The concern over greenhouse gas (GHG) emissions from fossil fuels leading to climate warming (aka the greenhouse effect) has pushed interest in fuels that contain less carbon. Just as a greenhouse traps heat, the GHGs in the atmosphere absorb heat from the sun and release it back into the atmosphere. By blending hydrogen, which contains no carbon, with natural gas, the carbon content of the fuel is decreased, and emissions per given volume of fuel consumed are lessened. Hydrogen blending (HB) is a time-sensitive topic with significant impact on the boiler industry. HB is thought to reduce GHG emissions, especially if the added hydrogen is produced from biomass, wind power, and/or nuclear power.  

Natural gas utilities are interested in HB’s ability to reduce the carbon intensity of the fuel they are delivering. Reducing GHG emissions to address global warming has been deemed “one of the most urgent challenges faced by humanity.” The media has begun to cover HB and its impact on, and relationship to, climate change.  

A significant issue associated with HB is the lower Btu content per volume than unblended fuel. This may result in extended equipment run times for the same Btu output or an increase in the volumetric flow rate. 

The HyBlend Initiative 

The HyBlend Initiative (HBI) was launched in 2021 by the U.S. Department of Energy (DOE) and is the main U.S. project focused on studying HB. The HBI is coordinating with ongoing DOE research projects focused on providing insight into the design and operation of future energy systems as well as assessing the compatibility of pipelines with HB. While the HBI has not yet studied HB’s impact on boilers, it is aware that boilers are one of the end uses for HB.

The Canadian Standards Association Study 

A Canadian Standards Association study provides useful results in supporting the need for further research in the U.S. While the CSA study did not report any catastrophic results from HB, it suggests that more HB gas is required to provide the equivalent heat of natural gas. The CSA study notes that boilers “showed no major operable issues and consistent trends of decreased heat output and CO2 emissions with an increase of hydrogen content in methane/hydrogen blends.” But the potential long-term impacts of HB could not be captured during a single short-term study. 

FIGURE 1. The colors of hydrogen. Image courtesy of S&P Global

Possible Boiler Issues Due to HB

Hydrogen Embrittlement — Hydrogen embrittlement (HE) is the process by which various metals become brittle and fracture after hydrogen exposure. The metal absorbs hydrogen, which makes it more likely to crack and fracture at a lower stress. HE has been studied in equipment used in oil field investigation and production, among other areas, and can occur in certain conditions even without HB fuel. Steel is susceptible to HE, and different metal alloys have varying degrees of susceptibility. The possibility of increased embrittlement-related boiler damage is important for boiler manufacturers to consider during research and development (R&D) and in voicing concerns to the HBI and natural gas utilities. 

Impact of Variance in Btu on Boiler Capacity and Life Span

The CSA study notes that boilers would need to operate for longer time periods to meet the same heat demand. This raises an issue with respect to the overall goal of reduction in GHG: The operation of boilers for longer periods could result in additional CO2 emissions. 

Current boiler design is based on assumptions regarding the chemical properties and Btu capacity of the input. A move to HB raises the question of impact on boiler capacity and life span. In simple terms: If combustion equipment has to do more work, this could cause more wear and tear over a shorter course of time. That, in turn, may impact decisions about boiler warranties, ratings, construction, and design. 

FIGURE 2. Supply chain and components of blending in natural gas networks. Image courtesy of U.S. Department of Energy Hydrogen and Fuel Cell Technologies Office

Suggestions for a Path Forward 

Advocacy — Boiler manufacturers have a valuable collective voice through ABMA. While the trend does appear toward HB, it is unknown to what extent it will become widespread. A recent California study concluded “it is critical to conduct real-world demonstrations of hydrogen under safe and controlled conditions to build on ... and determine the appropriate blend percentage suitable to mitigate operational risks[.]”  

Risk Management — Awareness of the impact of HB on ABMA member’s equipment is critical. Consideration should be given to future-proof individual products by evaluating design modifications. This includes evaluating the potential for HE and its impacts on a product’s life span. Based upon prior work with other equipment manufacturers, legacy products often are overlooked when design or language changes are made to new products and manuals. For all products, consider evaluating if there is an increased risk of a catastrophic failure due to the lower ignition point of hydrogen compared to methane.

Changes to Warnings 

Boiler user manuals typically include key notices and warnings. Introduction of HB by natural gas utilities may outpace R&D efforts to make boilers and other combustion equipment compatible with an HB-amended fuel. Alternatively, R&D may indicate it is not feasible to change equipment design to adequately account for HB. Updated warnings may be necessary based on how, if, and at what pace the boiler industry accounts for HB in product design. 

Involvement of Legal Counsel 

In addition to guidance in complying with any statutory requirements and good practices governing product warnings, boiler manufacturers should consider the involvement of outside legal counsel in the risk management process. Counsel may assist in reviewing a study or related policies regarding internal documentation. We have worked with multiple product manufacturers on a review and modification of equipment manuals to support a defense against failure to warn claims, and it's critical to have a candid evaluation of the product. Including counsel also can aid a free flow of attorney-client privileged communication and provide a basis for an argument in favor of confidentiality for some materials in litigation. 


In the U.S., the current administration has set a 50%-plus reduction target of GHG emissions by 2030 as compared to 2005 levels. While more research on HB is needed, natural gas utilities are evaluating HB integration. It's important for boiler manufacturers now to assess product compatibility with HB. The industry should consider using its voice in the discussion regarding the future and pace of the introduction of HB. Boiler manufacturers should consider what changes need to be made to product warnings and engage legal counsel as appropriate to assist with warnings and confidentiality. HB has not been met with universal praise, but it's being presented as a viable way to combat GHG emissions, and, in turn, global warming. It should not be ignored by the boiler industry as it works toward making functional, safe products for industrial, commercial, and residential applications.  

i Milford, Lew, Mullendore, Seth and Ramanan, Abbe, “Hydrogen Hype in the Air” Clean Energy Group, December 14, 2020, available at,green%20H2%20into%20ghastly%20H2.; Melaina, M. W. Antonia, O. and Penev, M. “Blending Hydrogen into Natural Gas Pipeline Networks: A Review of Key Issues,”, National Renewable Energy Laboratory, available at

ii “Enabling an Accelerated and Affordable Clean Hydrogen Future – Fossil Energy Sector’s Role WORKSHOP FINAL REPORT,” United States Department of Energy / National Energy Technology Laboratory, September 2021, available at 

iii Mahajan, Devinder, Tan, Kun. Venkatesh , T., Kileti, Pradheep and Clayton, Clive R., “Hydrogen Blending in Gas Pipeline Networks – A Review,” May 13, 2022, Energies 2022 15, 3582, available at

iv See, e.g., Frazier, Reid “Hydrogen may be a climate solution. There’s debate over how clean it will truly be,” NPR, May 27, 2022, available at

v “HyBlend: Opportunities for Hydrogen Blending in Natural Gas Pipelines” HyBlend, U.S. Department of Energy, June 2021, available at

vi Suchovsky, C.J., Ericksen, L., Williams, T.A., Nikolic, D.J., “Appliances and Equipment Performance with Hydrogen-Enriched Natural Gases” Canadian Standards Association, 2021, available at

vii University of California, Riverside, “Hydrogen Blending Impacts Study,” California Public Utilities Commission, July 18, 2022, available at

viii “FACT SHEET: President Biden Sets 2030 Greenhouse Gas Pollution Reduction Target Aimed at Creating Good-Paying Union Jobs and Securing U.S. Leadership on Clean Energy Technologies,” White House Briefing Room, Statements and Releases, available at