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Hydrogen-enriched natural gas as a domestic fuel: An analysis based on flash-back and blow-off limits for domestic natural gas appliances within the UK / Daniel Raymond Jones; Waheed Al-Masry; Charles W Dunnill
Sustainable Energy & Fuels
Swansea University Author: Dunnill, Charlie
Accepted Manuscript under embargo until: 5th February 2019
In the effort to reduce carbon emissions from an ever-increasing global population, it has become increasingly vital to monitor and counteract the environmental impact of our domestic energy usage given its contribution to overall carbon emissions. To this end, hydrogen has emerged as a foremost can...
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In the effort to reduce carbon emissions from an ever-increasing global population, it has become increasingly vital to monitor and counteract the environmental impact of our domestic energy usage given its contribution to overall carbon emissions. To this end, hydrogen has emerged as a foremost candidate to offset and eventually replace the use of traditional gaseous fossil fuels. Hydrogen as the universal energy carrier or vector is easily produced from all forms of renewable or recovered energy as a storable, transportable commodity that can be used on demand, thus decoupling the supply from demand that is often considered to be the down-side of intermittent renewable energy usage. European trials have already been conducted to investigate the practical implementation of hydrogen-enriched natural gas (HENG) within a mains gas supply. In this work, the limitations of such a strategy are evaluated based on a novel meta-analysis of experimental studies within the literature, with a focus on the constraints imposed by the phenomena of flash-back and blow-off. Through consideration of the Wobbe Index, we discuss the relationship between molar hydrogen percentage and annual carbon dioxide output, as well as the predicted effect of hydrogen-enrichment on fuel costs. It is further shown that in addition to suppressing both blow-off and yellow-tipping, hydrogen-enrichment of natural gas does not significantly increase the risk of flash-back on ignition for realistic burner setups, while flash-back at extinction is avoided for circular port diameters of less than 3.5 mm unless the proportion of hydrogen exceeds 34.7 mol%. It is thus proposed that up to 30 mol% of the natural gas supply may be replaced in the UK with guaranteed safety and reliability for the domestic end-user, without any modification of the appliance infrastructure.
This article although new has been passed around social media and is generating much interest. We show how 30% of the natural gas stream can be replaced or enriched with hydrogen providing an instantaneous carbon reduction to the national carbon emissions. This can be achieved with no need to change any infrastructure. The impact is that a 22% reduction in domestic green house gasses can be realised with almost no cost implication using otherwise wasted renewable energy from wind farms and solar plants that are unable to feed all their energy into the grid.
College of Engineering