Missing pieces in the hydrogen puzzle

Yanjie Zheng; Ziye Zhu; Zhiwei Ouyang; Shen Liang; Xinglong Ma

doi:10.59717/j.xinn-energy.2026.100173

The Innovation Energy > 2026 Vol. 3 > No. 3 > 100173

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Missing pieces in the hydrogen puzzle

1.
School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
2.
College of New Energy, Beijing University of Technology, Beijing 100124, China
3.
School of Environment, Nanjing Normal University, Nanjing 210023, China

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Corresponding authors: liangshen09@bjut.edu.cn(S. L.); 75061@njnu.edu.cn(X. M.)
Received Date: March 07, 2026

Accepted Date: July 17, 2026

Published Online: July 22, 2026

The Innovation Energy 3(3), https://doi.org/10.59717/j.xinn-energy.2026.100173 | Cite this article

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1. Hydrogen is widely promoted for energy transition, yet its reputation as ultimate clean energy requires systematic re-evaluation via interdisciplinary systems analysis.
  
  Power-to-hydrogen conversion suffers inherent thermodynamic defects with inevitable exergy loss, while liquefaction and compression induce severe energy penalties.
  
  Renewable-based green hydrogen still produces measurable carbon footprints, and hydrogen leakage may indirectly exacerbate atmospheric greenhouse effects.
  
  Hydrogen is irreplaceable for hard-to-abate industries and long-duration energy storage; targeted deployment instead of universal application is rational.

ABSTRACT

ABSTRACT

Hydrogen has attracted substantial attention and investment as a pathway for climate mitigation and energy transition. However, beneath the grand narrative of the hydrogen economy, its designation as the “ultimate clean energy” requires critical re-examination. Through an interdisciplinary systems analysis framework, this perspective critically evaluates the hydrogen value chain across multiple dimensions. Thermodynamic analysis reveals that power-to-hydrogen conversion inevitably degrades energy quality. Even under ideal oxy-combustion conditions, hydrogen exhibits an exergy coefficient of merely 0.9. This irreversible exergy loss exposes inherent thermodynamic deficiencies in power-to-hydrogen as an energy storage pathway, fundamentally limiting high-quality energy utilization. The energy penalties make electricity-to-hydrogen conversion inherently inefficient. Liquefaction demands a theoretical minimum of 43.2% of hydrogen's energy content, and compression to 70 MPa requires 5.74%. Life-cycle carbon footprint analysis challenges the prevailing “green hydrogen” narrative. Even when produced via renewable electricity, solar photovoltaic pathways yield carbon intensities of 1.98 kgCO₂/kgH₂, while wind power pathways generate 0.495 kgCO₂/kgH₂. Furthermore, hydrogen's high permeability presents non-negligible leakage risks. Atmospheric hydrogen accumulation indirectly amplifies greenhouse effects through hydroxyl radical interactions. Despite these constraints, hydrogen retains irreplaceable value in hard-to-abate industrial processes, weight-constrained transport, and long-duration energy storage where direct electrification is infeasible. Rational hydrogen deployment requires matching the carrier to its comparative advantages rather than pursuing a universal hydrogen economy.
- Hydrogen /
- Hydrogen storage /
- Thermodynamics /
- Carbon footprint /
- Energy transition

