ACS Publications. Most Trusted. Most Cited. Most Read
Climate Impacts of Hydrogen and Methane Emissions Can Considerably Reduce the Climate Benefits across Key Hydrogen Use Cases and Time Scales
My Activity

Figure 1Loading Img
  • Open Access
Energy and Climate

Climate Impacts of Hydrogen and Methane Emissions Can Considerably Reduce the Climate Benefits across Key Hydrogen Use Cases and Time Scales
Click to copy article linkArticle link copied!

Open PDFSupporting Information (1)

Environmental Science & Technology

Cite this: Environ. Sci. Technol. 2024, 58, 12, 5299–5309
Click to copy citationCitation copied!
https://doi.org/10.1021/acs.est.3c09030
Published February 21, 2024

Copyright © 2024 The Authors. Published by American Chemical Society. This publication is licensed under

CC-BY-NC-ND 4.0 .

Abstract

Click to copy section linkSection link copied!

Recent investments in “clean” hydrogen as an alternative to fossil fuels are driven by anticipated climate benefits. However, most climate benefit calculations do not adequately account for all climate warming emissions and impacts over time. This study reanalyzes a previously published life cycle assessment as an illustrative example to show how the climate impacts of hydrogen deployment can be far greater than expected when including the warming effects of hydrogen emissions, observed methane emission intensities, and near-term time scales; this reduces the perceived climate benefits upon replacement of fossil fuel technologies. For example, for blue (natural gas with carbon capture) hydrogen pathways, the inclusion of upper-end hydrogen and methane emissions can yield an increase in warming in the near term by up to 50%, whereas lower-end emissions decrease warming impacts by at least 70%. For green (renewable-based electrolysis) hydrogen pathways, upper-end hydrogen emissions can reduce climate benefits in the near term by up to 25%. We also consider renewable electricity availability for green hydrogen and show that if it is not additional to what is needed to decarbonize the electric grid, there may be more warming than that seen with fossil fuel alternatives over all time scales. Assessments of hydrogen’s climate impacts should include the aforementioned factors if hydrogen is to be an effective decarbonization tool.

This publication is licensed under

CC-BY-NC-ND 4.0 .
  • cc licence
  • by licence
  • nc licence
  • nd licence
Copyright © 2024 The Authors. Published by American Chemical Society

Synopsis

This study shows that “clean” hydrogen deployment can be significantly better or worse for the climate depending on factors that are not usually considered in life cycle assessment frameworks.

1. Introduction

Click to copy section linkSection link copied!

The urgency of addressing the climate crisis has accelerated global momentum for low-carbon (herein termed “clean”) hydrogen as a pathway to reduce carbon dioxide emissions while also providing energy security and driving economic growth. Governments, companies, and investors around the world have announced commitments to spend over $500 billion on more than 1000 hydrogen projects over the next decade. (1) Decisions to scale up clean hydrogen systems are often driven by the assumption that they will accrue large climate benefits when compared to fossil fuels. (2−6) However, there are several shortcomings within the hydrogen assessment frameworks that are often the basis for estimating hydrogen’s benefits.
Currently, conventional hydrogen technology assessments lack consideration of hydrogen emissions and their warming effects, (2−5,7−9) yet hydrogen is a leak-prone gas with a potent indirect warming effect in the near term due to the fact that its chemical oxidation in the atmosphere increases the levels of other short-lived greenhouse gases (GHGs) in the atmosphere (methane, tropospheric ozone, and stratospheric water vapor). (10−13) This needs to be considered to fully understand the implications of deploying hydrogen at scale. Hydrogen’s indirect warming effects have been documented over the past several decades, (14−23) with a consensus emerging that hydrogen’s global warming potential (GWP) is approximately 12 over a 100-year period and approximately 35–40 over a 20-year period. (10−13) The largest uncertainties in hydrogen’s GWP are associated with the removal of atmospheric hydrogen by soil and potential future changes in the atmospheric concentrations of other GHGs such as methane. (10−13)
First, hydrogen emissions are of particular concern given that molecular hydrogen is the smallest molecule and can easily leak from infrastructure in addition to being routinely released to the atmosphere through venting and purging operations. (24−28) Emission estimates to date (leakage, venting, and purging) range from <1% to 20% varying across value chain components with higher emission rates often associated with liquid hydrogen, but no empirical measurements of real-world infrastructure and facilities are available. (27,28) Given the similarity between hydrogen and natural gas infrastructure, and the fact that natural gas emissions have been shown to be higher than previously thought, (29,30) it is reasonable to expect that hydrogen emissions may also be significant.
Second, while methane emissions are often included in hydrogen technology climate impact assessments (relevant for both blue hydrogen technologies and fossil fuel alternatives), the emission rates are often not consistent with those empirically measured across a diversity of facilities and supply chains. Direct measurements that have been made over the past decade suggest that there are large regional- and basin-level variations in methane emission intensities, from <1% to >3%. (29−33) However, the assumption of a low level of methane leakage is common, while some studies assume a high level of methane leakage. (34,35) Given that ground-level, airborne, and satellite measurements of methane emissions over the past decade have greatly improved our understanding of oil and gas methane emissions, a more sophisticated treatment of methane emissions is warranted. Higher than anticipated methane emissions could undercut the climate benefits of deploying hydrogen technologies as a replacement for fossil fuels, especially in the near term. (12,34,36−38)
Third, the availability of renewable electricity is a fundamental component of the impact of the green hydrogen pathways. It is often assumed that green hydrogen production utilizes excess or new renewable resources and does not influence the rate of decarbonization of the electric grid. However, given the large gap between the availability of and demand for zero-carbon electricity, there is concern that green electrons could be diverted from decarbonizing the power grid. If this occurs, then the resulting gap would need to come from natural gas- or coal-fired power plants, leading to increased GHG emissions. (39)
Fourth, the standard metric employed for assessing climate impacts (GWP with a 100-year time horizon) does not convey warming effects in the near term and assumes an unrealistic one-time pulse of emissions rather than continuous emissions over time. GWP is used to combine emissions of multiple GHGs by converting non-carbon dioxide climate pollutant emissions to their carbon dioxide “equivalent” based on radiative properties and atmospheric lifetimes. Conventional technology assessment frameworks often use GWPs with a 100-year time horizon, which considers the long-term warming effect from a one-time pulse of emissions. For climate pollutants with short-lived warming effects, including methane and hydrogen, evaluating warming effects over 100 years masks their near-term impacts, and using a one-time pulse approach disregards their atmospheric replenishment from continuous emissions. (36,40,41)
This study addresses these shortcomings by reanalyzing a widely referenced life cycle assessment (LCA) analysis of blue and green hydrogen technologies (5) and incorporating (1) a range of plausible hydrogen emission rates, (2) a range of observed methane emission rates from different regions, (3) impacts of additional versus non-additional renewable electricity, and (4) multiple time horizons for evaluation of climate impacts and continuous emissions rather than pulse emissions (Table S1). This analysis provides an illustrative example of how the climate impacts of hydrogen deployment change when these factors are considered. It also offers a more complete understanding of the climate benefits, or lack thereof, of specific hydrogen applications relative to their fossil fuel alternatives.

2. Methods

Click to copy section linkSection link copied!

Utilizing recent improvements in our understanding of the underlying factors affecting hydrogen value chains, we reanalyze a set of hydrogen LCA pathways published by the Hydrogen Council (2021, termed “HC21” here). (5) Although the designs of these pathways (the production method, transportation mode, and end use application) are arbitrary and do not cover all possible future hydrogen pathways comprehensively, they provide a set of illustrative blue and green hydrogen scenarios that cover diverse applications in multiple economic sectors that are envisioned for future hydrogen value chains.
The LCA analysis in HC21 includes eight hydrogen production-to-end use pathways across the industrial, power, and transportation sectors, four for blue hydrogen (natural gas autothermal reforming with a 98% carbon capture rate) used in long-distance passenger vehicles, ships, industrial heat, and ammonia-based power generation, and four for green hydrogen (electrolysis with wind and/or solar power) used in fertilizer production, buses, heavy-duty trucks, and steel making (Table S2 and Exhibit 4 in HC21). Each hydrogen pathway has a fossil fuel-based alternative, and the blue hydrogen long-distance passenger vehicle pathway also includes a low-carbon alternative, a battery electric vehicle using grid electricity.
HC21 estimates the life cycle GHG emissions for each pathway and alternative for “well-to-use” at two points in time, 2030 and 2050, with overall lower GHG emissions in 2050 due to decreased emissions from grid electricity [which is used for manufacturing, processing, and other auxiliary electricity demand (details on page 7 of HC21)]. While our analysis considers conditions in both 2030 and 2050, the results presented in the text primarily focus on 2050, with the results for 2030 presented in the Supporting Information.
We supplement HC21 with additional climate pollutants, assumptions, and metrics (Table S1). The HC21 analysis includes emissions of the following GHGs: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbon (HFC) 134a, and carbon tetrafluoride (CF4). Our study includes hydrogen emissions for all hydrogen pathways given that it is an indirect GHG. We assume that 1–10% of total hydrogen consumption is lost to the atmosphere. While emission rates lower or higher than this range can occur for specific components of the hydrogen value chain, the estimates are highly uncertain due to the lack of empirical evidence. (28) Therefore, we follow the assumptions of value chain hydrogen emissions from previous studies (10,20−25,27,42−46) in that we exclude the extreme cases and assume a moderate range of emission rates of 1–10%.
Given that the original upstream CH4 emissions associated with blue hydrogen production (and the fossil fuel alternatives) in the HC21 analysis are assumed to be very low (0.2–0.5% leak rate), we replace the original emission rates with three levels of emission intensities (low, 0.6%; medium, 0.9%; and high, 2.1%) based on data representative of the top 25 oil- and gas-producing countries (IEA Methane Tracker; note that these intensities are for gas-related methane emissions only and do not include oil-related methane emissions; see the Supporting Information for more information). (47) We also assess the impacts when extremely low (0.01%) and extremely high (5.4%) emission rates are considered. For the fossil fuel pathways that utilize gasoline and diesel, we replace the original upstream methane emissions rates (∼0.35 g/kWh) with multiple levels of emission intensities that are associated with oil production [extremely low, 0.006 g/kWh; low, 0.6 g/kWh; medium, 1.0 g/kWh; high, 2.6 g/kWh; and extremely high, 11.4 g/kWh (see the Supporting Information for more information)]. (47) Although the estimates of country-level methane emission intensities are highly uncertain (especially in data-poor regions), they are useful for capturing the plausible range of methane emissions associated with natural gas use for blue hydrogen production as well as fossil fuel alternatives. When we isolate the effect of hydrogen emissions in the LCA, a medium methane emission rate (0.9%) is applied to all pathways and alternatives.
The assumption of carbon capture efficiency with autothermal reforming is 98% with permanent storage in the original LCA. Given that this is a very optimistic assumption that can have significant impacts on the climate benefits of hydrogen pathways, (38,48) we also consider a lower carbon capture rate, 60%, to assess the impact of carbon capture efficiency on the climate benefits of blue hydrogen pathways (more information in the Supporting Information).
To assess how renewable electricity capacity assumptions can affect the climate impacts of green hydrogen pathways given the near-term limitation of renewable resources, we consider two alternative scenarios for 2030 in addition to the original LCA that assumes additional renewable capacity: the renewable electricity used to produce hydrogen that would have otherwise gone into the power grid, which is replaced with electricity from either (1) a natural gas power plant or (2) a coal-fired power plant. We also compare the warming effects of the utilization of a projected global-averaged grid electricity mix in 2030 [emission factors from IRENA 2022 (see Table S4)] that is consistent with a 1.5 °C decarbonization pathway. (49)
To quantify the relative climate impacts of hydrogen pathways compared to their fossil fuel alternatives, we utilize two methods. First, we compare the cumulative radiative forcing from continuous (i.e., constant) emissions from the hydrogen pathways to that from the fossil fuel pathways they are replacing, considering 10-, 20-, 50-, and 100-year time scales. This is a metric known in the literature as the technology warming potential (TWP) and was first introduced by Alvarez et al. (40) Second, we compare the total emissions in CO2 equivalences (CO2e) using GWPs for the 20- and 100-year time horizons (Table S8). While both approaches utilize the same radiative properties and lifetimes of GHGs (see the Supporting Information for equations and their inputs), the first approach (TWP) more realistically represents the climate impacts of switching from one technology to another because it considers continuous emissions as opposed to a one-time pulse. On the other hand, the second approach (CO2e) directly expands on the standard one-time pulse method used in current LCAs (and in the original HC21 LCA) by adding a near-term time scale (20 years) in addition to a long-term time scale (100 years).

