Green Ammonia – An Alternative Fuel

Currently, the whole world is facing the challenge of climate change and the global temperature is rising mainly because of greenhouse gas emissions due to human activities. As per the report of the Intergovernmental Panel on Climate Change (IPCC), a temperature rise of 2.5 to 10 degrees Fahrenheit is expected over the next 100 years. Given this emerging global concern, everyone is looking for new and innovative solutions for the decarbonization of the entire energy value chain and ammonia (NH₃) is one of the possible solutions.

Potential energy usage for ammonia

In recent years ammonia has been used in the energy sector for

• Energy storage
• Electricity generation
• Heat transfer.
• Transport fuel
• Hydrogen carrier

Exhibit 1 below represents different uses of ammonia

Global Market Outlook

In 2021, around 183 million tons of ammonia were produced globally, with less than 0.02 million tonnes of green ammonia. But with the discovery of some new applications of green ammonia as a carbon-free maritime fuel and for application in stationary power generation, IRENA projected that the global demand for ammonia is expected to reach up to 688 million tonnes including 566 million tonnes of green ammonia by 2050 in 1.5 degrees Celsius (°C) scenario. In the IRENA 1.5°C scenario, most of the demand will come from the maritime sector representing new demand of around 197 million tonnes by 2050. An additional demand of 127 million tonnes of ammonia will come from the international trade of ammonia as a hydrogen carrier by 2050.

Ammonia production is expected to increase in the future owing to government initiatives, an increase in investments in green energy generation, and a focus on fuel cell and hydrogen projects. Apart from Europe, the Asia-Pacific region is expected to be the second-largest market for green ammonia production. Based on end users, the power generation and transportation sector (especially marine transport) are expected to be the major end-users of green ammonia. According to the International Maritime Organisation (IMO), it is expected that ammonia will contribute about 25% of the shipping fuel mix by 2050 to decarbonise the shipping sector.

 Exhibit 2 Existing and Planned facilities and key technology providers

Green Ammonia as Fuel

Green ammonia is gaining commercial and policy attention because of its use in decarbonization of various sectors. It can be used in the agricultural sector, chemical industries, etc. to reduce carbon footprints, to decarbonize the power and transportation sector, and have applications in transportation including heavy goods vehicles, trains, aviation, and shipping. In 2020, CO₂ emissions from the transportation sector were around 7.2 gigatonnes (Gt), Therefore, there is a target to reduce CO₂ emissions from the transportation sector by 20% i.e. 7.2 Gt (2020) to 5.7 Gt (2030) to meet the net zero emission target by 2050. Research is being conducted all over the world to retrofit current marine engines, internal combustion engines, and gas turbines to run on green ammonia.

Apart from the transportation sector, green ammonia can play a vital role to decarbonise the power sector by replacing fossil fuels with green ammonia in thermal power plants for electricity production. It can be used to produce green electricity by using different kinds of fuel cells. Thus, green ammonia can act as a prominent solution to decarbonize the transportation and power sector to achieve net zero goals.

Green ammonia as a hydrogen carrier

Although central hydrogen production and transportation by pipeline appear to be the ultimate solution to transporting hydrogen efficiently, the high capital investment required suggests that pipelines are unlikely to be used at the early stages of the transition to a hydrogen economy. Ammonia is one of the only materials that can be produced cheaply, transported efficiently, and transformed directly to yield hydrogen, a non-polluting byproduct. Urea is also appealing since it doesn’t suffer from the toxicity problems associated with ammonia, but its hydrogen content is only 9.1 wt% – a little over half that of ammonia. Ammonia is currently transported by pipeline, oceangoing tankers, rail, and truck.

• Ammonia as a hydrogen carrier can solve the challenge of storage and distribution of hydrogen
• Green Ammonia can be cracked, and hydrogen can be released back for industrial applications
• These crackers currently operate at high temperatures and further improvements in energy efficiency and operating conditions are required for widespread adoption
• There are two facilities that are being planned for large-scale ammonia decomposition –one in the Netherlands (port of Rotterdam) and the second one in Germany
• As a hydrogen carrier, green ammonia can boost the clean economy

How green ammonia is produced?

