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Abstract

Hydrogen is often viewed as an important energy carrier in a future decarbonized world. Currently, most hydrogen is produced by steam reforming of methane in natural gas (“gray hydrogen”), with high carbon dioxide emissions. Increasingly, many propose using carbon capture and storage to reduce these emissions, producing so-called “blue hydrogen,” frequently promoted as low emissions. We undertake the first effort in a peer-reviewed paper to examine the lifecycle greenhouse gas emissions of blue hydrogen accounting for emissions of both carbon dioxide and unburned fugitive methane. Far from being low carbon, greenhouse gas emissions from the production of blue hydrogen are quite high, particularly due to the release of fugitive methane. For our default assumptions (3.5% emission rate of methane from natural gas and a 20-year global warming potential), total carbon dioxide equivalent emissions for blue hydrogen are only 9%-12% less than for gray hydrogen. While carbon dioxide emissions are lower, fugitive methane emissions for blue hydrogen are higher than for gray hydrogen because of an increased use of natural gas to power the carbon capture. Perhaps surprisingly, the greenhouse gas footprint of blue hydrogen is more than 20% greater than burning natural gas or coal for heat and some 60% greater than burning diesel oil for heat, again with our default assumptions. In a sensitivity analysis in which the methane emission rate from natural gas is reduced to a low value of 1.54%, greenhouse gas emissions from blue hydrogen are still greater than from simply burning natural gas, and are only 18%-25% less than for gray hydrogen. Our analysis assumes that captured carbon dioxide can be stored indefinitely, an optimistic and unproven assumption. Even if true though, the use of blue hydrogen appears difficult to justify on climate grounds.

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... M olecular hydrogen (H 2 ) is increasingly presented as a key element of the worldwide energy transformation required to limit global warming and meet the Paris Agreement 1 climate objectives. H 2 is recognised as an important future energy vector for applications ranging from power generation, transportation, industry, building heating and energy storage [2][3][4][5][6][7][8] . The use of hydrogen produced by a renewable source of electricity enables the conversion and the storage of energy, and may provide a way to decarbonize sectors of the economy difficult to decarbonize such as long-distance transportation by trucks and airplane, heavy industries, or for domestic uses blended with natural gas 4 . ...
... H 2 is recognised as an important future energy vector for applications ranging from power generation, transportation, industry, building heating and energy storage [2][3][4][5][6][7][8] . The use of hydrogen produced by a renewable source of electricity enables the conversion and the storage of energy, and may provide a way to decarbonize sectors of the economy difficult to decarbonize such as long-distance transportation by trucks and airplane, heavy industries, or for domestic uses blended with natural gas 4 . H 2 is a symmetric molecule with no direct impact on infrared radiation at temperature and pressure conditions prevailing in the Earth's atmosphere 9 . ...
... A first reason is that the climate impact of a hydrogen economy depends on how hydrogen is produced. In particular the production of "decarbonized" hydrogen from oil and gas depends on capture and storage of the CO 2 produced 4,30 , and on the associated upstream methane leakage 4,[31][32][33] . Secondly, since the indirect hydrogen impact on climate involves chemical reactions in the atmosphere, the uncertainties on key processes affecting the H 2 distribution and budget hamper a precise quantification of the associated radiative forcings 13,34 . ...
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Article
Hydrogen is recognised as an important future energy vector for applications in many sectors. Hydrogen is an indirect climate gas which induces perturbations of methane, ozone, and stratospheric water vapour, three potent greenhouse gases. Using data from a state-of-the-art global numerical model, here we calculate the hydrogen climate metrics as a function of the considered time-horizon and derive a 100-year Global Warming Potential of 12.8 ± 5.2 and a 20-year Global Warming Potential of 40.1 ± 24.1. The considered scenarios for a future hydrogen transition show that a green hydrogen economy is beneficial in terms of mitigated carbon dioxide emissions for all policy-relevant time-horizons and leakage rates. In contrast, the carbon dioxide and methane emissions associated with blue hydrogen reduce the benefit of a hydrogen economy and lead to a climate penalty at high leakage rate or blue hydrogen share. The leakage rate and the hydrogen production pathways are key leverages to reach a clear climate benefit from a large-scale transition to a hydrogen economy.
... The climate benefits of low-CO 2 natural gas technologies, such as pyrolysis, have recently come under scrutiny (Timmerberg et al 2020, Howarth and Jacobson 2021, Bauer et al 2022. To assess the potential of H 2 production from pyrolysis for the mitigation of global warming, it is useful to compare it to the climate benefit of H 2 produced from electric power through electrolysis (i.e. the splitting of water into H 2 and O 2 ). ...
... It should be noted that inclusion of end use emissions would likely render the 'direct natural gas use' pathway less attractive because of the higher global warming impact of CH 4 compared to H 2 . For supply chain CO 2 emissions, an estimate of 7.5% of combustion emissions was used (Howarth and Jacobson 2021). The obtained specific CO 2 emissions of power generation are compiled in table S1. ...
... Besides natural gas pyrolysis, blue hydrogen produced from steam methane reforming (SMR) of natural gas with CO 2 capture and geological storage is frequently discussed as a bridge technology. However, the natural gas consumption, the feasibility of autothermal reforming vs. SMR, and especially the realistically achievable carbon capture rate from a blue H 2 plant are unclear and estimates vary widely (Howarth andJacobson 2021, Bauer et al 2022). Nevertheless, preliminary estimates with the model developed herein (assuming SMR + carbon capture and storage (CCS), 1.37 MJ NG MJ H2 −1 , ∼73% CO 2 capture rate based on an ammonia plant configuration) indicate that the warming effect of blue hydrogen could be quite similar to that of natural gas pyrolysis. ...
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Article
Pyrolysis of natural gas to produce H2 and solid carbon through methane cracking can be characterized as a high-CH4, low-CO2 process. It results in low CO2 emissions because no direct CO2 is generated at the point of H2 generation if solid carbon is not combusted further. However, it results in high CH4 emissions because of its higher natural gas consumption compared to the direct use of natural gas and, thus, higher CH4 losses along the natural gas supply chain. Here, I analyzed whether this process can provide climate benefit in comparison to the direct, unabated utilization of natural gas and also in comparison with H2 produced from water electrolysis with grid electricity. To this end, Monte Carlo simulations of time-resolved and US state-specific emission profiles and their impact on mid-century global warming under different CH4 mitigation scenarios were conducted. It was found that the climate benefit of natural gas pyrolysis is highly dependent on plant location and the speed at which CH4 emissions can be abated. New York, Pennsylvania, and Ohio emerged as the most promising locations. This is because of their projected long reliance on natural gas for power generation, which renders electrolysis using grid electricity less attractive, as well as the relatively low estimate of current CH4 emissions from the natural gas supply chain. However, without fast action on CH4 emission mitigation, the climate benefit of natural gas pyrolysis is small or non-existent, irrespective of the plant location. Overall, the uncertainty in the relative climate benefit of natural gas pyrolysis was found to be large; however, this study developed an easy-to-adapt MS Excel/VBA tool that can be updated as soon as more accurate data on CH4 emissions becomes available. Policymakers, businesspeople, and scholars can use this tool to estimate the climate impact within their own scenarios and locations.
... At present, hydrogen is generally produced from natural gas ("gray hydrogen") and coal ("brown hydrogen"), with small contributions from oil and electricity. "Gray hydrogen" is mainly manufactured through the steam reforming of methane (SRM, Reactions (1) and (2)), which is accomplished by CO 2 emission [9]: ...
... It is predicted that by 2050, the production of hydrogen from natural gas will be almost entirely based on low-carbon technologies: water electrolysis accounts for more than 60% of world production, and natural gas in combination with CCUS (carbon capture, utilization, and storage) accounts for almost 40% ("blue hydrogen") [10]. However, the future of the latter technology is doubtful [6,9,11], since greenhouse gas footprints from "blue hydrogen" are only 18-20% less than those from "gray hydrogen" due to the use of fossil C-derived energy to implement the CCUS technology. Thus, the improvement of cost-effective processes of converting methane into a hydrogen-containing gas is still relevant. ...
... The bi-reforming of methane is a complex process [20,21]. It involves the reactions of steam (1) and (2) and carbon dioxide (4) and the conversion of methane, leading to the production of the target products (synthesis gas or hydrogen), a number of additional reactions that increase the yield of hydrogen (5) and (6), and side reactions of carbon formation (6)- (9 (9) Extensive application in the reforming process was given to Ni-based catalysts due to their low cost, wide availability, and sufficiently high activity [22][23][24][25][26][27][28]. An obstacle that arises when using nickel catalysts is their deactivation under harsh reaction conditions and the impossibility of self-activation [29]. ...