3. Results

Click to copy section linkSection link copied!

Overall, the cumulative warming impact from constant emissions of switching from fossil fuel technologies to blue or green hydrogen technologies depends on the specific application, production method, hydrogen and methane emissions rates, and time scale of interest (Figure 1). The relative impact across all time scales (under 2050 conditions) ranges from a 93% reduction in warming to a 46% increase in warming (considering extreme cases), meaning either a near elimination of the warming impacts of fossil fuel technologies or even more warming from the hydrogen technologies. The results under 2030 conditions are similar (see the Supporting Information).

Figure 1

Figure 1. Overview of the life cycle climate impacts of eight hydrogen pathways relative to their fossil fuel alternatives in 2050 considering a range of hydrogen emission rates (1–10%) and methane emission intensities (from extremely low, 0.01%, to extremely high, 5.4%). Each vertical bar represents the range of climate benefits (or disbenefits) by switching to hydrogen from fossil fuels for the best-case scenario (1% hydrogen emissions and a low methane emission intensity of 0.6%) to the worst-case scenario (10% hydrogen emissions and a high methane emissions intensity of 2.1%). Near-term (NT, 20 years) and long-term (LT, 100 years) climate impacts are presented for each pathway. The originally reported climate impacts of these pathways in Hydrogen Council report (2021) are denoted as black triangles. The climate impact of the battery electric alternative for the light-duty vehicle pathway is noted with the letter E.

For blue hydrogen applications with low methane and hydrogen emission rates, hydrogen technologies can be 64–80% (72–86%) better for the climate than fossil fuel technologies in the near (long) term. With high emission rates, hydrogen technologies can be 51% (68%) better for the climate to 14% worse (32% better) for the climate than fossil fuel technologies in the near (long) term. There are two pathways that can lead to an increase in warming in the near term under extremely high-methane and high-hydrogen emission scenarios: (1) replacing natural gas industrial heat with blue hydrogen industrial heat and (2) replacing natural gas power generation with blue ammonia (derived from hydrogen) power generation. However, if both hydrogen and methane emissions are low (extremely low), then these technologies can reduce warming impacts by more than 60% (85%).
For green hydrogen applications with low hydrogen emission rates, hydrogen technologies can be 91–94% (92–95%) better for the climate than fossil fuel technologies in the near (long) term. With high emission rates, hydrogen technologies can be 66–82% (79–88%) better for the climate than fossil fuel technologies in the near (long) term. This means that high hydrogen emissions (10% rate) can reduce the anticipated climate benefits of green hydrogen technologies by up to 25% in the near term and 13% in the long term. The technologies with the least amount of climate benefits from fuel switching under high-emission scenarios are replacing natural gas-derived fertilizer with hydrogen-derived fertilizer and replacing heavy-duty diesel internal combustion engine (ICE) trucks with hydrogen fuel cell trucks.
Figure 1 also shows the results from the original LCA analysis (HC21) under 2050 conditions, which does not consider hydrogen emissions or near-term impacts and has very low methane emission intensities. Across all cases, the original results approximately align with our best-case scenarios (extremely low methane emissions and low hydrogen emissions) where the long-term climate benefits consistently show a ≥75% decrease in warming impacts from all hydrogen technologies relative to their fossil fuel alternatives.
Furthermore, the addition of hydrogen emissions and varying levels of representative methane emissions shows that the climate benefits of battery electric vehicles (BEVs) are considerably larger than those of blue hydrogen light-duty vehicles (LDVs). Blue hydrogen LDVs can be 10–45% worse for the climate in the near term than BEVs depending on the hydrogen and methane emission levels (Figure 1). On the contrary, the hydrogen LDVs and BEVs show similar climate benefits from replacing gasoline ICE vehicles in the original LCA. However, the greater benefit of BEVs in our analysis is more pronounced under 2050 assumptions than under 2030 assumptions (Figure S1), because grid electricity used by the electric vehicle is assumed to have greater (90%) renewable penetration and thus lower GHG emissions in 2050 than in 2030 (66% renewable penetration).

3.1. Blue Hydrogen Pathways

3.1.1. Effect of Hydrogen Emissions

Figure 2 compares the life cycle warming impacts of blue hydrogen use cases with their fossil fuel counterparts under assumptions of 1–10% hydrogen emission rates with medium methane emission rates (to isolate the effects of different hydrogen emission rates). We calculate the warming impacts using both TWP [cumulative radiative forcing from continuous emissions over 10-, 20-, 50-, and 100-year time horizons (Figure 2a–d)] and the GWP/CO2e metric [for 20- and 100-year time horizons (Figure 2e–l)].

Figure 2

Figure 2. Life cycle climate impacts of four blue hydrogen pathways relative to their fossil fuel alternatives in 2050 considering a range of 1–10% hydrogen emission rates and medium, 0.9%, methane emission intensity, presented as (a–d) the percentage change in cumulative radiative forcing from continuous emissions over 10, 20, 50, and 100 years after the technology switch and (e–l) annual emissions per function unit (kilometer or kilowatt hour) in CO2e on 20- and 100-year time horizons. Values in panels a–d range from 1% hydrogen emissions (bottom of the bars) to 10% hydrogen emissions (top of the bars). Error bars indicate the uncertainties associated with hydrogen’s radiative efficiency and lifetime. The climate impact of battery electric vehicle relative to fossil fuel is shown as purple horizontal lines in panel a for comparison with blue hydrogen. Percentage changes derived from panels e–l, which are emissions based on the GWP-20 and GWP-100 metrics, are also denoted as “x” (high H2 emissions) and “Δ” (low H2 emissions) in panels a–d. Note that in the case of blue hydrogen, high hydrogen emissions also lead to a small amount of additional methane emissions from increased natural gas use to make up for lost hydrogen (see the Supporting Information for more information).

All four blue hydrogen pathways reduce the level of warming relative to the fossil fuel pathways over all time scales when medium methane emissions are assumed (this is in contrast to Figure 1, where high and extremely high methane emissions are also considered). In the near term (20 years following the technology switch), high hydrogen emissions can reduce blue hydrogen’s climate benefits from replacing fossil fuel technologies by approximately 20% to 45% compared to the benefits from low hydrogen emissions. This reduction is less pronounced in the long term (100 years following the technology switch) at 10–25%.
The technologies with the largest range of climate outcomes from different hydrogen emission rates are industrial heat and power generation. For example, one could lose 40% of the anticipated climate benefits in the near term from replacing industrial natural gas boilers with industrial hydrogen boilers and replacing natural gas turbine power generation with blue ammonia turbine power generation if hydrogen emissions are high (10% rate). Over time, the benefits of hydrogen applications become stronger, but high hydrogen emissions (10% rate) can still reduce climate benefits by 20% for these technologies in the long term compared to low emissions (1%). For the transport cases (light-duty vehicles and ships), there is still a 20% reduction in climate benefits in the near term from high hydrogen emission rates and a 10% reduction in the long term.
Analyzing the climate benefits of hydrogen technologies relative to their fossil fuel counterparts using both TWP (cumulative effects from continuous emissions) and CO2e (cumulative effects from a one-time pulse of emissions) allows for assessment of the importance of including continuous emissions in LCAs rather than relying on pulse-based metrics. We find that near-term warming effects are adequately represented using GWP with a 20-year time horizon, and long-term effects are underestimated by GWP with a 100-year time horizon, especially when hydrogen emission rates are high. For example, the blue ammonia power generation case yields a reduction in warming of 54–75% over the 100-year time scale with continuous emissions, but GWP-100 suggests a reduction of 64–81%.

3.1.2. Effect of Regional Methane Emission Intensity Variations

Figure 3 considers the influence of different methane emission levels on the climate benefits of blue hydrogen technologies. Overall, high methane emissions have fewer climate benefits (and potentially disbenefits, i.e., more warming) relative to the fossil fuel applications even though methane emissions at the same levels are also avoided from the alternative fossil fuel technologies. However, the impact of methane emissions varies considerably by use case. Methane emissions are more influential in impacting warming effects for blue hydrogen industrial heating and power generation pathways (Figure 3b,d) than for light-duty vehicle and ship pathways (Figure 4a,c). For example, high methane emissions may reduce the climate benefit of replacing natural gas with blue hydrogen for industrial heating by ∼20% in the near term and ∼10% in the long term compared with low methane emissions (Figure 3b). For the blue ammonia power generation pathway, high methane emissions can lead to more warming in the near term than using natural gas for power generation (Figure 3d). Note that we have not accounted for the various levels of N2O that can be directly emitted and indirectly formed from the release of reactive nitrogen compounds across the blue ammonia pathway, which can further increase its overall climate impact. (50,51)

Figure 3

Figure 3. Life cycle climate impacts of four blue hydrogen pathways relative to their fossil fuel alternatives in 2050 considering a range of hydrogen emission rates of 1–10% (heights of the bars) and three levels of methane emission intensities (different colored bars), presented as the percentage change in cumulative radiative forcing from continuous emissions over 10, 20, 50, and 100 years after the technology switch. The error bars indicate the uncertainties associated with hydrogen’s radiative efficiency and lifetime.

Figure 4

Figure 4. Life cycle climate impacts of four green hydrogen pathways relative to their fossil fuel alternatives in 2050 considering a range of hydrogen emission rates of 1–10%, presented as (a–d) the percentage change in cumulative radiative forcing from continuous emissions over 10, 20, 50, and 100 years after the technology switch and (e–l) annual emissions per function unit (kilometer or kilogram of product) in CO2e on 20- and 100-year time horizons. Values in panels a–d range from 1% hydrogen emissions (bottoms of bars) to 10% hydrogen emissions (tops of bars). The error bars indicate the uncertainties associated with hydrogen’s radiative efficiency and lifetime. Percentage changes derived from panels e–l, which are emissions based on the GWP-20 and GWP-100 metrics, are also denoted as “x” (high H2 emissions) and “Δ” (low H2 emissions) in panels a–d. Note there is a small amount of methane emissions associated with the green hydrogen pathways due to the inclusion of manufacturing emissions associated with the end use equipment.

3.1.3. Effect of Carbon Capture Rates

The original LCA assumes a 98% carbon capture rate with autothermal reforming in the blue hydrogen pathways, which is an optimistic assumption given that current operating carbon capture with steam methane reforming plants can only remove 30–60% of the CO2 emissions at the facility level, partly due to not capturing combustion CO2 emissions. (38,48) Figure S4 shows an illustrative example of how a lower carbon capture rate can substantially increase the climate impact of blue hydrogen pathways, undercutting their climate benefits relative to fossil fuel technologies. Compared to the assumption of a 98% carbon capture rate (Figure 2), a 60% carbon capture rate can reduce the climate benefits of blue hydrogen pathways by 15–50% in the near term and 20–60% in the long term (Figure S4). Unlike the strong near-term impact of hydrogen and methane emissions, the impact of the carbon capture rate is more pronounced in the long term, because CO2 is a long-lived GHG.

