Comparative well-to-pump assessment of fueling pathways for zero-carbon transportation in China: Hydrogen economy or methanol economy?

Abstract

Decarbonization of the fuel sector is crucial to achieving a zero-carbon economy. Both hydrogen and methanol are promising solutions to contribute to this goal. Herein, a comprehensive well-to-pump (WTP) energetic, environmental and economic (3E) assessment for various methanol and hydrogen production pathways is conducted based on the GREET software and data for China. Energy efficiency, levelized cost of fuel, direct and indirect emission, as well as other midpoint environmental impact indicators are compared. The gaseous and liquid hydrogen are produced from coal gasification (CGT), coal coking (CCT), natural gas reforming, and alkaline water electrolysis by renewable and grid electricity. Methanol production pathways include CGT, CCT and CO2 hydrogenation. The results indicate that most methanol produced from CO2 hydrogenation as well as green H2 yield environmental benefits but also entail energy efficiency loss. Specifically, compared to conventional methanol, hydrogen and green hydrogen, the environmental benefits increase by up to 101%, 103% and 104%, whereas the energy efficiency drops by up to 71%, 75% and 85%, respectively. With current technology, the levelized costs of methanol production can be between 12% and 75% lower than most hydrogen production pathways. Compared to hydrogen supply chain, the levelized cost of methanol supply is primarily concentrated in the production stage (67%∼93%). In general, although hydrogen can be an important carbon emission free fuel in the long run, methanol produced from CO2 hydrogenation assisted by renewable sources is the most feasible near-term pathway in China, offering an easier to market carbon neutral fuel source.