Life cycle assessment of the power-to-gas process in the context of Quebec

Abstract

Storing electricity from renewable energy sources for long term is a power-to-gas (PtG) concept. This electricity then produces fuels for industry, transportation, and household. However, this technology has different system variations with various environmental performances that should be investigated and compared to the conventional technologies before industrialization. Hydropower, as a low-carbon electricity source, is the highest contributor to Quebec electricity (about 94%), making the life cycle assessment of power to gas valuable to be investigated. In this study, life cycle assessment of PtG in Quebec was conducted as a baseline scenario and compared with the natural gas. Then, the sensitivity analyses were carried based on different electricity sources from different provinces in Canada (Alberta and Quebec). For the baseline scenario, CO2 was assumed to captured from the cement plant gas emission. Human health and ecosystem quality for the baseline scenario were acquired to be 4.89E-06 (DALY) and 0.77 (PDF.m2.yr), respectively. Also, greenhouse gas emission for the baseline scenario was equal to 0.04 (kg CO2 eq). Impact categories in all damage levels were significantly higher for natural gas compared to producing methane from PtG (synthetic natural gas-SNG). 5.13 (kg CO2 eq) was obtained for the climate change impact for natural gas. The fossil fuel base of Alberta’s electricity is responsible for the %60 of impacts on the climate change in natural gas. Sensitivity analysis were implemented based on different sources of electricity for producing SNG. It was concluded that if Alberta electricity is used in the system, more environmental impacts can be seen. The outcome of this study showed that the climate change impact for Alberta scenario is five times higher than the climate change for the Quebec scenario. CO2 unit was calculated to demonstrate higher contributions to the impacts on the environment, whereas these impacts can be mitigated by employing more clean electricity in this unit process. Outcomes showed that methanation with Quebec electricity source leads to larger environmental benefits compared to the conventional natural gas and other sources of electricity.

Date	24 Feb 2023
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Annie Levasseur (Supervisor)