3.2. Green Hydrogen Pathways

3.2.1. Effect of Hydrogen Emissions

Figure 4 compares the life cycle warming impacts of green hydrogen use cases with their fossil fuel counterparts under assumptions of 1–10% hydrogen emissions rates with the same methods and time horizons as in Figure 2. Note that medium methane emission rates are applied to fossil fuel technologies where appropriate.
Overall, green hydrogen pathways consistently reduce warming impacts from fossil fuel technologies by >60% for all time scales, even when hydrogen emission rates are high. However, limiting hydrogen emissions to the lower end (e.g., 1%) greatly increases climate benefits to >90%. For example, replacing natural gas-derived fertilizer with green hydrogen-derived fertilizer can achieve an ∼90% reduction in warming over the 20 years following the technology switch if hydrogen emissions are low but a reduction of only ∼70% if hydrogen emissions are high (Figure 4a).
For all green hydrogen pathways, high hydrogen emissions considerably reduce the climate benefits from switching from fossil fuel technologies to hydrogen alternatives. This effect is more pronounced in the near term than in the long term. In the near term (20 years following the technology switch), high hydrogen emission rates relative to low rates can reduce climate benefits by ∼10%, ∼15%, and ∼25% for steel production, buses and heavy-duty trucking, and fertilizer production, respectively. In the long term, the decrease in the level of benefits is as much as 10% for fertilizer and as little as 4% for steel production.
Unlike blue hydrogen, green hydrogen pathways do not have significant methane emissions. Therefore, regional variations in methane emission intensities mostly impact the warming effects from fossil fuel alternatives. However, we find only small impacts on the magnitudes of climate benefits from fuel switching when we consider different methane emission intensity levels (not shown). We also find that both GWP-20 and GWP-100 adequately convey the results from the more sophisticated continuous emissions method.

3.2.2. Effect of GHG Emissions Associated with Electricity Supply

The original LCA assumed that renewable electricity used for green hydrogen production is additional to what is needed to decarbonize the electric grid. Figure 5 shows an example of the added warming effects if the renewable electricity used in 2030 is not in addition to what is needed to decarbonize the electric grid, and therefore, the electricity needs to be replaced by natural gas or coal. We also compare these scenarios to warming impacts from using grid electricity to produce hydrogen. For all of the green hydrogen pathways of switching from diesel buses to hydrogen fuel cell buses, we find that the additional GHGs emitted from needing to generate more electricity to support the grid can greatly increase overall climate impacts if one must rely on fossil fuels. If natural gas- or coal-based electricity is used, the added GHG emissions would lead to an increase in the level of warming over all time scales (by 15–150%) as a systemwide impact from replacing fossil fuel technologies with non-additional renewable-based green hydrogen. If a globally averaged grid electricity mix is assumed (using the conditions projected for 2030), the climate benefit from replacing the diesel buses with green hydrogen fuel cell buses is significantly reduced by ∼45% for the near term and long term. Similar results are found in the other three green hydrogen pathways (Figure S3).

Figure 5

Figure 5. Life cycle climate impacts of a green hydrogen fuel cell bus relative to the diesel alternative in 2030 considering a range of hydrogen emission rates of 1–10% and different power supply assumptions (dashed lines), presented as annual emissions per kilometer of vehicle operation in CO2e on 20- and 100-year time horizons. The emission factors of the electricity grid mix in 2030 follow the 1.5 °C-compatible pathway projection by the International Renewable Energy Agency (IRENA). (49) The emission factors of natural gas- and coal-fired power plant are also taken from IRENA. Similar analyses are conducted for the other three green hydrogen pathways and shown in Figure S3.

4. Discussion

Click to copy section linkSection link copied!

We find that the climate benefits of hydrogen applications depend strongly on the specific use case, the production method, the hydrogen and methane emission rates, the availability of renewable electricity, and the time scale of interest. The climate impacts of hydrogen technologies range from a near elimination of warming to increased warming relative to the fossil fuel technologies that are replaced. For blue hydrogen applications, the range is a 93% reduction in warming to a 46% increase in warming. For green hydrogen applications, the range is a 66–95% reduction in warming with additional renewable electricity but nearly a quadrupling of the fossil fuel technology’s warming impacts if renewable electricity is non-additional and is replaced in the grid by coal-fired power plants. These results are in stark contrast to the original LCA (HC21) that found that the blue (green) hydrogen pathways cause a 77–92% (94–96%) reduction in warming relative to the replaced fossil fuel technologies because of the strong near-term warming effects of both hydrogen and methane.
Our analysis builds upon previous studies that show how hydrogen emissions can considerably reduce the climate benefits of hydrogen systems by quantitatively evaluating how hydrogen emissions affect the climate impacts of individual use cases. (11−13,36) The inclusion of hydrogen emissions increases the warming effects of all hydrogen pathways analyzed, especially in the near and medium term because hydrogen’s warming effects are short-lived. (11,13) Hydrogen emissions have been omitted from analysis of the benefit of deploying hydrogen as a decarbonization strategy as it is not included in the list of GHGs considered under the Kyoto Protocol, and until recently, there was a low level of awareness of its atmospheric warming effects. However, this assessment makes it clear that ignoring hydrogen emissions can considerably overestimate the decarbonization benefits of hydrogen systems. This is particularly relevant when hydrogen systems are compared to other clean alternatives, such as direct electrification. It is important to note that the rates of hydrogen emissions are currently unknown across the value chain. (28) Empirical measurements are needed to improve our understanding of where emissions are coming from and in what quantities.
Methane emissions also play a major role in reducing the climate benefits of blue hydrogen applications, as shown in previous studies. (12,34,36−38) However, our analysis shows that because methane emissions are also associated with fossil fuel technologies, the trade-offs and net warming effects are complex and vary considerably. The energy efficiency of end use applications in particular plays a large role in how much natural gas or oil is needed (and, therefore, how much methane is emitted or avoided). For example, in the blue hydrogen light-duty vehicle and ship pathways, hydrogen fuel cell engines are more energy efficient than internal combustion engines; (52,53) a light-duty vehicle consumes 0.3 kWh of hydrogen or 0.5 kWh of gasoline per kilometer, and a ship consumes 65 kWh of hydrogen or 83 kWh of diesel per kilometer, which helps counteract the energy used in blue hydrogen production. Therefore, blue hydrogen used in fuel cells is more efficient at replacing gasoline and diesel and therefore at avoiding the upstream methane emissions associated with crude oil production. In contrast, the heating and power generation pathways use similar boiler and turbine technologies for blue hydrogen/ammonia and natural gas with similar energy efficiencies; (54,55) a boiler for heating consumes 1.1 kWh of either hydrogen or natural gas per kilowatt hour of thermal energy generated, and a turbine for power consumes 1.7 kWh of either ammonia or natural gas per kilowatt hour of electricity generated, which does not help to offset the energy intensity of producing blue hydrogen or ammonia. Therefore, there is a net increase in upstream methane emissions in blue hydrogen/ammonia pathways compared to directly using natural gas because more natural gas is needed to compensate for the energy loss during conversions to hydrogen or ammonia (Figure 3c,d). Note that we do not explicitly analyze a situation in which high methane intensity blue hydrogen from one country or region is used to replace fossil fuel applications with low methane emission intensity in another country or region, or vice versa, which can have implications for the international or interstate trade of blue hydrogen.
Our analysis of additional versus non-additional renewable capacity is also consistent with previous studies that show how green hydrogen production could lead to an increase in fossil fuel-based electricity generation and increase in GHG emissions on the system level. (39,56) In our analysis, we find that the potential emission increases due to non-additional renewable electricity could make green hydrogen marginally beneficial or even worse for the climate (increased warming up to a factor of 4) in the near term and long term. Although the policy and/or regulatory mechanisms that can ensure that green hydrogen does not inadvertently delay grid decarbonization are highly debated, (57−59) the significance of the renewable fraction of the power grid in determining the climate benefits (or lack thereof) of green hydrogen is clear. This illustrative analysis highlights the importance of considering the system-level impact of producing green hydrogen and not unintentionally increasing the demand for fossil fuel-based electricity generation.
The time scale and methods for evaluating emissions over time are clearly significant in our results, as well. The climate benefits of hydrogen technologies can be considerably reduced in the near term if there are high emissions of hydrogen and/or methane, each of which has short-lived, but powerful, warming effects. If long-term time horizons are used exclusively, then potentially large near-term warming effects are overlooked.
Our analysis provides an improved temporal framework for technology assessments by directly comparing the total cumulative radiative forcing from annual and continuous emissions of climate pollutants. If hydrogen emissions were incorporated into simple climate models, such as the Finite Amplitude Impulse Response (FaIR) model and Model for the Assessment of Greenhouse Gas Induced Climate Change (MAGICC), it will enable faster quantification of climate impacts from hydrogen emissions to inform decision making. However, in general, we find that using GWPs with both 20- and 100-year time horizons can adequately characterize climate impacts of continuous emissions and over all time scales if reported simultaneously, consistent with findings from previous studies. (36,60) This approach can be applied to existing assessment tools (such as LCAs) with small adjustments in functionality.
There are other factors that influence the climate implications of deploying hydrogen that have not been fully explored in this study. For example, we test the effect of different carbon capture rates at blue hydrogen production facilities but how the captured carbon is utilized and the permanence of carbon storage can also affect the overall climate impacts of hydrogen deployment. (61,62) Moreover, deploying hydrogen to replace fossil fuel may reduce other co-emitted pollutants such as carbon monoxide, nitrogen oxides, and volatile organic compounds. These species are also indirect greenhouse gases that impact atmospheric chemistry and ultimately yield relatively short-lived warming or cooling effects on the climate. More work is needed to fully understand the atmospheric chemistry dynamics among all of these emitted species as their concentrations change in the future. (11) We have also not considered the implications of deploying hydrogen that is extracted from geological reservoirs. (63) These are important factors to consider in the development of future climate scenarios that include substantial hydrogen deployment.
Our analysis is subject to the same uncertainties as simplified climate metrics, such as in radiative properties, atmospheric lifetimes, and atmospheric chemistry parametrizations. Furthermore, as in any evaluation of the impacts of different technologies, the results depend strongly on the specific well-to-use pathway. Climate impacts and benefits relative to alternative fossil fuel technologies will vary across the value chains. This analysis is intended to explore the implications of considering additional climate pollutants, more realistic assumptions, and multiple time scales in hydrogen assessments through a limited set of illustrative examples. Given that the case study pathways that we examine are relatively arbitrary, our analysis does not serve as a comparison of climate benefits between different hydrogen applications. A more comprehensive comparison between hydrogen applications will be addressed in future work. Lastly, it is important to note that additional environmental factors such as water demand, raw material requirement, and air quality impacts are often included in LCA frameworks but are not explored in this study. These aspects are also critical considerations in policy making.
While there are many tools for decarbonization, hydrogen has the potential to serve an important role for certain value chains. By including hydrogen emissions, observed methane emissions, systemwide energy impacts, and multiple time scales, we can more accurately determine the climate benefits of different clean energy alternatives that thus serve as the basis for more effective policy making.

Supporting Information

Click to copy section linkSection link copied!

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.3c09030.

