This factsheet considers steam boilers fueled by 100% hydrogen. Hydrogen can be used as an alternative input energy carrier for boilers. To be considered as a renewable option, the hydrogen (H₂) has to be produced from a renewable source, such as from electrolysis using renewable electricity.
The combustion characteristics of hydrogen, such as velocity and flame heating properties, are different than from natural gas. The use of hydrogen in generic industrial boilers has proven feasible and only requires a retrofit of the burner to accommodate hydrogen gas properties (E4tech, 2015). Ricardo-AEA (2012) assumes that burner replacement is required to burning hydrogen at concentrations higher than 30%.
Whereas up to a 30% blend of hydrogen with natural gas has possibly the same efficiency as natural gas, 100% hydrogen oxyfuel burners are 15 percentage points more efficient than natural gas due to flue gas condensation and recycling plus reduced volume of exhaust gas (Ricardo-AEA, 2012). Whether this includes the energy required for the production of O₂ (that might be used instead of air in the combustion process) is not specified.