Tim Bushman

Senior Science Analyst

Julio Friedmann, PhD

Chief Scientist

What do various chemicals, household cleaning solutions, and fertilizers have in common? They rely on ammonia as a critical input for production.

Ammonia is a common industrial chemical that has been synthesized for commercial use for over a century. We use it for a variety of applications, most notably to make nitrogen fertilizers that support food production. In fact, ammonia has been regarded as a pillar of modern civilization and an indispensable contributor to agricultural systems, responsible for feeding roughly half of the global population that otherwise would not have access to an adequate food supply. In other words, ammonia is today’s imperative that helps to feed and sustain our growing population.

But ammonia also holds tomorrow’s promise: If produced sustainably, it has the ability to be used as a clean fuel in everything from shipping to power generation, which can help reduce greenhouse gas (GHG) emissions across the economy and address climate change.

How Ammonia Can Reduce Greenhouse Gas Emissions

To meet shared global climate goals, society will need to deploy numerous low-carbon technologies and emissions-reduction strategies. While electrification of energy end-uses is poised to do a lot of the heavy lifting for decarbonization, clean fuels will likely play a critical, complementary role in reducing emissions across the economy (particularly for the harder-to-abate sectors such as heavy industry and long-distance transportation). Enter ammonia, which can serve as a versatile low-carbon fuel to help reduce emissions along with other options such as hydrogen, methanol, biomethane, and sustainable aviation fuel.

Download the Full Report—Clean Ammonia: Prospects for Decarbonization

However, considerable progress needs to occur to address the emissions-intensive nature of the ammonia production process before it becomes a viable clean fuel substitute. For context, according to a 2022 report by the International Renewable Energy Agency (IRENA), the world currently produces around 183 million metric tonnes (Mt) of ammonia per year, for which demand could grow by a factor of 3-4 times current levels to an estimated 688 Mt by midcentury. According to the same report, the global ammonia industry is also responsible for an estimated 500 Mt of CO2 emissions per year—comparable to the annual CO2 emissions of Mexico or Canada. This environmental burden is due in part to the fact that conventional ammonia production relies heavily on the use of fossil fuels (particularly natural gas) to produce the required hydrogen and provide process heat.

Figure 1. Ammonia Production Pathways and Major End Uses

Ammonia Production Pathways
Source: Carbon Direct Inc., 2023. Images from Noun Project.

So what are our options to reduce GHG emissions across the ammonia industry? Thankfully there are many possible solutions that include (but are not limited to):

  • Producing clean hydrogen for ammonia synthesis through multiple pathways (e.g., carbon capture and storage [CCS] or electrolysis with clean electricity)

  • Improving technology performance (e.g., electrolyzer efficiency)

  • Pursuing fuel-switching (e.g., biomass)

  • Reduce market demand for ammonia

  • Using fertilizer alternatives

Uses for Clean Ammonia

Once clean ammonia has been produced, it can then be deployed for a range of end-use applications and markets. Notably, ammonia will continue to play a central role in global fertilizer production, for which emissions from the fertilizer industry are expected to increase into the future to help feed a growing population. The use of clean ammonia will therefore be paramount to reducing emissions from that industry. In other words, we need a lot more ammonia with far fewer emissions.

One promising new use case for clean ammonia is as a maritime fuel. Maritime shipping is a major economic sector that involves the transport of goods over long distances aboard ocean-going vessels. The industry already has a sizable emissions footprint—about 2 percent of global emissions in 2020, according to a study conducted by the International Maritime Organization (IMO). Swapping out traditional bunker fuels for alternatives like clean ammonia could be a viable solution through fuel blending, ammonia fuel cells, or the construction of purpose-built ammonia-fueled ships. The IMO has set a target to halve GHG emissions by 2050 (from a 2008 baseline) and fully eliminate emissions as soon as possible during the course of this century, which could help spur new markets for clean ammonia as a maritime fuel.

Other promising use cases include using ammonia as a hydrogen carrierThe term carrier refers to hydrogen being chemically bound to another atom (i.e., packaged together with something else). For ammonia (NH3), that means that the nitrogen atom is bound to the hydrogen atoms which serves as a means to transport or ‘carry’ the hydrogen. For decarbonization purposes, ammonia can either be consumed directly as a fuel or reconverted to hydrogen depending on the intended application. and as a fuel for power generation. Several benefits of using ammonia as a fuel include being cheaper and safer to transport than hydrogen (not typically explosive), has a higher volumetric energy density than hydrogen, and allows for ease of detection if leakage occurs.

Ensuring Successful Clean Ammonia Adoption

Despite its promise, clean ammonia also comes with some potential environmental concerns: From a usage standpoint, the combustion of ammonia generates nitrous oxide (N2O), which is a potent GHG with relatively strong heat-trapping properties and nitrogen oxide gases that can negatively impact human health. Furthermore, improper addition of large nitrogen loads to natural landscapes can lead to bad environmental consequences such as toxic algae blooms and air quality problems. Stringent operational controls and regulations across the entire ammonia value chain will prove important to the future success of ammonia as a decarbonization tool.

Clean ammonia presents an important opportunity to reduce GHG emissions across multiple sectors, but its ultimate success will be predicated on factors such as a commitment to lower the emissions intensity of production and a supportive policy and regulatory environment to help drive decarbonization outcomes. If these factors fall into place, the ammonia industry is poised for continued growth to help serve the dual societal imperatives of global food security and decarbonization.