  • More detailed information about methods and data used in this study as well as additional figures that show the climate impact of hydrogen pathways relative to other alternatives under the 2030 condition (PDF)

Terms & Conditions

Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

Author Information

Click to copy section linkSection link copied!

  • Corresponding Author
  • Authors
    • Eriko Shrestha - Environmental Defense Fund, New York, New York 10010, United States
    • Steven P. Hamburg - Environmental Defense Fund, New York, New York 10010, United States
    • Roland Kupers - University of Arizona, Tucson, Arizona 85721, United States
    • Ilissa B. Ocko - Environmental Defense Fund, New York, New York 10010, United StatesOrcidhttps://orcid.org/0000-0001-8617-2249
  • Author Contributions

    T.S., I.B.O., and S.P.H. conceptualized the study. T.S., I.B.O., and E.S. conducted the data analysis, prepared the figures, and drafted the manuscript. All authors contributed to refining the analysis, refining the figures, and editing of the manuscript.

  • Funding

    This research was conducted with support from ClimateWorks Foundation and Breakthrough Energy. Results reflect the views of the authors and not necessarily those of the supporting organizations.

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

Click to copy section linkSection link copied!

The authors thank Ludwig-Bölkow-Systemtechnik GmbH for helping us to understand the data in the Hydrogen Council report and Jane Long and Joan Odgen for insightful discussions that helped improve this study. Results reflect the views of the authors and not necessarily those of the supporting organizations.

References

Click to copy section linkSection link copied!

This article references 63 other publications.