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REFERENCES

[1]	Ballentine C.J., Karolytė R., Cheng A., et al. (2025). Natural hydrogen resource accumulation in the continental crust. Nat. Rev. Earth Environ. 6:342−356. DOI:10.1038/s43017-025-00670-1 View in Article CrossRef Google Scholar
[2]	Fan G., Zhang H., Sun B., et al. (2025). Economic and environmental competitiveness of multiple hydrogen production pathways in China. Nat. Commun. 16:4284. DOI:10.1038/s41467-025-59412-y View in Article CrossRef Google Scholar
[3]	Liu Q., Wei Y., Li P., et al. (2025). Natural hydrogen in the volcanic-bearing sedimentary basin: Origin, conversion, and production rates. Sci. Adv. 11:eadr6771. DOI:10.1126/sciadv.adr6771 View in Article CrossRef Google Scholar
[4]	Hydrogen Council (2021). Hydrogen for Net-Zero. https://hydrogencouncil.com/wp-content/uploads/2021/11/Hydrogen-for-Net-Zero. View in Article Google Scholar
[5]	Hydrogen Council, McKinsey & Company (2024). Hydrogen Insights September 2024. View in Article Google Scholar
[6]	International Energy Agency (2025). Global Hydrogen Review 2025. View in Article Google Scholar
[7]	Clarivate (n.d.). Web of Science database. https://webofscience.clarivate.cn/wos/alldb/smart-search. View in Article Google Scholar
[8]	Kovač, A., Paranos, M. and Marciuš, D. (2021). Hydrogen in energy transition: A review. Int. J. Hydrog. Energy 46:10016−10035. DOI:10.1016/j.ijhydene.2020.11.256 View in Article CrossRef Google Scholar
[9]	Haynes, W.M. (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. View in Article Google Scholar
[10]	Zhou Z., Shan S., Chen L., et al. (2017). Exergy of Blackbody Radiation and Monochromatic Photon. Int. J. Thermophys. 38:57. DOI:10.1007/s10765-017-2196-8 View in Article CrossRef Google Scholar
[11]	Gupta P., Toksh B. and Rahaman M. (2024). A Critical Review on Hydrogen Based Fuel Cell Technology and Applications. Chem. Rec. 24:e202300295. DOI:10.1002/tcr.202300295 View in Article CrossRef Google Scholar
[12]	Zhang T., Uratani J., Huang Y., et al. (2023). Hydrogen liquefaction and storage: Recent progress and perspectives. Renew. Sustain. Energy Rev. 176:113204. DOI:10.1016/j.rser.2023.113204 View in Article CrossRef Google Scholar
[13]	Chen Q.F., Cai L.C., Gu Y.J., et al. (2010). Compressibility and isotope effect of fluid hydrogen. Phys. Lett. A 374:3875−3880. DOI:10.1016/j.physleta.2010.07.041 View in Article CrossRef Google Scholar
[14]	Harvey J.-P., Courchesne W., Vo M. D., et al. (2022). Greener reactants, renewable energies and environmental impact mitigation strategies in pyrometallurgical processes. MRS Energy Sustain. 9:212−247. DOI:10.1557/s43581-022-00042-y View in Article CrossRef Google Scholar
[15]	Wang X., Cheng T., Hong H., et al. (2025). Challenges and opportunities in hydrogen storage and transportation: A comprehensive review. Renew. Sustain. Energy Rev. 219:115881. DOI:10.1016/j.rser.2025.115881 View in Article CrossRef Google Scholar
[16]	Hua Z., Gao W., Chi S., et al. (2025). Development status and challenges of high-pressure gaseous hydrogen storage vessels and cylinders in China. Renew. Sustain. Energy Rev. 214:115567. DOI:10.1016/j.rser.2025.115567 View in Article CrossRef Google Scholar
[17]	Cheng Q., Zhang R., Shi Z. et al. (2024). Review of common hydrogen storage tanks and current manufacturing methods for aluminium alloy tank liners. Int. J. Lightweight Mater. Manuf. 7:269−284. DOI:10.1016/j.ijlmm.2023.08.002 View in Article CrossRef Google Scholar
[18]	Aziz M. (2021). Liquid Hydrogen: A Review on Liquefaction, Storage, Transportation, and Safety. Energies 14. DOI:10.3390/en14215988. View in Article Google Scholar