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Article
Hydrogen production through the bi-reforming of methane over exsolution-derived Ni catalysts has been studied. Nickel-based catalysts were prepared through the activation of (CeM)1−xNixOy (M = Al, La, Mg) solid solutions in a reducing gaseous medium. Their performance and resistance to coking under the reaction conditions were controlled by regulating their textural, structural, morphological, and redox properties through adjustments to the composition of the oxide matrix (M/Ce = 0–4; x = 0.2–0.8; y = 1.0–2.0). The role of the M-dopant type in the genesis and properties of the catalysts was established. The efficiency of the catalysts in the bi-reforming of methane increased in the following series of M: M-free < La < Al < Mg, correlating with the structural behavior of the nickel active component and the anti-coking properties of the support matrix. The preferred M-type and M/Ce ratio determined the best performance of (CeM)1−xNixOy catalysts. At 800 °C the optimum Ce0.6Mg0.2Ni0.2O1.6 catalyst provided a stable H2 yield of 90% at a high level of CO2 and CH4 conversions (>85%).
... Indirect upstream emissions are caused during the production, processing, and transportation of NG, which are 7.5% of the CO2 produced during the overall process [25,29]. The total CO2 produced during the overall process is 47.70 g/MJ i.e., the sum of CO2 from the SMR (38.47 g CO2/MJ) and the heat source (9.23 g CO2/MJ) (sum of Equations (2) and (6)). ...
... Methane's global warming potential (GWP) has been estimated by the Intergovernmental Panel on Climate Change (IPCC) to be between 84 and 87 when using a 20-year timeframe (GWP20) and between 28 and 36 when using a 100-year timeframe (GWP100) [36]. For further calculations, the GWP20 of 86 has been considered [25]. Thereby, the conversion of FME in Equations (9) and (10) is 42.33 g CO2eq/MJ and 10.15 g CO2eq/MJ (Equations (11) and (12)), respectively. ...
... According to statistics of the Shell plant in Alberta, the average capture efficiency of CO2 emitted from SMR is 78.8%, with daily rates of 53% to 90% [25,39]. Here, 85% efficiency has been considered, which is between 78.8% and 90% [25]; as a result, 5.77 g/MJ of CO2 (Equation (13)) ( Table 2) is directly released into the atmosphere. ...
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Article
Hydrogen has received substantial attention because of its diverse application in the energy sector. Steam methane reforming (SMR) dominates the current hydrogen production and is the least expensive endothermic reaction to produce grey hydrogen. This technology provides the advantages of low cost and high energy efficiency; however, it emits an enormous amount of CO2. Carbon capture storage (CCS) technology helps reduce these emissions by 47% to 53%, producing blue hydrogen. Methane pyrolysis is an alternative to SMR that produces (ideally) CO2-free turquoise hydrogen. In practice, methane pyrolysis reduces CO2 emissions by 71% compared to grey hydrogen and 46% compared to blue hydrogen. While carbon dioxide emissions decrease with CCS, fugitive methane emissions (FMEs) for blue and turquoise hydrogen are higher than those for grey hydrogen because of the increased use of natural gas to power carbon capture. We undertake FMEs of 3.6% of natural gas consumption for individual processes. In this study, we also explore the utilization of biogas as a feedstock and additional Boudouard reactions for efficient utilization of solid carbon from methane pyrolysis and carbon dioxide from biogas. The present study focuses on possible ways to reduce overall emissions from turquoise hydrogen to provide solutions for a sustainable low-CO2 energy source.
... Today 96% of hydrogen is produced from fossil fuels [19]. As GHG emissions from such hydrogen are high [20], natural gas industry is promoting blue hydrogen [19]. ...
... Today 96% of hydrogen is produced from fossil fuels [19]. As GHG emissions from such hydrogen are high [20], natural gas industry is promoting blue hydrogen [19]. It is produced from natural gas, but CO2 emissions from the production are captured and stored. ...
... It is produced from natural gas, but CO2 emissions from the production are captured and stored. However, recent research questions the environmental credentials of such hydrogen [19,21]. ...
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Article
Transition to net zero greenhouse gas (GHG) emissions from urban transport requires strategies improving energy efficiency and contributing to energy conservation. Efficiency gains can be achieved via combination of new technologies, such as electrification, connectivity, and automation. Energy conservation focuses on reducing the total miles travelled by private cars. Supporting modal shift to public transport (PT) is the essential element of that strategy. It starts with policy support enabling time and space prioritisation of PT vehicles. Next, the emerging technologies can optimise performance and comfort of PT vehicles by making the best use of the assigned resources. This article shows how these technologies can reduce GHG emissions directly, as well as indirectly by making PT an attractive choice boosting patronage. A case study illustrating the improvement of the environmental performance of full hybrid buses via connectivity and geofencing is given.
... Again, the range of GHG emission values provided in the literature is broad, between 10.9-18.4 kg CO2eq /kg H2 [19,20]. The highest value might seem quite conservative since the second highest value is 13.8 kg CO2eq /kg H2 [21]. ...
... The highest value might seem quite conservative since the second highest value is 13.8 kg CO2eq /kg H2 [21]. A reason for this could be that Howarth and Jacobson [20], who estimated a carbon footprint of 18.4 kg CO2eq /kg H2 , considered also the emission of fugitive methane (unintentional release) from the hydrogen production plant. ...
... Moreover, these authors claimed that even negative GHG emissions could be reached by using biomethane for hydrogen production and the biogas digestate as fertilizer. On the other hand, other authors concluded that the blue hydrogen carbon footprint can be much higher (16.7 kg CO2eq /kg H2 [20]) if a methane leakage rate of 3.5% is considered. According to the International Energy Agency (IEA) [9], methane emissions can have an impact of 5.2 kg CO2eq /kg H2 in addition to the CO 2 emissions. ...
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Article
The European Green Deal aims to transform the EU into a modern, resource-efficient, and competitive economy. The REPowerEU plan launched in May 2022 as part of the Green Deal reveals the willingness of several countries to become energy independent and tackle the climate crisis. Therefore, the decarbonization of different sectors such as maritime shipping is crucial and may be achieved through sustainable energy. Hydrogen is potentially clean and renewable and might be chosen as fuel to power ships and boats. Hydrogen technologies (e.g., fuel cells for propulsion) have already been implemented on board ships in the last 20 years, mainly during demonstration projects. Pressurized tanks filled with gaseous hydrogen were installed on most of these vessels. However, this type of storage would require enormous volumes for large long-range ships with high energy demands. One of the best options is to store this fuel in the cryogenic liquid phase. This paper initially introduces the hydrogen color codes and the carbon footprints of the different production techniques to effectively estimate the environmental impact when employing hydrogen technologies in any application. Afterward, a review of the implementation of liquid hydrogen (LH2) in the transportation sector including aerospace and aviation industries, automotive, and railways is provided. Then, the focus is placed on the maritime sector. The aim is to highlight the challenges for the adoption of LH2 technologies on board ships. Different aspects were investigated in this study, from LH2 bunkering, onboard utilization, regulations, codes and standards, and safety. Finally, this study offers a broad overview of the bottlenecks that might hamper the adoption of LH2 technologies in the maritime sector and discusses potential solutions.
... Specific reduction steps have not been indicated, but the significant role of the energy sector in this regard is underlined. The key solution seems to be to abandon fossil fuels as quickly as possible and ensure that methane does not leak from closed mines or from abandoned gas or oil wells [60]. Highlight-the highest levels of negative environmental consequences. ...
... Increased concentrations of CO 2 disrupt human cognitive processes (from making simple decisions to complex strategic thinking); its concentration achieved after several hours in a closed room has a negative impact on the effectiveness of learning, memory, and concentration. Carbon dioxide is a substance without which life on Earth and the functioning of organisms would not be possible, but the problem is not its existence itself, but the increase in its concentration, which is occurring at an increasingly faster pace [60,61]. In the life cycle of both analyzed technical objects, the impact on human health accounted for approximately 94% of all negative consequences in relation to the environment (for ecosystems it was approximately 5%, and for resources it was approximately 1%). ...
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Article
The conversion of kinetic energy from wind and solar radiation into electricity during the operation of wind and photovoltaic power plants causes practically no emissions of chemical compounds that are harmful to the environment. However, the production of their materials and components, as well as their post-use management after the end of their operation, is highly consumptive of energy and materials. For this reason, this article aims to assess the life cycle of a wind and photovoltaic power plant in the context of the sustainable development of energy systems. The objects of the research were two actual technical facilities—a 2 MW wind power plant and a 2 MW photovoltaic power plant, both located in Poland. The analysis of their life cycle was carried out on the basis of the LCA (life-cycle assessment) method, using the ReCiPe 2016 calculation procedure. The impact of the examined renewable energy systems was assessed under 22 impact categories and 3 areas of influence (i.e., human health, ecosystems, and resources), and an analysis was conducted for the results obtained as part of three compartments (i.e., air, water, and soil). The life cycle of the wind power plant was distinguished by a higher total potential negative environmental impact compared to the life cycle of the photovoltaic power plant. The highest levels of potential harmful impacts on the environment in both life cycles were recorded for areas of influence associated with negative impacts on human health. Emissions to the atmosphere accounted for over 90% of all emissions in the lifetimes of both the wind and the photovoltaic power plants. On the basis of the obtained results, guidelines were proposed for pro-ecological changes in the life cycle of materials and elements of the considered technical facilities for renewable energy sources, aimed at better implementation of the main assumptions of contemporary sustainable development (especially in the field of environmental protection).
