Emissions of anthropogenic hydrogen to the atmosphere during the potential transition to an increasingly H_2-intensive economy

摘要

In this study, current and future anthropogenic hydrogen (H_2) emissions to the atmosphere from technological processes are assessed. Current emissions are dominated by the direct exhaust gas of road-based motor vehicles and losses during the industrial production of H_2 from fossil-fuels. H_2 emissions from transportation are estimated at 4.5 Tg for 2010. An additional ~ 0.5-2 Tg H_2 are estimated to be lost to the atmosphere from industrial processes in 2010. In 2020, emissions from transportation are estimated at approximately 50% of those in 2010. Future emissions will occur as losses along the entire production, distribution, and end-use chain, including emissions from H_2 fuel cell vehicles (FCVs). In 2050, overall anthropogenic H_2 emissions will only approach current levels at high-end loss rates; direct emissions from transportation are expected to be significantly lower than current levels. In 2100, an average loss rate of 0.5% would result in overall H_2 emissions exceeding current levels even with no net H_2 emissions from FCVs. However, based on an average loss rate of 0.1%, H_2 emission factors from FCVs on the order to 120-170 mg km~(-1) are projected to result in overall anthropogenic H_2 emissions similar to 2010 levels.