In the quest for sustainable energy solutions, researchers have turned their attention to green ammonia, a promising energy storage carrier and sustainable chemical. A recent study published in Energy Nexus, the English translation of Energy Nexus, sheds light on the techno-economic and life cycle greenhouse gas assessment of green ammonia produced through a low-pressure Haber-Bosch process. The research, led by Guohui Song from the School of Energy and Power Engineering at the Nanjing Institute of Technology, offers insights that could significantly impact the energy sector’s future.
The study compares two power-to-ammonia (PtA) processes: one integrated with a low-pressure (LP) Haber-Bosch technique and the other with an ultra-low-pressure (ULP) technique. The findings reveal that while both methods have their merits, the LP technique emerges as the preferred option due to its simpler configuration and slightly lower levelized cost. “The LP technique’s simplicity and cost-effectiveness make it a more viable option for large-scale implementation,” Song explains.
One of the standout findings is the energy efficiency of the LP process. Excluding the cold energy of liquid ammonia, the systematic energy efficiency reaches an impressive 68.71%. When including the cold energy, this figure jumps to 73.75%. This high efficiency is coupled with a remarkably low unit power consumption of just 7.64 kWh per kilogram of green ammonia.
The research also underscores the importance of plant scale and operating hours for profitability. To achieve economic viability, the plant scale should not be less than 10 tons per hour, and the equivalent operating hours should exceed 5,000 hours. Given the current electricity price for energy storage at 0.041 €/kWh, these parameters are crucial for making green ammonia a commercially attractive option.
From an environmental perspective, the study reveals that the life cycle greenhouse gas emission of green ammonia derived from wind power in China ranges from 257 to 316 kgCO2e per ton. Additionally, ammonia emissions with NH3 recovery from the purge gas are less than 0.06 kgNH3 per ton, highlighting the process’s environmental benefits.
The implications of this research are far-reaching. As the energy sector grapples with the challenges of intermittent renewable energy sources, green ammonia offers a viable solution for energy storage. The high energy efficiency and low power consumption of the LP Haber-Bosch process make it an attractive option for large-scale implementation. Moreover, the environmental benefits of green ammonia could help decarbonize the ammonia industry, contributing to global efforts to combat climate change.
As Guohui Song puts it, “This study indicates that PtA technology can efficiently store intermittent electricity with cold energy utilization and effectively decarbonize the ammonia industry.” The findings published in Energy Nexus provide a roadmap for future developments in the field, paving the way for a more sustainable and energy-efficient future. The energy sector is on the cusp of a green ammonia revolution, and this research is a significant step forward in that direction.
