Towards importing renewable hydrogen within planetary boundaries

Abstract

In pursuit of reducing greenhouse gas emissions, the European Union plans to annually import ten million tonnes of renewable hydrogen. While the economic viability of hydrogen importation is established, environmental assessments are limited to comparisons and lack an evaluation of absolute sustainability. Therefore, we conducted a multi-objective optimization and absolute sustainability assessment with respect to planetary boundaries under current conditions and future scenarios, considering hydrogen, ammonia, and methane as energy carriers. Under current conditions, absolute sustainability is achievable under utilitarian sharing principles, utilizing hydrogen or ammonia as energy carrier, and relying on wind energy and storage at the source location. Looking ahead, cost-effective import pathways, powered by wind and solar energy, can achieve absolute sustainability from 2030 onward, when the world follows an optimistic sustainability pathway with ambitious climate mitigation targets. To attain absolute sustainability in other scenarios, improved practices and new materials in photovoltaic array design should be prioritized.