Abstract
Hydrogen holds tremendous potential to decarbonize many economic sectors, from chemical and material industries to energy storage and generation. However, hydrogen is a tiny, leak-prone molecule that can indirectly warm the climate. Thus, hydrogen emissions from its value chain (production, conversion, transportation/distribution, storage, and end-use) could considerably undermine the anticipated climate benefits of a hydrogen economy. Several studies have identified value chain components that may intentionally and/or unintentionally emit hydrogen. However, the amount of hydrogen emitted from infrastructure is unknown as emissions have not yet been empirically quantified. Without the capacity to make accurate direct measurements, over the past two decades, some studies have attempted to estimate total value chain and component-level hydrogen emissions using various approaches, e.g., assumptions, calculations via proxies, laboratory experiments, and theory-based models (simulations). Here, we synthesize these studies to provide an overview of the available knowledge on hydrogen emissions across value chains. Briefly, the largest ranges in estimated emissions rates are associated with liquefaction (0.15%–10%), liquid hydrogen transporting and handling (2%–20%), and liquid hydrogen refueling (2%–15%). Moreover, present and future value chain emission rate estimates vary widely (0.2%–20%). Field measurements of hydrogen emissions throughout the value chain are critically needed to sharpen our understanding of hydrogen emissions and, with them, accurately assess the climate impact of hydrogen deployment.
Introduction
Hydrogen (H2) is a feedstock and an energy carrier with huge potential to limit the extent of climate change. Today, H2 is used in specialized industrial applications, such as chemical production and oil refining. Many propose a broad expansion of its use to a wide range of new applications, including renewable energy storage and power generation in industry and transportation, and by so doing have established H2 as a key component of global decarbonization efforts and the energy transition. The successful development of a hydrogen economy (ranging from H2 production to its use) could accelerate a transition to a global low-carbon economy, thereby helping to meet the Paris Agreement objective of limiting global warming to below 2°C (; ). Thus, policymakers and industries worldwide have begun a massive push for hydrogen, investing hundreds of billions of dollars into hydrogen projects (). However, whether the broad deployment of H2 will fulfill its promise to help meet near-term climate goals will depend on how it is produced, managed, and used ().
Currently, H2 is overwhelmingly produced from fossil fuels with very high associated levels of climate pollution (i.e., gray H2). Low-carbon H2 can be achieved by including carbon capture and sequestration (CCS) within this process (i.e., blue H2). Near-zero-carbon H2 can be produced from water electrolysis using a diversity of renewable energy sources (wind, solar, and hydro) (i.e., green or electrolytic H2), as well as nuclear energy (i.e., pink H2) (; ; ). Moreover, net zero-carbon H2 can be produced from biomass and renewable energy (i.e., bio H2) (). However, achieving climate-neutrality status also requires no hydrogen emissions.
Regardless of how it is produced, the H2 molecule is leak-prone and has indirect warming effects. H2 induces atmospheric perturbations that increase concentrations of three potent greenhouse gases (GHG): methane (CH4), water vapor in the stratosphere (H2O), and ozone in the troposphere (; ; ; ; ; ). Specifically, tropospheric H2 oxidation (H2 + OH = H + H2O) depletes the hydroxyl radical (OH), the primary sink for CH4, leading to a lengthening of the CH4 atmospheric lifetime. Additionally, producing atomic hydrogen (H) from H2 oxidation leads to a chain of reactions that produces tropospheric ozone. Furthermore, when this reaction occurs in the stratosphere, the increased water vapor produced leads to stratospheric cooling due to the enhancement of its radiative capacity, which results in the planet’s overall warming (; ).
Hydrogen’s warming effects play out over a period of a couple of decades (). The latest science suggests that over a 20-year period, H2 can cause 30 to 40 times more warming than CO2 for equal initial emissions in mass (). Because its impacts are short-lived, hydrogen’s warming potency is around 12 times that of CO2 over 100 years. Thus, the overall climate benefits, especially in the near term, from replacing fossil fuel systems with hydrogen alternatives will depend on how much H2 is emitted.
Studies show that if effectively handled, H2 could bring real climate benefits. With a low emissions rate, green H2 could nearly eliminate climate impacts compared to fossil fuels, and blue H2 could dramatically reduce impacts (; ). However, climate benefits decrease significantly with the increase in H2 emissions, posing a risk to decarbonization goals (; ; ).
