The successful transition to global clean energy is contingent upon meeting the increasing worldwide energy demand for power while simultaneously curbing greenhouse gas emissions. This study delves into the complexities of transitioning to cleaner energy sources and the challenges posed by utilizing hydrogen and hydrogen/natural gas mixtures as a potential fuel source alternative to traditional carbon-based combustion cycles. By addressing the technical intricacies and conducting thorough testing, researchers aim to enhance our understanding of auto-ignition behavior in different fuel-air mixtures under varying conditions, ultimately contributing to the development of safer and more efficient energy solutions in the pursuit of clean and sustainable power generation. This study outlines the test methodology employed to assess conditions leading to auto-ignition for various fuel-air mixtures operating at different pressures (1 - 30 atm) and temperatures. The testing encompassed 100% H2 and multiple H2/NG blends at stoichiometric conditions. Similar testing was conducted for 100% NG to validate the test procedures and data collection methods referenced in previous literature. Under atmospheric conditions, 0-1 ATM, H2 exhibits a broader flammability range of EQs where ignition is more likely to occur compared to methane. H2's flammability ranges from 4% to 75% molar (volume) fuel concentration, corresponding to an EQ range of 0.137 - 2.57, while methane's flammability limit spans from 5% to 15% molar (volume) or an EQ between 0.53 – 1.58. Previous studies have explored the effect of longer hydrocarbons present in natural gas mixtures, with ethane (C2H6) and propane (C3H8) shown to decrease the ignition temperature (AIT) of natural gas, particularly at elevated pressures. These longer hydrocarbons are inclined to promote ignition in richer conditions, whereas methane tends to ignite more readily in slightly lean conditions. Besides pressure, fuel, and EQ, numerous variables such as chamber volume size, chamber materials, presence of diluents, and other factors can influence the AIT. The results revealed that, at atmospheric pressures, an increase in H2 concentration led to a reduced AIT. However, at 30 atm, a higher presence of H2 increased the AIT. At pressures exceeding 10 atm, an increased equivalence ratio resulted in a decreased AIT for all mixtures, with NG, exhibiting the greatest sensitivity to equivalence ratio variations.

A successful transition to clean energy hinges on meeting the world's growing energy demand while reducing greenhouse gas emissions. Achieving this will require significant growth in electricity generation from clean and carbon-free energy sources. Several energy providers have already begun the transition from traditional carbon-based fuels to cleaner alternatives, such as hydrogen and hydrogen enriched natural gas. However, there are still many technical challenges that must be addressed when applying these fuels in gas turbines. The application of hydrogen or hydrogen/natural gas blends to advanced class gas turbines, which have higher operating pressures and temperatures has raised concerns about the potential for leakages or fuel sequencing operations where flammable mixtures of fuel and air could auto-ignite. Public information on the auto-ignition of hydrogen in air at atmospheric pressure is well documented. Such data shows the auto-ignition temperature of hydrogen is roughly 100 °C lower than that of methane. Studies also show that as pressure increases, methane's auto-ignition temperature decreases. However, there was insufficient information in the published literature to characterize the influence of pressure on auto-ignition for hydrogen fuel applications. This study describes the test methodology used to evaluate conditions where auto-ignition occurs for various fuel-air mixtures operating at pressures between 1-30 atmospheres and equivalence ratios between 0.2-1.6. Testing was completed with hydrogen, natural gas and blends at various equivalence ratios using a heated volume with multiple reactant delivery methods. Testing was performed for natural gas to validate the test and data collection methods cited in prior published literature. Results indicate that at atmospheric pressures, an increase in hydrogen concentration results in a reduced auto-ignition temperature. However, at 30 atmospheres, the auto-ignition temperature increased with higher hydrogen concentrations. iv Variations of auto-ignition delay times were also observed during the testing and are compared to modeling predictions, providing insight into auto-ignition characteristics.

