Blending low-carbon hydrogen with natural gas: Impact on energy and life cycle emissions in natural gas pipelines

Abstract

Hydrogen (H2) is considered an alternative energy carrier to reduce greenhouse gas (GHG) emissions related to power and heat generation. A quantitative analysis was conducted to estimate the energy intensity and GHG emissions associated with the transportation of NG/H2 mixture in high-pressure transmission pipeline, considering blending ratios up to 100% of low-carbon H2. The life cycle emissions were obtained by including upstream supply chain emissions, compression and transportation emissions, and end use combustion emissions of the NG/H2 blend. This study accounts for global warming potential of fugitive methane and H2 emissions associated with pipeline transportation of the blend in the life cycle analysis. A significant reduction in the overall life cycle GHG emissions can be achieved when delivering the same volume throughput but at a reduced energy flow to end users. However, to maintain the nominal energy throughput of the pipeline regardless of the H2 mole fraction, a maximum reduction of about 6% is obtained as the H2 mole fraction in the blend will be practically limited to approximately 30% H2 when the pipeline operates at capacity.