New green tech produces ammonia fertilizer using Earth's natural forces

Imagine a future where one of the biggest pollutants of our environment, the production of ammonia, is no longer a headache. Instead, the Earth itself could become a productive partner in generating this chemical. All it takes is the use of Earth’s natural forces and heat.

In an unexpected twist of events, a scientific breakthrough at the globally renowned Massachusetts Institute of Technology (MIT), points in this very direction.

The ground-breaking study was motivated by a mysterious natural phenomenon observed in Mali, West Africa, in the 1980s.

Locals came across a well that was gushing with hydrogen gas, an oddity that scientists attributed to a water-rock chemical reaction beneath Earth’s surface.

Green shift in the fertilizer industry

“It was an ‘aha’ moment,” shared senior author Iwnetim Abate of MIT. “We may be able to use Earth as a factory, harnessing its heat and pressure to produce valuable chemicals like ammonia in a cleaner manner.”

Ammonia’s importance cannot be overstated. It is a key ingredient in fertilizers and potentially a clean fuel source. However, its current production methods are far from energy-efficient or green.

Today’s industrial ammonia production is a significant consumer of global energy and a major emitter of CO₂. In fact, for every ton of ammonia produced, there’s a release of around 2.4 tons of CO₂.

Traditional ammonia production

For over a century, the production of ammonia has been dominated by the Haber-Bosch process, an energy-intensive method that relies heavily on the use of fossil fuels.

This conventional approach operates at high temperatures and pressures, consumes vast amounts of natural gas and contributes significantly to greenhouse gas emissions.

Despite its efficiency in meeting global fertilizer demands, the process is far from sustainable.

As industries face mounting pressure to reduce their carbon footprints, the search for greener alternatives has intensified.

Scientists and engineers are now exploring innovative methods that utilize Earth’s natural processes to revolutionize ammonia production, offering a path toward cleaner, more efficient solutions.

Finding the solution under our feet

With sustainability in their sights, the research team at MIT set out to test this idea of an “Earth factory.” They constructed an environment that replicated the conditions beneath Earth’s surface.

Iron-rich minerals were exposed to nitrogen-laced water, which ignited a chemical reaction that transformed the rock and gave rise to what they termed “geological ammonia.”

Remarkably, the process didn’t require any additional energy input, and there were no CO₂ emissions. To top it all, the entire process even took place under ambient conditions!

To replicate real-world conditions, the team replaced synthetic mineral with olivine, a naturally iron-laden rock. They optimized the process further by introducing a copper catalyst and elevating the heat to 300°C.

In just 21 hours, they managed to produce about 1.8 kg of ammonia per ton of olivine, demonstrating the method’s feasibility and sustainability.

Why does green ammonia production matter?

“These rocks are all over the world, so the method could be adapted very widely across the globe,” enthused Abate.

However, he acknowledged that implementation would come with its own set of challenges, including drilling into iron-rich rocks deep within the Earth and dealing with the complexities of the rocks’ interactions with gases and liquids.

On the economic front, geological ammonia production is encouraging. The cost is around $0.55 per kilogram, roughly equivalent to the price of conventional methods.

But the game-changer is the potential to address environmental crises like CO₂ production and wastewater pollution.

Nature, life, and ammonia

Yifan Gao of MIT, the first author of the study, postulated a win-win strategy.

“Nitrogen sources are considered as pollution in wastewater, and removing them costs money and energy,” he explained.

The team suggested turning this problem on its head by using wastewater to produce ammonia. This perspective could potentially add an additional profit of $3.82 per kilogram of ammonia formed.

“Ammonia is pretty important for life. The only other natural way that ammonia is produced on Earth is when lightning strikes nitrogen gas,” commented senior author Ju Li.

“That’s why the geological production of ammonia is quite interesting when you think about where life came from,” Li concluded.

This initiative by the scientists at MIT highlights the innovative solutions that can arise when we look towards nature for inspiration.

With every small step, we move closer to a future where sustainable chemical production is not just a dream but a reality.

The full study was published in the journal Joule.

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