René Bañares-Alcántara

Green hydrogen and ammonia are forecast to play key roles in the deep decarbonization of the global economy. Here we explore the potential of using green hydrogen and ammonia to couple the energy, agriculture, and industrial sectors with India’s national-scale electricity grid. India is an ideal test case as it currently has one of the most ambitious hydrogen programs in the world, with projected electricity demands for hydrogen and ammonia production accounting for over 1500 TWh/yr or nearly 25% of India’s total electricity demand by 2050. We model the ambitious deep decarbonization of India’s electricity grid and half of its steel and fertilizer industries by 2050. We uncover modest risks for India from such a strategy, with many benefits and opportunities. Our analysis suggests that a renewables-based energy system coupled with ammonia off-take sectors has the potential to dramatically reduce India’s greenhouse emissions, reduce requirements for expensive long-duration energy storage or firm generating capacity, reduce the curtailment of renewable energy, provide valuable short-duration and long-duration load-shifting and system resilience to inter-annual weather variations, and replace tens of billions of USD in ammonia and fuel imports each year. All this while potentially powering new multi-billion USD green steel and maritime fuel export industries. The key risk for India in relation to such a strategy lies in the potential for higher costs and reduced benefits if the rest of the world does not match their ambitious investment in renewables, electrolyzers, and clean storage technologies. We show that such a pessimistic outcome could result in the costs of green hydrogen and ammonia staying high for India through 2050, although still within the range of their gray counterparts. If on the other hand, renewable and storage costs continue to decline further with continued global deployment, all the above benefits could be achieved with a reduced levelized cost of hydrogen and ammonia (10–25%), potentially with a modest reduction in total energy system costs (5%). Such an outcome would have profound global implications given India’s central role in the future global energy economy, establishing India’s global leadership in green shipping fuel, agriculture, and steel, while creating an affordable, sustainable, and secure domestic energy supply.

Ammonia and hydrogen production are currently dominated by fossil fuels, which is carbon emissions-intensive. Production of ammonia and hydrogen is also possible with renewable energy, generating no direct carbon emissions. Tidal stream energy is a predictable renewable energy source, and utilising the difference in phase of tidal stream currents in close-by locations can provide a more stable power profile. This stable power profile could be useful as ammonia production has limited flexibility, and although hydrogen production is more flexible, hydrogen storage is particularly expensive. This paper explores the effect of tidal stream phasing on both green ammonia and green hydrogen production in the English Channel for the first time. The coefficient of variation (CV) of the power profiles between pairs of locations is used as a metric of tidal phasing, and the minimum is determined from locations in the English Channel appropriate for an Orbital O2 turbine with a similar energy. This minimum CV method is novel and can be applied to other tidal regions. For 66 MW of Orbital O2 turbines with an average capacity factor 20.5%, utilising phasing reduces the levelized cost of ammonia by 5% and the levelized cost of hydrogen by 4%.

There is growing recognition of the need for long-duration energy storage to cope with low frequency (i.e. seasonal to multi-annual) variability in renewable energy supplies. Recent analysis for the UK has estimated that 60–100 TWh of hydrogen storage could be required to provide zero-carbon backup for renewable energy supplies in 2050. However, the analysis did not consider the potential role of green energy imports as a supplement to domestic energy storage. Using a global spatially-explicit model of green hydrogen/ammonia production and shipping we estimate the lowest import costs for green ammonia to the UK, and compare them with the levelized costs of energy storage across scenarios of varying domestic renewable energy production. The results indicate that imported green ammonia could offer a cost-comparable alternative to domestic hydrogen production, storage and power generation, whilst increasing energy system resilience through supply diversification, at a similar or cheaper delivered energy cost compared to a hydrogen-only storage system. In countries lacking the geological potential for low-cost hydrogen storage, green ammonia imports could have an even more significant role.

The 15 short chapters that form this 2023 ammonia-for-energy roadmap provide a comprehensive assessment of the current worldwide ammonia landscape and the future opportunities and associated challenges facing the use of ammonia, not only in the part that it can play in terms of the future displacement of fossil-fuel reserves towards massive, long-term, carbon-free energy storage and heat and power provision, but also in its broader holistic impacts that touch all three components of the future global food-water-energy nexus.

Inability to predict the weather, and to rapidly adjust the operating rate of Haber–Bosch synthesis, are major challenges for green ammonia production. This article assesses and provides methods for managing both challenges.