Theses

The motivation for this project is to support the urgent global climate challenge of preventing a global mean surface temperature (GMST) increase of more than 1.5 °C compared to the preindustrial average (1850–1900). As a carbon-free energy carrier at the point of use, hydrogen (H2) is a promising fuel to decarbonise road freight, shipping, and aviation. However, about 95 % of H2 is currently produced from fossil fuels, which results in significant carbon emissions even when carbon capture is implemented. Previous life cycle assessments (LCAs) of H2 have limited their scope to a subset of production technologies and/or environmental impacts (often global warming potential and acidification potential only). This project aims to fill this gap by producing an LCA of promising H2 supply pathways from raw materials to refilling stations with broad coverage of environmental areas, and scenarios that account for variations in grid electricity mix and the latest and projected technological developments in the H2 field.

Scenarios were developed using information from governmental, industrial, and scientific literature, supplemented by expert elicitation interviews. Sensitivity analysis explored ranges of technological improvements by the years 2035 and 2050. The results show that when the impacts of fuel consumption are included, H2 would have 2.8 to 4.8 times lower global warming potential than conventional fossil-based fuels. However, supplying large quantities of H2 to large transport vehicles would contribute significantly to freshwater ecotoxicity and ozone formation. Sensitivity analysis shows that the following would significantly lower the environmental impacts of H2 supply: 1) electricity powered mostly by renewable energy sources, with minimal use of fossil fuels; 2) a well-developed H2 pipeline infrastructure; 3) a high CO2 capture rate where H2 is produced from methane or bio-methane; 4) minimising the carbon footprint of producing steel, concrete, and solar panels; 5) reducing the environmental impacts of mining for minerals, especially copper and nickel; 6) increasing the circularity of critical materials; and 7) reducing the environmental impacts of processing wastes.

Recommendations are made for future studies, whose findings will be significantly strengthened if issues of commercial sensitivity can be overcome and more primary data can be sourced regarding the manufacture and performance of H2 production plants and critical components of their supply chains.