Biogas, a renewable energy source produced through the anaerobic digestion of organic waste, has gained significant attention in recent years. With a large-scale biogas production and utilization, China has set an example for the world in coping with the energy crisis. However, the impurities present in biogas, such as CO2 and H2S, pose challenges to its efficient utilization. Biogas upgrading technologies have emerged to remove these impurities and increase the share of methane, making it a cleaner and more sustainable fuel. This article explores the development and potential of biogas upgrading, focusing on a novel approach using renewable ammonia aqueous absorbent.
Biogas, consisting of approximately 60% CH4 and 40% CO2, is an attractive source of renewable energy. However, the presence of CO2 reduces its combustion performance, while H2S leads to pipeline corrosion. These impurities must be removed to enhance the quality and economic viability of biogas. Traditional biogas upgrading technologies, such as water scrubbing and pressure-swing adsorption, offer effective CO2 and H2S removal but suffer from high methane losses. Addressing these challenges is crucial to maximizing the potential of biogas as a green energy source.
Researchers, led by Prof. Shuiping Yan, have proposed a promising solution using a renewable ammonia aqueous absorbent derived from biogas slurry. By combining the principles of green energy engineering, they have developed a method that efficiently removes CO2 and H2S from biogas while minimizing methane loss. The renewable ammonia aqueous absorbent also offers the potential for direct application as an ammonium nitrogen fertilizer, avoiding the drawbacks associated with traditional chemical absorbents.
The team conducted experiments using a gas-liquid membrane contactor, employing the renewable ammonia aqueous solvent for simultaneous removal of CO2 and H2S from biogas. The results were remarkable. The 0.1 mol·L-1 NH3 renewable ammonia aqueous solvent achieved 97% removal of H2S from biogas, surpassing the efficiency of physical absorption methods. Furthermore, the removal efficiency of H2S remained unaffected by impurities in the absorbent. By adjusting the ammonia concentration to 0.5 mol·L-1 NH3, the biogas could be purified for conversion into biomethane, ready for pipeline injection. The team also determined the optimum operating conditions for the membrane contactor, providing a solid theoretical basis and technical support for the green development of biogas upgrading processes.
The utilization of renewable ammonia aqueous absorbents offers significant advantages for biogas upgrading. The method not only achieves efficient CO2 and H2S removal but also minimizes CH4 loss, making it a more sustainable approach. Additionally, the renewable ammonia aqueous absorbent can be used as an agricultural fertilizer, further contributing to the circular economy. By utilizing biogas more efficiently, we can reduce greenhouse gas emissions and advance towards a carbon-neutral future.
Biogas upgrading technologies are crucial for maximizing the potential of biogas as a green renewable energy source. The use of renewable ammonia aqueous absorbents presents a promising solution for efficient CO2 and H2S removal, while minimizing CH4 losses. This innovative approach not only enhances the economic viability of biogas plants but also contributes to the reduction of greenhouse gas emissions. The research conducted by Prof. Shuiping Yan and his team provides a solid foundation for the green development of biogas upgrading processes. With further advancements, biogas upgrading can pave the way for a sustainable and carbon-neutral future.
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