... The boundary of performance evaluation begins with hydrogen production process ( Figure 1). Presently, sustainability of hydrogen production process is typically evaluated in terms of its GHG emissions by classifying hydrogen as green, blue, brown and grey (Howarth & Jacobson, 2021). However, other factors such as local pollutions, safety issues during mining and resources availability should also be taken into account. ...
... Green hydrogen produced from electrolysers powered by renewable energy also have environmental implications such as huge demand for highly pure freshwater (EPRI, 2020) and needs to be fuel cell performance considered in the evaluation. It is also noteworthy that green hydrogen generally costs more than blue, brown or grey hydrogen (Howarth & Jacobson, 2021). ...
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Article
Hydrogen fuel cell-based ship propulsion is one of the approaches to reduce greenhouse gases emissions from maritime transportation. For such propulsion to be feasible, production and transportation modes of hydrogen need to be sustainable in addition to efficient operation of fuel cells. Although life cycle assessments and well-to-wake approaches have been used to evaluate the performance of hydrogen fuel cells, there is a need for holistic performance framework that also incorporates safety in addition to technical, economic and environmental considerations. In order to address this, a framework to holistically assess the overall performance of hydrogen fuel cell-based ship propulsion is proposed here. The approach proposed in this paper can aid in evaluating the performance of hydrogen based marine transportation in addition to identifying optimal implementation options.
... shows current limits to powering planes by H 2 are storage needs: 4 times kerosene-fuel space, and condensation. 2 There is also debate on how 'green' hydrogen production methods are, 3 which is beyond the scope of this work on selective low-energy input hydrogen production. ...
Preprint
Hydrogen production as a clean, sustainable replacement for fossil fuels is gathering pace. Doubling the capacity of Paris-CDG airport has been halted, even with the upcoming Olympic Games, until hydrogen-powered planes can be used. It is thus timely to work on catalytic selective hydrogen production and optimise catalyst structure. Over 90% of all chemical manufacture uses a solid catalyst. This work describes the dissociation of a C-H bond in methane, chemisorbed at Ni(111) that stabilises the ensuing Ni-H linkage. In a subsequent step, gaseous hydrogen is given off. Many chemical reactions involve bond-dissociation. This process is often the key to rate-limiting reaction steps at solid surfaces. Since bond-breaking is poorly described by Hartree-Fock and DFT methods, Quantum Monte Carlo (QMC) methodology is used. Our embedded active site approach demonstrates novel QMC. The rate-limiting reaction step of methane decomposition to hydrogen and carbon is the initial C-H bond stretch. The full dissociation energy is offset by Ni-H bond formation at the surface. Reactive methyl (CH$_3$) radicals also interact with a vicinal Ni. These adsorbed methyl radicals subsequently produce methylene and hydrogen, with one atom dissociated from the methyl radical and the other desorbed from the Ni surface. The QMC activation barrier found is 85.4 +/- 1.1 kJ/mol JCP C (2020). Thus, QMC is shown to be encouraging for investigating similar catalytic systems.
... This green hydrogen can be used directly in conventional ammonia production, and other chemical synthesis steps [26]. Blue hydrogenproduced from steam reforming of fossil gas but with carbon capture and storage (CCS) -remains a questionable solution due to the very high climate impact of methane emissions that occur throughout the gas value chain and are at high risk of being significantly underestimated [27,28]. While CCS could enable reduction of emissions in the industry, the rapidly decreasing costs for renewable energy indicate that only in a few cases is CCS likely to make a significant long-term contribution [29]and that the additional costs for capture and storage could soon make green hydrogen the more attractive solution compared to blue hydrogen [30]. ...
Article
Chemicals is the industrial sector with the highest energy demand, using a substantial share of global fossil energy and emitting increasing amounts of greenhouse gasses following rapid growth over the past 25 years. Emissions associated with energy used have increased with growth in coal dependent regions but are also commonly underestimated in regions with higher shares of renewable energy. Renewable energy is key to reducing greenhouse gas emissions yet remains niche when considering corporate targets and initiatives aiming at emission reductions, which instead favour incremental energy efficiency improvements. These findings point to a risk for continued lock-in to fossil energy in the industry.
... There are various propositions in favor of "blue hydrogen"; i.e., employing carbon capture and storage to reduce GHG emissions from fossil-fuel-based production of hydrogen, which is often endorsed as a low carbon emitter [41]. The process typically employs steam methane reforming or auto thermal reforming and captures carbon dioxide emissions, which are either used in other chemical processes or stored in underground reservoirs. ...
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Article
Across the globe, energy production and usage cause the greatest greenhouse gas (GHG) emissions, which are the key driver of climate change. Therefore, countries around the world are aggressively striving to convert to a clean energy regime by altering the ways and means of energy production. Hydrogen is a frontrunner in the race to net-zero carbon because it can be produced using a diversity of feedstocks, has versatile use cases, and can help ensure energy security. While most current hydrogen production is highly carbon-intensive, advances in carbon capture, renewable energy generation, and electrolysis technologies could help drive the production of low-carbon hydrogen. However, significant challenges such as the high cost of production, a relatively small market size, and inadequate infrastructure need to be addressed before the transition to a hydrogen-based economy can be made. This review presents the state of hydrogen demand, challenges in scaling up low-carbon hydrogen, possible solutions for a speedy transition, and a potential course of action for nations.
... The resulting products are known as green and blue hydrogen, respectively, and are defined in the following. Integrating carbon capture and storage with grey hydrogen production to reduce CO 2 is known as "blue hydrogen" production [12]. Despite the low emissions of the blue hydrogen pathway, it has been reported that the environmental impact of the production of grey and blue hydrogen, is considerable, with annual global CO 2 emissions of approximately 830 million tonnes [13,14]. ...
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Article
Among multiple alternative clean and renewable energy sources, hydrogen is the most promising green fuel because of its high conversion efficiency, energy potentiality, and sustainability. In this review, green biohydrogen production by anoxygenic photosynthetic bacteria (APB) is summarized with the aim to enhance the present understanding of the underlying mechanisms and to gain a definite presentation of the current state of biohydrogen production. Mechanisms of biohydrogen derived from APB are briefly summarized, including the transformation of light energy into adenosine triphosphate, the metabolism of organic matter producing hydrogen ions, and photosynthetic bacteria coupled with reducing substances. In addition, factors affecting biohydrogen production by APB, including internal factors and external factors, are systematically described and discussed. Moreover, current methods for improving the hydrogen production efficiency from APB are presented. Promising applications ingratiating sustainable development goals are summarized, and both economic viability and environmental sustainability are reviewed.
... A more environmentally friendly method, where no carbon dioxide is formed, is by electrolysis of water using wind or solar energy as a power source [2]. This technique is quite expensive compared to the traditional steam methane reforming of natural gas, but it will become cheaper since both the efficiency of the electrolysers is improving, and the cost of renewable sources is decreasing [3]. Hydrogen is an energy carrier, and it is used in the industry, transport, power, and building sectors [4]. ...
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Article
To meet the target of reducing greenhouse gas emissions, hydrogen as a carbon-free fuel is expected to play a major role in future energy supplies. A challenge with hydrogen is its low density and volumetric energy value, meaning that large tanks are needed to store and transport it. By injecting hydrogen into the natural gas network, the transportation issue could be solved if the hydrogen–natural gas mixture satisfies the grid gas quality requirements set by legislation and standards. The end consumers usually have stricter limitations on the gas quality than the grid, where Euromot, the European association of internal combustion engine manufacturers, has specific requirements on the parameters: the methane number and Wobbe index. This paper analyses how much hydrogen can be added into the natural gas grid to fulfil Euromot’s requirements. An average gas composition was calculated based on the most common ones in Europe in 2021, and the results show that 13.4% hydrogen can be mixed with a gas consisting of 95.1% methane, 3.2% ethane, 0.7% propane, 0.3% butane, 0.3% carbon dioxide, and 0.5% nitrogen. The suggested gas composition indicates for engine manufacturers how much hydrogen can be added into the gas to be suitable for their engines.
... This forestalls the transition to current renewable energy sources such as solar and wind. From the perspective of Lamb et al. 22 , favourability towards natural gas as expressed by academic surrogates, including more recently 'blue hydrogen' [23][24][25][26] , can be viewed as climate action-delaying tactics. Nevertheless, top research universities continue to receive fossil fuel company donations to fund their energy policy centres. ...
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Article
Methane is 28 to 86 times more potent as a driver of global warming than CO2. Global methane concentrations have increased at an accelerating rate since 2004, yet the role of fossil fuels and revitalized natural gas extraction and distribution in accelerating methane concentrations is poorly recognized. Here we examine the policy positioning of university-based energy centres towards natural gas, given their growing influence on climate discourse. We conducted sentiment analysis using a lexicon- and rule-based sentiment scoring tool on 1,168,194 sentences in 1,706 reports from 26 universities, some of which receive their primary funding from the natural gas industry. We found that fossil-funded centres are more favourable in their reports towards natural gas than towards renewable energy, and tweets are more favourable when they mention funders by name. Centres less dependent on fossil funding show a reversed pattern with more neutral sentiment towards gas, and favour solar and hydro power.