[19]	Bardhan R., Ruminski A.M., Brand A. et al. (2011). Magnesium nanocrystal-polymer composites: A new platform for designer hydrogen storage materials. Energy Environ. Sci. 4:4882−4895. DOI:10.1039/C1EE02258J View in Article CrossRef Google Scholar
[20]	Sadhasivam T., Kim H.T., Jung S., et al. (2017). Dimensional effects of nanostructured Mg/MgH₂ for hydrogen storage applications: A review. Renew. Sustain. Energy Rev. 72:523−534. DOI:10.1016/j.rser.2017.01.107 View in Article CrossRef Google Scholar
[21]	Tashie-Lewis, B.C. and Nnabuife, S.G. (2021). Hydrogen Production, Distribution, Storage and Power Conversion in a Hydrogen Economy - A Technology Review. Chem. Eng. Adv. 8:100172. DOI:10.1016/j.ceja.2021.100172 View in Article CrossRef Google Scholar
[22]	Cirrone, D., Makarov, D., Proust, C., et al. (2023). Minimum ignition energy of hydrogen-air mixtures at ambient and cryogenic temperatures. Int. J. Hydrog. Energy 48:16530−16544. DOI:10.1016/j.ijhydene.2023.01.115 View in Article CrossRef Google Scholar
[23]	Hu S., Zhang L., Hu Q., et al. (2025). Analysis of hydrogen leakage characteristics and hazard assessment of hydrogen production container. Int. J. Hydrog. Energy 139:835−845. DOI:10.1016/j.ijhydene.2023.10.052 View in Article CrossRef Google Scholar
[24]	Duportal M., Oudriss A., Feaugas X. et al. (2020). On the estimation of the diffusion coefficient and distribution of hydrogen in stainless steel. Scr. Mater. 186:282−286. DOI:10.1016/j.scriptamat.2020.05.040 View in Article CrossRef Google Scholar
[25]	Maggio G., Nicita A. and Squadrito G. (2019). How the hydrogen production from RES could change energy and fuel markets: A review of recent literature. Int. J. Hydrog. Energy 44:11371−11384. DOI:10.1016/j.ijhydene.2019.03.121 View in Article CrossRef Google Scholar
[26]	Jiang Q., Wang Q., Xie P., et al. (2019). Development status and analysis of long-distance hydrogen pipeline at home and abroad. Oil-Gas Field Surf. Eng. 38:6−8. View in Article Google Scholar
[27]	Oei D.-G. (1996). Direct Hydrogen-Fueled Proton-Exchange-Membrane (PEM) Fuel Cell for Transportation. SAE Trans. 105:1750−1755. View in Article Google Scholar
[28]	Liu F., Akram M.Z. and Wu H. (2020). Hydrogen effect on lean flammability limits and burning characteristics of an isooctane–air mixture. Fuel 266:117144. DOI:10.1016/j.fuel.2020.117144 View in Article CrossRef Google Scholar
[29]	Fan Z., Bhardwaj A., Corbeau A.-S., et al. (2022). Hydrogen leakage: a potential risk for the hydrogen economy. Center on Global Energy Policy, Columbia University. View in Article Google Scholar
[30]	Lakshmanan S. and Bhati M. (2024). Unravelling the atmospheric and climate implications of hydrogen leakage. Int. J. Hydrog. Energy 53:807−815. DOI:10.1016/j.ijhydene.2023.12.010 View in Article CrossRef Google Scholar
[31]	Kobayashi H., Naruo Y., Maru Y., et al. (2018). Experiment of cryo-compressed (90-MPa) hydrogen leakage diffusion. Int. J. Hydrog. Energy 43:17928−17937. DOI:10.1016/j.ijhydene.2018.07.145 View in Article CrossRef Google Scholar
[32]	Yang N., Deng J., Wang C., et al. (2024). High pressure hydrogen leakage diffusion: Research progress. Int. J. Hydrog. Energy 50:1029−1046. DOI:10.1016/j.ijhydene.2023.08.221 View in Article CrossRef Google Scholar
[33]	Molkov V., D.M. and Bragin M. (2009). Physics and modelling of underexpanded jets and hydrogen dispersion in atmosphere. Russian Academy of Sciences. View in Article Google Scholar
[34]	Sun B., et al. (2024). Current challenges in the utilization of hydrogen energy-a focused review on the issue of hydrogen-induced damage and embrittlement. Adv. Appl. Energy 14:100168. DOI:10.1016/j.adapen.2024.100168 View in Article CrossRef Google Scholar
