APPENDIX A: EPA AVERT ANALYSIS OF UPSTREAM ELECTROLYSIS EMISSIONS

Using the EPA's AVERT tool and 2021 data, the analysis finds that ignoring additionality, regionality, line loss accounting, or hourly time-matching can lead to hydrogen production emissions that exceed the threshold for the top $3/kg 45V tax credit. Specifically, forgoing additionality could result in emissions 22 to 40 kgCO2/kgH2, which is more than twice the emissions of steam methane reformation.

• Forgoing the additionality principle in 45V guidance would lead to substantial GHG emissions across all 14 modeled U.S. regions, with rates between 22 and 40 kgCO2/kgH2. This is more than twice the emissions of steam methane reformation (SMR) and approximately 50 times the threshold required for the $3/kg tax credit.
• Ignoring regionality (part of the deliverability principle) can cause high emissions depending on the location of the electrolyzer relative to the clean energy source. For instance, an electrolyzer in the Rocky Mountains region using hourly-matched clean energy from California would have a GHG emissions intensity exceeding 17 kgCO2/kgH2, which is over 1.5 times that of SMR.
• Failure to account for transmission line losses would result in GHG emissions that push projects in every U.S. region beyond the threshold for the $3/kg tax credit, although they might still qualify for lower tax credit tiers.
• Forgoing hourly time-matching can push emissions above the $3/kg threshold, though results vary by region and resource. For example, an electrolyzer in the Southeast using onshore wind would produce hydrogen with an intensity over 1 kgCO2/kgH2, more than double the allowable limit for the top tier.
• The analysis is limited to short-run marginal emissions and likely underestimates true impacts because it does not account for long-run structural changes, such as how clean energy deployments for electrolysis might displace other investments or how marginal emissions rates evolve as the power system develops.

APA

ESPOSITO, D., GIMON, E., & O’BOYLE, M. (2023). APPENDIX A: EPA AVERT ANALYSIS OF UPSTREAM ELECTROLYSIS EMISSIONS. Energy Innovation. https://energyinnovation.org/wp-content/uploads/45V-Paper-Appendix-A.pdf

Chicago

ESPOSITO, DAN, ERIC GIMON, and MIKE O’BOYLE. APPENDIX A: EPA AVERT ANALYSIS OF UPSTREAM ELECTROLYSIS EMISSIONS. Energy Innovation, 2023. https://energyinnovation.org/wp-content/uploads/45V-Paper-Appendix-A.pdf.

Wikipedia

{{cite report |last1=ESPOSITO |first1=DAN |last2=GIMON |first2=ERIC |last3=O’BOYLE |first3=MIKE |title=APPENDIX A: EPA AVERT ANALYSIS OF UPSTREAM ELECTROLYSIS EMISSIONS |publisher=Energy Innovation |date=May 2023 |url=https://energyinnovation.org/wp-content/uploads/45V-Paper-Appendix-A.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{esposito2023appendix, author = {ESPOSITO, DAN and GIMON, ERIC and O’BOYLE, MIKE}, title = {{APPENDIX A: EPA AVERT ANALYSIS OF UPSTREAM ELECTROLYSIS EMISSIONS}}, institution = {Energy Innovation}, year = {2023}, month = may, url = {https://energyinnovation.org/wp-content/uploads/45V-Paper-Appendix-A.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }