO2) that can be used as a fuel. Treated biogas may be called renewable natural gas or biomethane.
- Pyrolysis, producing bio-oil, syngas (CO and H2) and biochar (black residue, made of carbon and ashes, which is a form of charcoal.
Energy produced from biomass is usually considered carbon neutral or even negative; while burning biomass releases carbon dioxide, the plants absorbed that CO2 during their growth, making it a closed carbon cycle and generally considered carbon neutral.
When biomass energy is combined with carbon capture and storage (CCS) it achieves negative carbon emissions, capturing and storing more CO2 than is released during combustion. The cycle of biomass energy is schematically presented in Fig. NN
Fig. NN. The cycle of biomass energy
According to the IRENA report, biomass power capacity is estimated to triple by 2030 to nearly 290 GW, being one of the most attractive technologies for the energy transition.
Research and development in this area at Khalifa University is focusing on the following areas
- Advanced Combustion: Technologies like fluidized bed combustion and advanced gasification improve the efficiency of burning biomass and reduce emissions.
- Biochemical Conversion: Biochemical processes, such as anaerobic digestion and fermentation, are used to produce biogas, bioethanol, and biodiesel from organic materials.
- Microbial Fuel Cells (MFCs): MFCs can convert organic matter directly into electricity through the metabolic activity of microorganisms.
- Advanced Biofuels: Second- and third-generation biofuels, such as advanced bioethanol, biodiesel, and biojet fuels produced from non-food feedstocks, such as algae, agricultural residues, and dedicated energy crops.
- Waste-to-energy: Biomass is increasingly used to generate energy from organic waste, providing an environmentally friendly way to manage waste while producing energy, based on the concept of circular economy.
- Fundamental Research and Development: Efforts are focusing on improving the efficiency of biomass conversion technologies, exploring new feedstocks, and addressing environmental concerns.
Figure NN: A mass-burn waste-to-energy plant
(Adapted by the IAE with permission from Deltaway Energy)