To achieve the promised maximum climate benefits of H2, measures are needed to keep it from escaping into the atmosphere across the entire value chain (i.e., production, conversion, transport/distribution, storage, and end use). However, it is virtually unknown how much H2 is emitted intentionally and unintentionally from hydrogen systems since, to date, these emissions have not been measured, mainly because the instrumentation to measure H2 emissions at low-level concentrations has been lacking. Current commercially available sensors suitable for use in industrial settings can only detect H2 at higher concentrations (i.e., ppm level) that are relevant for ensuring safe operating conditions but not suitable for quantifying overall site-level emissions (; ). Sensors for site-level emissions quantification require high sensitivity (i.e., at the low ppb level), selectivity, and fast response (i.e., in seconds) in situ. However, such sensors are currently unavailable, with a new technology that can fill this gap only recently announced (). Accordingly, quantitative studies only analyze H2 leakage with a safety focus, often in confined spaces (; ; ; ; ).
Over the past two decades, several studies have attempted to estimate total value chain (; ; ) and component-level H2 emissions to assess the risk of large-scale hydrogen use on the climate (; ; ; ; ). Due to the lack of direct measurements, their estimation methods are heavily dependent on assumptions, calculations via proxies, laboratory experiments, or theoretically-based models or simulations. Here, we synthesized these studies to provide a complete picture of our current understanding of H2 emissions sources and magnitudes across the hydrogen value chain. This synthesis is instrumental in identifying research needs and strengthening the integrity of hydrogen initiatives. Specifically, identifying and quantifying H2 emissions from infrastructure will help determine prevention and mitigation opportunities that maximize hydrogen’s decarbonization benefits.
Literature surveyed
The issue of hydrogen emissions from energy infrastructure has enormous climate implications but is vastly understudied. The few studies that have attempted to estimate H2 emissions from the hydrogen economy (; ; ; ; ), hydrogen systems (e.g., H2 fuel cell vehicles (), refueling stations ()), or a specific value chain component (e.g., liquid H2 [LH2] handling ()) have served as a basis for similar studies that assess the effect of H2 deployment on the atmosphere and the climate (; ; ; ). Further studies have estimated H2 emissions from each value chain component considering previous estimates. This mini-review summarizes these initial attempts to estimate H2 emissions from hydrogen value chains. Notably, we synthesize the studies by , , , Frazer-Nash (2022), and , which are the sole studies that provide hydrogen emissions estimates for total and per-component value chains. Because of the limited number of publications on hydrogen emissions, which are well-known among the community in this field, no specific strategy was employed to find literature on this topic.
assumed low and high H2 emissions scenarios based on previously estimated H2 emission rates (; ; ). published a technical report based on a 2022 workshop focused on the environmental impacts of hydrogen emissions, which includes the H2 emissions estimates presented by Air Liquide for today and 2030. However, the underlying assumptions/data leading to their reported estimates are not detailed. estimated the potential emissions of H2 supply chains in the UK using natural gas supply chain emissions as a proxy. Similarly, used natural gas emission estimates and conventional fluid mechanics to predict H2 emissions in a 2050 UK hydrogen economy using a probabilistic model with 50% and 99% confidence intervals. Lastly, estimated the emissions of different value chain components in 2050 for low- and high-emission cases. For their estimates, they used published emission rates and extrapolated from comparisons with similar technologies (e.g., ; ; ; ; ; ).
Potential sources of H2 emissions throughout the value chain
Hydrogen emissions from hydrogen systems described in the literature can be divided into intentional and unintentional emissions or operational and fugitive emissions (see Supplementary Figure S1). The intentional emissions comprise operational purging and venting (; ; ; ). Most unintentional emissions are assumed to occur because H2 is the smallest molecule and has low molecular weight, high diffusivity, and low viscosity (; ), making it hard to contain. Therefore, H2 leaks more easily than other molecules managed (e.g., compressed, liquefied), transported, and stored. Accordingly, the reported unintentional and fugitive emissions include leakage from pipework (pipes, valves, joints, traps, assets, seals, etc.) and equipment, diffusion from pipelines, and permeation from where it is stored (e.g., compression or liquefaction tanks, salt caverns, and depleted oil and gas fields). Other unintentional emissions, such as residual H2 in exhaust streams and natural boil-off from liquefied H2, derive from operational procedures.