... e., assuming 3.5 % leakage in the H 2 supply chain). Otherwise, carbon footprint of blue-H 2 is 135 g CO 2 -eq/MJ of H 2 , being 39.7 g CO 2 -eq/MJ directly emitted in the overall chain supply and 95.4 g CO 2 -eq/MJ of H 2 associated with CH 4 fugitive emissions [45]. In contrast, green-H 2 refers to H 2 produced from renewable primary sources, such as wind, solar, and hydropower, and biomass. ...
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Article
Hydrogen (H2) is a low-carbon carrier. Hence, measuring the impact of its supply chain is key to guaranteeing environmental benefits. This research proposes a classification of H2 in Colombia based on its carbon footprint and source. Such environmental characterization enables the design of regulatory instruments to incentivize the demand for low carbon-H2. Life cycle assessment (LCA) was used to determine the carbon footprint of H2 production technologies. Based on our LCA, four classes of H2 were defined based on the emission threshold: (i) gray-H2 (21.8–17.0 kg CO2-eq/kg H2), (ii) low-carbon-H2 (4.13 – 17.0 kg CO2-eq/kg H2), (iii) blue-H2 (<4.13 kg CO2-eq/kg H2), and (iv) green-H2 (<4.13 kg CO2-eq/kg H2). While low-carbon-H2 could be employed to reduce 22 % of the national greenhouse gas (GHG) emissions as defined in the Nationally Determined Contribution (NDC), both blue and green-H2 could be employed for national and international trade since the standard emissions are aligned with international schemes such as CertifHy and the Chinese model. Besides, gasification of biomass results in environmental savings, indicating that biomass is a promising feedstock for international and local trade. Furthermore, combinations of H2 production technologies such as renewable-based electrolysis, natural gas steam reforming with CCS, and ethanol conversion were evaluated to explore the production of a combination of green- and blue-H2 to meet the current and future demand of low-carbon emission H2 in Colombia. However, to comply with the proposed carbon emission threshold, the installed capacities of solar and wind energies must be increase.
... In contrast to the above optimistic perspectives concerning the utility of transforming natural gas to blue hydrogen a recent publication, examining the lifecycle greenhouse gas emissions upon this transformation, showed that the greenhouse gas emissions from the production of blue hydrogen are quite high because fugitive methane emissions for the production of blue hydrogen are higher than for the production of gray hydrogen due to the increased use of natural gas to obtain additional energy required for the carbon dioxide capture (Howarth and Jacobson 2021). There is no doubt that if the findings of this study will be confirmed by other researchers, the prospect of producing blue hydrogen from natural gas will be questioned. ...
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Article
This essay deals with the prospects of supplying humanity with energy in the twenty-first century. The gradual replacement of fossil fuels by green electricity, hydrogen and biofuels is examined in the context of deteriorating climate change and the ongoing depletion of fossil fuels. The production of large amounts of green electricity through the spreading of wind-energy, photovoltaic, concentrated solar power, hydroelectric power and high temperature geothermal plants and its storage through the global interconnection of electricity grids, the spreading of pumped hydro energy storage and melting salts plants and the lithium batteries leads certainly to a future world largely but not exclusively electrical. Hydrogen will be a very important energy carrier. The production of blue and green hydrogen, their transport and usage in cars, industry and trains in the near future as well as in ships and airplanes in the distant future is outlined. Biofuels must be inevitably added to the future energy profile of mankind besides green electricity and hydrogen. The modern trend of producing biofuels from residual fatty raw materials, microalgae and agricultural/forest residual raw materials to overcome the competition with foods production for land and water as well as the residual biomass utility for the production of aircraft fuels and bio-chemicals in the near future is also illustrated. Finally, the increasing contribution of biogas/biomethane to the future energy profile has been presented.
... However, so-called blue hydrogen can never be zero carbon and analysis of existing carbon capture facilities suggests that current blue hydrogen production is associated with significant residual emissions. 7 Green hydrogen made via electrolysis using electricity can be zero carbon if all of the electricity used is from zero carbon electricity sources. In order to achieve full decarbonisation of heating only green hydrogen from 100% zero carbon electricity is able to deliver on this. ...
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Article
This paper reviews independent analyses on the use of hydrogen for space and how water heating. Independent in this context is defined as “not carried out by or on behalf of a specific industry (e.g. gas, oil, electricity, heat pumps, boiler manufacturers)”. The review includes a total of 32 studies carried out at international, regional, national, state and city-level by a wide range of different organisations including universities, research institutes, intergovernmental organisations and consulting firms. Industry-funded studies have been excluded because such studies are often carried out on behalf of industry groups in order to support a position that suits their vested interests. The evidence assessment shows that the widespread use of hydrogen for heating is not supported by any of the 32 studies identified in this review. Instead, existing independent research so far suggests that, compared to other alternatives such as heat pumps, solar thermal and district heating, hydrogen use for domestic heating is less economic, less efficient, more resource intensive, and associated with larger environmental impacts.
... Apart from the alkyl amine route, many other processes are being tested at pilot scale (Global CCS Institute, 2022; Boot-Handford et al., 2014). All processes, however are not very efficient, with a capture ratio of 80% to 90%, and the present technologies fails to capture the fugitive methane, which is a more damaging greenhouse gas than CO2 (Howarth and Jacobson, 2021;Rapier, 2020). In order to reach 100% carbon removal, the absorber would have to be infinitely high. ...
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Conference Paper
Hydrogen could play a critical role as both an energy carrier and a chemical feedstock in the decarbonisation of South Africa's electricity and liquid fuel sectors. This potential has sparked major international and local effort in technologies for the production of green hydrogen, with much of the focus being directed at the use of hydrolysis and renewable energy. Unfortunately, this route is still severalfold more expensive than the conventional process, the latter being based on the steam reforming of fossil fuels. Given the existing infrastructure in Mpumulanga, and the importance of green and inclusive industrial development, which is one of the themes of this conference and also an important priority for the country's energy transition, it may be important to consider in more detail alternative hydrogen technologies. In this paper, the production of hydrogen using coal or gas with carbon capture and storage (CCS), known as blue hydrogen, is outlined. The present status of the technology for CCS and the techno-economic feasibility of a local blue hydrogen facility, as an interim measure to address decarbonisation while maintaining some of the employment and industrial activity within coal-producing areas, is discussed. The results are used to propose the necessary industrial policy framework to support a new hydrogen technological innovation system in South Africa.
... The color codes of hydrogen are used to associate the source used in hydrogen production. For example, hydrogen produced by the methane reforming process using natural gas is called gray hydrogen [51]. Hydrogen produced using fossil fuels is defined as blue hydrogen [52]. ...
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Hydrogen fuel cells (HFCs), which have shown significant technological developments in recent years, are promising alternative energy sources with high electrical efficiency and zero-emission in the coming years. Currently, these alternative sources are employed as energy units in many areas. The existing studies show that HFCs are structurally and operationally more efficient, durable, and usable year after year. However, a detailed study is needed showing the forthcoming structures, future socio-economic impacts, and production/cost prospects for the future vision of HFCs. To this end, this work aims to contribute a considerable view on the future vision of utilization and prediction in the HFC field. In this context, the forthcoming HFC structures basis fuel types and the future of hydrogen production are first presented. Further, the future applications of HFCs are detailed for potential areas like stationary, portable, transportation, and space applications. Subsequently, the expected socio-economic impacts like new job opportunities, environmental improvement, and health issues are detailed and explained for the following years. Implementation trends in several sectors like transportation, heating, industry heat, industry feedstock, and power generation are clarified for the 2050 vision. Finally, the production/cost forecasting values are demonstrated for the future vision of HFC technologies.
... When comparing various H 2 generation techniques, the key concern is the resulting CO 2 emissions and subsequent influence on the climate. Several studies conduct a life cycle assessment for each technology to accurately quantify the emission implications of H 2 generation [57][58][59][60]. At the same time, Frank et al. [61] concentrate on emissions during the distribution, transmission, and dispensing of the generated H 2 . ...
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... When they analyze the greenhouse gas emissions of blue hydrogen by taking into account not only carbon dioxide but also unburned fugitive methane, they conclude that even with a low (1.54%) methane emission rate, greenhouse gas emissions from blue hydrogen are only 18e25% lower than grey hydrogen. According to their findings, blue hydrogen will not provide any benefit in terms of climate protection; on the contrary, it will cause an increase in natural gas demand [43]. ...
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Over the past two years, requirements to meet climate targets have been intensified. In addition to the tightening of the climate targets and the demand for net-zero achievement by as early as 2045, there have been discussions on implementing and realizing these goals. Hydrogen has emerged as a promising climate-neutral energy carrier. Thus, over the last 1.5 years, more than 25 countries have published hydrogen roadmaps. Furthermore, various studies by different authorities have been released to support the development of a hydrogen economy. This paper examines published studies and hydrogen country roadmaps as part of a meta-analysis. Furthermore, a market analysis of electrolyzer manufacturers is conducted. The prospected demand for green hydrogen from various studies is compared to electrolyzer manufacturing capacities and selected green hydrogen projects to identify potential market ramp-up scenarios, and to evaluate if green hydrogen demand forecasts can be filled.
