Development of an Atmospheric Plasma Generator for Nitrogen Fixation in Air

The conventional nitric acid manufacturing method uses natural gas as a feedstock for hydrogen and an energy intensive thermal process that emits a large amount of carbon dioxide. A new low-temperature plasma system, which can be driven electrically by a renewable or nuclear energy source, could reduce the energy consumed by the synthesis of nitric acid while eliminating the emission of greenhouse gases. Recent technology advances will be leveraged to develop a new green nitric acid plant capable of competing directly with conventional nitric acid sources: A novel low-temperature plasma generator that will synthesize nitric acid using electricity, air, and water while reducing energy consumption and greenhouse gas emissions is in development. The system uses a new atmospheric-pressure pulsed-wave-form-driven dielectric barrier discharge plasma generator with key features designed to selectively optimize the generation of nitrogen dioxide, which will mix with water to form nitric acid. A laboratory-scale LTP system was developed and tested during Phase I. Key research findings include: • The necessity of operating in plasma regimes that avoid ozone production and favors production of nitrogen dioxide. • The sensitivity of nitrogen dioxide decomposition to high plasma temperatures. • That nitrogen dioxide should be removed from the plasma quickly to avoid destruction by successive plasma formation cycles. • That pulsed waveforms outperform comparable sinusoidal waveforms. These findings point the way to achieving the target energy cost and nitric acid yield in the proposed Phase II project. The Phase II objective is to build a prototype nitric acid reactor that combines the Phase I performance improvements with innovations that maximize nitrogen dioxide production and reduce nitrogen dioxide destruction. Nitric acid is a mature product with about 64 million tons produced worldwide in 2021, with a total market value over $24B annually. Because of its reliance on natural gas as the hydrogen feedstock, the industry is responsible for 108 million tons of carbon dioxide-equivalent emissions every year (equivalent to the emissions of about 21 million internal combustion cars). When powered by low-cost renewable electricity with multiyear power purchase agreements, Arctura’s green nitric acid plant has the potential to capture market share by offering long-term contracts to customers at a lower price than conventional market prices.