Penetration of hydrogen-based energy system and its potential for causing global environmental change: Scoping risk analysis based on life cycle thinking

A hydrogen-based economy seems superficially to be environmentally friendly, and many people have worked toward its realization. Today hydrogen is mainly produced by decarbonizing fossil fuels (e.g. natural gas), and in the future decarbonization of both fossil fuels and biomass will play a leading role in the production of hydrogen. The main purpose of this paper is to suggest the identification of potential environmental risks in terms of “life cycle thinking” (which considers all aspects from production to utilization) with regard to the hydrogen-based economy to come.Hydrogen production by decarbonization results in CO2 emissions. The final destination of the recovered CO2 is uncertain. Furthermore, there is a possibility that hydrogen molecules will escape to the atmosphere, posing risks that could occasion global environmental changes such as depletion of stratospheric ozone, temperature change in the stratosphere and change of the hydrides cycle through global vaporization. Based on the results of simulation, requirements regarding the following items are proposed to minimize potential risks: hydrogen source, production and storage loss.