Abstract
The literature provides conflicting guidance about the appropriate time-matching requirement between electricity consumption by electrolysers and contracted variable renewable energy (VRE) for qualifying hydrogen (H2) as ‘low carbon’. Here we show that these findings are highly influenced by different interpretations of additionality. Substantially lower consequential emissions are achievable under annual time matching when presuming that VRE for non-H2 electricity demand does not compete with VRE contracted for H2, as opposed to when assuming that all VRE resources are in direct competition. Further analysis considering four energy system-relevant policies suggests that the latter interpretation of additionality is likely to overestimate the emissions impacts of annual matching and underestimate those of hourly matching. We argue for starting with annual time matching in the near term for the attribution of the H2 US production tax credits, where conditions resemble the ‘non-compete’ framework, followed by phase-in and subsequent phase-out of hourly time-matching requirements as the grid is deeply decarbonized.
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The input data for the various scenarios evaluated along with the outputs are available at https://zenodo.org/records/10198811.
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The model source code used for this study is available at https://github.com/macroenergy/Dolphyn.jl/tree/main.
Change history
05 February 2024
A Correction to this paper has been published: https://doi.org/10.1038/s41560-024-01475-0
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Acknowledgements
This work was funded by the Future Energy Systems Center at the MIT Energy Initiative. We gratefully acknowledge feedback from J. Parsons, R. Stoner and R. Field.
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M.A.G. gathered data for the model, performed research, participated in the writing and framework development and generated figures. A.N.C. and D.S.M. performed the model runs, analysed the output, generated figures and contributed to the writing. D.S.M. developed the framework for the study. T.S. performed analysis and contributed to the framework and to the writing.
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Extended data
Extended Data Fig. 1 Grid dispatch impacts with different qualifying requirements.
Difference in average hourly dispatch in ERCOT between counterfactual and baseline grid under the ‘compete’ (1st column) and ‘non-compete’ definitions (2nd column) of additionality and annual (top row) and hourly time-matching requirements (bottom row): A and B: 5 GW of H2 production with baseload electrolyzer operation and annual time-matching requirements. C and D: 5 GW of H2 production with baseload electrolyzer operation and hourly time-matching requirements. Resources with suffix ‘_PPA’ refer to resources added specifically to meet time-matching requirements for H2 production.
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Supplementary Tables 1–9, Figs. 1–30, Methods 1, Notes 1–5 and References.
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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 (2024). https://doi.org/10.1038/s41560-023-01435-0
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DOI: https://doi.org/10.1038/s41560-023-01435-0
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