Image caption: Green Ammonia has the potential to reduce the carbon footprint of agricultural fertilizer. Image Credit: CC BY 2.0 / Openverse
Script by: Olivia Rounsaville | Audio by: Themi Perera | Blurb by: Olivia Rounsaville
What is “Green Ammonia”?
Ammonia is a vital chemical that sustains half of all food production around the world (through the creation of agricultural fertilizer), but the process we use to make it results in significant greenhouse gas emissions. Ammonia, which is made up of nitrogen and hydrogen, requires extreme heat and pressure and large amounts of energy (usually from fossil fuels) in order to synthesize. “Green ammonia” production reduces this reliance on emission-intensive energy by using cleaner hydrogen inputs and processes that require less energy.
Green ammonia, while easier on the planet, is a much harder task to accomplish than mainstream methods. In the Haber-Bosch process, the standard industrial procedure used today, high pressure steam is shot at methane or coal, breaking up the components to produce hydrogen and carbon dioxide. This process requires fossil fuels as an input and releases greenhouse gasses during production, making it a significant contributor to climate change. Once the hydrogen is produced, the Haber-Bosch process synthesizes the hydrogen and nitrogen and separates out ammonia using high temperatures and extreme pressure swings, conditions that require large energy input. The Haber-Bosch process is so energy intensive that this chemical reaction alone accounts for about 1% of global annual CO2 emissions!
The Chemical with the Biggest Footprint
Green Ammonia aims to reduce reliance on fossil fuels in multiple stages of this procedure through different approaches. Areas of research include creating reactors that convert sunlight and air into hydrogen, binding together the hydrogen and nitrogen under less pressure than nearly 200 atmospheres, and using less pressure to separate the finished ammonia from other residual gasses at the end of the procedure.
The Ammonia Separation Challenge
While the Haber-Bosh process uses a large pressure change to liquefy ammonia gas, this method, and many current separation techniques, are carbon intensive and not fully compatible with cleaner hydrogen sources. Creating technology that can more efficiently capture ammonia at lower temperatures and pressures would reduce the energy costs of producing ammonia significantly. An added bonus? Downscaled reactors require lower temperatures and pressures, potentially enabling small-scale ammonia production on farms themselves.
About Benjamin Snyder
Dr. Benjamin Snyder is an Assistant Professor of Chemistry at the University of Illinois, where he conducts research combining inorganic, physical, and materials chemistry. He led green ammonia research as an Arnold O. Beckman Postdoctoral Fellow at UC Berkeley, focusing on alternative methods to separate ammonia.
- Industrial Ammonia Production and its Huge CO2 Footprint, C&EN
- How Green Ammonia Relates to Solar Panels, PacificGreen Solar Technologies
- An Overview of Hydrogen Production, Alternative Fuels Data Center
- More About Benjamin Snyder, University of Illinois
- Read Benjamin Snyder’s Green Ammonia Work, Nature
Ethan: I’m Ethan Elkind, and you’re listening to Climate Break. Climate solutions in a hurry. Today’s proposal: reducing the carbon footprint of agricultural fertilizer through its key ingredient: chemically produced ammonia. We spoke to Ben Snyder, Assistant Professor of Chemistry at the University of Illinois, about so-called “green ammonia” production.
Dr. Snyder: ammonia is one of the most important molecules that we make. It’s basically the molecule that sustains all of global agriculture. We make an absolutely fantastically large amount of ammonia each year.
Ethan: But this production emits significant greenhouse gasses. Fossil fuel is typically used to generate dihydrogen, a key input into ammonia. But Snyder thinks farmers can produce this dihydrogen on-site using solar power instead.
Dr. Snyder: What you really need to do is you need to be able to build a small unit that can take advantage of a small source of solar hydrogen. We’re talking about a unit that a farmer could build on site on their farm as opposed to a square mile chemical plant.
Ethan: Snyder and other researchers are now examining how to more efficiently capture the ammonia that is created from solar power.
Dr. Snyder: if you can capture more of the ammonia, it essentially allows you to operate the reactor at lower temperatures, so less input of heat.
Ethan: Snyder wants to see the government invest in more research to scale this technology.
Dr. Snyder: Many years down the road, this is the sort of technology that could allow some farm to produce their own ammonia on site and be more self-sufficient.
Ethan: To learn more about the opportunity to create Green Ammonia, visit climatebreak.org.