... In theory, the development of blue hydrogen, which captures the carbon from otherwise grey hydrogen, provides a low-carbon fuel. However, it remains controversial, as blue hydrogen has been shown to have a potential greenhouse footprint greater than burning natural gas or coal [59]. Therefore, green hydrogen from electrolysis will be required for a zero-carbon solution, but the technology is immature, and the electrical power requirements are very high [60,61]. ...
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Chapter
The capabilities of hydrogen as a key role in the upcoming transition to a more sustainable green energy future have increased rapidly in recent years and gained interest globally. COVID-19 Outbreak drew attention to how important it is for us as societies to have Clean Air, Water, Food And re-established consumers behavior regarding the consumption of energy which pointed the attention at hydrogen Starting from the first meeting to fight climate change until today, the biggest steps and strategies taken against global warming focusing on hydrogen cost-reduction technologies and Carbon-based industries where hydrogen is a promising solution to transform them into Emission-free industries. This chapter reviews the most recent publications and papers on green hydrogen, its applications, and the challenges that faces us as societies to empower green hydrogen utilization in a transition to a carbon-free future, and how it can play a vital role in the energy transition with Europe latest hydrogen-based strategies to become a climate-neutral continent. And how hydrogen and its application will lead the energy transition to renewables in Turkey.KeywordsGreen hydrogenClimate changeRenewable energyTurkish hydrogen roadmapHydrogen transitionCovid-19
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Thesis
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Methane is a potent greenhouse gas emitted by both human activity and the natural environment. Due to its relatively short atmospheric lifetime, controlling methane emissions is increasingly recognised as a powerful climate mitigation strategy. Methane is a potent greenhouse gas emitted by both human activity and the natural environment. Due to its relatively short atmospheric lifetime, controlling methane emissions is increasingly recognised as a powerful climate mitigation strategy.
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Maintaining global warming well below 2 °C, as stipulated in the Paris Agreement, will require a complete overhaul of the world energy system. Hydrogen is considered to be a key component of the decarbonization strategy for large parts of the transport system, as well as some heavy industries. Today, about 96% of current hydrogen production comes from the steam reforming of coal or natural gas (labelled black and grey hydrogen, respectively). If hydrogen is to become a solution, then black and grey hydrogen need to be replaced by a low-carbon option. One method that has received much attention is to produce so-called green hydrogen by coupling water electrolysis with renewable energies. However, green hydrogen is expensive and energy-intensive to produce. Here, we explore an alternative option and highlight the benefits of rock-based hydrogen (white and orange) compared with classic electrolysis-based technologies. We show that the exploitation of native hydrogen and its combination with carbon sequestration has the potential to fuel a large part of the energy transition without the substantial energy and raw material cost of green hydrogen. Enhancing natural subsurface hydrogen production through water injection could make a substantial contribution to achieving the low-carbon energy transition that is required to limit global warming.
Conference Paper
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A bottom-up technology rich model ETEM-Qatar is used to assess different scenarios for a transition to zero-net emissions in Qatar. The key technologies involved in the transition include electric mobility, hydrogen, carbon capture and storage and direct air capture. Through numerical simulations it is shown that Qatar could (i) start immediately to foster hybrid and electric cars for mobility, (ii) develop electricity generation from solar sources, (iii) develop carbon-free hydrogen production, (iv) introduce carbon capture and storage in all industrial sectors and, (v) develop actively direct air capture with carbon capture and storage to produce emission permits to be sold on an international carbon market. In the long-term, carbon-free hydrogen exports and emission permit sales could contribute to compensate the gas exports revenue losses that are expected in a global zero-net emissions context.
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Thesis
L’existence de fluides géologiques riches en hydrogène (H2) doit nécessairement faire l’objet de travaux d’exploration afin de statuer sur le potentiel énergétique de cette éventuelle ressource décarbonée. Depuis plus d’un siècle de nombreuses exhalations naturelles d’H2 ont été mis en évidence. Or à ce jour il n’existe aucun guide d’exploration basé sur une méthodologie et sur des indicateurs robustes. La détection d’occurrence gazeuse en surface correspond bien évidemment à l’approche la plus efficace et la plus rapide à mettre en œuvre pour identifier des flux. Il n’en reste pas moins qu’un flux ne constitue pas une ressource pour autant, puisqu’à ce jour, l’homme n’exploite que les stocks de ressources énergétiques fossiles. Il sera donc important de développer un guide d’exploration non pas orienté uniquement sur une problématique de surface, mais aussi sur des considérations géologiques profondes intégrant le système hydrogène dans son entier de la source au piège ou à la fuite dans l’atmosphère.Au cours de ce travail de thèse nous proposons d’utiliser le cadre géologique du piémont nord Pyrénéen pour élaborer un guide d’exploration. La compilation des données bibliographiques a révélé un contexte prometteur pour un système H2 du fait d’un lien entre sources profondes, chemins de migration crustale, dynamique de circulation de fluides, et pièges sédimentaires. En effet le nord-ouest des Pyrénées et plus particulièrement le Bassin Mauléon est caractérisé par la présence i) d’un corps mantellique (<10 km) où les conditions pression-température sont favorables à la serpentinisation ; ii) d’accidents structuraux majeurs tels que le Chevauchement Frontal Nord Pyrénéens (CFNP) constituant des drains collecteurs de grande ampleur, iii) des gradients hydrauliques, conjugués à des gradients de température et de pressions qui permettent la mise en mouvement des fluides ; iv) des formations sédimentaires imperméables ou de couvertures comme les évaporites ou les argiles consitutant des pièges pour accumuler l’H2.Suite à cette étude préalable, nous avons mis en place une campagne d’analyses des gaz du sol (H2, CO2, 222Rn, O2, CH4) à l’échelle régionales. Cette campagne d’analyse réalisée sur plus de 7500 km2 a très vite permis de mettre en évidence une zone à très fortes anomalies en H2, CO2, et 222Rn sur le pourtour du Bassin de Mauléon. Cette découverte nous a permis de resserrer rapidement le maillage de prospection sur la partie nord du bassin de Mauléon. Une campagne d’analyses géochimiques et géophysiques a été réalisée à Sauveterre-de-Béarn afin de déterminer l’origine et le parcours des gaz à l’origine de cette anomalie. Sur la base de l'analyse des gaz du sol et des levés électromagnétiques, nous avons confirmé l'existence d'une faille drainant les fluides profonds. De plus, l’étude des données historiques des forages entrepris dans la région il y a plus de 50 ans, conjugué à une mise en perspective des dernières connaissances géologiques et géophysiques de la région, nous a permis de mettre en évidence des zones où l’H2 pourrait s’accumuler.Enfin une partie expérimentale de broyage de quartz et de roches de la région a été menée afin d’explorer de nouveaux mécanismes de production d’H2 le long des failles. Nous avons mis en évidence une très forte influence du rapport eau/roche (W/R) et du pH sur la production d’H2. Ces découvertes apportent un éclairage nouveau sur les mécanismes mécano-radicalaires de production d’H2 où la spéciation des sites des surface des minéraux sont des paramètres clés contrôlant la production d’H2. Nous révélons pour la première fois que le broyage du quartz en présence de solutions carbonatés induit la formation d’espèces carboxylates (formate, acétate, oxalate). En plus de produire de l’H2, les mécanismes mécano-radicalaires permettent donc de produire des espèces réduites du carbones pouvant constituer une source d’énergie pour les écosystèmes microbiens lithotrophe de subsurface.
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Sustainable ammonia synthesis at mild conditions that relies on renewable energy sources and feedstocks is globally sought to replace the current Haber-Bosch process. Electricity-driven plasma catalysis is receiving increasing attention...
Article
The European Union's target to reach greenhouse gas neutrality by 2050 calls for a sharp decrease in the consumption of natural gas. This study assesses impacts of greenhouse gas neutrality on the gas system, taking France and Germany as two case studies which illustrate a wide range of potential developments within the European Union. Based on a review of French and German GHG-neutral scenarios, it explores impacts on gas infrastructure and estimates the changes in end-user methane price considering a business-as-usual and an optimised infrastructure pathway. Our results show that gas supply and demand radically change by mid-century across various scenarios. Moreover, the analysis suggests that deep transformations of the gas infrastructure are required and that according to the existing pricing mechanisms the end-user price of methane will increase, driven by the switch to low-carbon gases and intensified by infrastructure costs.