[35]	Roueff E., Abgrall H., Czachorowski P., et al. (2019). The full infrared spectrum of molecular hydrogen. A & A. 630:A58. DOI:10.1051/0004-6361/201936249 View in Article CrossRef Google Scholar
[36]	Laadel N.-E., El Mansori M., Kang N., et al. (2022). Permeation barriers for hydrogen embrittlement prevention in metals – A review on mechanisms, materials suitability and efficiency. Int. J. Hydrog. Energy 47:32707−32731. DOI:10.1016/j.ijhydene.2022.07.164 View in Article CrossRef Google Scholar
[37]	Field R.A. and Derwent R.G. (2021). Global warming consequences of replacing natural gas with hydrogen in the domestic energy sectors of future low-carbon economies in the United Kingdom and the United States of America. Int. J. Hydrog. Energy 46:30190−30203. DOI:10.1016/j.ijhydene.2021.06.120 View in Article CrossRef Google Scholar
[38]	Ocko I.B. and Hamburg S.P. (2022). Climate consequences of hydrogen emissions. Atmos. Chem. Phys. 22:9349−9368. DOI:10.5194/acp-22-9349-2022 View in Article CrossRef Google Scholar
[39]	Bryant H. N., Stevenson D. S., Heal M. R., et al. (2024). Impacts of hydrogen on tropospheric ozone and methane and their modulation by atmospheric NOx. Front. Energy Res. 12:1415593. DOI:10.3389/fenrg.2024.1415593 View in Article CrossRef Google Scholar
[40]	Paulot F., Pétron G., Crotwell A.M., et al. (2024). Reanalysis of NOAA H₂ observations: implications for the H₂ budget. Atmos. Chem. Phys. 24:4217−4229. DOI:10.5194/acp-24-4217-2024 View in Article CrossRef Google Scholar
[41]	Sand M., Skeie R.B., Sandstad M., et al. (2023). A multi-model assessment of the Global Warming Potential of hydrogen. Commun. Earth Environ. 4:203. DOI:10.1038/s43247-023-00857-8 View in Article CrossRef Google Scholar
[42]	Crutzen P.J. (1974). Photochemical reactions initiated by and influencing ozone in unpolluted tropospheric air. Tellus B 26:47−57. DOI:10.3402/tellusa.v26i1-2.9736 View in Article CrossRef Google Scholar
[43]	Ballentine C.J., et al. (2025). Natural hydrogen resource accumulation in the continental crust. Nat. Rev. Earth Environ. 6:342−356. DOI:10.1038/s43017-025-00670-1 View in Article CrossRef Google Scholar
[44]	Chen C., Solomon S. and Stone, K. (2024). On the chemistry of the global warming potential of hydrogen. Front. Energy Res. 12. DOI:10.3389/fenrg.2024.1463450 View in Article CrossRef Google Scholar
[45]	El-Shafie M. (2023). Hydrogen production by water electrolysis technologies: A review. Results Eng. 20:101426. DOI:10.1016/j.rineng.2023.101426 View in Article CrossRef Google Scholar
[46]	International Energy Agency (2024). CO₂ emissions from electricity generation in China, 2014-2026. https://www.iea.org/data-and-statistics/charts/co2-emissions-from-electricity-generation-in-china-2014-2026. View in Article Google Scholar
[47]	Liu Z., Sun T., Yu Y., et al. (2022). Near-real-time carbon emission accounting technology toward carbon neutrality. Engineering 14:44−51. DOI:10.1016/j.eng.2022.04.006 View in Article CrossRef Google Scholar
[48]	Tama A. and V. D. (2023). Carbon and Water Footprint Evaluation of 120Wp Rural Household Photovoltaic System. Smart Grid Renew. Energy 14. DOI:10.4236/sgre.2023.143003. View in Article Google Scholar
[49]	Nassar Y.F., El- Khozondar H. J., El-Osta. W., et al. (2024). Carbon footprint and energy life cycle assessment of wind energy industry in Libya. Energy Convers. Manag. 300:117846. DOI:10.1016/j.enconman.2023.117846 View in Article CrossRef Google Scholar
