Climate change performance of hydrogen production based on life cycle assessment

Hydrogen has the potential to revolutionize how we power our lives, from transportation to energy production. This study aims to compare the climate change impacts and the main factors affecting them for different categories of hydrogen production, including grey hydrogen (SMR), blue hydrogen (SMR-CCS), turquoise hydrogen (TDM), and green hydrogen (PEM electrolysis). Grey hydrogen, blue hydrogen, and turquoise hydrogen, which are derived from fossil sources, are produced using natural gas and green hydrogen is produced from water and renewable electricity sources. When considering natural gas as a feedstock, it is sourced from the pipeline route connected to Russia and through the liquefied natural gas (LNG) route from the USA. The life cycle assessment (LCA) result showed that grey hydrogen had the highest emissions, with the LNG route showing higher emissions, 13.9 kg CO2 eq. per kg H2, compared to the pipeline route, 12.3 kg CO2 eq. per kg H2. Blue hydrogen had lower emissions due to the implementation of carbon capture technology (7.6 kg CO2 eq. per kg H2 for the pipeline route and 9.3 kg CO2 eq. per kg H2 for the LNG route), while turquoise hydrogen had the lowest emissions (6.1 kg CO2 eq. per kg H2 for the pipeline route and 8.3 kg CO2 eq. per kg H2 for the LNG route). The climate change impact showed a 12-25% increase for GWP20 compared to GWP100 for grey, blue, and turquoise hydrogen. The production of green hydrogen using wind energy resulted in the lowest emissions (0.6 kg CO2 eq. per kg H2), while solar energy resulted in higher emissions (2.5 kg CO2 eq. per kg H2). This article emphasizes the need to consider upstream emissions associated with natural gas and LNG extraction, compression, liquefaction, transmission, and regasification in assessing the sustainability of blue and turquoise hydrogen compared to green hydrogen. Green H2 production reduces emissions by 80-95% compared to grey H2 thus meeting the REDII directive. However, blue and turquoise H2 fall short of meeting this criterion without CO2 sequestration.