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Thesis
This thesis explores recent proposals for novel carbon sinks (carbon removal) and planetary sunshades (sunlight reflection) – often treated as forms of climate engineering, or deliberate and large-scale climate interventions. I examine sunlight reflection and carbon removal as case studies of emerging sociotechnical strategies in climate governance, where imperfect projections produced by expert assessments influence political debate and planning. I explore the hidden politics of expert assessment: How knowledge is constructed, contested, and communicated by expert networks, and how these shape understandings of future climate options. My inquiries are grounded in analytical frameworks from the intersection of global environmental governance and science and technology studies, as well as stakeholder-facing technology governance frameworks such as ‘responsible research and innovation’. I ask three research questions. Firstly: How is knowledge and evidence about sunlight reflection and carbon removal created (Chapters 2 and 3)? I focus on scientific expert networks in the global North, and the aims, epistemologies, and effects of their assessment practices. Secondly: What does this knowledge do (Chapters 2, 3, 4, and 5)? I examine how assessment practices set in play resonant terms and frames of reference that actively – if imperfectly – steer climate governance in their image. Thirdly: How can this knowledge be used to bridge differences (Chapters 5 and 6)? I move from how knowledge is constructed to focusing on that construction as a form of experimentation – engaging with different expert networks and knowledge types to use assessment practices as platforms exploring new directions for research and policy. The chapters represent three directions. The first is from analytical to engagement work, using critical mappings of the knowledge economy to inform bridging activities amongst experts and stakeholders. The second is from retrospective to generative work – from analysis of how knowledge is constructed, to activities that use the future as a sandbox to generate new knowledge, and that in turn shape assessments. The final direction moves from general technological categories to specific approaches – engaging first with the wider politics of planetary interventions, and then with those of particular approaches and their expert networks. I begin with interpretive reviews. Tools of the Trade (Chapter 2) juxtaposes a mission-oriented mode of assessment prioritizing actionable evidence for policy audiences against a deliberative mode aiming for open-ended appraisal with diverse stakeholders. The Practice of Responsible Research and Innovation (Chapter 3) takes a more critical look at deliberative activities, pointing out that these, by setting themselves up against mission-oriented work, engage in the same implicit and instrumental politics of knowledge-making. Delaying Decarbonization (Chapter 4) examines the longer and wider arc of climate governance, treating sunlight reflection and carbon removal as sociotechnical strategies that draw on the same political rationales that have informed a host of antecedent strategies, from market mechanisms and carbon capture to shale gas and short-lived climate pollutants. I conclude with bridging and generative engagements on particular approaches. Is Bioenergy Carbon Capture and Storage Feasible? (Chapter 5) engages members of integrated assessment modeling groups and a multi-disciplinary group of critical experts, and finds that perspectives on how the ‘feasibility’ of novel climate options should be calculated are actually reflections on the influence of economic modeling work in climate policy. Engineering Imaginaries (Chapter 6) engages scholars invested in early conversations on the risk profiles and appropriate governance of a planetary form of sunlight reflection, and explores the value of anticipatory foresight approaches to create mutual learning amongst entrenched perspectives, and to generate governance that might be robust against many future plausibilities.
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We use 2010–2015 Greenhouse Gases Observing Satellite (GOSAT) observations of atmospheric methane columns over North America in a high-resolution inversion of methane emissions, including contributions from different sectors and their trends over the period. The inversion involves an analytical solution to the Bayesian optimization problem for a Gaussian mixture model (GMM) of the emission field with up to 0.5∘×0.625∘ resolution in concentrated source regions. The analytical solution provides a closed-form characterization of the information content from the inversion and facilitates the construction of a large ensemble of solutions exploring the effect of different uncertainties and assumptions in the inverse analysis. Prior estimates for the inversion include a gridded version of the Environmental Protection Agency (EPA) Inventory of US Greenhouse Gas Emissions and Sinks (GHGI) and the WetCHARTs model ensemble for wetlands. Our best estimate for mean 2010–2015 US anthropogenic emissions is 30.6 (range: 29.4–31.3) Tg a−1, slightly higher than the gridded EPA inventory (28.7 (26.4–36.2) Tg a−1). The main discrepancy is for the oil and gas production sectors, where we find higher emissions than the GHGI by 35 % and 22 %, respectively. The most recent version of the EPA GHGI revises downward its estimate of emissions from oil production, and we find that these are lower than our estimate by a factor of 2. Our best estimate of US wetland emissions is 10.2 (5.6–11.1) Tg a−1, on the low end of the prior WetCHARTs inventory uncertainty range (14.2 (3.3–32.4) Tg a−1), which calls for better understanding of these emissions. We find an increasing trend in US anthropogenic emissions over 2010–2015 of 0.4 % a−1, lower than previous GOSAT-based estimates but opposite to the decrease reported by the EPA GHGI. Most of this increase appears driven by unconventional oil and gas production in the eastern US. We also find that oil and gas production emissions in Mexico are higher than in the nationally reported inventory, though there is evidence for a 2010–2015 decrease in emissions from offshore oil production.
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From typhoons to wildfires, as the visible impacts of climate change mount, calls for mitigation through carbon drawdown are escalating. Environmentalists and many climatologists are urging steps to enhance biological methods of carbon drawdown and sequestration. Market actors seeing avenues for profit have launched ventures in mechanical–chemical carbon dioxide removal (CDR), seeking government support for their methods. Governments are responding. Given the strong, if often unremarked, momentum of demands for public subsidy of these commercial methods, on what cogent bases can elected leaders make decisions that, first and foremost, meet societal needs? To address this question, we reviewed the scientific and technical literature on CDR, focusing on two methods that have gained most legislative traction: point-source capture and direct air capture–which together we term “industrial carbon removal” (ICR), in contrast to biological methods. We anchored our review in a standard of “collective biophysical need,” which we define as a reduction of the level of atmospheric CO2. For each ICR method, we sought to determine (1) whether it sequesters more CO2 than it emits; (2) its resource usage at scale; and (3) its biophysical impacts. We found that the commercial ICR (C-ICR) methods being incentivized by governments are net CO2 additive: CO2 emissions exceed removals. Further, the literature inadequately addresses the resource usage and biophysical impacts of these methods at climate-significant scale. We concluded that dedicated storage, not sale, of captured CO2 is the only assured way to achieve a reduction of atmospheric CO2. Governments should therefore approach atmospheric carbon reduction as a public service, like water treatment or waste disposal. We offer policy recommendations along this line and call for an analysis tool that aids legislators in applying biophysical considerations to policy choices.
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In 2019, New York State passed aggressive new climate legislation to reduce greenhouse gas (GHG) emissions and laid out major changes for how emissions are reported. One change is the inclusion of emissions from outside of the boundaries of the State if they are associated with energy use within NY; the traditional inventory considered emissions only within the State. The new legislation also mandated that methane emissions be compared with carbon dioxide over a 20-year time frame rather than the 100-year time frame previously used by NY and still used by virtually all other governments globally. This reflected the desire of NY's policymakers for a tool that evaluates emissions from the standpoint of energy consumption and that more heavily weighs the role of methane as an agent of warming over the next few decades. This paper compares emissions based on the new approach for GHG reporting with the traditional inventory. The traditional inventory is driven almost entirely by carbon dioxide emissions. As of 2015, these carbon dioxide emissions had declined by 15% since 1990 due to an 88% decrease in coal consumption and a 27% decrease in consumption of petroleum products, although consumption of natural gas had increased by 57%. Methane emissions increased by almost 30% between 1990 and 2015, largely due to the increased consumption of natural gas. According to the new GHG reporting rules, methane contributed 28% of all fossil-fuel emissions in 1990 and 37% in 2015. Total GHG emissions remained virtually unchanged from 1990 to 2015.
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Methane has been rising rapidly in the atmosphere over the past decade, contributing to global climate change. Unlike the late 20th century when the rise in atmospheric methane was accompanied by an enrichment in the heavier carbon stable isotope (¹³C) of methane, methane in recent years has become more depleted in ¹³C. This depletion has been widely interpreted as indicating a primarily biogenic source for the increased methane. Here we show that part of the change may instead be associated with emissions from shale-gas and shale-oil development. Previous studies have not explicitly considered shale gas, even though most of the increase in natural gas production globally over the past decade is from shale gas. The methane in shale gas is somewhat depleted in ¹³C relative to conventional natural gas. Correcting earlier analyses for this difference, we conclude that shale-gas production in North America over the past decade may have contributed more than half of all of the increased emissions from fossil fuels globally and approximately one-third of the total increased emissions from all sources globally over the past decade.
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Plain Language Summary Recent efforts to quantify fugitive methane associated with the oil and gas sector, with a particular focus on production, have resulted in significant revisions upward of emission estimates. In comparison, however, there has been limited focus on urban methane emissions. Given the volume of gas distributed and used in cities, urban losses can impact national‐level emissions. In this study we use aircraft observations of methane, carbon dioxide, carbon monoxide, and ethane to determine characteristic correlation slopes, enabling quantification of urban methane emissions and attribution to natural gas. We sample nearly 12% of the U.S. population and 4 of the 10 most populous cities, focusing on older, leak‐prone urban centers. Emission estimates are more than twice the total in the U.S. EPA inventory for these regions and are predominantly attributed to fugitive natural gas losses. Current estimates for methane emissions from the natural gas supply chain appear to require revision upward, in part possibly by including end‐use emissions, to account for these urban losses.
