(339d) Ammonia As an Alternative Energy Carrier for Electricity Generation in India

The advantages of higher hydrogen density, easier liquification, and capable of co-combust with coal makes ammonia an attractive energy storage and carrier chemical for power generation domestically and overseas. India’s coal contributes to 81% of electricity generation as of 2021. In this work, two decarbonization method are been compared economically and environmentally. One is the ammonia co-firing with coal, the other is using carbon capture and storage (CCS). Ammonia is supposed to be produced from Australia and then transported to India to co-firing with coal in power plants. One blue and one green ammonia production pathways are been considered. Aspen Plus models were built for the power plants for mass and energy balance. The cost analysis was based on greenfield plants. The results show that the levelized cost of electricity and greenhouse gas emissions of 20% blue ammonia co-firing with coal was estimated to be $90.5/MWh and 1191 kg CO₂ e/MWh, respectively. While the green ammonia co-firing with coal was estimated to be $150/MWh and 1597 kgCO₂e/MWh, respectively. Green ammonia is more expensive and emits more CO₂ mainly because the grid electricity price and carbon intensity are high. When using wind power, where electricity price drop to $40/MWh, the blue ammonia co-firing case would results in $88.6/MWh and 1079 kg CO₂e/MWh; while the green ammonia co-firing case would results in $124.6/MWh and 1062 kg CO₂e/MWh. Coal-firing with 20% carbon capture would results in $68/MWh and 1226.6 kgCO₂e/MWh. In general, if technology and location available, CCS is less expensive than ammonia co-firing for decarbonization. However, if we also consider the geological availability of CO₂ storage, government regulations, social acceptance of CO₂ storage, there are additional constraint for the CCS decarbonization method. In addition, the technology readiness level of CCS in India is relatively low compared to the U.S. or European countries, and there is high energy penalty, the net plant efficiency would drop by about 8% for the CCS case, while ammonia co-firing case only has slight efficiency drop (~1%). Another advantage is that the ammonia co-firing case requires relatively less modification for the plant, and it could reduce the direct emission. No additional construction is needed for downstream CO₂ transportation and storage. As an chemical energy storage carrier, ammonia could further help provide a sustain electricity grid.