open letter: Expert Consensus on carbon impact

open letter: Expert Consensus on carbon impactopen letter: Expert Consensus on carbon impactopen letter: Expert Consensus on carbon impact

open letter: Expert Consensus on carbon impact

open letter: Expert Consensus on carbon impactopen letter: Expert Consensus on carbon impactopen letter: Expert Consensus on carbon impact

To whom it may concern,

Several recent policy-related publications have stated or implied that the academic and expert community are in consensus that corporate-level hourly carbon-free matching (“24/7 energy matching”) is the only approach that is effective at reducing system-level emissions. [1,2,3]


We, the 26 listed signatories representing experts in energy systems modeling, carbon impact analysis, and carbon accounting across academic, non-governmental organizations, and commercial organizations, dispute this statement. 


No expert consensus has been established that 24x7 energy matching is the only—or even necessarily the most effective—method for incentivizing real-world carbon-reducing decisions and rigorously measuring the carbon impact of those decisions.


While the specific views of the signatories to this letter vary significantly, what all of the signatories to this letter agree upon is:


  1. The current Scope 2 carbon accounting methodologies defined by the GHG Protocol, which have motivated considerable corporate procurement of carbon-free energy, likely require changes to recognize the fact that the environmental impact of carbon-free energy varies significantly in time and place; and
  2. 24x7 energy matching may be an important tool in an improved carbon accounting toolkit, but 24x7 is far from the only method by which rigorous carbon impact can be effectively incentivized and accurately measured, and 
  3. 24x7 energy matching has significant shortcomings that limit its real-world applicability, as its modeled impacts tend to rely on simplified assumptions that do not reflect the economic or physical realities of project development or grid operations. Importantly, 24x7 energy matching ignores the lessons learned from the development of Locational Marginal Prices (LMPs): in power systems, it is not possible to match individual production and consumption at different locations.


Going forward, it is our hope that the press and policymakers will look a level deeper into the large pool of academic research, expert analysis, and real-world demonstrations that underpins the above statements, which includes but is not limited to the referenced articles attached hereto in Annex A.  

Sincerely,

Ross Baldick, PhD

The University of Texas at Austin

Michael Caramanis, PhD

Boston University

Judith Cardell, PhD

Smith College

Dennis Carlberg

Boston University

Yury Dvorkin, PhD

Johns Hopkins University

Peter Freed

Stanford University

Michael Gillenwater, PhD

Greenhouse Gas Management Institute

Ben Hobbs, PhD

Johns Hopkins University

Brent Hollenbeck

TimberRock

Daniel Howard, PhD

Quantum Energy

Alexia Kelly

High Tide Foundation

Holly Lahd

Individual Expert

Michael Leggett

Ever.green

Gavin McCormick

WattTime

Doug Miller

Energy Peace Partners

Peter Minor, PhD

Absolute Climate

Frank O'Sullivan, PhD

S2G, Formerly MIT Energy Initiative

Morgan Putnam, PhD

Individual Expert

Henry Richardson

WattTime

Line Roald, PhD

University of Wisconsin - Madison

Alex Rudkevich, PhD

Tabors Caramanis Rudkevich (TCR)

Tim Smith, PhD

University of Minnesota

Abe Silverman

Johns Hopkins University

Sarah Sofia, PhD

REsurety, Inc.

Richard Tabors, PhD

Tabors Caramanis Rudkevich (TCR)

Lee Taylor

REsurety, Inc.