  1. 1
    Hydrogen Council. Hydrogen Insights 2023: An Update on the State of the Global Hydrogen Economy, with a Deep Dive into North America. 2023. https://hydrogencouncil.com/wp-content/uploads/2023/05/Hydrogen-Insights-2023.pdf (last accessed 2024-01-12).
  2. 2
    Valente, A.; Iribarren, D.; Dufour, J. Life Cycle Assessment of Hydrogen Energy Systems: A Review of Methodological Choices. Int. J. Life Cycle Assess. 2017, 22 (3), 346363,  DOI: 10.1007/s11367-016-1156-z
  3. 3
    Rinawati, D. I.; Keeley, A. R.; Takeda, S.; Managi, S. A Systematic Review of Life Cycle Assessment of Hydrogen for Road Transport Use. Prog. Energy 2022, 4 (1), 012001  DOI: 10.1088/2516-1083/ac34e9
  4. 4
    Rinawati, D. I.; Keeley, A. R.; Takeda, S.; Managi, S. Life-Cycle Assessment of Hydrogen Utilization in Power Generation: A Systematic Review of Technological and Methodological Choices. Front. Sustain. 2022, 3, 920876  DOI: 10.3389/frsus.2022.920876
  5. 5
    Hydrogen Council. Hydrogen Decarbonization Pathways: A Life-Cycle Assessment. 2021. https://hydrogencouncil.com/en/hydrogen-decarbonization-pathways/ (last accessed 2024-01-12).
  6. 6
    Bhandari, R.; Trudewind, C. A.; Zapp, P. Life Cycle Assessment of Hydrogen Production via Electrolysis – a Review. J. Clean. Prod. 2014, 85, 151163,  DOI: 10.1016/j.jclepro.2013.07.048
  7. 7
    Cetinkaya, E.; Dincer, I.; Naterer, G. F. Life Cycle Assessment of Various Hydrogen Production Methods. Int. J. Hydrogen Energ 2012, 37 (3), 20712080,  DOI: 10.1016/j.ijhydene.2011.10.064
  8. 8
    Lee, D.-Y.; Elgowainy, A.; Kotz, A.; Vijayagopal, R.; Marcinkoski, J. Life-Cycle Implications of Hydrogen Fuel Cell Electric Vehicle Technology for Medium- and Heavy-Duty Trucks. J. Power Sources 2018, 393, 217229,  DOI: 10.1016/j.jpowsour.2018.05.012
  9. 9
    Frank, E. D.; Elgowainy, A.; Reddi, K.; Bafana, A. Life-Cycle Analysis of Greenhouse Gas Emissions from Hydrogen Delivery: A Cost-Guided Analysis. Int. J. Hydrogen Energ 2021, 46 (43), 2267022683,  DOI: 10.1016/j.ijhydene.2021.04.078
  10. 10
    Paulot, F.; Paynter, D.; Naik, V.; Malyshev, S.; Menzel, R.; Horowitz, L. W. Global Modeling of Hydrogen Using GFDL-AM4.1: Sensitivity of Soil Removal and Radiative Forcing. Int. J. Hydrogen Energ 2021, 46 (24), 1344613460,  DOI: 10.1016/j.ijhydene.2021.01.088
  11. 11
    Warwick, N. J.; Archibald, A. T.; Griffiths, P. T.; Keeble, J.; O’Connor, F. M.; Pyle, J. A.; Shine, K. P. Atmospheric Composition and Climate Impacts of a Future Hydrogen Economy. Atmos. Chem. Phys. 2023, 23 (20), 1345113467,  DOI: 10.5194/acp-23-13451-2023
  12. 12
    Hauglustaine, D.; Paulot, F.; Collins, W.; Derwent, R.; Sand, M.; Boucher, O. Climate Benefit of a Future Hydrogen Economy. Commun. Earth Environ 2022, 3 (1), 295,  DOI: 10.1038/s43247-022-00626-z
  13. 13
    Sand, M.; Skeie, R. B.; Sandstad, M.; Krishnan, S.; Myhre, G.; Bryant, H.; Derwent, R.; Hauglustaine, D.; Paulot, F.; Prather, M.; Stevenson, D. A Multi-Model Assessment of the Global Warming Potential of Hydrogen. Commun. Earth Environ. 2023, 4 (1), 203,  DOI: 10.1038/s43247-023-00857-8
  14. 14
    Hauglustaine, D. A.; Ehhalt, D. H. A Three-dimensional Model of Molecular Hydrogen in the Troposphere. J. Geophys. Res.: Atmos. 2002, 107 (D17), ACH 4-1ACH 4-16,  DOI: 10.1029/2001JD001156
  15. 15
    Field, R. A.; Derwent, R. G. 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 Energ 2021, 46 (58), 3019030203,  DOI: 10.1016/j.ijhydene.2021.06.120
  16. 16
    Derwent, R. G.; Stevenson, D. S.; Utembe, S. R.; Jenkin, M. E.; Khan, A. H.; Shallcross, D. E. Global Modelling Studies of Hydrogen and Its Isotopomers Using STOCHEM-CRI: Likely Radiative Forcing Consequences of a Future Hydrogen Economy. Int. J. Hydrogen Energ 2020, 45 (15), 92119221,  DOI: 10.1016/j.ijhydene.2020.01.125
  17. 17
    Derwent, R.; Simmonds, P.; O’Doherty, S.; Manning, A.; Collins, W.; Stevenson, D. Global Environmental Impacts of the Hydrogen Economy. Int. J. Nucl. Hydrogen Prod Appl. 2006, 1 (1), 57,  DOI: 10.1504/IJNHPA.2006.009869
  18. 18
    Derwent, R. G.; Collins, W. J.; Johnson, C. E.; Stevenson, D. S. Transient Behaviour of Tropospheric Ozone Precursors in a Global 3-D CTM and Their Indirect Greenhouse Effects. Climatic Change 2001, 49 (4), 463487,  DOI: 10.1023/A:1010648913655
  19. 19
    Prather, M. J. An Environmental Experiment with H2?. Science 2003, 302 (5645), 581582,  DOI: 10.1126/science.1091060
  20. 20
    Schultz, M. G.; Diehl, T.; Brasseur, G. P.; Zittel, W. Air Pollution and Climate-Forcing Impacts of a Global Hydrogen Economy. Science 2003, 302 (5645), 624627,  DOI: 10.1126/science.1089527
  21. 21
    Warwick, N. J.; Bekki, S.; Nisbet, E. G.; Pyle, J. A. Impact of a Hydrogen Economy on the Stratosphere and Troposphere Studied in a 2-D Model. Geophys. Res. Lett. 2004, 31 (5), L05107  DOI: 10.1029/2003GL019224
  22. 22
    Colella, W. G.; Jacobson, M. Z.; Golden, D. M. Switching to a U.S. Hydrogen Fuel Cell Vehicle Fleet: The Resultant Change in Emissions, Energy Use, and Greenhouse Gases. J. Power Sources 2005, 150, 150181,  DOI: 10.1016/j.jpowsour.2005.05.092
  23. 23
    Wuebbles, D. J. Evaluation of the Potential Environmental Impacts from Large-Scale Use and Production of Hydrogen in Energy and Transportation Applications. 2008. https://digital.library.unt.edu/ark:/67531/metadc841210/ (last accessed 2024-01-12).
  24. 24
    Frazer-Nash Consultancy. Fugitive Hydrogen Emissions in a Future Hydrogen Economy. 2022. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1067137/fugitive-hydrogen-emissions-future-hydrogen-economy.pdf (last accessed 2024-01-12).
  25. 25
    Arrigoni, A.; Bravo, D. L. Hydrogen Emissions from a Hydrogen Economy and Their Potential Global Warming Impact. 2022; OP KJ-NA-31-188-EN-N. DOI: 10.2760/065589
  26. 26
    Cooper, J.; Dubey, L.; Bakkaloglu, S.; Hawkes, A. Hydrogen Emissions from the Hydrogen Value Chain-Emissions Profile and Impact to Global Warming. Sci. Total Environ. 2022, 830, 154624  DOI: 10.1016/j.scitotenv.2022.154624
  27. 27
    Fan, Z.; Sheerazi, H.; Bhardwaj, A.; Corbeau, A.-S.; Longobardi, K.; Castañeda, A.; Merz, A.-K.; Woodall, C. M.; Agrawal, M.; Orozco-Sanchez, S.; Friedmann, J. Hydrogen Leakage: A Potential Risk for the Hydrogen Economy; Center on Global Energy Policy. 2022. https://www.energypolicy.columbia.edu/publications/hydrogen-leakage-potential-risk-hydrogen-economy/ (last accessed 2024-01-12).
  28. 28
    Esquivel-Elizondo, S.; Hormaza Mejia, A.; Sun, T.; Shrestha, E.; Hamburg, S. P.; Ocko, I. B. Wide Range in Estimates of Hydrogen Emissions from Infrastructure. Front. Energy Res. 2023, 11, 0108,  DOI: 10.3389/fenrg.2023.1207208
  29. 29
    Alvarez, R. A.; Zavala-Araiza, D.; Lyon, D. R.; Allen, D. T.; Barkley, Z. R.; Brandt, A. R.; Davis, K. J.; Herndon, S. C.; Jacob, D. J.; Karion, A.; Kort, E. A.; Lamb, B. K.; Lauvaux, T.; Maasakkers, J. D.; Marchese, A. J.; Omara, M.; Pacala, S. W.; Peischl, J.; Robinson, A. L.; Shepson, P. B.; Sweeney, C.; Townsend-Small, A.; Wofsy, S. C.; Hamburg, S. P. Assessment of Methane Emissions from the U.S. Oil and Gas Supply Chain. Science 2018, 361 (6398), 186188,  DOI: 10.1126/science.aar7204
  30. 30
    Shen, L.; Gautam, R.; Omara, M.; Zavala-Araiza, D.; Maasakkers, J. D.; Scarpelli, T. R.; Lorente, A.; Lyon, D.; Sheng, J.; Varon, D. J.; Nesser, H.; Qu, Z.; Lu, X.; Sulprizio, M. P.; Hamburg, S. P.; Jacob, D. J. Satellite Quantification of Oil and Natural Gas Methane Emissions in the US and Canada Including Contributions from Individual Basins. Atmos. Chem. Phys. 2022, 22 (17), 1120311215,  DOI: 10.5194/acp-22-11203-2022
  31. 31
    Foulds, A.; Allen, G.; Shaw, J. T.; Bateson, P.; Barker, P. A.; Huang, L.; Pitt, J. R.; Lee, J. D.; Wilde, S. E.; Dominutti, P.; Purvis, R. M.; Lowry, D.; France, J. L.; Fisher, R. E.; Fiehn, A.; Pühl, M.; Bauguitte, S. J. B.; Conley, S. A.; Smith, M. L.; Lachlan-Cope, T.; Pisso, I.; Schwietzke, S. Quantification and Assessment of Methane Emissions from Offshore Oil and Gas Facilities on the Norwegian Continental Shelf. Atmos Chem. Phys. 2022, 22 (7), 43034322,  DOI: 10.5194/acp-22-4303-2022
  32. 32
    MacKay, K.; Lavoie, M.; Bourlon, E.; Atherton, E.; O’Connell, E.; Baillie, J.; Fougère, C.; Risk, D. Methane Emissions from Upstream Oil and Gas Production in Canada Are Underestimated. Sci. Rep-uk 2021, 11 (1), 8041,  DOI: 10.1038/s41598-021-87610-3
  33. 33
    Chen, Y.; Sherwin, E. D.; Berman, E. S. F.; Jones, B. B.; Gordon, M. P.; Wetherley, E. B.; Kort, E. A.; Brandt, A. R. Quantifying Regional Methane Emissions in the New Mexico Permian Basin with a Comprehensive Aerial Survey. Environ. Sci. Technol. 2022, 56 (7), 43174323,  DOI: 10.1021/acs.est.1c06458
  34. 34
    Howarth, R. W.; Jacobson, M. Z. How Green Is Blue Hydrogen?. Energy Sci. Eng. 2021, 9, 16761687,  DOI: 10.1002/ese3.956
  35. 35
    Stocks, M.; Fazeli, R.; Hughes, L.; Beck, F. J. Global Emissions Implications from Co-Combusting Ammonia in Coal Fired Power Stations: An Analysis of the Japan-Australia Supply Chain. J. Clean. Prod. 2022, 336, 130092  DOI: 10.1016/j.jclepro.2021.130092
  36. 36
    Ocko, I. B.; Hamburg, S. P. Climate Consequences of Hydrogen Emissions. Atmos. Chem. Phys. 2022, 22, 93499368,  DOI: 10.5194/acp-22-9349-2022
  37. 37
    Bertagni, M. B.; Pacala, S. W.; Paulot, F.; Porporato, A. Risk of the Hydrogen Economy for Atmospheric Methane. Nat. Commun. 2022, 13 (1), 7706,  DOI: 10.1038/s41467-022-35419-7
  38. 38
    Bauer, C.; Treyer, K.; Antonini, C.; Bergerson, J.; Gazzani, M.; Gencer, E.; Gibbins, J.; Mazzotti, M.; McCoy, S. T.; McKenna, R.; Pietzcker, R.; Ravikumar, A. P.; Romano, M. C.; Ueckerdt, F.; Vente, J.; van der Spek, M. On the Climate Impacts of Blue Hydrogen Production. Sustainable Energy Fuels 2021, 6 (1), 6675,  DOI: 10.1039/D1SE01508G
  39. 39
    Ricks, W.; Xu, Q.; Jenkins, J. D. Minimizing Emissions from Grid-Based Hydrogen Production in the United States. Environ. Res. Lett. 2023, 18 (1), 014025  DOI: 10.1088/1748-9326/acacb5
  40. 40
    Alvarez, R. A.; Pacala, S. W.; Winebrake, J. J.; Chameides, W. L.; Hamburg, S. P. Greater Focus Needed on Methane Leakage from Natural Gas Infrastructure. Proc. National Acad. Sci. 2012, 109 (17), 64356440,  DOI: 10.1073/pnas.1202407109
  41. 41
    Ocko, I. B.; Hamburg, S. P. Climate Impacts of Hydropower: Enormous Differences among Facilities and over Time. Environ. Sci. Technol. 2019, 53 (23), 1407014082,  DOI: 10.1021/acs.est.9b05083
  42. 42
    Tromp, T. K.; Shia, R.-L.; Allen, M.; Eiler, J. M.; Yung, Y. L. Potential Environmental Impact of a Hydrogen Economy on the Stratosphere. Science 2003, 300 (5626), 17401742,  DOI: 10.1126/science.1085169
  43. 43
    Jacobson, M. Z.; Colella, W. G.; Golden, D. M. Cleaning the Air and Improving Health with Hydrogen Fuel-Cell Vehicles. Science 2005, 308 (5730), 19011905,  DOI: 10.1126/science.1109157
  44. 44
    Jacobson, M. Z. Effects of Wind-powered Hydrogen Fuel Cell Vehicles on Stratospheric Ozone and Global Climate. Geophys. Res. Lett. 2008, 35 (19), L19803  DOI: 10.1029/2008GL035102
  45. 45
    van Ruijven, B.; Lamarque, J.-F.; van Vuuren, D. P.; Kram, T.; Eerens, H. Emission Scenarios for a Global Hydrogen Economy and the Consequences for Global Air Pollution. Global Environ. Change 2011, 21 (3), 983994,  DOI: 10.1016/j.gloenvcha.2011.03.013
  46. 46
    Bond, S. W.; Gül, T.; Reimann, S.; Buchmann, B.; Wokaun, A. Emissions of Anthropogenic Hydrogen to the Atmosphere during the Potential Transition to an Increasingly H2-Intensive Economy. Int. J. Hydrogen Energ 2011, 36 (1), 11221135,  DOI: 10.1016/j.ijhydene.2010.10.016
  47. 47
    IEA. Global Methane Tracker Documentation 2022 Version. 2022. https://iea.blob.core.windows.net/assets/b5f6bb13-76ce-48ea-8fdb-3d4f8b58c838/GlobalMethaneTracker_documentation.pdf (last accessed 2024-01-12).
  48. 48
    Gorski, J.; Jutt, T.; Wu, K. T. Carbon Intensity of Blue Hydrogen Production. 2021. https://www.pembina.org/reports/carbon-intensity-of-blue-hydrogen-revised.pdf (last accessed 2024-01-12).
  49. 49
    IRENA. World Energy Transitions Outlook 2022. 2022. https://www.irena.org/Digital-Report/World-Energy-Transitions-Outlook-2022 (last accessed 2024-01-12).
  50. 50
    Bertagni, M. B.; Socolow, R. H.; Martirez, J. M. P.; Carter, E. A.; Greig, C.; Ju, Y.; Lieuwen, T.; Mueller, M. E.; Sundaresan, S.; Wang, R.; Zondlo, M. A.; Porporato, A. Minimizing the Impacts of the Ammonia Economy on the Nitrogen Cycle and Climate. Proc. Natl. Acad. Sci. United States Am. 2023, 120 (46), e2311728120  DOI: 10.1073/pnas.2311728120
  51. 51
    Wolfram, P.; Kyle, P.; Zhang, X.; Gkantonas, S.; Smith, S. Using Ammonia as a Shipping Fuel Could Disturb the Nitrogen Cycle. Nat. Energy 2022, 7 (12), 11121114,  DOI: 10.1038/s41560-022-01124-4
  52. 52
    Schaller, K. V.; Gruber, C. Hydrogen Powered Fuel-Cell Buses Meet Future Transport Challenges. 2001. https://www.citelec.org/eledrive/Afuelcellarticles/PP301.PDF (last accessed 2024-01-12).
  53. 53
    Marcinkoski, J.; Vijayagopal, R.; Adams, J.; James, B.; Kopasz, J.; Ahluwalia, R. DOE Advanced Truck Technologies: Subsection of the Electrified Powertrain Roadmap Technical Targets for Hydrogen-Fueled Long-Haul Tractor-Trailer Trucks. 2019. https://www.hydrogen.energy.gov/docs/hydrogenprogramlibraries/pdfs/19006_hydrogen_class8_long_haul_truck_targets.pdf?Status=Master (last accessed 2024-01-12).
  54. 54
    Ueckerdt, F.; Bauer, C.; Dirnaichner, A.; Everall, J.; Sacchi, R.; Luderer, G. Potential and Risks of Hydrogen-Based e-Fuels in Climate Change Mitigation. Nat. Clim Change 2021, 11 (5), 384393,  DOI: 10.1038/s41558-021-01032-7
  55. 55
    Gudmundsson, O.; Thorsen, J. E. Source-to-Sink Efficiency of Blue and Green District Heating and Hydrogen-Based Heat Supply Systems. Smart Energy 2022, 6, 100071  DOI: 10.1016/j.segy.2022.100071
  56. 56
    de Kleijne, K.; de Coninck, H.; van Zelm, R.; Huijbregts, M. A. J.; Hanssen, S. V. The Many Greenhouse Gas Footprints of Green Hydrogen. Sustainable Energy Fuels 2022, 6, 43834387,  DOI: 10.1039/D2SE00444E
  57. 57
    CE Delft. Additionality of Renewable Electricity for Green Hydrogen Production in the EU. 2022. https://cedelft.eu/wp-content/uploads/sites/2/2022/12/CE_Delft_220358_Final_report.pdf (last accessed 2024-01-12).
  58. 58
    Wolak, F. Re: Section 45V Credit for Production of Clean Hydrogen and Additionality. 2023. https://static1.squarespace.com/static/53ab1feee4b0bef0179a1563/t/6452ad18d54ae3543c305f15/1683139864709/FCHEA+Additionality+Sign+On+Letter+Final+2023-5-4.pdf (last accessed 2024-01-12).
  59. 59
    Pototschnig, A. Renewable Hydrogen and the “Additionality” Requirement: Why Making It More Complex than Is Needed?. European University Institute 2021, 16,  DOI: 10.2870/201657
  60. 60
    Ocko, I. B.; Hamburg, S. P.; Jacob, D. J.; Keith, D. W.; Keohane, N. O.; Oppenheimer, M.; Roy-Mayhew, J. D.; Schrag, D. P.; Pacala, S. W. Unmask Temporal Trade-Offs in Climate Policy Debates. Science 2017, 356 (6337), 492493,  DOI: 10.1126/science.aaj2350
  61. 61
    Deng, H.; Bielicki, J. M.; Oppenheimer, M.; Fitts, J. P.; Peters, C. A. Leakage Risks of Geologic CO2 Storage and the Impacts on the Global Energy System and Climate Change Mitigation. Clim. Chang. 2017, 144 (2), 151163,  DOI: 10.1007/s10584-017-2035-8
  62. 62
    Vinca, A.; Emmerling, J.; Tavoni, M. Bearing the Cost of Stored Carbon Leakage. Front. Energy Res. 2018, 6, 40,  DOI: 10.3389/fenrg.2018.00040
  63. 63
    Hidden hydrogen: Earth may hold vast stores of a renewable, carbon-free fuel. Science https://www.science.org/content/article/hidden-hydrogen-earth-may-hold-vast-stores-renewable-carbon-free-fuel (last accessed 2024-01-12).

Cited By

Click to copy section linkSection link copied!
Citation Statements
Explore this article's citation statements on scite.ai

This article is cited by 27 publications.

