Hydrogen-enriched LPG: Towards Decarbonisation of Domestic Fuel

Liquid Petroleum Gas (LPG) is regarded as one of the cleanest domestic fuels. However, the emission of Carbon Dioxide (CO2), a major combustion products of LPG, is becoming a great concern as it is one of the principal greenhouse gases contributing to global warming. In this study, potential of hydrogen-enriched LPG as a low carbon alternative domestic fuel has been investigated to address some of the concerns related to direct burning of LPG. Hydrogen (H2) is a zero-carbon energy source and is the subject of increasing research due to its favorable properties. However, H2 is not yet a feasible option for domestic use because of the associated risks in its storage, distribution and use. Blending H2 with LPG provides an alternative fuel that can capitalize on the favorable properties of H2 safely while reducing carbon emissions associated with direct burning of LPG.
The thermal, combustion and emission performance of hydrogen-enriched LPG were investigated experimentally by varying the H2 fraction in the blended fuel from 0% - 30% by volume. There is a gradual reduction in thermal efficiency as the H2 fraction in the blended fuel is increased. It is due to relatively low heating value of H2 by volume compared with LPG. The combustion performance of blended fuel as evaluated by estimated burning velocity has shown an improvement with the increment of H2 fraction. However, the lean-burn limit increased with higher H2 fractions. Importantly, the emissions of CO2 and CO are reduced with the increment of H2 fraction in the blended fuel.
Fuel interchangeability analysis has been performed for the blended fuel by estimating the Wobbe Index. The interchangeability analysis and experimental verifications show that the existing domestic LPG appliances can work with the LPG enriched with up to 15 – 20% hydrogen. Beyond this limit, it is difficult to maintain a stable flame without flash back. Physical changes to the design of the domestic gas appliances are necessary to use LPG enriched with high percentages of hydrogen and benefit from decarbonisation potential.