Annex A

  1. Chen Ling, Qing Yang, Qingrui Wang, Pietro Bartocci, Lei Jiang, Zishuo Xu, Luyao Wang, “A comprehensive consumption-based carbon accounting framework for power system towards low-carbon transition”, Renewable and Sustainable Energy Reviews, Volume 206, 114866, ISSN 1364-0321, Dec. 2024.  https://doi.org/10.1016/j.rser.2024.114866
  2. Sarah Sofia, Yury Dvorkin, “Carbon Impact of Transmission Constraints,” SSRN Pre-publication, Oct. 2024. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4972564
  3. Anthony Degleris, Lucas F. Valenzuela, Ram Rajagopal, Marco Pavone, Abbas E. Gamal, "Fast Grid Emissions Sensitivities using Parallel Decentralized Implicit Differentiation", 2024 IEEE International Conference on Communications, Control, and Computing Technologies for Smart Grids (SmartGridComm), Oslo, Norway, pp. 458-464, Aug. 2024. https://www.arxiv.org/abs/2408.10620
  4. Zhang, Shixu, Yaowang Li, Ershun Du, Wei Wang, Min Wang, Haoran Feng, Yi Xie, Qiuyu Chen, "Research on Carbon-Reduction-Oriented Demand Response Technology Based on Generalized Nodal Carbon Emission Flow Theory", Energies 17, no. 18: 4672, July 2024. https://doi.org/10.3390/en17184672
  5. Arne Olson, Kushal Patel, Liz Mettetal, Gregory Gangelhoff, Angineh Zohrabian, Hugh Somerset, Ruoshui Li, Joshua Spooner. “Consequential Impacts of Voluntary Clean Energy Procurement,” July 2024. https://www.ethree.com/wp-content/uploads/2024/07/E3_VoluntaryCorporateProcurement_HourlyEmissions_June-2024.pdf
  6. Dawei Qiu, Yi Wang, Zhaohao Ding, Yi Wang, Goran Strbac, "Graph Reinforcement Learning for Carbon-Aware Electric Vehicles in Power-Transport Networks", IEEE Transactions on Smart Grid, vol. 15, no. 4, pp. 3919-3935, July 2024. https://ieeexplore.ieee.org/document/10415871
  7. Yaowang Li, Xuxin Yang, Ershun Du, Yuliang Liu, Shixu Zhang, Chen Yang, Ning Zhang, Chang Liu, “A review on carbon emission accounting approaches for the electricity power industry”, Applied Energy, Volume 359, 122681, ISSN 0306-2619, Apr. 2024. https://doi.org/10.1016/j.apenergy.2024.122681 
  8. Hua He, Alexander Derenchuk, Richard Tabors, Aleksandr Rudkevich, “Cost and emissions impact of voluntary clean energy procurement strategies,” The Electricity Journal, Volume 37, Issue 3, April 2024. https://doi.org/10.1016/j.tej.2024.107383
  9. Zhanhe Li, Xiaoqian Li, Chao Lu, Kechun Ma, Weihan Bao, “Carbon emission responsibility accounting in renewable energy-integrated DC traction power systems”, Applied Energy, Volume 355, 122191, ISSN 0306-2619, Feb. 2024. https://www.sciencedirect.com/science/article/abs/pii/S0306261923015556?via%3Dihub
  10. Md A. Arif, Fengyu Wang, Di Shi, Liang Sun, Zongjie Wang, "Analysis of the Impacts of Reserve Requirements on Marginal Emission Rate", 2024 IEEE Power & Energy Society Innovative Smart Grid Technologies Conference (ISGT), Washington, DC, USA, pp. 1-5, Feb. 2024. https://ieeexplore.ieee.org/document/10454116
  11. Lucas F. Valenzuela, Anthony Degleris, Abbas E. Gamal, Marco Pavone, Ram Rajagopal, "Dynamic Locational Marginal Emissions via Implicit Differentiation", IEEE Transactions on Power Systems, vol. 39, no. 1, pp. 1138-1147, Jan. 2024. https://ieeexplore.ieee.org/document/10049684
  12. Giovanniello, M.A., Cybulsky, A.N., Schittekatte, T. et al. “The influence of additionality and time-matching requirements on the emissions from grid-connected hydrogen production,” Nat Energy 9, 197–207, Jan. 2024. https://doi.org/10.1038/s41560-023-01435-0
