Ammonia from air: Researchers tap wind energy to produce fertilizer ingredient for sustainable agriculture

Scientists in the US and Saudi Arabia are using wind energy to develop a new prototype device that produces ammonia — a key component of fertilizers. They claim the innovative approach could transform the agriculture industry, which accounts for about “one-third” of global greenhouse gas emissions, according to the UN Environment Programme.

Conventionally, manufacturers produce ammonia using the Haber-Bosch process, combining nitrogen and hydrogen at high temperatures (350° to 450°C) and high pressures (150 to 200 bar). The method is associated with environmental concerns since it consumes 2% of global energy and contributes 1% of annual CO2 emissions from its reliance on natural gas, the study states.

Additionally, ammonia production currently accounts for nearly 1.8% of global CO2 emissions, according to the Royal Society of London. The process is also one of the “big four” industrial processes where scientists urge a decarbonization plan is needed, besides cement, steel and ethylene production, to meet the net zero carbon emissions target by 2050.

A team of researchers at Stanford University, US, and King Fahd University of Petroleum and Minerals in Saudi Arabia developed the innovative on-site ammonia synthesis method using a catalyst “mesh” composed of magnetite and Nafion polymer.

It works at room temperature and atmospheric pressure and eliminates the need for additional electricity or radiation, thereby “substantially reducing CO2 emissions compared to the traditional Haber-Bosch process,” notes the study. 

“This breakthrough allows us to harness the nitrogen in our air and produce ammonia sustainably,” says study senior author Richard Zare, professor of chemistry in the Stanford School of Humanities and Sciences.

“It’s a significant step toward a decentralized and eco-friendly approach to agriculture.” 

The scientists’ method produced ammonia sufficient to fertilize plants grown in a greenhouse in two hours.The study, published in Science Advances, involved the first “on-site” demonstration of the technology rather than in a lab. 

Scaling the process

The Stanford team believes the innovative approach, if perfected, might eliminate the need for the “century-old” Haber-Bosch method. It produces ammonia “cleanly and inexpensively” and utilizes the surrounding air to get nitrogen and hydrogen from water vapor. 

The team optimized the reaction conditions in laboratory experiments and scaled up the process. After two hours of spraying, the ammonia concentration increased to 270.2 ± 25.1 μM, sufficient to fertilize plants grown in a greenhouse.

Farmers can also use the portable device for on-site ammonia production to avoid dependence on manufacturers for purchasing and shipping fertilizers.

“This approach significantly reduces the carbon footprint of ammonia production,” says study lead author Xiaowei Song, a chemistry research scientist at Stanford.

Lab-to-market

According to study co-author Chanbasha Basheer of King Fahd University of Petroleum and Minerals, the device is two to three years away from being market-ready and needs future development. 

The portable ammonia production device can reduce farmers’ reliance on manufacturers for buying and shipping fertilizers. “Our portable on-site device is a pivotal step toward creating an efficient system suitable for further development to improve the scaling up to meet the needs of agricultural and industrial use. The present system is truly primitive and needs improvement,” reads the study.

The team collected 20 ml/hour [of ammonia] in the field and 500 ml/hour in the lab. However, they believe these amounts can be “majorly increased with suitable engineering.”

Meanwhile, the team plans to use increasingly large mesh systems to produce more ammonia and envisions integrating the device into irrigation systems in the future, enabling farmers to generate fertilizer “directly from the air.”