One-tenth of the EU’s sustainable biomethane coupled with carbon capture and storage can enable net-zero ammonia production

<h2>Summary</h2> Ammonia is a vital industrial chemical, but its production is greenhouse gas (GHG) emissions intensive. Prevailing mitigation options, such as electrification of heating, carbon capture and storage (CCS), and green hydrogen, face challenges related to limited mitigation potential, switch to new infrastructure, and likely high costs. Sustainable biomethane, derived from biomass that does not compete with food production for land and can leverage existing ammonia facilities, emerges as a promising option. However, whether and how biomethane can catalyze net-zero ammonia production remains underexplored. Here, using life-cycle assessment, we show that the European Union (EU)'s ammonia production can achieve cradle-to-gate net-zero GHG emission using, on average, a blend of natural gas (56%) and biomethane (44%) combined with CCS. This strategy would require only 11.7% of the EU's sustainable biomethane potential and is at least 16% cheaper than the green hydrogen option. Moreover, cradle-to-gate negative GHG emissions can be attained by completely switching to biomethane coupled with CCS, but the natural gas-biomethane blend strategy provides a sensible starting point.