Computational fluid dynamic modeling of methane-hydrogen mixture transportation in pipelines: estimating energy costs

Replacing fossil fuels and natural gas with alternative fuels like hydrogen is an important step toward the goal of reaching a carbon neutral economy. As an important intermediate step toward utilizing pure hydrogen, blending hydrogen in an existing natural gas network is a potential choice for reducing carbon emissions. A computational fluid dynamic model is developed to quantify frictional losses and energy efficiency of transport of methane-hydrogen blends across straight pipe sections. It is observed that, in general, an increase in the energy costs is expected when hydrogen, with its lower density, is transported along with methane (which has higher density) in various blend ratios. However, the amount of increase in energy costs depends on the volume fraction of hydrogen and the nature of the flow conditions. The lowest energy costs are projected for transporting pure hydrogen under the conditions where the inlet velocity flow rates are similar to that used for transporting pure methane while the highest energy costs are expected when hydrogen is transported at the same mass flow rate as methane.