[50]	Burkhardt J.J., Heath G.A. and Turchi C.S. (2011). Life Cycle Assessment of a Parabolic Trough Concentrating Solar Power Plant and the Impacts of Key Design Alternatives. Environ. Sci. Technol. 45:2457−2464. DOI:10.1021/es1033266 View in Article CrossRef Google Scholar
[51]	Rödl A. (2025). Powerfuels: Status and Prospects. In N. Bullerdiek, U. Neuling and M. Kaltschmitt (eds). Powerfuels (pp:155–177). Springer Nature Switzerland. View in Article Google Scholar
[52]	Gunawardena M.A., Lokupitiya E. and Gunawardena P. (2024). Land degradation neutrality and carbon neutrality. Front. For. Glob. Change 7:1398864. DOI:10.3389/ffgc.2024.1398864 View in Article CrossRef Google Scholar
[53]	Li, Y., Zhang Q., Li Y., et al. (2025). Improving the efficiency of seawater desalination and hydrogen production: Challenges, strategies, and the future of seawater electrolysis. Desalination 609:118882. DOI:10.1016/j.desal.2025.118882 View in Article CrossRef Google Scholar
[54]	Zhu C., Guan B., Zhang Z., et al. (2025). Research status and advances of ammonia and hydrogen in the field of energy: Combined utilization. Energy Convers. Manag. 327:119610. DOI:10.1016/j.enconman.2025.119610 View in Article CrossRef Google Scholar
[55]	You Y., Kim S. and Lee J.C. (2023). Comparative study on ammonia and liquid hydrogen transportation costs in comparison to LNG. Int. J. Naval Arch. Ocean Eng. 15:100523. DOI:10.1016/j.ijnaoe.2023.100523 View in Article CrossRef Google Scholar
[56]	Ishaq T., Yousaf M., Ahmad Bhatti I. A., et al. (2021). A perspective on possible amendments in semiconductors for enhanced photocatalytic water splitting hydrogen generation. Int. J. Hydrog. Energy 46:39036−39057. DOI:10.1016/j.ijhydene.2021.09.165 View in Article CrossRef Google Scholar
[57]	Zhang, X., Zhao Y., Xu L., et al. (2022). Polarization Decomposing of Proton Exchange Membrane Fuel Cell Considering Liquid Water Accumulation. J. Electrochem. Soc. 169:124517. DOI:10.1149/1945-7111/aca6a8 View in Article CrossRef Google Scholar
[58]	Azizi M.A. and Brouwer J. (2018). Progress in solid oxide fuel cell-gas turbine hybrid power systems: System design and analysis, transient operation, controls and optimization. Appl. Energy 215:237−289. DOI:10.1016/j.apenergy.2018.01.098 View in Article CrossRef Google Scholar
[59]	Lin Z., L D. and Zou Y. (2023). Energy efficiency of lithium-ion batteries: Influential factors and long-term degradation. J. Energy Storage 74:109386. DOI:10.1016/j.est.2023.109386 View in Article CrossRef Google Scholar
[60]	Arsalis A., Papanastasiou P. and Georghiou G.E. (2022). A comparative review of lithium-ion battery and regenerative hydrogen fuel cell technologies for integration with photovoltaic applications. Renew. Energy 191:943−960. DOI:10.1016/j.renene.2022.04.075 View in Article CrossRef Google Scholar
[61]	Meng J., Zhao W., Li J., et al. (2025). Technologies and gaps in deep decarbonization of hard-to-abate industrial sectors. Nat. Rev. Clean Technol. 1:578−595. DOI:10.1038/s44359-025-00047-1 View in Article CrossRef Google Scholar
[62]	Wang Y., Chen C., Tao Y., et al. (2025). Uneven renewable energy supply constrains the decarbonization effects of excessively deployed hydrogen-based DRI technology. Nat. Commun. 16:4916. DOI:10.1038/s41467-025-50871-6 View in Article CrossRef Google Scholar
[63]	Lin S., Stephan A., Speth D., et al. (2024). Rapidly declining costs of truck batteries and fuel cells enable large-scale road freight electrification. Nat. Energy 9:1032−1039. DOI:10.1038/s41560-024-01220-9 View in Article CrossRef Google Scholar
[64]	Hyundai Motor Group (2026). XCIENT fuel truck surpasses 20 million km cumulative driving in Europe. shturl.cc/5zM6lEtimdAmz48JY2XWdjx6TJOiqFgqhRPI9RfQ8DMXJDbjhRgM. View in Article Google Scholar
