  Low-carbon hydrogen (H2) is envisioned to play a central role in
decarbonizing European hard-to-abate industries, such as refineries, ammonia,
methanol, steel, and cement. To enable its widespread use, H2 supply chain
(HSC) infrastructure is required. Mature and economically viable low-carbon H2
production pathways include steam methane reforming (SMR) of natural gas
coupled with carbon dioxide capture and storage (CCS), water-electrolysis from
renewable electricity, biomethane reforming, and biomass gasification. However,
uncertainties surrounding demand and feedstock availabilities hamper their
proliferation. Here, we investigate the impact of uncertainty in H2 demand and
biomass availability on the optimal HSC design. The HSC is modeled as a network
of H2 production and consumption sites that are interconnected with H2 and
biomass transport technologies. A CCS supply chain is modeled alongside the
HSC. The cost-optimal HSC design is determined based on a linear optimization
problem that considers a regional resolution and a multi-year time horizon
(2022-2050). We adopt a scenario-based uncertainty quantification approach and
define discrete H2 demand and biomass availability scenarios. Applying a
minimum-regret strategy, we show that sufficiently large low-carbon H2
production capacities (about 9.6 Mt/a by 2030) are essential to flexibly scale
up HSCs and accommodate H2 demands of up to 35 Mt/a by 2050. While
biomass-based H2 production emerges as the most cost-efficient low-carbon H2
production pathway, investments are not recommended unless the availability of
biomass feedstocks is guaranteed. Instead, investments in SMR-CCS and
electrolysis often offer greater flexibility. In addition, we highlight the
importance of CCS infrastructure, which is required across scenarios.