H2 emissions are likely to occur throughout the value chain, from production, conversion, transport, and storage to end-use applications. Figure 1 and Supplementary Table S1 summarize the type of potential H2 emissions described in the literature for value chain components. The primary potential H2 emissions attributed to H2 production are leakage through pipework and equipment and operational purging for maintenance, removal of impurities, and during fault conditions. Additionally, for blue H2 production, there may be residual H2 in the CO2 stream. Similarly, for green H2 production, the vented O2 stream may carry residual H2 (due to H2 cross-over through the membrane between the electrodes). While venting of process gases is assumed negligible in new blue H2 plants (gases will be sent to flare), venting during startup (venting air within the cathode) and shutdown (to remove moisture and any explosive gas mixture from the system) has been identified as a potential source of H2 emissions in green H2 production (; ).
FIGURE 1
Regarding H2 conversion, potential H2 emissions reported for compression and liquefaction are mainly due to leakage through pipework and equipment (e.g., engine slip and compressor leakage through seals). Planned process venting, pipeline venting (e.g., for maintenance), and purging during startup and shutdown have also been identified as potential emissions sources during compression (; ).
As for transportation, potential H2 emissions attributed to transmission and distribution pipelines include pipework and equipment leakage, venting, and diffusion (; ; ). For the transport of gaseous H2 on road tube trailers, leakage from fittings and valves and purging of the trailer hose have been reported as primary potential emissions sources. Boil-off is the main potential source reported for LH2 trucking. For LH2 handling (e.g., loading/unloading), leakage through equipment and venting, in addition to boil-off, have also been reported (; ; ; ).
The primary potential H2 emissions from H2 storage (above ground as a compressed gas or a cryogenic liquid and below ground in salt caverns and depleted oil and gas fields) include natural permeation and leakages through equipment due to pressurization and depressurization. For aboveground LH2 storage, there are additional identified potential emissions from boil-off and venting when boil-off leads to pressures deemed the safe maximum or releases to avoid getting close to critical pressures. In addition, for underground storage, venting and purging at surface processing plants due to annual maintenance, shutdown, and fault conditions (emergency shutdown) are other potential sources of emissions (; ; ).
The H2 emissions from the last component of the value chain, end uses, will vary depending on the application (e.g., transport, industrial, power generation with fuel cells, internal combustion engines, or gas turbines). However, emissions from leakages through equipment and purging or venting have been identified as potential sources of emissions across end-uses (Figure 1 and Supplementary Table S1).
Estimated H2 emission rates for value chain components reported to date
To provide a comprehensive overview of potential H2 emissions from each value chain component, we compiled published H2 emission rates and summarized them in Figure 2 and Supplementary Table S2. In the absence of direct measurements, these H2 emission rates were estimated through assumptions, calculations via proxies, laboratory experiments, and theory-based models (simulations). Many of these estimates are based on previously published H2 emissions assumptions and estimates from natural gas systems.
FIGURE 2
The synthesized references report emissions rates as a percentage of hydrogen produced, managed, or used in the respective supply chain component. All studies report ranges except , who provide a single estimate for today and 2030. Moreover, while and estimate current H2 emissions, and predict H2 emissions within three decades. It is also important to emphasize that and Frazer-Nash’s estimates are specific to UK hydrogen systems. Consequently, due to these differences and the different methodologies used to estimate emissions rates, it is evident in Figure 2 that there is a very wide range of estimates for each value chain component.
For H2 production, estimated emissions rates range between 0.5% and 1.0% for gray H2, 0.0%–1.5% for blue H2, and 0.03%–9.2% for green H2. Blue H2 production may have a higher leakage risk than gray H2 due to additional separation processes (). Green H2 production may have higher emissions than blue and other pathways (e.g., bioH2) due to the higher emission rates associated with electrolysis compared to steam methane reforming and biomass gasification ().
Estimated emissions rates associated with LH2 have the largest ranges; 0.15%–10.0% for liquefaction, 2.0%–13.2% for LH2 trucking, 2.0%–20% for LH2 handling, and 2.0%–15.0% for LH2 refueling stations. While some studies report emissions specific for liquefaction (; ), LH2 trucking (; ) or refueling (; ), others mention LH2 handling in general (; ).