[65]	Lokar, N., Ortiz M. M., Rachah A., et al. (2026). The role of hydrogen in mining decarbonisation. Renew. Sustain. Energy Rev. 226:116447. DOI:10.1016/j.rser.2026.116447 View in Article CrossRef Google Scholar
[66]	Tiwari S., Pekris M.J. and Doherty J.J. (2024). A review of liquid hydrogen aircraft and propulsion technologies. Int. J. Hydrog. Energy 57:1174−1196. DOI:10.1016/j.ijhydene.2024.1196 View in Article CrossRef Google Scholar
[67]	Yu Y., Zheng W., Li B., et al. (2025). A comprehensive review of cold start in proton-exchange membrane fuel cells: Challenges, strategies, and prospects. Appl. Energy 390:125846. DOI:10.1016/j.apenergy.2025.125846 View in Article CrossRef Google Scholar
[68]	Talukdar M., Blum P., Heinemann N. et al. (2024). Techno-economic analysis of underground hydrogen storage in Europe. iScience 27. DOI:10.1016/j.isci.2024.109447. View in Article Google Scholar
[69]	Mongird K., Viswanathan V., Alam J., et al. (2020). 2020 grid energy storage technology cost and performance assessment. Energy 2020:6−15. DOI:10.1016/j.energy.2020.117432 View in Article CrossRef Google Scholar
[70]	Dowling J.A., Rinaldiet K. Z., Ruggles T. H., et al. (2020). Role of long-duration energy storage in variable renewable electricity systems. Joule 4:1907−1928. DOI:10.1016/j.joule.2020.06.013 View in Article CrossRef Google Scholar
[71]	Wen Z., Huang B., Wang Y., et al. (2025). Ammonia as a renewable energy carrier from synthesis to utilization. Nat. Rev. Clean Technol. 1:755−770. DOI:10.1038/s44359-025-00050-4 View in Article CrossRef Google Scholar
[72]	Xu C., Steubing B., Hu M., et al. (2022). Future greenhouse gas emissions of automotive lithium-ion battery cell production. Resour. Conserv. Recycl. 187:106606. DOI:10.1016/j.resconrec.2022.106606 View in Article CrossRef Google Scholar
[73]	Johnson N., Liebreich M., Kammen D. M., et al. (2025). Realistic roles for hydrogen in the future energy transition. Nat. Rev. Clean Technol. 1:351−371. DOI:10.1038/s44359-025-00050-4 View in Article CrossRef Google Scholar
[74]	Télessy K., Barner L. and Holz F. (2024). Repurposing natural gas pipelines for hydrogen: Limits and options from a case study in Germany. Int. J. Hydrog. Energy 80:821−831. DOI:10.1016/j.ijhydene.2024.07.110 View in Article CrossRef Google Scholar
[75]	Brandt J., Iversen T., Eckert C., et al. (2024). Cost and competitiveness of green hydrogen and the effects of the European Union regulatory framework. Nat. Energy 9:703−713. DOI:10.1038/s41560-024-01511-z View in Article CrossRef Google Scholar
[76]	Ueckerdt, F., Verpoort P. C., Anantharaman R., et al. (2024). On the cost competitiveness of blue and green hydrogen. Joule 8:104−128. DOI:10.1016/j.joule.2023.12.004 View in Article CrossRef Google Scholar
[77]	Raviprabhakaran V. and Pabbu P. (2026). Machine learning optimized green hydrogen fuel cell system for sustainable and efficient electric vehicle charging. Proc. Inst. Mech. Eng. Part A J. Power Energy 240:468−484. DOI:10.1177/0957650925139663 View in Article CrossRef Google Scholar

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Zheng Y., Zhu Z., Ouyang Z., et al. (2026). Missing pieces in the hydrogen puzzle. The Innovation Energy 3:100173. https://doi.org/10.59717/j.xinn-energy.2026.100173

Zheng Y., Zhu Z., Ouyang Z., et al. (2026). Missing pieces in the hydrogen puzzle. The Innovation Energy 3:100173. https://doi.org/10.59717/j.xinn-energy.2026.100173

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Missing pieces in the hydrogen puzzle

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