By M. Srinivas, DGM; R.V. Kiran, Sr. Manager; Rohan Sabat, Manager; and P. Krishna Kishore, Manager, NTPC Limited
The escalating impacts of climate change demand a shift from carbon-intensive energy to cleaner alternatives. As a Paris Agreement signatory, India has committed to reducing carbon intensity by 45 per cent by 2030 and achieving net zero emissions by 2070. With the power sector being the largest contributor to India’s Carbon dioxide (CO2) emissions, its transition to renewables is critical. Green ammonia, produced through renewable energy, presents a viable decarbonisation pathway. Its co-firing in coal-based thermal power plants (TPPs) leverages existing infrastructure while reducing carbon emissions.
This article explores the implementation of green ammonia co-firing in TPPs, focusing on its feasibility, benefits and road map for adoption. Green ammonia is an innovative solution for decarbonising TPPs by reducing greenhouse gas (GHG) emissions and promoting renewable energy integration. The authors also propose a pilot project in this space…
Technical feasibility of green ammonia co-firing
Green ammonia’s technical feasibility as a co-firing fuel in TPPs is influenced by its properties, integration challenges and emission reduction potential. The critical parameters with respect to technical feasibility include:
Combustion compatibility: Studies demonstrate that co-firing up to 20 per cent ammonia with coal is technically feasible and does not require significant modifications to boiler efficiency. Experimental set-ups confirm stable combustion characteristics even at higher ammonia co-firing ratios (up to 80 per cent). Modifications required include ammonia injection systems, optimised nozzle designs, burner front modifications and selective catalytic reduction (SCR) units to address nitrogen oxide (NOX) emissions.
Emission characteristics: Ammonia co-firing significantly reduces CO2 emissions. However, it introduces challenges with NOX emissions. Advanced SCR systems or staged combustion are necessary to mitigate NOX. Life cycle analysis indicates that green ammonia produces the lowest GHG emissions (1,062 kg CO2e per MWh) compared to blue and grey ammonia.
Energy efficiency: Co-firing reduces boiler efficiency by only about 1 per cent compared to baseline coal plants, whereas CCS integration reduces it by approximately 8 per cent due to the energy-intensive CO2 capture process.
Infrastructure requirements: Existing coal-fired plants require modifications to store, transport and inject ammonia. Storage systems for ammonia must maintain temperature at -33 °C at ambient pressure to ensure safety and efficiency.
NOX emission control: Experiments show that using staged combustion and SCR systems can reduce NOX levels to permissible limits, even with high ammonia co-firing ratios. Further research on optimal injection techniques and SCR designs can ensure compliance with emission regulations.
Scalability and integration: Globally, ammonia infrastructure exists primarily for fertilisers, requiring adaptation for energy applications. Integration into existing plants is faster and less complex than deploying CCS, providing an advantage for near-term decarbonisation.
Technical challenges for co-firing ammonia in existing coal-based TPPs
Ammonia slip and toxicity: Unburned ammonia (ammonia slip) can cause safety and environmental concerns. Improved combustion techniques and SCR systems can address these issues.
Storage and transportation: Safe storage and handling are crucial due to ammonia’s toxicity and flammability. Expanding the infrastructure for large-scale ammonia use in power plants requires significant investment.
Cost of green ammonia: The current production cost of green ammonia is high ($666 per tonne) primarily driven by the cost of renewable electricity. Scaling production and reducing renewable energy costs are essential to enhance feasibility.
The technical feasibility of green ammonia for co-firing in TPPs is well supported by existing research and pilot projects. It offers a promising pathway for decarbonisation when paired with appropriate emission control measures and cost reduction strategies. While challenges related to NOX emissions, storage and production costs remain, ongoing advancements in ammonia combustion technologies and green ammonia production hold the potential to make it a viable and scalable solution for decarbonising the energy sector.
Proposed pilot project: Team Green Fusion
We propose a pilot project to implement green ammonia co-firing as a sustainable energy solution, leveraging advanced technologies to drive decarbonisation. Renewable energy sources, such as solar and wind, will power an electrolyser to produce green hydrogen, while an air separation unit will extract nitrogen from the atmosphere. These will combine to synthesise green ammonia in an eco-friendly ammonia synthesis unit.