  1. Sofia Esquivel-Elizondo, Blake Walkowiak, Stavroula S. Sartzetakis, Brian Buma. Climate Impact of Direct and Indirect N2O Emissions from the Ammonia Marine Fuel Value Chain. Environmental Science & Technology 2025, 59 (18) , 9037-9048. https://doi.org/10.1021/acs.est.4c13135
  2. Alissa Ganter, Tyler H. Ruggles, Paolo Gabrielli, Giovanni Sansavini, Ken Caldeira. Utilizing Curtailed Wind and Solar Power to Scale Up Electrolytic Hydrogen Production in Europe. Environmental Science & Technology 2025, 59 (7) , 3495-3507. https://doi.org/10.1021/acs.est.4c10168
  3. Esther G. Goita, Emily A. Beagle, Ansh N. Nasta, Derek L. Wissmiller, Arvind Ravikumar, Michael E. Webber. Effect of hydrogen leakage on the life cycle climate impacts of hydrogen supply chains. Communications Earth & Environment 2025, 6 (1) https://doi.org/10.1038/s43247-025-02141-3
  4. Fabrice Ndayisenga, Bobo Wang, Chengyu Zhang, Longyu Wang, Guilin Du, Zhisheng Yu. Calcium hydroxyapatite nanoparticle-induced bio-electrocatalytic hydrogen production in a single-chambered carbon cloth-based cathodic microbial electrolysis cell. Chemical Engineering Science 2025, 313 , 121752. https://doi.org/10.1016/j.ces.2025.121752
  5. T.J. Wallington, M. Woody, G.M. Lewis, G.A. Keoleian, E.J. Adler, J.R.R.A. Martins, M.D. Collette. Hydrogen as a sustainable transportation fuel. Renewable and Sustainable Energy Reviews 2025, 217 , 115725. https://doi.org/10.1016/j.rser.2025.115725
  6. Davide Trapani, Paolo Marocco, Marta Gandiglio, Massimo Santarelli. Hydrogen leakages across the supply chain: Current estimates and future scenarios. International Journal of Hydrogen Energy 2025, 145 , 1084-1095. https://doi.org/10.1016/j.ijhydene.2025.06.103
  7. Nigel N. Clark, David L. McKain, Derek R. Johnson. Estimates of emissions from hydrogen transportation fueling infrastructure and vehicles. Journal of the Air & Waste Management Association 2025, 36 , 1-32. https://doi.org/10.1080/10962247.2025.2495811
  8. Qingjin Lin, Pu Zhang, Li Zhou, Peiying Zhang, Bowen Sheng, Maoqiong Gong. Density characterization of hydrogen-blended natural gas system by a single-sinker densimeter for future hydrogen economy. International Journal of Hydrogen Energy 2025, 135 , 507-514. https://doi.org/10.1016/j.ijhydene.2025.04.392
  9. Ife Elegbeleye, Olusegun Oguntona, Femi Elegbeleye. Green Hydrogen: Pathway to Net Zero Green House Gas Emission and Global Climate Change Mitigation. Hydrogen 2025, 6 (2) , 29. https://doi.org/10.3390/hydrogen6020029
  10. Alexander Jülich, Maximilian Blum, Ole Zelt, Peter Viebahn. From natural gas to hydrogen: Climate impacts of current and future gas transmission networks in Germany. Frontiers in Energy Research 2025, 13 https://doi.org/10.3389/fenrg.2025.1548309
  11. David A. Wood. Critical review of development challenges for expanding hydrogen-fuelled energy systems. Fuel 2025, 387 , 134394. https://doi.org/10.1016/j.fuel.2025.134394
  12. Nathan Johnson, Michael Liebreich, Daniel M. Kammen, Paul Ekins, Russell McKenna, Iain Staffell. Realistic roles for hydrogen in the future energy transition. Nature Reviews Clean Technology 2025, 1 (5) , 351-371. https://doi.org/10.1038/s44359-025-00050-4
  13. Charuka Muktha Arachchige, Andreas Muller. Portable Raman hydrogen concentration mapping with parts-per-billion sensitivity. Applied Optics 2025, 64 (13) , 3646. https://doi.org/10.1364/AO.558965
  14. C. Anand, B. Chandraja, P. Nithiya, M. Akshaya, P. Tamizhdurai, G. Shoba, A. Subramani, R. Kumaran, Krishna Kumar Yadav, Amel Gacem, Javed Khan Bhutto, Maha Awjan Alreshidi, Mir Waqas Alam. Green hydrogen for a sustainable future: A review of production methods, innovations, and applications. International Journal of Hydrogen Energy 2025, 111 , 319-341. https://doi.org/10.1016/j.ijhydene.2025.02.257
  15. Antonella Sola, Roberto Rosa, Anna Maria Ferrari. Green Hydrogen and Its Supply Chain. A Critical Assessment of the Environmental Impacts. Advanced Sustainable Systems 2025, 9 (2) https://doi.org/10.1002/adsu.202400708
  16. Steven Griffiths, Benjamin Sovacool, Marfuga Iskandarova, Hans Jakob Walnum. Bridging the gap between defossilization and decarbonization to achieve net-zero industry. Environmental Research Letters 2025, 20 (2) , 024063. https://doi.org/10.1088/1748-9326/adaed6
  17. Iris M. Westra, Hubertus A. Scheeren, Firmin T. Stroo, Steven M. A. C. van Heuven, Bert A. M. Kers, Wouter Peters, Harro A. J. Meijer. First detection of industrial hydrogen emissions using high precision mobile measurements in ambient air. Scientific Reports 2024, 14 (1) https://doi.org/10.1038/s41598-024-76373-2
  18. Putri Permatasari, Haruka Goto, Manabu Miyamoto, Yasunori Oumi, Yogi Wibisono Budhi, Shigeyuki Uemiya. Combined Reaction System for NH3 Decomposition and CO2 Methanation Using Hydrogen Permeable Membrane Reactor in 1D Model Analysis. Membranes 2024, 14 (12) , 273. https://doi.org/10.3390/membranes14120273
  19. Mohammed H. Alshareef, Ayman F. Alghanmi. Optimizing Maritime Energy Efficiency: A Machine Learning Approach Using Deep Reinforcement Learning for EEXI and CII Compliance. Sustainability 2024, 16 (23) , 10534. https://doi.org/10.3390/su162310534
  20. Paul Martin, Ilissa B. Ocko, Sofia Esquivel‐Elizondo, Roland Kupers, David Cebon, Tom Baxter, Steven P. Hamburg. A review of challenges with using the natural gas system for hydrogen. Energy Science & Engineering 2024, 12 (10) , 3995-4009. https://doi.org/10.1002/ese3.1861
  21. Emilio José Medrano-Sánchez, Freddy Antonio Ochoa-Tataje. Impact of green hydrogen on climate change in Peru: An analysis of perception, policies, and cooperation. Energy Conversion and Management: X 2024, 24 , 100778. https://doi.org/10.1016/j.ecmx.2024.100778
  22. Yasemin Balci, Celal Erbay. Harnessing solar energy for sustainable green hydrogen production in Türkiye: Opportunities, and economic viability. International Journal of Hydrogen Energy 2024, 87 , 985-996. https://doi.org/10.1016/j.ijhydene.2024.09.098
  23. Amit Pratap Singh. Assessment of India's Green Hydrogen Mission and environmental impact. Renewable and Sustainable Energy Reviews 2024, 203 , 114758. https://doi.org/10.1016/j.rser.2024.114758
  24. Christian Fabrice Magoua Mbeugang, Bin Li, Xing Xie, Juntao Wei, Yusuf Makarfi Isa, Alexander Kozlov, Maxim Penzik. Catalysis/sorption enhanced pyrolysis-gasification of biomass for H2-rich gas production: Effects of various nickel-based catalysts addition and the combination with calcined dolomite. Fuel 2024, 372 , 132195. https://doi.org/10.1016/j.fuel.2024.132195
  25. Jing Wang, Min Wang, Zhenjiang Lu, Jing Xie, Jianguo Huang, Jindou Hu, Yali Cao. Multielectronic synergetic Hf-doped NiFe-LDH/NF for efficient bifunctional electrocatalytic OER/UOR. International Journal of Hydrogen Energy 2024, 82 , 724-732. https://doi.org/10.1016/j.ijhydene.2024.07.426
  26. Sergio Nogales-Delgado, Juan Félix González González. The Role of Catalysts in Life Cycle Assessment Applied to Biogas Reforming. Catalysts 2024, 14 (9) , 592. https://doi.org/10.3390/catal14090592
  27. Emmanuel Sey, Zoheir N. Farhat. Investigating the Fatigue Response of Cathodically Charged Cold-Finished Mild Steel to Varied Hydrogen Concentrations. Corrosion and Materials Degradation 2024, 5 (3) , 406-426. https://doi.org/10.3390/cmd5030018

Environmental Science & Technology

Cite this: Environ. Sci. Technol. 2024, 58, 12, 5299–5309
Click to copy citationCitation copied!
https://doi.org/10.1021/acs.est.3c09030
Published February 21, 2024

Copyright © 2024 The Authors. Published by American Chemical Society. This publication is licensed under

CC-BY-NC-ND 4.0 .

Article Views

14k

Altmetric

-

Citations

Learn about these metrics

Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.

Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.

The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.

  • Abstract

    Figure 1

    Figure 1. Overview of the life cycle climate impacts of eight hydrogen pathways relative to their fossil fuel alternatives in 2050 considering a range of hydrogen emission rates (1–10%) and methane emission intensities (from extremely low, 0.01%, to extremely high, 5.4%). Each vertical bar represents the range of climate benefits (or disbenefits) by switching to hydrogen from fossil fuels for the best-case scenario (1% hydrogen emissions and a low methane emission intensity of 0.6%) to the worst-case scenario (10% hydrogen emissions and a high methane emissions intensity of 2.1%). Near-term (NT, 20 years) and long-term (LT, 100 years) climate impacts are presented for each pathway. The originally reported climate impacts of these pathways in Hydrogen Council report (2021) are denoted as black triangles. The climate impact of the battery electric alternative for the light-duty vehicle pathway is noted with the letter E.

    Figure 2

    Figure 2. Life cycle climate impacts of four blue hydrogen pathways relative to their fossil fuel alternatives in 2050 considering a range of 1–10% hydrogen emission rates and medium, 0.9%, methane emission intensity, presented as (a–d) the percentage change in cumulative radiative forcing from continuous emissions over 10, 20, 50, and 100 years after the technology switch and (e–l) annual emissions per function unit (kilometer or kilowatt hour) in CO2e on 20- and 100-year time horizons. Values in panels a–d range from 1% hydrogen emissions (bottom of the bars) to 10% hydrogen emissions (top of the bars). Error bars indicate the uncertainties associated with hydrogen’s radiative efficiency and lifetime. The climate impact of battery electric vehicle relative to fossil fuel is shown as purple horizontal lines in panel a for comparison with blue hydrogen. Percentage changes derived from panels e–l, which are emissions based on the GWP-20 and GWP-100 metrics, are also denoted as “x” (high H2 emissions) and “Δ” (low H2 emissions) in panels a–d. Note that in the case of blue hydrogen, high hydrogen emissions also lead to a small amount of additional methane emissions from increased natural gas use to make up for lost hydrogen (see the Supporting Information for more information).

    Figure 3

    Figure 3. Life cycle climate impacts of four blue hydrogen pathways relative to their fossil fuel alternatives in 2050 considering a range of hydrogen emission rates of 1–10% (heights of the bars) and three levels of methane emission intensities (different colored bars), presented as the percentage change in cumulative radiative forcing from continuous emissions over 10, 20, 50, and 100 years after the technology switch. The error bars indicate the uncertainties associated with hydrogen’s radiative efficiency and lifetime.

