Executive Summary

Mixing of hydrogen into natural gas, as a means of mitigating environmental concerns associated with the use of fossil fuels, poses a question of performance of appliances designed for use with natural gas, when fuelled by blends of hydrogen and natural gas. This study examines the performance of space and water heating appliances fuelled by methane as a natural gas proxy, and methane/hydrogen blends containing up to 15% hydrogen. The appliances were tested for input rate, ignition and burner operating characteristics, combustion products properties, and gas leakage, using three gas mixtures (pure methane, 5% hydrogen/methane blend, and 15% hydrogen/methane blend mixtures) per applicable CSA/ANSI Z21 series Standards. Effects of gas composition on furnaces were also tested for temperature rise and heating tube temperatures. Condensing appliances were additionally assessed for dew point temperatures and acidity. Overall, appliances showed no major operable issues and consistent trends of decreased heat output and CO₂ emissions with increase of hydrogen content in methane/hydrogen blends. Consequently, to meet the same heat demand, the appliances would need to operate for longer periods which would result in additional carbon dioxide emissions. However, the overall CO₂ emissions for the same heat output are still expected to be lower with the use of blends compared to natural gas. Carbon monoxide and nitrogen oxide measurements were in the acceptable ranges regardless of the type of fuel used. No consistent trends were observed for other measured properties, indicating that hydrogen mixtures up to 15% do not significantly affect these parameters. Future testing of gas blends containing 5% and 15% of hydrogen as examined herein, as well as higher hydrogen amounts, ought to incorporate natural gases to determine more representative results.