  13. Zifei Wang, Hongyi Li, Yuting Oi, Hongxun Hui, "Distributed Settlement Mechanism Design for Carbon Market Based on Blockchain-Enabled Edge Intelligence", 2023 IEEE 7th Conference on Energy Internet and Energy System Integration (EI2), Hangzhou, China, pp. 2110-2115, Dec. 2023. https://ieeexplore.ieee.org/document/10512811
  14. Oliver Ruhnau, Johanna Schiele, “Flexible green hydrogen: The effect of relaxing simultaneity requirements on project design, economics, and power sector emissions,” Energy Policy, Volume 182, Nov. 2023. https://doi.org/10.1016/j.enpol.2023.113763
  15. Mo Sodwatana, Saif R. Kazi, Kaarthik Sundar, Anatoly Zlotnik, "Optimization of Hydrogen Blending in Natural Gas Networks for Carbon Emissions Reduction", 2023 American Control Conference (ACC), San Diego, CA, USA, pp. 1229-1236, May 2023. https://ieeexplore.ieee.org/document/10156202
  16. Anatoly Zlotnik, Saif R. Kazi, Kaarthik Sundar, Vitaliy Gyrya, Luke Baker, Mo Sodwatana, Yan Brodskyi, “Effects of Hydrogen Blending on Natural Gas Pipeline Transients, Capacity, and Economics”, PSIG Annual Meeting, OP PSIG-2312, May 2023. https://onepetro.org/PSIGAM/proceedings-abstract/PSIG23/All-PSIG23/PSIG-2312/520076
  17. Byungkwon Park, Jin Dong, Boming Liu, Teja Kuruganti, “Decarbonizing the grid: Utilizing demand-side flexibility for carbon emission reduction through locational marginal emissions in distribution networks”, Applied Energy, Volume 330, Part A, 120303, ISSN 0306-2619, Jan. 2023.  https://doi.org/10.1016/j.apenergy.2022.120303
  18. Kenji Santacruz, Yuanrui Sang, "Environmentally Aware Allocation of Electric Vehicle Charging Stations by Analyzing Locational Marginal Emissions", 2022 North American Power Symposium (NAPS), Salt Lake City, UT, USA, pp. 1-6, Oct. 2022. https://ieeexplore.ieee.org/document/10012206
  19. S.P. Holland, M.J. Kotchen, E.T. Mansur, A.J. Yates, “Why marginal CO2 emissions are not decreasing for US electricity: Estimates and implications for climate policy,” Proceedings of the National Academy of Sciences, Sept. 2022. https://doi.org/10.1073/pnas.2116632119 
  20. Jianrong Gong, Tingting Ruan, Hao Chen, Chen Ye, "Simulation Research on Multi-energy Participation in Electricity Market Operation Considering User-side Carbon Responsibility", 2022 5th International Conference on Energy, Electrical and Power Engineering (CEEPE), Chongqing, China, pp. 944-949, April 2022. https://ieeexplore.ieee.org/document/9783270
  21. Kenji Santacruz, Yuanrui Sang, "Tracking the Source of Marginal Electricity Generation on a Spatial-Temporal Basis in an Electricity Market", 2021 North American Power Symposium (NAPS), College Station, TX, USA, pp. 1-6, Nov. 2021. https://ieeexplore.ieee.org/abstract/document/9654548
  22. Hua He, Aleksandr Rudkevich, Xindi Li, Richard Tabors, Alexander Derenchuk, Paul Centolella, Ninad Kumthekar, Chen Ling, Ira Shavel, “Using marginal emission rates to optimize investment in carbon dioxide displacement technologies,” The Electricity Journal, Volume 34, Issue 9, Nov. 2021. https://doi.org/10.1016/j.tej.2021.107028 
  23. Julia Lindberg, Yasmine Abdennadher, Jiaqi Chen, Bernard C. Lesieutre, Line Roald, “A Guide to Reducing Carbon Emissions through Data Center Geographical Load Shifting”, Proceedings of the Twelfth ACM International Conference on Future Energy Systems (e-Energy '21). Association for Computing Machinery, New York, NY, USA, 430–436, June 2021. https://dl.acm.org/doi/10.1145/3447555.3466582  
  24. Mahdi Rouholamini, Carol J. Miller, Caisheng Wang, “Determining consumer's carbon emission obligation through virtual emission tracing in power systems”, Environmental Progress & Sustainable Energy. Vol 39, Issue 1, Jan/Feb 2020, May 2019. https://doi.org/10.1002/ep.13279