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Carbon capture and storage (CCS) for fossil-fuel power plants is perceived as a critical technology for climate mitigation. Nevertheless, limited installed capacity to date raises concerns about the ability of CCS to scale sufficiently. Conversely, scalable renewable electricity installations—solar and wind—are already deployed at scale and have demonstrated a rapid expansion potential. Here we show that power-sector CO2 emission reductions accomplished by investing in renewable technologies generally provide a better energetic return than CCS. We estimate the electrical energy return on energy invested ratio of CCS projects, accounting for their operational and infrastructural energy penalties, to range between 6.6:1 and 21.3:1 for 90% capture ratio and 85% capacity factor. These values compare unfavourably with dispatchable scalable renewable electricity with storage, which ranges from 9:1 to 30+:1 under realistic configurations. Therefore, renewables plus storage provide a more energetically effective approach to climate mitigation than constructing CCS fossil-fuel power stations.
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Significance Our results demonstrate that access to high-resolution spatiotemporal activity data and multiscale, contemporaneous measurements is critical to understanding oil- and gas-related methane emissions. Careful consideration of all factors influencing methane emissions—including temporal variation—is necessary in scientific and policy discussions to develop effective strategies for mitigating greenhouse gas emissions from natural gas infrastructure.
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Methane emissions from the U.S. oil and natural gas supply chain were estimated using ground-based, facility-scale measurements and validated with aircraft observations in areas accounting for ~30% of U.S. gas production. When scaled up nationally, our facility-based estimate of 2015 supply chain emissions is 13 ± 2 Tg/y, equivalent to 2.3% of gross U.S. gas production. This value is ~60% higher than the U.S. EPA inventory estimate, likely because existing inventory methods miss emissions released during abnormal operating conditions. Methane emissions of this magnitude, per unit of natural gas consumed, produce radiative forcing over a 20-year time horizon comparable to the CO2 from natural gas combustion. Significant emission reductions are feasible through rapid detection of the root causes of high emissions and deployment of less failure-prone systems.
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In the past decade there has been a massive growth in the horizontal drilling and hydraulic fracturing of shale gas and tight oil reservoirs to exploit formerly inaccessible or unprofitable energy resources in rock formations with low permeability. In North America, these unconventional domestic sources of natural gas and oil provide an opportunity to achieve energy self-sufficiency and to reduce greenhouse gas emissions when displacing coal as a source of energy in power plants. However, fugitive methane emissions in the production process may counter the benefit over coal with respect to climate change and therefore need to be well quantified.Here we demonstrate that positive methane anomalies associated with the oil and gas industries can be detected from space and that corresponding regional emissions can be constrained using satellite observations. Based on a mass-balance approach, we estimate that methane emissions for two of the fastest growing production regions in the United States, the Bakken and Eagle Ford formations, have increased by 990 ± 650 ktCH 4 yr − 1 and 530 ± 330 ktCH 4 yr − 1 between the periods 2006–2008 and 2009–2011. Relative to the respective increases in oil and gas production, these emission estimates correspond to leakages of 10.1 ± 7.3 % and 9.1 ± 6.2 % in terms of energy content, calling immediate climate benefit into question and indicating that current inventories likely underestimate fugitive emissions from Bakken and Eagle Ford.
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In April 2011, we published the first peer-reviewed analysis of the greenhouse gas footprint (GHG) of shale gas, concluding that the climate impact of shale gas may be worse than that of other fossil fuels such as coal and oil because of methane emissions. We noted the poor quality of publicly available data to support our analysis and called for further research. Our paper spurred a large increase in research and analysis, including several new studies that have better measured methane emissions from natural gas systems. Here, I review this new research in the context of our 2011 paper and the fifth assessment from the Intergovernmental Panel on Climate Change released in 2013. The best data available now indicate that our estimates of methane emission from both shale gas and conventional natural gas were relatively robust. Using these new, best available data and a 20-year time period for comparing the warming potential of methane to carbon dioxide, the conclusion stands that both shale gas and conventional natural gas have a larger GHG than do coal or oil, for any possible use of natural gas and particularly for the primary uses of residential and commercial heating. The 20-year time period is appropriate because of the urgent need to reduce methane emissions over the coming 15–35 years.
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Significance Successful regulation of greenhouse gas emissions requires knowledge of current methane emission sources. Existing state regulations in California and Massachusetts require ∼15% greenhouse gas emissions reductions from current levels by 2020. However, government estimates for total US methane emissions may be biased by 50%, and estimates of individual source sectors are even more uncertain. This study uses atmospheric methane observations to reduce this level of uncertainty. We find greenhouse gas emissions from agriculture and fossil fuel extraction and processing (i.e., oil and/or natural gas) are likely a factor of two or greater than cited in existing studies. Effective national and state greenhouse gas reduction strategies may be difficult to develop without appropriate estimates of methane emissions from these source sectors.
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We evaluate the greenhouse gas footprint of natural gas obtained by high-volume hydraulic fracturing from shale formations, focusing on methane emissions. Natural gas is composed largely of methane, and 3.6% to 7.9% of the methane from shale-gas production escapes to the atmosphere in venting and leaks over the life-time of a well. These methane emissions are at least 30% more than and perhaps more than twice as great as those from conventional gas. The higher emissions from shale gas occur at the time wells are hydraulically fractured—as methane escapes from flow-back return fluids—and during drill out following the fracturing. Methane is a powerful greenhouse gas, with a global warming potential that is far greater than that of carbon dioxide, particularly over the time horizon of the first few decades following emission. Methane contributes substantially to the greenhouse gas footprint of shale gas on shorter time scales, dominating it on a 20-year time horizon. The footprint for shale gas is greater than that for conventional gas or oil when viewed on any time horizon, but particularly so over 20years. Compared to coal, the footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100years. KeywordsMethane–Greenhouse gases–Global warming–Natural gas–Shale gas–Unconventional gas–Fugitive emissions–Lifecycle analysis–LCA–Bridge fuel–Transitional fuel–Global warming potential–GWP
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Thispaperreviewsandranksmajorproposedenergy-relatedsolutionstoglobalwarming,airpollutionmortality,andenergysecuritywhileconsideringotherimpactsoftheproposedsolutions,suchasonwatersupply,landuse,wildlife,resourceavailability,thermalpollution,waterchemicalpollution,nuclearproliferation,andundernutrition.Nineelectricpowersourcesandtwoliquidfueloptionsareconsidered.Theelectricitysourcesincludesolar-photovoltaics(PV),concentratedsolarpower(CSP),wind,geothermal,hydroelectric,wave,tidal,nuclear,andcoalwithcarboncaptureandstorage(CCS)technology.Theliquidfueloptionsincludecorn-ethanol(E85)andcellulosic-E85.Toplacetheelectricandliquidfuelsourcesonanequalfooting,weexaminetheircomparativeabilitiestoaddresstheproblemsmentionedbypoweringnew-technologyvehicles,includingbattery-electricvehicles(BEVs),hydrogenfuelcellvehicles(HFCVs),andflex-fuelvehiclesrunonE85.Twelvecombinationsofenergysource-vehicletypeareconsidered.Uponrankingandweightingeachcombinationwithrespecttoeachof11impactcategories,fourcleardivisionsofranking,ortiers,emerge.Tier1(highest-ranked)includeswind-BEVsandwind-HFCVs.Tier2includesCSP-BEVs,geothermal-BEVs,PV-BEVs,tidal-BEVs,andwave-BEVs.Tier3includeshydro-BEVs,nuclear-BEVs,andCCS-BEVs.Tier4includescorn-andcellulosic-E85.Wind-BEVsrankedfirstinsevenoutof11categories,includingthetwomostimportant,mortalityandclimatedamagereduction.AlthoughHFCVsaremuchlessefficientthanBEVs,wind-HFCVsarestillverycleanandwererankedsecondamongallcombinations.Tier2optionsprovidesignificantbenefitsandarerecommended.Tier3optionsarelessdesirable.However,hydroelectricity,whichwasrankedaheadofcoal-CCSandnuclearwithrespecttoclimateandhealth,isanexcellentloadbalancer,thusrecommended.TheTier4combinations(cellulosic-andcorn-E85)wererankedlowestoverallandwithrespecttoclimate,airpollution,landuse,wildlifedamage,andchemicalwaste.Cellulosic-E85rankedlowerthancorn-E85overall,primarilyduetoitspotentiallylargerlandfootprintbasedonnewdataanditshigherupstreamairpollutionemissionsthancorn-E85.Whereascellulosic-E85maycausethegreatestaveragehumanmortality,nuclear-BEVscausethegreatestupper-limitmortalityriskduetotheexpansionofplutoniumseparationanduraniumenrichmentinnuclearenergyfacilitiesworldwide.Wind-BEVsandCSP-BEVscausetheleastmortality.Thefootprintareaofwind-BEVsis2-6ordersofmagnitudelessthanthatofanyotheroption.Becauseoftheirlowfootprintandpollution,wind-BEVscausetheleastwildlifeloss.Thelargestconsumerofwateriscorn-E85.Thesmallestarewind-,tidal-,andwave-BEVs.TheUScouldtheoreticallyreplaceall2007onroadvehicleswithBEVspoweredby73000-1440005MWwindturbines,lessthanthe300000airplanestheUSproducedduringWorldWarII,reducingUSCO2by32.5-32.7%andnearlyeliminating15000/yrvehicle-relatedairpollutiondeathsin2020.Insum,useofwind,CSP,geothermal,tidal,PV,wave,andhydrotoprovideelectricityforBEVsandHFCVsand,byextension,electricityfortheresidential,industrial,andcommercialsectors,willresultinthemostbenefitamongtheoptionsconsidered.Thecombinationofthesetechnologiesshouldbeadvancedasasolutiontoglobalwarming,airpollution,andenergysecurity.Coal-CCSandnuclearofferlessbenefitthusrepresentanopportunitycostloss,andthebiofueloptionsprovidenocertainbenefitandthegreatestnegativeimpacts.