Estimated emissions rates associated with gaseous H2 transport, storage, and use also vary widely; 0.02%–5.0% for transmission pipelines, 0.0003%–5.0% for distribution pipelines, 0.3%–2.3% for transportation on road tube trailers, 2.8%–6.5% for storage above ground, and 0.25%–3.0% for gas refueling stations (including the estimations for gaseous H2-powered vehicles by ()). H2 emissions rates estimated for common end-uses include 0.01%–3.0% for power generation, 1.0%–2.3% for ships and ports, and 3.0% for aviation (Figure 2). It should be noted that some of these emissions rates include emissions from two value-chain components (see details in Supplementary Table S2).
Overall, H2 transport is predicted to generate the most emissions (), especially transporting and handling LH2, which implies the need to manage boil-off (; ). Our survey of published emissions estimates makes it clear that more robust data is required to have confidence in the H2 emissions rates for each value chain or its components.
Estimated H2 emission rates of the total value chain
Without empirical data, very little confidence should be placed in total value chain emissions, as they are expected to be highly dependent on the configuration of the pathway and existing technology. To assess the environmental impacts of a potential hydrogen economy, several studies have estimated total H2 emissions rates between 0.2% and 20% from a diversity of value chains (e.g., ; ; ; ) (Supplementary Table S3). Specifically, estimated total value chain H2 emissions from 0.2% to 10% based on a per-component configuration. However, this range does not include emissions from production and compression and components of storage and end-use applications (Supplementary Table S2). Comparatively, Frazer-Nash includes components of production, transportation, storage, and several end-use applications but estimates total H2 emissions rates of 0.96%, at 50% confidence, and 1.50%, at 99% confidence. estimate total H2 emissions rates between 10% and 20%, mainly due to H2 transport. However, indicate that only for extreme individual cases, like uncontrolled evaporation from LH2 storage tanks, would 10%–20% emissions rates be possible. Further studies on the climate impacts of H2 have assumed a range of 1%–10% of total value chain emissions citing previous studies (; ; ; ; ; ; ).
Discussion
It is unknown whether technological advancements have influenced hydrogen emissions over the last two decades due to the lack of empirical data. This paucity of experimental validation has resulted in a vast range of estimates among studies that attempt to quantify H2 emissions, as they are based on various assumptions that are often poorly supported. For example, and used the natural gas distribution system and conventional fluid mechanics to estimate H2 emissions. While this might be the only plausible approach, there is a high degree of uncertainty in current CH4 emissions estimates (; ; ), as well as the fluid flow regimes and mechanisms contributing to H2 leakage ().
Accurately assessing the climate impacts of switching to a hydrogen economy requires empirical data on H2 emissions from production through end uses (Figure 1 and Supplementary Table S1). However, until now, accurately measuring site-level H2 emissions was not feasible due to a lack of the high precision fast response instruments required (e.g., ∼10 ppb or 0.01 ppm sensitivity; one to a few seconds response time).
These measurements are critical for several reasons. First, they would support improvements in chemistry-climate models to understand the potential effects of hydrogen deployment on atmospheric composition and radiative forcing (; ). Second, field measurements of specific value chain components would improve life cycle assessments by accurately accounting for the warming effects from H2 emissions; this would improve comparisons between hydrogen systems and other alternatives to fossil fuels, like direct electrification. Third, measurements would help identify major emission sources and mitigation opportunities to inform best practices.
The H2 emissions magnitudes will depend on the industry scale in the future. Consequently, the industry size will play a major role in how these emissions influence the climate (). Nevertheless, mitigating H2 emissions from operational procedures will be essential for maximizing the climate benefits of hydrogen systems. For instance, waste H2 (residual, purged, or vented) could be used to produce process heat and electricity (), and boil-off could be recovered (). In electrolytic H2 production, H2 purged during purification and cross-over H2 passing into the O2 chamber could be recombined with O2 and converted back into water rather than vented into the atmosphere. Moreover, leakage can be minimized by tightening valves and seals, and leakage through the casing of electrolyzers and other equipment could be mitigated through laminated gaskets and welded joints ().
Lastly, it is important to mention that hydrogen systems have climate implications beyond hydrogen emissions (; ). Blue H2 pathways that rely on fossil fuel-based energy sources and have low carbon capture and long-term storage efficiencies result in high greenhouse gas emissions. In addition, the energy efficiency of hydrogen production, storage, and transportation compared to direct electrification has climate implications. Direct electrification of end uses using renewable energy is generally more energy-efficient and has lower GHG emissions than hydrogen systems (; ; ). Thus, using hydrogen (blue, green, or another pathway) in easily electrifiable end-use applications may result in higher overall GHG emissions than direct electrification.
