Blending green hydrogen from renewable sources into the natural gas infrastructure can effectively reduce the carbon emissions of energy consumers. However, distributed hydrogen blending could lead to heterogeneous gas compositions across the network. The traditional nodal energy price scheme is designed for uniform gas composition, which cannot reflect the hydrogen blending effects in terms of heterogeneous nodal gas composition and carbon emission reductions. This chapter proposes a novel nodal energy price scheme in the carbon emission-embedded hydrogen-blended integrated electricity and gas systems (H-IEGS), considering heterogeneous gas compositions. First, we propose a joint market-clearing model for H-IEGS, where the nonlinear physical properties of gas mixtures caused by varying gas compositions are characterised. The impacts of hydrogen blending on the carbon emission cost are also quantified. To retrieve the nodal energy price from this highly nonlinear and nonconvex optimisation problem, a successive second-order cone programming (SSOCP) method is tailored to get the dual variables tractably. Considering the continuous market-clearing process, a warm-start technique is proposed to provide initial reference points for the SSOCP to improve the computation efficiency. Finally, an H-IEGS test case and a large-scale practical case in Northwest China are used to validate the effectiveness of the proposed method [20].