Deployment of hydrogen in hard-to-abate transport sectors under limited carbon dioxide removal (CDR): Implications on global energy-land-water system

The decarbonization of hard-to-abate transport sectors presents a significant barrier to climate mitigation necessitating the deployment of hydrogen and carbon dioxide removal (CDR) methods. Existing studies are yet to look at the combined implications of these two carbon mitigation solutions on global climate-energy-land-water system. Using an integrated assessment model, several hydrogen transition scenarios for hard-to-abate transport sectors have been developed in the current study against a pathway with just fossil and biofuels. All pathways have been modelled to achieve below 1.5 and 2 & DEG;C global mean temperature by 2100. Results show that the transition of hard-to-abate transport sectors to hydrogen would lead to reduction in emissions from the transport sector but resulting emissions from other sectors such as buildings, industry, and power would increase compared to a pathway with just fossil and biofuels. Considering the amount of energy required to transition the hard-toabate transport sectors to hydrogen, the transition would cause an increase in land use for cultivating energy crops while reducing land allocated for food crops and pastures. Water and fertilizer demand for hydrogen production and energy crop cultivation is another issue to expect from the transition. Transitioning the hard-toabate transport sectors to hydrogen under limited reliance on CDRs (1.8-2 GtCO2yr  1 until mid-century) could lead to a reduction in primary energy consumption, CO2 emissions, CDR deployment, land expansion for bioenergy crops, water (for bioenergy crops, CDR, and hydrogen production), and fertilizer consumption by 3%, 13%, 14%, 22%, 23%, and 2%, respectively compared to a transition under an unlimited availability of CDRs.