Concluding remarks
Some studies have estimated hydrogen emissions magnitudes from total and per-component value chains with various assumptions and methodologies, leading to a wide range of emissions rate estimates. Based on our literature review, which includes the most extreme upper limits that are often criticized and considered “unrealistic” or “outdated”, we find little basis for characterizing the actual range in H2 emissions rates with reasonable confidence. Therefore, identifying and empirically quantifying H2 emissions throughout the value chain is fundamental.
Fortunately, there is still time to prevent suboptimal outcomes, as most of the hydrogen infrastructure proposed to meet decarbonization targets has yet to be built (; ; ). With accurate measurements of H2 emissions and knowledge of mitigation strategies and best practices, we can reduce the likelihood of developing leaky systems and minimize H2 emissions in the growing H2 value chain, which is critical to ensure the climate benefits we intend to achieve with H2 deployment (; ; ).
Statements
Author contributions
SH, IO, and TS conceptualized the project. AH, SE-E, and ES collected the information and data. SE-E and IO conducted the data visualization. SE-E wrote the first draft. All authors contributed to the article and approved the submitted version.
Acknowledgments
The authors thank Werner Weindorf, Patrick Schmidt, and Yanni Sandro Astono from the Ludwig-Bölkow-Systemtechnik GmbH consultancy for their insightful discussions on estimated hydrogen emissions rates from infrastructure. We also thank Dr. Jasmine Cooper for her communications on their reported hydrogen emissions estimates. AH thanks Jack Brouwer for his academic support. This manuscript has been released as a pre-print at OSF (Esquivel-Elizondo et al., 2023).
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Correction note
This article has been corrected with minor changes. These changes do not impact the scientific content of the article.
Publisher’s note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
Supplementary material
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fenrg.2023.1207208/full#supplementary-material
References
1
AlvarezR. A.PacalaS. W.WinebrakeJ. J.ChameidesW. L.HamburgS. P. (2012). Greater focus needed on methane leakage from natural gas infrastructure. PNAS109, 6435–6440. 10.1073/pnas.1202407109
2
AlvarezR. A.Zavala-AraizaD.LyonD. R.AllenD. T.BarkleyZ. R.BrandtA. R.et al (2018). Assessment of methane emissions from the U.S. oil and gas supply chain. Science361, 186–188. 10.1126/science.aar7204
3
ArrigoniA.DiazB. L. (2022). Hydrogen emissions from a hydrogen economy and their potential global warming impact. Belgium, Germany: European Commission, Joint Research Center.
4
BondS. W.GülT.ReimannS.BuchmannB.WokaunA. (2011). Emissions of anthropogenic hydrogen to the atmosphere during the potential transition to an increasingly H2-intensive economy. Int. J. Hydrogen Energy36, 1122–1135. 10.1016/j.ijhydene.2010.10.016
5
ChangY.ZhangC.ShiJ.LiJ.ZhangS.ChenG. (2019). Dynamic Bayesian network based approach for risk analysis of hydrogen generation unit leakage. Int. J. Hydrogen Energy44, 26665–26678. 10.1016/J.IJHYDENE.2019.08.065
6
ColellaW. G.JacobsonM. Z.GoldenD. M. (2005). Switching to a U.S. hydrogen fuel cell vehicle fleet: The resultant change in emissions, energy use, and greenhouse gases. J. Power Sources150, 150–181. 10.1016/J.JPOWSOUR.2005.05.092
7
CooperJ.DubeyL.BakkalogluS.HawkesA. (2022). Hydrogen emissions from the hydrogen value chain-emissions profile and impact to global warming. Sci. Total Environ.830, 154624. 10.1016/j.scitotenv.2022.154624
8
Department of Energy (2022). DOE National clean hydrogen strategy and roadmap. Washington, D.C., USA.
9
DerwentR. G.CollinsW. J.JohnsonC. E.StevensonD. S. (2001). Transient behaviour of tropospheric ozone precursors in a global 3-D CTM and their indirect greenhouse effects. Clim. Change49, 463–487. 10.1023/A:1010648913655
10
DerwentR. G. (2018). Hydrogen for heating: Atmospheric impacts. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/760538/Hydrogen_ atmospheric_impact_report.pdf.