The green ammonia will be stored and used for co-firing in boilers, replacing conventional fuels. This approach will reduce GHG emissions and help integrate renewable energy into existing infrastructure. The project aims to validate the feasibility, cost-effectiveness and environmental benefits of green ammonia co-firing, positioning it as a scalable solution for sustainable energy.
Project planning
The project spans 125 acres and features:
- A green hydrogen plant (350 TPD) – 30-35 acres.
- An ammonia synthesis unit (1,900 TPD) – 50-60 acres.
- An air separation unit – 10-15 acres.
- Switchyards, substations (10-15 acres) and a green belt (30 acres).
- Industrial support area (20 acres).
Phased implementation
The green ammonia production unit will be implemented in a phased approach:
Phase I: Preparatory activities (tendering, engineering, initial civil works).
Phase II: Scale-up of production to 150 TPD green hydrogen and 850 TPD green ammonia, and infrastructure enhancements (central business district, water systems, burner modifications, electrical switchyard).
Phase III: Completion of remaining civil works (water treatment systems and infrastructure).
Funding sources include equity, government subsidies, debt, carbon tax savings, carbon credits and ESG improvements. This structured approach ensures
gradual scale-up with financial and operational feasibility.
The proposed green ammonia production project across three phases is expected to cost Rs 124.0336 billion. The major expenditures include land acquisition, infrastructure development (roads, drainage, industrial sheds), power infrastructure and pre-operative expenses.
The phased approach ensures a structured allocation of resources for sustainable implementation.
The pilot project’s capital expenditure includes the cost of electrolysers, air separation units, and ammonia synthesis and storage facilities. The phased investment plan ensures gradual scalability. Key financial insights include:
- Green ammonia costs are expected to decrease from Rs 85 per kg in 2024 to Rs 70 per kg by 2035.
- Savings from reduced coal consumption and carbon taxes will offset initial investments.
- Revenue streams include carbon credits and improved ESG scores.
Key challenges in project implementation include high initial costs, infrastructure readiness and market acceptance.
Government incentives, subsidies and policy support are also crucial for economic viability.
Team Green Fusion’s business model: Analysis of operational and financial parameters
Our team has developed a business model to assess the impact of various operational and financial parameters for setting up a green ammonia generation unit and its subsequent co-firing in boilers.
Based on co-firing percentage input, the model has the capability to calculate the levellised cost of green ammonia, capex required for the project, carbon tax savings, capex distribution over project life, cost of electrolysers, variable cost of the co-fired plant, etc. Snapshots of our model are as below:
Capital cost: The capex breakdown for setting up a green ammonia plant includes major cost components such as hydrogen (48 per cent), nitrogen and ammonia (24 per cent), which collectively account for over 70 per cent of the total expenditure. This implies that over the next decade or so, a reduction in the cost of electrolysers through technological maturity and shift in supply demand curves is essential to make green ammonia production and co-firing more economical.
Change in variable cost vis-à-vis co-firing ratio: As the co-firing ratio increases, the change in the variable cost coal-fired units increases. While this is an obvious result, a point can be chosen for pilot project to balance the financial impact at current prices.
Reduction in the cost of electrolysers
Over the next few decades, as the cost of green ammonia production decreases, mainly due to a reduction in the cost of electrolysers, technological penetration, shifting supply demand economics and scalable projects, the variable cost of co-fired units is expected to decline as well.
Carbon tax savings
With the increase in co-firing ratio, savings on account of carbon tax also reduce. With 20 per cent co-firing, savings exceed Rs 5 million per day.
Conclusion and future outlook
Green ammonia co-firing represents a critical step in India’s energy transition journey. While challenges persist, the long-term benefits of reduced emissions, economic savings and alignment with national goals outweigh the hurdles. By leveraging technological innovations and strategic partnerships, TPPs can integrate green ammonia into India’s power sector. Future research should focus on scaling up technology, enhancing cost efficiency and ensuring stakeholder engagement.
