Evaluating Environmental Impacts of Hydrogen Applications using hourly consumption-based LCA Emission Factors

Abstract:

Global climate change is heavily influenced by greenhouse gas (GHG) emissions released into the atmosphere. Emission accounting is used to determine the amount of GHG emissions emitted into the atmosphere. Emission accounting is required to be as accurate as possible. Climate change mitigation strategies are based on the quantified amount of GHG emissions. Strategies based on erroneous information have the potential to cause detrimental effects.

The goal of the thesis is to evaluate the environmental impact of hydrogen (H2) produced from electrolysis. A methodology is developed to determine hourly emission factors (EMF) of energy carriers (EC) occurring within energy systems. Emissions are accounted to the region of EC consumption to consider emissions arising along the holistic production process of consumed ECs. Flow tracing methodologies are implemented to allocate emission occurring from EC production to EC consumption. Life Cycle assessment (LCA) methodologies are applied to integrate upstream emissions from EC production processes. The environmental impact evaluation of H2 produced from electrolysis is based on the calculated hourly consumption based LCA-EMFs. H2 is defined as green according to international regulatory framework. Frameworks differ in methodologies applied to determine H2’s carbon footprint, as well as different threshold values for the definition of green H2. Differences between regulatory frameworks are evaluated.

Hourly consumption based LCA-EMFs have been calculated and evaluated. The amount of H2 produced from electrolysis defined as green has been evaluated. Differences between regulatory frameworks have been evaluated. A loophole in the definition of green H2 has been detected and examined. Equivalent H2 may simultaneously be defined as green and not as green, depending on the methodology used to calculate H2’s carbon footprint.