11
DerwentR. G.StevensonD. S.UtembeS. R.JenkinM. E.KhanA. H.ShallcrossD. E. (2020). Global modelling studies of hydrogen and its isotopomers using STOCHEM-CRI: Likely radiative forcing consequences of a future hydrogen economy. Int. J. Hydrogen Energy45, 9211–9221. 10.1016/j.ijhydene.2020.01.125
12
DerwentR.SimmondsP.O’dohertyS.ManningA.CollinsW.StevensonD. (2006). Global environmental impacts of the hydrogen economy. Int. J. Nucl. Hydrogen Prod. Appl.1, 57–67. 10.1504/IJNHPA.2006.009869
13
DillmanK.HeinonenJ. (2023). Towards a safe hydrogen economy: An absolute climate sustainability assessment of hydrogen production. Climate11, 25. 10.3390/cli11010025
14
EDF and Aerodyne (2023). As climate concerns about hydrogen energy grow, new tech unveiled at CERAWeek delivers unprecedented results measuring leaks, other emissions. URL https://www.businesswire.com/news/home/20230305005045/en/As-Climate-Concerns-About-Hydrogen-Energy-Grow-New-Tech-Unveiled-at-CERAWeek-Delivers-Unprecedented-Results-Measuring-Leaks-Other-Emissions.
15
EhhaltD. H.RohrerF. (2009). The tropospheric cycle of H<sub>2</sub>: A critical review. Tellus B Chem. Phys. Meteorol.61, 500. 10.1111/j.1600-0889.2009.00416.x
16
Energy Transitions Commission (2021). Making the hydrogen economy possible: Accelerating clean hydrogen in an electrified economy. London, UK: Energy Transitions Commission.
17
FanZ.SheeraziH.BhardwajA.CorbeauA.-S.LongobardiK.CastañedaA.et al (2022). Hydrogen leakage: A potential risk for the hydrogen economy. New York, NY, USA: Columbia University.
18
FichtnerM.IdrissovaF. (2009). “Fundamental properties of hydrogen,” in The hydrogen economy: Opportunities and challenges (Cambridge, United Kingdom: Cambridge University Press), 271–276.
19
FieldR. A.DerwentR. 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. Hydrogen Energy46, 30190–30203. 10.1016/j.ijhydene.2021.06.120
20
Frazer-Nash Consultancy (2022). Fugitive hydrogen emissions in a future hydrogen economy. United Kingdom: Frazer-Nash Consultancy.
21
GenoveseM.BlekhmanD.DrayM.FragiacomoP. (2019). Hydrogen losses in fueling station operation. J. Clean. Prod.248, 119266. 10.1016/j.jclepro.2019.119266
22
HajjiY.JouiniB.BouteraaM.ElcafsiA.BelghithA.BournotP. (2015). Numerical study of hydrogen release accidents in a residential garage. Int. J. Hydrogen Energy40, 9747–9759. 10.1016/J.IJHYDENE.2015.06.050
23
HauglustaineD.PaulotF.CollinsW.DerwentR.SandM.BoucherO. (2022). Climate benefit of a future hydrogen economy. Commun. Earth Environ.3, 295. 10.1038/s43247-022-00626-z
24
Hormaza MejiaA.BrouwerJ.mac KinnonM. (2020). Hydrogen leaks at the same rate as natural gas in typical low-pressure gas infrastructure. Int. J. Hydrogen Energy45, 8810–8826. 10.1016/j.ijhydene.2019.12.159
25
Hormaza MejiaA. N.BrouwerJ. (2018). Gaseous fuel leakage from natural gas infrastructure. New York, NY, USA: American Society of Mechanical Engineers ASME.
26
Hydrogen Council (2021). Hydrogen insights report 2021. https://hydrogencouncil.com/en/hydrogen-insights-2021/.
27
Hydrogen Council (2017). Hydrogen scaling up. https://hydrogencouncil.com/en/study-hydrogen-scaling-up/.
28
International Energy Agency (2021). Global hydrogen review 2021. https://www.iea.org/reports/global-hydrogen-review-2021.
29
International Energy Agency (2019). The future of hydrogen. https://www.iea.org/reports/the-future-of-hydrogen.
30
JacobsonM. Z.ColellaW. G.GoldenD. M. (2005). Cleaning the air and improving health with hydrogen fuel-cell vehicles. Science308, 1898–1901.
