Comparative life cycle greenhouse gas emission and cost assessment of hydrogen fuel and power for Singapore

• Life cycle GHGs and costs of domestic vs. imported H 2 for heat/power in Singapore. • Local and Malaysia-produced turquoise H 2 has lowest costs if carbon product is sold. • Wind-powered H 2 transported as liquid H 2 or ammonia has lowest GHGs and high costs. • NG combustion with CCS offers the best balance of low emissions and cost-efficiency. • Projected impacts of carbon tax, CH 4 abatement, & renewable improvements by 2030. To identify lower-carbon and cost-effective hydrogen supplies for fuel and power generation in Singapore, we assessed the cradle-to-gate greenhouse gas (GHG) emissions and the landed costs of over fifty supply chains from Malaysia and Australia with current and emerging blue, turquoise, and green hydrogen production and carrier technologies. We found that with current technologies the total life cycle global warming potential of local H 2 production using steam methane reforming with carbon capture (4.47 kg CO 2 e/kg H 2 ) is lower than importing solar-generated green H 2 from Australia transported as NH 3 (6.48 kg CO 2 e/kg H 2 ) due to large emissions from conversion and transportation processes in the latter supply chain. When also considering emerging technologies, turquoise H 2 produced with the thermal decomposition of methane locally or in Malaysia is the most economical solution, while wind-generated H 2 from Australia transported as liquefied H 2 or NH 3 produce the least GHG emissions. In addition, we projected the impacts of the Singapore carbon tax, methane abatement in NG production, and reduction of renewable energy embodied emissions and costs on the supply chains in the year 2030. We estimated that with the expected renewable energy improvements, the emissions and costs of power generated from imported solar-powered H 2 could drop by as much as 74 % and 70 % respectively.