Implementation of Power-to-Gas to Reduce Carbon Intensity and Increase Renewable Content in Liquid Petroleum Fuels
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Power-to-gas (PtG) is an emerging energy storage concept, which can transfer the surplus and intermittent renewable generated power into a marketable hydrogen, as well as providing other ancillary services for the electrical grid. In the case of Ontario, excess power is encountered during periods of low electricity demand as a result of substantial generation from baseload nuclear and increasing integration of intermittent renewable sources powering the electrical grid. This thesis develops various simulation and analysis of Ontario’s energy system to illustrate the use of PtG when its electrolytic hydrogen is employed in the gasoline production cycle to reduce the carbon intensity of the production process, and increase the renewable content of this traditional transportation fuel. The work includes a case study for a simulated refinery to evaluate the production cost and life cycle emission for different production scenarios, related to the deployment of polymer electrolyte membrane (PEM) electrolyzers to meet the refinery demand of hydrogen. Moreover, the study involves examining the use of the province surplus baseload generation (SBG) for which currently results in net exports to neighboring jurisdictions, and curtailed power generation capacity from wind and nuclear to meet the overall demand of the refining industry. Furthermore, a comparative assessment is conducted of blending 10% corn-ethanol and using electrolytic hydrogen supply via PtG on the ‘well to wheel’ (WTW) impacts of gasoline fuel, according to the metrics of total energy use, greenhouse gas emissions, and criteria air pollutants. According to the study, it is found that steam methane reforming (SMR) provides a lower cost hydrogen as a result of the current low natural gas prices, even with stringent carbon-pricing policy. However, the electrolytic hydrogen production shows a potential to curb significant carbon emissions as a substitute for SMR hydrogen. At a single refinery level, the use of electrolytic hydrogen can be compared to eliminating as many as 35,000 gasoline passenger vehicles from the road when there is an installation of 130 PEM electrolyzer units (1 MW nameplate capacity per unit). Also, the analysis shows that PtG has the potential to supply the refineries within the province with the entire hydrogen demand with a fraction of the surplus power, particularly when making use of available seasonal storage at least for the next four years. Moreover, PtG is found to decrease 4.6% of the natural gas consumption on the gasoline cycle, and increase the renewable content of gasoline by extending the utilization of wind and hydro power. Furthermore, the deployment of electrolytic hydrogen results in minimizing gasoline carbon intensity by 0.5 gCO2e per MJ of the fuel. When associated with the annual gasoline sales in Ontario, it can offer the reduction of 0.26 Megaton of greenhouse gas (GHG) emissions yearly. Moreover, PtG may contribute to lowering VOCs, NOx, PM10 and PM2.5 criteria air pollutants from gasoline cycle, which cannot be achieved with blending corn based ethanol. Accordingly, the results of this thesis outline the benefits of using power-to-gas to mitigate the existing issue of surplus power generation. Utilizing the excess electricity to produce hydrogen for refinery end user also increases the utilization of CO2 free energy and renewable content of gasoline within its life cycle production scheme.
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Abdullah Alsubaie (2017). Implementation of Power-to-Gas to Reduce Carbon Intensity and Increase Renewable Content in Liquid Petroleum Fuels. UWSpace. http://hdl.handle.net/10012/12242