31
JacobsonM. Z. (2008). Effects of wind-powered hydrogen fuel cell vehicles on stratospheric ozone and global climate. Geophys Res. Lett.35, L19803. 10.1029/2008GL035102
32
KammenD. M.LipmanT. E.LovinsA. B.LehmanP. A.EilerJ. M.TrompT. K.et al (2003). Assessing the future hydrogen economy. Science302, 226–229. 10.1126/science.302.5643.226b
33
KobayashiH.NaruoY.MaruY.TakesakiY.MiyanabeK. (2018). Experiment of cryo-compressed (90-MPa) hydrogen leakage diffusion. Int. J. Hydrogen Energy43, 17928–17937. 10.1016/j.ijhydene.2018.07.145
34
KyriakopoulosG. L. (2021). “Should low carbon energy technologies be envisaged in the context of sustainable energy systems?,” in Low carbon energy technologies in sustainable energy systems (Amsterdam, Netherlands: Elsevier), 357–389. 10.1016/B978-0-12-822897-5.00015-8
35
NajjarY. S. (2019). Hydrogen leakage sensing and control: (Review). Biomed. J. Sci. Tech. Res.21, 16228–16240. 10.26717/bjstr.2019.21.003670
36
OckoI. B.HamburgS. P. (2022). Climate consequences of hydrogen emissions. Atmos. Chem. Phys.22, 9349–9368. 10.5194/acp-22-9349-2022
37
PanfilovM. (2016). “4 - underground and pipeline hydrogen storage,” in Compendium of hydrogen energy. Editors GuptaR. B.BasileA.VeziroğluT. N. (Sawston, United Kingdom: Woodhead Publishing), 91–115.
38
ParviniM.GharagouzlouE. (2015). Gas leakage consequence modeling for buried gas pipelines. J. Loss Prev. Process Ind.37, 110–118. 10.1016/J.JLP.2015.07.002
39
PaulotF.PaynterD.NaikV.MalyshevS.MenzelR.HorowitzL. W. (2021). Global modeling of hydrogen using GFDL-AM4.1: Sensitivity of soil removal and radiative forcing. Int. J. Hydrogen Energy46, 13446–13460. 10.1016/j.ijhydene.2021.01.088
40
PetitpasG. (2018), LLNL-TR-750685. Livermore CA, USA: Lawrence Livermore National Laboratory.Boil-off losses along LH2 pathway
41
PratherM. J. (2003). An environmental experiment with H2?Science302, 581–582. 10.1126/science.1091060
42
QianJ. Y.LiX. Y.GaoZ. X.JinZ. J. (2020). A numerical study of hydrogen leakage and diffusion in a hydrogen refueling station. Int. J. Hydrogen Energy45, 14428–14439. 10.1016/J.IJHYDENE.2020.03.140
43
RiddickS. N.MauzerallD. L. (2023). Likely substantial underestimation of reported methane emissions from United Kingdom upstream oil and gas activities. Energy Environ. Sci.16, 295–304. 10.1039/d2ee03072a
44
SchultzM. G.DiehlT.BrasseurG. P.ZittelW. (2003). Air pollution and climate-forcing impacts of a global hydrogen economy. Science302, 624–627. 10.1126/science.1089527
45
SEBEIS (2021). UK hydrogen strategy. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1011283/UK-Hydrogen-Strategy_web.pdf.
46
ShenL.Zavala-AraizaD.GautamR.OmaraM.ScarpelliT.ShengJ.et al (2021). Unravelling a large methane emission discrepancy in Mexico using satellite observations. Remote Sens. Environ.260, 112461. 10.1016/j.rse.2021.112461
47
SherifS. A.ZeytinogluN.VeziroglugT. N. (1997). Liquid hydrogen: Potential problems, and a proposed research program. Int. J. Hydrogen Energy22, 683–688. 10.1016/s0360-3199(96)00201-7
48
ShresthaE.SunT. (2023). Rule #1 of deploying hydrogen: Electrify first. URL https://blogs.edf.org/energyexchange/2023/01/30/rule-1-of-deploying-hydrogen-electrify-first/.