    Figure 4

    Figure 4. Life cycle climate impacts of four green hydrogen pathways relative to their fossil fuel alternatives in 2050 considering a range of hydrogen emission rates of 1–10%, presented as (a–d) the percentage change in cumulative radiative forcing from continuous emissions over 10, 20, 50, and 100 years after the technology switch and (e–l) annual emissions per function unit (kilometer or kilogram of product) in CO2e on 20- and 100-year time horizons. Values in panels a–d range from 1% hydrogen emissions (bottoms of bars) to 10% hydrogen emissions (tops of bars). The error bars indicate the uncertainties associated with hydrogen’s radiative efficiency and lifetime. Percentage changes derived from panels e–l, which are emissions based on the GWP-20 and GWP-100 metrics, are also denoted as “x” (high H2 emissions) and “Δ” (low H2 emissions) in panels a–d. Note there is a small amount of methane emissions associated with the green hydrogen pathways due to the inclusion of manufacturing emissions associated with the end use equipment.

    Figure 5

    Figure 5. Life cycle climate impacts of a green hydrogen fuel cell bus relative to the diesel alternative in 2030 considering a range of hydrogen emission rates of 1–10% and different power supply assumptions (dashed lines), presented as annual emissions per kilometer of vehicle operation in CO2e on 20- and 100-year time horizons. The emission factors of the electricity grid mix in 2030 follow the 1.5 °C-compatible pathway projection by the International Renewable Energy Agency (IRENA). (49) The emission factors of natural gas- and coal-fired power plant are also taken from IRENA. Similar analyses are conducted for the other three green hydrogen pathways and shown in Figure S3.

  • References


    This article references 63 other publications.