Energy storage technology is needed for the storage of surplus baseload generation and the storage of intermittent wind power, because it can increase the flexibility of power grid operations. Underground storage of hydrogen with natural gas (UHNG) is proposed as a new energy storage technology, to be considered for utility-scale energy storage applications. UHNG is a composite technology: using electrolyzers to convert electrical energy to chemical energy in the form of hydrogen. The latter is then injected along with natural gas into existing gas distribution and storage facilities. The energy stored as hydrogen is recovered as needed; as hydrogen for industrial and transportation applications, as electricity to serve power demand, or as hydrogen-enriched natural gas to serve gas demand. The storage of electrical energy in gaseous form is also termed “Power to Gas”. Such large scale electrical energy storage is desirable to baseload generators operators, renewable energy-based generator operators, independent system operators, and natural gas distribution utilities. Due to the low density of hydrogen, the hydrogen-natural gas mixture thus formed has lower volumetric energy content than conventional natural gas. But, compared to the combustion of conventional natural gas, to provide the same amount of energy, the hydrogen-enriched mixture emits less carbon dioxide. This thesis investigates the dynamic behaviour, financial and environmental performance of UHNG through scenario-based simulation. A proposed energy hub embodying the UHNG principle, located in Southwestern Ontario, is modeled in the MATLAB/Simulink environment. Then, the performance of UHNG for four different scenarios are assessed: injection of hydrogen for long term energy storage, surplus baseload generation load shifting, wind power integration and supplying large hydrogen demand. For each scenario, the configuration of the energy hub, its scale of operation and operating strategy are selected to match the application involved. All four scenarios are compared to the base case scenario, which simulates the operations of a conventional underground gas storage facility. For all scenarios in which hydrogen production and storage is not prioritized, the concentration of hydrogen in the storage reservoir is shown to remain lower than 7% for the first three years of operation. The simulation results also suggest that, of the five scenarios, hydrogen injection followed by recovery of hydrogen-enriched natural gas is the most likely energy recovery pathway in the near future. For this particular scenario, it was also found that it is not profitable to sell the hydrogen-enriched natural gas at the same price as regular natural gas. For the range of scenarios evaluated, a list of benchmark parameters has been established for the UHNG technology. With a roundtrip efficiency of 39%, rated capacity ranging from 25,000 MWh to 582,000 MWh and rated power from 1 to 100 MW, UHNG is an energy storage technology suitable for large storage capacity, low to medium power rating storage applications.

Energy storage technology is needed for the storage of surplus baseload generation and the storage of intermittent wind power, because it can increase the flexibility of power grid operations. Underground storage of hydrogen with natural gas (UHNG) is proposed as a new energy storage technology, to be considered for utility-scale energy storage applications. UHNG is a composite technology: using electrolyzers to convert electrical energy to chemical energy in the form of hydrogen. The latter is then injected along with natural gas into existing gas distribution and storage facilities. The energy stored as hydrogen is recovered as needed; as hydrogen for industrial and transportation applications, as electricity to serve power demand, or as hydrogen-enriched natural gas to serve gas demand. The storage of electrical energy in gaseous form is also termed “Power to Gas”. Such large scale electrical energy storage is desirable to baseload generators operators, renewable energy-based generator operators, independent system operators, and natural gas distribution utilities. Due to the low density of hydrogen, the hydrogen-natural gas mixture thus formed has lower volumetric energy content than conventional natural gas. But, compared to the combustion of conventional natural gas, to provide the same amount of energy, the hydrogen-enriched mixture emits less carbon dioxide. This thesis investigates the dynamic behaviour, financial and environmental performance of UHNG through scenario-based simulation. A proposed energy hub embodying the UHNG principle, located in Southwestern Ontario, is modeled in the MATLAB/Simulink environment. Then, the performance of UHNG for four different scenarios are assessed: injection of hydrogen for long term energy storage, surplus baseload generation load shifting, wind power integration and supplying large hydrogen demand. For each scenario, the configuration of the energy hub, its scale of operation and operating strategy are selected to match the application involved. All four scenarios are compared to the base case scenario, which simulates the operations of a conventional underground gas storage facility. For all scenarios in which hydrogen production and storage is not prioritized, the concentration of hydrogen in the storage reservoir is shown to remain lower than 7% for the first three years of operation. The simulation results also suggest that, of the five scenarios, hydrogen injection followed by recovery of hydrogen-enriched natural gas is the most likely energy recovery pathway in the near future. For this particular scenario, it was also found that it is not profitable to sell the hydrogen-enriched natural gas at the same price as regular natural gas. For the range of scenarios evaluated, a list of benchmark parameters has been established for the UHNG technology. With a roundtrip efficiency of 39%, rated capacity ranging from 25,000 MWh to 582,000 MWh and rated power from 1 to 100 MW, UHNG is an energy storage technology suitable for large storage capacity, low to medium power rating storage applications.