49
TrompT. K.ShiaR.-L.AllenM.EilerJ. M.YungY. L. (2003). Potential environmental impact of a hydrogen economy on the stratosphere. Potential Environ. impact a hydrogen Econ. Stratos.300, 1740–1742. 10.1126/science.1085169
50
UeckerdtF.BauerC.DirnaichnerA.EverallJ.SacchiR.LudererG. (2021). Potential and risks of hydrogen-based e-fuels in climate change mitigation. Nat. Clim. Chang.11, 384–393. 10.1038/s41558-021-01032-7
51
ValenteA.IribarrenD.DufourJ. (2017). Harmonised life-cycle global warming impact of renewable hydrogen. J. Clean. Prod.149, 762–772. 10.1016/j.jclepro.2017.02.163
52
van RuijvenB.LamarqueJ. F.van VuurenD. P.KramT.EerensH. (2011). Emission scenarios for a global hydrogen economy and the consequences for global air pollution. Glob. Environ. Change21, 983–994. 10.1016/j.gloenvcha.2011.03.013
53
VilbergssonK. V.DillmanK.EmamiN.ÁsbjörnssonE. J.HeinonenJ.FingerD. C. (2023). Can remote green hydrogen production play a key role in decarbonizing europe in the future? A cradle-to-gate lca of hydrogen production in Austria, Belgium, and Iceland. Int. J. Hydrogen Energy48, 17711–17728. 10.1016/j.ijhydene.2023.01.081
54
VölklJ.AlefeldG. (1975). “Hydrogen diffusion in metals,” in Diffusion in solids: Recent developments. Editors NowickA. S.BurtonJ. J. (New York, NY, USA: Academic Press), 231–302.
55
WarwickN.GriffithsP.KeebleJ.ArchibaldA.PyleJ. (2022). Atmospheric implications of increased hydrogen use. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1067144/atmospheric-implications-of-increased-hydrogen-use.pdf.
56
WarwickN. J.ArchibaldA. T.GriffithsP. T.KeebleJ.O’connorF. M.PyleJ. A.et al (2023). Atmospheric composition and climate impacts of a future hydrogen economy. Atmos. Chem. Phys. Prepr., 10.5194/acp-2023-29
57
WarwickN. J.BekkiS.NisbetE. G.PyleJ. A. (2004). Impact of a hydrogen economy on the stratosphere and troposphere studied in a 2-D model. Geophys Res. Lett.31. 10.1029/2003gl019224
58
WuebblesD. J.DubeyM. K.EdmondsJ.LayzellD.OlsenS.RahnT.et al (2010). “Evaluation of the potential environmental impacts from large-scale use and production of hydrogen in energy and transportation applications,”. DOE/07GO17109 (Denton, Texas, United States: UNT Digital Library). 10.2172/1044180
59
XiaX.ZhouH.ZhangY.JiangH. (2019). Innovative steam methane reforming for coproducing CO-free hydrogen and syngas in proton conducting membrane reactor. AIChE J.65. 10.1002/aic.16740
60
YugoM.SolerA. (2019). A look into the role of e-fuels in the transport system in Europe (2030-2050) (literature review). https://www.concawe.eu/wp-content/uploads/E-fuels-article.pdf.
61
ZhaoG.KraglundM. R.FrandsenH. L.WulffA. C.JensenS. H.ChenM.et al (2020). Life cycle assessment of H2O electrolysis technologies. Int. J. Hydrogen Energy45, 23765–23781. 10.1016/j.ijhydene.2020.05.282
Summary
Keywords
hydrogen economy, hydrogen value chain, hydrogen emissions, hydrogen leakage, hydrogen leaks
Citation
Esquivel-Elizondo S, Hormaza Mejia A, Sun T, Shrestha E, Hamburg SP and Ocko IB (2023) Wide range in estimates of hydrogen emissions from infrastructure. Front. Energy Res. 11:1207208. doi: 10.3389/fenrg.2023.1207208
Received
17 April 2023
Accepted
26 July 2023
Published
04 August 2023
Corrected
22 January 2026
Volume
11 - 2023
Edited by
Siamak Hoseinzadeh, Sapienza University of Rome, Italy
Reviewed by
Kevin Dillman, University of Iceland, Iceland
Grigorios L. Kyriakopoulos, National Technical University of Athens, Greece
Updates
Copyright
© 2023 Esquivel-Elizondo, Hormaza Mejia, Sun, Shrestha, Hamburg and Ocko.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Sofia Esquivel-Elizondo, sesquivelelizondo@edf.org
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.