  25. Imran Khan, “Greenhouse gas emission accounting approaches in electricity generation systems”, A review, Atmospheric Environment, Volume 200, Pages 131-141, ISSN 1352-2310, March 2019. https://www.sciencedirect.com/science/article/abs/pii/S1352231018308628
  26. Imran Khan, Michael W. Jack, Janet Stephenson, “Analysis of greenhouse gas emissions in electricity systems using time-varying carbon intensity”, Journal of Cleaner Production, Volume 184, Pages 1091-1101, ISSN 0959-6526, May 2018. https://www.sciencedirect.com/science/article/abs/pii/S0959652618306474
  27. Iván Chaparro, David Watts, Esteban Gil, “Modeling marginal CO2 emissions in hydrothermal systems: Efficient carbon signals for renewables”, Applied Energy, Volume 204, Pages 318-331, ISSN 0306-2619, Oct. 2017. https://doi.org/10.1016/j.apenergy.2017.06.107
  28. Mo Li, Timothy M. Smith, Yi Yang, Elizabeth J. Wilson, “Marginal Emission Factors Considering Renewables: A Case Study of the U.S. Midcontinent Independent System Operator (MISO) System,” Environmental Science & Technology, Sept. 2017. https://pubs.acs.org/doi/10.1021/acs.est.7b00034
  29. Thomas Dandres, Reza Farrahi Moghaddam, Kim Khoa Nguyen, Yves Lemieux, Réjean Samson, Mohamed Cheriet, “Consideration of marginal electricity in real-time minimization of distributed data centre emissions,” Journal of Cleaner Production, Volume 143, Feb. 2017. https://doi.org/10.1016/j.jclepro.2016.12.143
  30. Nicole A. Ryan, Jeremiah X. Johnson, Gregory A. Keoleian, “Comparative Assessment of Models and Methods To Calculate Grid Electricity Emissions,” Environmental Science & Technology, Aug. 2016. https://pubs.acs.org/doi/10.1021/acs.est.5b05216
  31. Q. Zhou, Tao Sun, Teng Ding, Donghan Feng, "Application of carbon intensity in generation expansion planning: A comparative study", 2015 IEEE Power & Energy Society General Meeting, Denver, CO, USA, pp. 1-5, July 2015. https://ieeexplore.ieee.org/document/7286450
  32. Graff Zivin, J.S., et al., “Spatial and temporal heterogeneity of marginal emissions: Implications for electric cars and other electricity-shifting policies,” Journal of Economic Behavior and Organization, Nov. 2014. http://dx.doi.org/10.1016/j.jebo.2014.03.010
  33. Michelle M. Rogers, Yang Wang, Caisheng Wang, Shawn P. McElmurry, Carol J. Miller, “Evaluation of a rapid LMP-based approach for calculating marginal unit emissions,” Applied Energy, Volume 111, Nov. 2013. https://doi.org/10.1016/j.apenergy.2013.05.057
  34. Baowei Li, Yonghua Song, Zechun Hu, "Carbon Flow Tracing Method for Assessment of Demand Side Carbon Emissions Obligation", IEEE Transactions on Sustainable Energy, vol. 4, no. 4, pp. 1100-1107, Oct. 2013. https://ieeexplore.ieee.org/abstract/document/6566168
  35. Kai E. Van Horn, Dimitra Apostolopoulou, "Assessing Demand Response Resource locational impacts on system-wide carbon emissions reductions", 2012 North American Power Symposium (NAPS), Champaign, IL, USA, pp. 1-6, Sept. 2012. https://ieeexplore.ieee.org/document/6336436
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References

1. Letter from Lawmakers regarding 45V, September 11, 2024. Link. 

2. The Once in a Generation Chance to Fix Corporate Emissions Reporting, NRDC, November 4, 2024. Link. 

3. Briefing: 24/7 renewable electricity matching is a far more credible approach for the GHG protocol and the SBTi than the emissions first partnership proposal. New Climate Institute, October 10, 2024. Link.

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