The basic elements needed to produce ammonia are nitrogen and hydrogen. The conventional ammonia production process involves the conversion of fossil fuel (e.g., natural gas) to produce gaseous hydrogen by the steam reforming process. The other element nitrogen is obtained from the air. Ammonia is then produced by ammonia synthesis in the presence of a catalyst at high temperature and pressure. Ammonia thus produced is called grey ammonia and the synthesis process is known as the Haber Bosch process.

In 2021, less than 0.02 MT of green ammonia was produced. The energy needed in the whole process of production is powered by renewable energy such as solar, wind, geothermal, etc. resulting in carbon-free green ammonia production process.

Alternate methods of green ammonia production

Apart from the electrolysis process of green ammonia production, research is being conducted on green ammonia production technologies such as electrochemical, nitrogenase process, and chemical looping processes.

Electrochemical process

• Green ammonia is directly produced from water and nitrogen using electricity
• No separate hydrogen production process
• Ideal for distributed (small-scale) generation
• This production process is TRL 1 – 2

Nitrogenase process

•  Green ammonia is produced naturally by bacteria that contain an enzyme catalyst – Nitrogenase.
• It operates at room temperature and pressure to synthesize ammonia from water and nitrogen.
• Needs more research and development for large-scale industrial production
• This production process is TRL 1

Chemical looping processes

• Green ammonia is produced as a byproduct of a series of chemical/electrochemical reactions.
• A few cycles eliminate the need for a separate hydrogen production process by reacting with water directly.
• This production process is TRL 1 – 4.

Recent developments in green ammonia technology include:

• Solid oxide electrolysis system developed by Haldor Topsoe uses renewable energy to produce ammonia synthesis feed-gas without an air separation unit, significantly reducing capital expenditure
• Atmonia– an Iceland-based start-up is developing a catalyst for sustainable ammonia production as this catalyst will use new materials considering the net zero-carbon goals
• Starfire Energy has developed a modular system to produce carbon-free ammonia and this system requires lower pressure than the traditional Haber-Bosch system

Cost of green ammonia

Though the current cost of green ammonia is very high compared to traditional ammonia. However, this cost is expected to decrease as the renewable energy cost decreases. The current Price of green ammonia is in the range of $ 700 – 1400 per tonne at sites with renewable resources like sun and wind. By 2030, it is expected to drop to $ 480 per tonne, and by 2050, to $ 310 per tonne. To make green ammonia competitive with traditional ammonia, a carbon price reduction of around $ 150 per tonne of CO₂ is needed. It is also estimated that, if the renewable electricity price is below $ 20 per megawatt-hour, green ammonia will be competitive with traditional ammonia.

Challenges related to green ammonia

Cost: The cost of production of green ammonia is much higher than traditional ammonia production cost. According to IRENA, current production costs for new green ammonia plants are in the range of $ 720 – 1,400 per ton which is about six times higher than the traditional ammonia (natural gas-based ammonia and coal-based ammonia), which is in the range of USD 110-340 per ton.

Low conversion rate: When ammonia is used for power generation, its conversion rate is very low which is around 17%, meaning 83% of the input energy is lost.

Access to technology: The current green ammonia technology needs to be scaled with the innovation in new electrolyser technologies like solid oxide electrolyser, polymer electrolyte membrane (PEM), etc. with improved operational efficiency to make green ammonia more cost competitive. To achieve the goal of green ammonia production by 2050, global electrolyser production capacity must be increased by 20 times, from 2.1 GW per year to 42 GW per year.

Environmental challenge: Green ammonia can replace fossil fuels at scale in hard-to-abate areas of the electricity and transportation industries. However, it may result in a rise in pollutant emissions such as nitrogen oxides (NO_X) and nitrous oxide (N₂O), which must be avoided.

Policy challenge: Government policies and regulatory development support will be required for green ammonia to be economical.

Way forward

Despite very low production and limited energy application of green ammonia today, green ammonia demand and production is likely to increase in upcoming years due to the focus on reducing carbon emissions. In recent years, green ammonia production and its applications have shown a substantial push with the announcement of projects by multiple players working in sustainability. Although ammonia has the potential to be used as a clean fuel, considerable effort is required in developing and scaling new green ammonia production technologies, as well as inventing efficient and innovative ways to harness the energy it stores. In addition to this, a proper regulatory framework must be in place to realize the full-scale potential of green ammonia for decarbonization.

References:

1. Effects of climate change
2. IRENA: Renewable Ammonia
3. IEA: Transport