    1. 1
      Hydrogen Council. Hydrogen Insights 2023: An Update on the State of the Global Hydrogen Economy, with a Deep Dive into North America. 2023. https://hydrogencouncil.com/wp-content/uploads/2023/05/Hydrogen-Insights-2023.pdf (last accessed 2024-01-12).
    2. 2
      Valente, A.; Iribarren, D.; Dufour, J. Life Cycle Assessment of Hydrogen Energy Systems: A Review of Methodological Choices. Int. J. Life Cycle Assess. 2017, 22 (3), 346363,  DOI: 10.1007/s11367-016-1156-z
    3. 3
      Rinawati, D. I.; Keeley, A. R.; Takeda, S.; Managi, S. A Systematic Review of Life Cycle Assessment of Hydrogen for Road Transport Use. Prog. Energy 2022, 4 (1), 012001  DOI: 10.1088/2516-1083/ac34e9
    4. 4
      Rinawati, D. I.; Keeley, A. R.; Takeda, S.; Managi, S. Life-Cycle Assessment of Hydrogen Utilization in Power Generation: A Systematic Review of Technological and Methodological Choices. Front. Sustain. 2022, 3, 920876  DOI: 10.3389/frsus.2022.920876
    5. 5
      Hydrogen Council. Hydrogen Decarbonization Pathways: A Life-Cycle Assessment. 2021. https://hydrogencouncil.com/en/hydrogen-decarbonization-pathways/ (last accessed 2024-01-12).
    6. 6
      Bhandari, R.; Trudewind, C. A.; Zapp, P. Life Cycle Assessment of Hydrogen Production via Electrolysis – a Review. J. Clean. Prod. 2014, 85, 151163,  DOI: 10.1016/j.jclepro.2013.07.048
    7. 7
      Cetinkaya, E.; Dincer, I.; Naterer, G. F. Life Cycle Assessment of Various Hydrogen Production Methods. Int. J. Hydrogen Energ 2012, 37 (3), 20712080,  DOI: 10.1016/j.ijhydene.2011.10.064
    8. 8
      Lee, D.-Y.; Elgowainy, A.; Kotz, A.; Vijayagopal, R.; Marcinkoski, J. Life-Cycle Implications of Hydrogen Fuel Cell Electric Vehicle Technology for Medium- and Heavy-Duty Trucks. J. Power Sources 2018, 393, 217229,  DOI: 10.1016/j.jpowsour.2018.05.012
    9. 9
      Frank, E. D.; Elgowainy, A.; Reddi, K.; Bafana, A. Life-Cycle Analysis of Greenhouse Gas Emissions from Hydrogen Delivery: A Cost-Guided Analysis. Int. J. Hydrogen Energ 2021, 46 (43), 2267022683,  DOI: 10.1016/j.ijhydene.2021.04.078
    10. 10
      Paulot, F.; Paynter, D.; Naik, V.; Malyshev, S.; Menzel, R.; Horowitz, L. W. Global Modeling of Hydrogen Using GFDL-AM4.1: Sensitivity of Soil Removal and Radiative Forcing. Int. J. Hydrogen Energ 2021, 46 (24), 1344613460,  DOI: 10.1016/j.ijhydene.2021.01.088
    11. 11
      Warwick, N. J.; Archibald, A. T.; Griffiths, P. T.; Keeble, J.; O’Connor, F. M.; Pyle, J. A.; Shine, K. P. Atmospheric Composition and Climate Impacts of a Future Hydrogen Economy. Atmos. Chem. Phys. 2023, 23 (20), 1345113467,  DOI: 10.5194/acp-23-13451-2023
    12. 12
      Hauglustaine, D.; Paulot, F.; Collins, W.; Derwent, R.; Sand, M.; Boucher, O. Climate Benefit of a Future Hydrogen Economy. Commun. Earth Environ 2022, 3 (1), 295,  DOI: 10.1038/s43247-022-00626-z
    13. 13
      Sand, M.; Skeie, R. B.; Sandstad, M.; Krishnan, S.; Myhre, G.; Bryant, H.; Derwent, R.; Hauglustaine, D.; Paulot, F.; Prather, M.; Stevenson, D. A Multi-Model Assessment of the Global Warming Potential of Hydrogen. Commun. Earth Environ. 2023, 4 (1), 203,  DOI: 10.1038/s43247-023-00857-8
    14. 14
      Hauglustaine, D. A.; Ehhalt, D. H. A Three-dimensional Model of Molecular Hydrogen in the Troposphere. J. Geophys. Res.: Atmos. 2002, 107 (D17), ACH 4-1ACH 4-16,  DOI: 10.1029/2001JD001156
    15. 15
      Field, R. A.; Derwent, R. G. 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 Energ 2021, 46 (58), 3019030203,  DOI: 10.1016/j.ijhydene.2021.06.120
    16. 16
      Derwent, R. G.; Stevenson, D. S.; Utembe, S. R.; Jenkin, M. E.; Khan, A. H.; Shallcross, D. E. Global Modelling Studies of Hydrogen and Its Isotopomers Using STOCHEM-CRI: Likely Radiative Forcing Consequences of a Future Hydrogen Economy. Int. J. Hydrogen Energ 2020, 45 (15), 92119221,  DOI: 10.1016/j.ijhydene.2020.01.125
    17. 17
      Derwent, R.; Simmonds, P.; O’Doherty, S.; Manning, A.; Collins, W.; Stevenson, D. Global Environmental Impacts of the Hydrogen Economy. Int. J. Nucl. Hydrogen Prod Appl. 2006, 1 (1), 57,  DOI: 10.1504/IJNHPA.2006.009869
    18. 18
      Derwent, R. G.; Collins, W. J.; Johnson, C. E.; Stevenson, D. S. Transient Behaviour of Tropospheric Ozone Precursors in a Global 3-D CTM and Their Indirect Greenhouse Effects. Climatic Change 2001, 49 (4), 463487,  DOI: 10.1023/A:1010648913655
    19. 19
      Prather, M. J. An Environmental Experiment with H2?. Science 2003, 302 (5645), 581582,  DOI: 10.1126/science.1091060
    20. 20
      Schultz, M. G.; Diehl, T.; Brasseur, G. P.; Zittel, W. Air Pollution and Climate-Forcing Impacts of a Global Hydrogen Economy. Science 2003, 302 (5645), 624627,  DOI: 10.1126/science.1089527
    21. 21
      Warwick, N. J.; Bekki, S.; Nisbet, E. G.; Pyle, J. A. Impact of a Hydrogen Economy on the Stratosphere and Troposphere Studied in a 2-D Model. Geophys. Res. Lett. 2004, 31 (5), L05107  DOI: 10.1029/2003GL019224
    22. 22
      Colella, W. G.; Jacobson, M. Z.; Golden, D. M. Switching to a U.S. Hydrogen Fuel Cell Vehicle Fleet: The Resultant Change in Emissions, Energy Use, and Greenhouse Gases. J. Power Sources 2005, 150, 150181,  DOI: 10.1016/j.jpowsour.2005.05.092
    23. 23
      Wuebbles, D. J. Evaluation of the Potential Environmental Impacts from Large-Scale Use and Production of Hydrogen in Energy and Transportation Applications. 2008. https://digital.library.unt.edu/ark:/67531/metadc841210/ (last accessed 2024-01-12).
    24. 24
      Frazer-Nash Consultancy. Fugitive Hydrogen Emissions in a Future Hydrogen Economy. 2022. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1067137/fugitive-hydrogen-emissions-future-hydrogen-economy.pdf (last accessed 2024-01-12).
    25. 25
      Arrigoni, A.; Bravo, D. L. Hydrogen Emissions from a Hydrogen Economy and Their Potential Global Warming Impact. 2022; OP KJ-NA-31-188-EN-N. DOI: 10.2760/065589
    26. 26
      Cooper, J.; Dubey, L.; Bakkaloglu, S.; Hawkes, A. Hydrogen Emissions from the Hydrogen Value Chain-Emissions Profile and Impact to Global Warming. Sci. Total Environ. 2022, 830, 154624  DOI: 10.1016/j.scitotenv.2022.154624
    27. 27
      Fan, Z.; Sheerazi, H.; Bhardwaj, A.; Corbeau, A.-S.; Longobardi, K.; Castañeda, A.; Merz, A.-K.; Woodall, C. M.; Agrawal, M.; Orozco-Sanchez, S.; Friedmann, J. Hydrogen Leakage: A Potential Risk for the Hydrogen Economy; Center on Global Energy Policy. 2022. https://www.energypolicy.columbia.edu/publications/hydrogen-leakage-potential-risk-hydrogen-economy/ (last accessed 2024-01-12).
    28. 28
      Esquivel-Elizondo, S.; Hormaza Mejia, A.; Sun, T.; Shrestha, E.; Hamburg, S. P.; Ocko, I. B. Wide Range in Estimates of Hydrogen Emissions from Infrastructure. Front. Energy Res. 2023, 11, 0108,  DOI: 10.3389/fenrg.2023.1207208
    29. 29
      Alvarez, R. A.; Zavala-Araiza, D.; Lyon, D. R.; Allen, D. T.; Barkley, Z. R.; Brandt, A. R.; Davis, K. J.; Herndon, S. C.; Jacob, D. J.; Karion, A.; Kort, E. A.; Lamb, B. K.; Lauvaux, T.; Maasakkers, J. D.; Marchese, A. J.; Omara, M.; Pacala, S. W.; Peischl, J.; Robinson, A. L.; Shepson, P. B.; Sweeney, C.; Townsend-Small, A.; Wofsy, S. C.; Hamburg, S. P. Assessment of Methane Emissions from the U.S. Oil and Gas Supply Chain. Science 2018, 361 (6398), 186188,  DOI: 10.1126/science.aar7204
    30. 30
      Shen, L.; Gautam, R.; Omara, M.; Zavala-Araiza, D.; Maasakkers, J. D.; Scarpelli, T. R.; Lorente, A.; Lyon, D.; Sheng, J.; Varon, D. J.; Nesser, H.; Qu, Z.; Lu, X.; Sulprizio, M. P.; Hamburg, S. P.; Jacob, D. J. Satellite Quantification of Oil and Natural Gas Methane Emissions in the US and Canada Including Contributions from Individual Basins. Atmos. Chem. Phys. 2022, 22 (17), 1120311215,  DOI: 10.5194/acp-22-11203-2022
    31. 31
      Foulds, A.; Allen, G.; Shaw, J. T.; Bateson, P.; Barker, P. A.; Huang, L.; Pitt, J. R.; Lee, J. D.; Wilde, S. E.; Dominutti, P.; Purvis, R. M.; Lowry, D.; France, J. L.; Fisher, R. E.; Fiehn, A.; Pühl, M.; Bauguitte, S. J. B.; Conley, S. A.; Smith, M. L.; Lachlan-Cope, T.; Pisso, I.; Schwietzke, S. Quantification and Assessment of Methane Emissions from Offshore Oil and Gas Facilities on the Norwegian Continental Shelf. Atmos Chem. Phys. 2022, 22 (7), 43034322,  DOI: 10.5194/acp-22-4303-2022
    32. 32
      MacKay, K.; Lavoie, M.; Bourlon, E.; Atherton, E.; O’Connell, E.; Baillie, J.; Fougère, C.; Risk, D. Methane Emissions from Upstream Oil and Gas Production in Canada Are Underestimated. Sci. Rep-uk 2021, 11 (1), 8041,  DOI: 10.1038/s41598-021-87610-3
    33. 33
      Chen, Y.; Sherwin, E. D.; Berman, E. S. F.; Jones, B. B.; Gordon, M. P.; Wetherley, E. B.; Kort, E. A.; Brandt, A. R. Quantifying Regional Methane Emissions in the New Mexico Permian Basin with a Comprehensive Aerial Survey. Environ. Sci. Technol. 2022, 56 (7), 43174323,  DOI: 10.1021/acs.est.1c06458
    34. 34
      Howarth, R. W.; Jacobson, M. Z. How Green Is Blue Hydrogen?. Energy Sci. Eng. 2021, 9, 16761687,  DOI: 10.1002/ese3.956
    35. 35
      Stocks, M.; Fazeli, R.; Hughes, L.; Beck, F. J. Global Emissions Implications from Co-Combusting Ammonia in Coal Fired Power Stations: An Analysis of the Japan-Australia Supply Chain. J. Clean. Prod. 2022, 336, 130092  DOI: 10.1016/j.jclepro.2021.130092
    36. 36
      Ocko, I. B.; Hamburg, S. P. Climate Consequences of Hydrogen Emissions. Atmos. Chem. Phys. 2022, 22, 93499368,  DOI: 10.5194/acp-22-9349-2022
    37. 37
      Bertagni, M. B.; Pacala, S. W.; Paulot, F.; Porporato, A. Risk of the Hydrogen Economy for Atmospheric Methane. Nat. Commun. 2022, 13 (1), 7706,  DOI: 10.1038/s41467-022-35419-7
    38. 38
      Bauer, C.; Treyer, K.; Antonini, C.; Bergerson, J.; Gazzani, M.; Gencer, E.; Gibbins, J.; Mazzotti, M.; McCoy, S. T.; McKenna, R.; Pietzcker, R.; Ravikumar, A. P.; Romano, M. C.; Ueckerdt, F.; Vente, J.; van der Spek, M. On the Climate Impacts of Blue Hydrogen Production. Sustainable Energy Fuels 2021, 6 (1), 6675,  DOI: 10.1039/D1SE01508G
    39. 39
      Ricks, W.; Xu, Q.; Jenkins, J. D. Minimizing Emissions from Grid-Based Hydrogen Production in the United States. Environ. Res. Lett. 2023, 18 (1), 014025  DOI: 10.1088/1748-9326/acacb5
    40. 40
      Alvarez, R. A.; Pacala, S. W.; Winebrake, J. J.; Chameides, W. L.; Hamburg, S. P. Greater Focus Needed on Methane Leakage from Natural Gas Infrastructure. Proc. National Acad. Sci. 2012, 109 (17), 64356440,  DOI: 10.1073/pnas.1202407109
    41. 41
      Ocko, I. B.; Hamburg, S. P. Climate Impacts of Hydropower: Enormous Differences among Facilities and over Time. Environ. Sci. Technol. 2019, 53 (23), 1407014082,  DOI: 10.1021/acs.est.9b05083
    42. 42
      Tromp, T. K.; Shia, R.-L.; Allen, M.; Eiler, J. M.; Yung, Y. L. Potential Environmental Impact of a Hydrogen Economy on the Stratosphere. Science 2003, 300 (5626), 17401742,  DOI: 10.1126/science.1085169
    43. 43
      Jacobson, M. Z.; Colella, W. G.; Golden, D. M. Cleaning the Air and Improving Health with Hydrogen Fuel-Cell Vehicles. Science 2005, 308 (5730), 19011905,  DOI: 10.1126/science.1109157
    44. 44
      Jacobson, M. Z. Effects of Wind-powered Hydrogen Fuel Cell Vehicles on Stratospheric Ozone and Global Climate. Geophys. Res. Lett. 2008, 35 (19), L19803  DOI: 10.1029/2008GL035102
    45. 45
      van Ruijven, B.; Lamarque, J.-F.; van Vuuren, D. P.; Kram, T.; Eerens, H. Emission Scenarios for a Global Hydrogen Economy and the Consequences for Global Air Pollution. Global Environ. Change 2011, 21 (3), 983994,  DOI: 10.1016/j.gloenvcha.2011.03.013
    46. 46
      Bond, S. W.; Gül, T.; Reimann, S.; Buchmann, B.; Wokaun, A. Emissions of Anthropogenic Hydrogen to the Atmosphere during the Potential Transition to an Increasingly H2-Intensive Economy. Int. J. Hydrogen Energ 2011, 36 (1), 11221135,  DOI: 10.1016/j.ijhydene.2010.10.016
    47. 47
      IEA. Global Methane Tracker Documentation 2022 Version. 2022. https://iea.blob.core.windows.net/assets/b5f6bb13-76ce-48ea-8fdb-3d4f8b58c838/GlobalMethaneTracker_documentation.pdf (last accessed 2024-01-12).
    48. 48
      Gorski, J.; Jutt, T.; Wu, K. T. Carbon Intensity of Blue Hydrogen Production. 2021. https://www.pembina.org/reports/carbon-intensity-of-blue-hydrogen-revised.pdf (last accessed 2024-01-12).
    49. 49
      IRENA. World Energy Transitions Outlook 2022. 2022. https://www.irena.org/Digital-Report/World-Energy-Transitions-Outlook-2022 (last accessed 2024-01-12).
    50. 50
      Bertagni, M. B.; Socolow, R. H.; Martirez, J. M. P.; Carter, E. A.; Greig, C.; Ju, Y.; Lieuwen, T.; Mueller, M. E.; Sundaresan, S.; Wang, R.; Zondlo, M. A.; Porporato, A. Minimizing the Impacts of the Ammonia Economy on the Nitrogen Cycle and Climate. Proc. Natl. Acad. Sci. United States Am. 2023, 120 (46), e2311728120  DOI: 10.1073/pnas.2311728120
    51. 51
      Wolfram, P.; Kyle, P.; Zhang, X.; Gkantonas, S.; Smith, S. Using Ammonia as a Shipping Fuel Could Disturb the Nitrogen Cycle. Nat. Energy 2022, 7 (12), 11121114,  DOI: 10.1038/s41560-022-01124-4
    52. 52
      Schaller, K. V.; Gruber, C. Hydrogen Powered Fuel-Cell Buses Meet Future Transport Challenges. 2001. https://www.citelec.org/eledrive/Afuelcellarticles/PP301.PDF (last accessed 2024-01-12).
    53. 53
      Marcinkoski, J.; Vijayagopal, R.; Adams, J.; James, B.; Kopasz, J.; Ahluwalia, R. DOE Advanced Truck Technologies: Subsection of the Electrified Powertrain Roadmap Technical Targets for Hydrogen-Fueled Long-Haul Tractor-Trailer Trucks. 2019. https://www.hydrogen.energy.gov/docs/hydrogenprogramlibraries/pdfs/19006_hydrogen_class8_long_haul_truck_targets.pdf?Status=Master (last accessed 2024-01-12).
    54. 54
      Ueckerdt, F.; Bauer, C.; Dirnaichner, A.; Everall, J.; Sacchi, R.; Luderer, G. Potential and Risks of Hydrogen-Based e-Fuels in Climate Change Mitigation. Nat. Clim Change 2021, 11 (5), 384393,  DOI: 10.1038/s41558-021-01032-7
    55. 55
      Gudmundsson, O.; Thorsen, J. E. Source-to-Sink Efficiency of Blue and Green District Heating and Hydrogen-Based Heat Supply Systems. Smart Energy 2022, 6, 100071  DOI: 10.1016/j.segy.2022.100071
    56. 56
      de Kleijne, K.; de Coninck, H.; van Zelm, R.; Huijbregts, M. A. J.; Hanssen, S. V. The Many Greenhouse Gas Footprints of Green Hydrogen. Sustainable Energy Fuels 2022, 6, 43834387,  DOI: 10.1039/D2SE00444E
    57. 57
      CE Delft. Additionality of Renewable Electricity for Green Hydrogen Production in the EU. 2022. https://cedelft.eu/wp-content/uploads/sites/2/2022/12/CE_Delft_220358_Final_report.pdf (last accessed 2024-01-12).
    58. 58
      Wolak, F. Re: Section 45V Credit for Production of Clean Hydrogen and Additionality. 2023. https://static1.squarespace.com/static/53ab1feee4b0bef0179a1563/t/6452ad18d54ae3543c305f15/1683139864709/FCHEA+Additionality+Sign+On+Letter+Final+2023-5-4.pdf (last accessed 2024-01-12).
    59. 59
      Pototschnig, A. Renewable Hydrogen and the “Additionality” Requirement: Why Making It More Complex than Is Needed?. European University Institute 2021, 16,  DOI: 10.2870/201657
    60. 60
      Ocko, I. B.; Hamburg, S. P.; Jacob, D. J.; Keith, D. W.; Keohane, N. O.; Oppenheimer, M.; Roy-Mayhew, J. D.; Schrag, D. P.; Pacala, S. W. Unmask Temporal Trade-Offs in Climate Policy Debates. Science 2017, 356 (6337), 492493,  DOI: 10.1126/science.aaj2350
    61. 61
      Deng, H.; Bielicki, J. M.; Oppenheimer, M.; Fitts, J. P.; Peters, C. A. Leakage Risks of Geologic CO2 Storage and the Impacts on the Global Energy System and Climate Change Mitigation. Clim. Chang. 2017, 144 (2), 151163,  DOI: 10.1007/s10584-017-2035-8
    62. 62
      Vinca, A.; Emmerling, J.; Tavoni, M. Bearing the Cost of Stored Carbon Leakage. Front. Energy Res. 2018, 6, 40,  DOI: 10.3389/fenrg.2018.00040
    63. 63
      Hidden hydrogen: Earth may hold vast stores of a renewable, carbon-free fuel. Science https://www.science.org/content/article/hidden-hydrogen-earth-may-hold-vast-stores-renewable-carbon-free-fuel (last accessed 2024-01-12).
  • Supporting Information

    Supporting Information


    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.3c09030.

    • More detailed information about methods and data used in this study as well as additional figures that show the climate impact of hydrogen pathways relative to other alternatives under the 2030 condition (PDF)


    Terms & Conditions

    Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.