NitroVolt technology achieves stable continuous ammonia electrosynthesis

In the quest for sustainable solutions to meet the world’s growing energy and food demands, a groundbreaking study has emerged, revolutionizing the way we produce ammonia.

Traditionally, ammonia production has relied heavily on the Haber-Bosch process, a century-old method that, while effective, is energy-intensive and contributes significantly to global carbon dioxide (CO₂) emissions.

However, the recent study reported by Shaofeng Li and his team at the Technical University of Denmark, together with NitroVolt’s founders Suzanne Zamany Andersen and Mattia Saccoccio, presents a novel approach to stabilize ammonia electrosynthesis that could change the game.

The limitations of the Haber-Bosch process

Before delving into the intricacies of the new method, it’s crucial to understand the limitations of the Haber-Bosch process. Developed in the early 20th century, this method synthesizes ammonia from nitrogen and hydrogen gasses under high temperatures and pressures. It’s the backbone of the global nitrogen fertilizer industry, which, in turn, supports about half of the global population’s food supply. However, the process consumes about 1-2% of the world’s energy supply and emits a significant amount of CO₂, making it a target for sustainable innovation.

NitroVolt technology for stable continuous ammonia electrosynthesis

The study, titled “Long-term Continuous Ammonia Electrosynthesis,” introduces a lithium-mediated nitrogen reduction reaction (Li-NRR) as a promising alternative for sustainable ammonia production. This method operates at ambient conditions, significantly reducing the energy requirements and environmental impact compared to the Haber-Bosch process.

The diagram below depicts the processes of ammonia electrosynthesis in a continuous-flow electrolyzer.

NitroVolt ammonia electrosynthesis processes in the continuous-flow electrolyzer.
NitroVolt ammonia electrosynthesis processes in the continuous-flow electrolyzer.

The anode and cathode are separated by the electrolyte chamber. Both electrodes are made of stainless-steel cloth coated with platinum/gold (Pt/Au) alloy catalyst. The stainless-steel cloth serves as the gas diffusion layer, which is attached to the gas flow fields with patterned gas flow channels. The gas flow fields are attached to the current collectors.

During operation, lithium ions (Li⁺) diffuses from the bulk electrolyte through the solid-electrolyte interphase. They are electrochemically reduced into metallic lithium on the cathode. The metallic lithium subsequently reacts with N₂ which diffuses from the gas flow field channels to the cathode, forming lithium nitride (Li₃N). The lithium nitride is protonated by a proton (H⁺) shuttle of ethanol (EtOH) to continuously release ammonia (NH₃).

The sustainable source of protons is provided by hydrogen oxidation on the anode.

The key innovation lies in the use of a chain ether-based solvent, which overcomes the limitations of traditional solvents like tetrahydrofuran (THF) that hinder long-term operation due to issues like polymerization and volatility.

You can check out our detailed research for NitroVolt to understand how they produce green ammonia.

The role of chain ether-based solvents

The researchers discovered that a chain ether-based solvent, specifically diethylene glycol dimethyl ether (DG), exhibits non-polymerization properties, a high boiling point, and forms a compact solid-electrolyte interphase (SEI) layer on the gas diffusion electrode (GDE). These characteristics facilitate ammonia release in the gas phase and ensure electrolyte stability, enabling 300 hours of continuous operation in a flow electrolyzer at room temperature and atmospheric pressure. Remarkably, this method achieved a current-to-ammonia efficiency of 64 ± 1% with an unprecedented gas phase ammonia content of ~98%.

Implications for sustainable agriculture and energy

The implications of this breakthrough are profound. First and foremost, it offers a more sustainable pathway for ammonia production, which is crucial for the global fertilizer industry. By reducing the energy consumption and carbon footprint associated with ammonia synthesis, this method aligns with global efforts to combat climate change and promote sustainable agriculture.

Moreover, ammonia has the potential to serve as a carbon-free fuel, offering a promising solution for the energy sector’s transition towards renewable sources. The high efficiency and long-term stability demonstrated by Li and his team’s method make it a viable candidate for large-scale ammonia production, which could be used for energy storage and transportation, further reducing our reliance on fossil fuels.

Challenges and future directions

While the study marks a significant advancement, challenges remain for the industrial application of this technology. Achieving industrial-relevant current densities, optimizing the gas diffusion electrode (GDE), electrolyte formulation, cycling procedure, and reactor design are critical steps towards commercialization. Future research should focus on addressing these challenges, aiming for high faradaic efficiency and energy efficiency at industrial-relevant current densities while maintaining long-term stability and gas-phase ammonia production in pilot-scale flow cells.

Conclusion

The study by Li and his team represents a pivotal step forward in the quest for sustainable ammonia production. By leveraging the unique properties of chain ether-based solvents, this method offers a viable alternative to the Haber-Bosch process, with the potential to revolutionize agriculture and energy sectors. As we continue to explore and optimize this technology, we move closer to a future where sustainable ammonia synthesis (check out our startups list of green ammonia) can support the world’s food and energy needs without compromising our planet’s health.

Leave a Comment

Your email address will not be published. Required fields are marked *

8 + 5 =

Scroll to Top