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Evaluating multicomponent climate change mitigation strategies requires knowledge of the diverse direct and indirect effects of emissions. Methane, ozone, and aerosols are linked through atmospheric chemistry so that emissions of a single pollutant can affect several species. We calculated atmospheric composition changes, historical radiative forcing, and forcing per unit of emission due to aerosol and tropospheric ozone precursor emissions in a coupled composition-climate model. We found that gas-aerosol interactions substantially alter the relative importance of the various emissions. In particular, methane emissions have a larger impact than that used in current carbon-trading schemes or in the Kyoto Protocol. Thus, assessments of multigas mitigation policies, as well as any separate efforts to mitigate warming from short-lived pollutants, should include gas-aerosol interactions.
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This work presents a perspective on the production and use of hydrogen as an automotive fuel. Hydrogen has been hailed as the key to a clean energy future primarily because it can be produced from a variety of energy sources, it satisfies all energy needs, it is the least polluting, and it is the perfect carrier for solar energy in that it affords solar energy a storage medium. Efforts are underway to transform the global transportation energy economy from one dependent on oil to that based on sustainable hydrogen. The rationale behind these efforts is that hydrocarbon-based automobiles are a significant source of air pollution, while hydrogen-powered fuel cell vehicles produce effectively zero emissions. Besides the transportation area, fuel cells can also reduce emissions in other applications such as the residential or commercial distributed electricity generation. Hydrogen is the perfect partner for electricity, and together they create an integrated energy system based on distributed power generation and use. A discussion on the sources of hydrogen in the near- and long-term future as well as the cost of hydrogen production is provided.
Article
Data from a coal with carbon capture and use (CCU) plant and a synthetic direct air carbon capture and use (SDACCU) plant are analyzed for the equipment’s ability, alone, to reduce CO2. In both plants, natural gas turbines power the equipment. A net of only 10.8% of the CCU plant’s CO2-equivalent (CO2e) emissions and 10.5% of the CO2 removed from the air by the SDACCU plant are captured over 20 years, and only 20-31%, are captured over 100 years. The low net capture rates are due to uncaptured combustion emissions from natural gas used to power the equipment, uncaptured upstream emissions, and, in the case of CCU, uncaptured coal combustion emissions. Moreover, the CCU and SDACCU plants both increase air pollution and total social costs relative to no capture. Using wind to power the equipment reduces CO2e relative to using natural gas but still allows air pollution emissions to continue and increases the total social cost relative to no carbon capture. Conversely, using wind to displace coal without capturing carbon reduces CO2e, air pollution, and total social cost substantially. In sum, CCU and SDACCU increase or hold constant air pollution health damage and reduce little carbon before even considering sequestration or use leakages of carbon back to the air. Spending on capture rather than wind replacing either fossil fuels or bioenergy always increases total social cost substantially. No improvement in CCU or SDACCU equipment can change this conclusion while fossil power plant emissions exist, since carbon capture always incurs an equipment cost never incurred by wind, and carbon capture never reduces, instead mostly increases, air pollution and fuel mining, which wind eliminates. Once fossil power plant emissions end, CCU (for industry) and SDACCU social costs need to be evaluated against the social costs of natural reforestation and reducing nonenergy halogen, nitrous oxide, methane, and biomass burning emissions.
Article
The global and U.S. domestic effort to develop a clean energy economy and curb environmental pollution incentivizes the use of hydrogen as a transportation fuel, owing to its zero tailpipe pollutant emissions and high fuel efficiency in fuel cell electric vehicles (FCEVs). However, the hydrogen production process is not emissions free. Conventional hydrogen production via steam methane reforming (SMR) is energy intensive, co-produces carbon dioxide, and emits air pollutants. Thus, it is necessary to quantify the environmental impacts of SMR hydrogen production alongside the use-phase of FCEVs. This study fills the information gap, analyzing the greenhouse gas (GHG) and criteria air pollutant (CAP) emissions associated with hydrogen production in U.S. SMR facilities by compiling and matching the facility-reported GHG and CAP emissions data with facilities’ hydrogen production data. The actual amounts of hydrogen produced at U.S. SMR facilities are often confidential. Thus, we have developed four approaches to estimate the hydrogen production amounts. The resultant GHG and CAP emissions per MJ of hydrogen produced in individual facilities were aggregated to develop emission values for both a national median and a California state median. This study also investigates the breakdown of facility emissions into combustion emissions and non-combustion emissions.
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The current focus on the long-term global warming potential in climate policy-making runs the risk of mitigation options for short-lived climate pollutants being ignored, and tipping points being crossed. We outline how a more balanced perspective on long- and short-lived climate pollutants could become politically feasible.
Article
Hydrogen is a crucial raw materials to other industries. Globally, nearly 90% of the hydrogen or HyCO gas produced is consumed by the ammonia, methanol and oil refining industries. In the future, hydrogen could play an important role in the decarbonisation of transport fuel (i.e. use of fuel cell vehicles) and space heating (i.e. industrial, commercial, building and residential heating). This paper summarizes the results of the feasibility study carried out by Amec Foster Wheeler for the IEA Greenhouse Gas R&D Programme (IEA GHG) with the purpose of evaluating the performance and costs of a modern steam methane reforming without and with CCS producing 100,000 Nm³/h H2 and operating as a merchant plant. This study focuses on the economic evaluation of five different alternatives to capture CO2 from SMR. This paper provides an up-to-date assessment of the performance and cost of producing hydrogen without and with CCS based on technologies that could be erected today. This study demonstrates that CO2 could be captured from an SMR plant with an overall capture rate ranging between 53 to 90%. The integration of CO2 capture plant could increase the NG consumption by -0.03 to 1.41 GJ per Nm³/h of H2. The amount of electricity exported to the grid by the SMR plant is reduced. The levelised cost of H2 production could increase by 2.1 to 5.1 € cent per Nm³ H2 (depending on capture rate and technology selected). This translates to a CO2 avoidance cost of 47 to 70 €/t.
Article
Global warming potentials (GWPs) have become an essential element of climate policy and are built into legal structures that regulate greenhouse gas emissions. This is in spite of a well-known shortcoming: GWP hides trade-offs between short- and long-term policy objectives inside a single time scale of 100 or 20 years ( 1 ). The most common form, GWP100, focuses on the climate impact of a pulse emission over 100 years, diluting near-term effects and misleadingly implying that short-lived climate pollutants exert forcings in the long-term, long after they are removed from the atmosphere ( 2 ). Meanwhile, GWP20 ignores climate effects after 20 years. We propose that these time scales be ubiquitously reported as an inseparable pair, much like systolic-diastolic blood pressure and city-highway vehicle fuel economy, to make the climate effect of using one or the other time scale explicit. Policy-makers often treat a GWP as a value-neutral measure, but the time-scale choice is central to achieving specific objectives ( 2 – 4 ).
Article
This study examines the potential change in primary emissions and energy use from replacing the current U.S. fleet of fossil-fuel on-road vehicles (FFOV) with hybrid electric fossil fuel vehicles or hydrogen fuel cell vehicles (HFCV). Emissions and energy usage are analyzed for three different HFCV scenarios, with hydrogen produced from: (1) steam reforming of natural gas, (2) electrolysis powered by wind energy, and (3) coal gasification. With the U.S. EPA's National Emission Inventory as the baseline, other emission inventories are created using a life cycle assessment (LCA) of alternative fuel supply chains. For a range of reasonable HFCV efficiencies and methods of producing hydrogen, we find that the replacement of FFOV with HFCV significantly reduces emission associated with air pollution, compared even with a switch to hybrids. All HFCV scenarios decrease net air pollution emission, including nitrogen oxides, volatile organic compounds, particulate matter, ammonia, and carbon monoxide. These reductions are achieved with hydrogen production from either a fossil fuel source such as natural gas or a renewable source such as wind. Furthermore, replacing FFOV with hybrids or HFCV with hydrogen derived from natural gas, wind or coal may reduce the global warming impact of greenhouse gases and particles (measured in carbon dioxide equivalent emission) by 6, 14, 23, and 1%, respectively. Finally, even if HFCV are fueled by a fossil fuel such as natural gas, if no carbon is sequestered during hydrogen production, and 1% of methane in the feedstock gas is leaked to the environment, natural gas HFCV still may achieve a significant reduction in greenhouse gas and air pollution emission over FFOV. © 2005 Published by Elsevier B.V.
Decarbonized Hydrogen in the US Power and Industrial Sectors: Identifying and Incentivizing Opportunities to Lower Emissions
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Bartlett J, Krupnick A. Decarbonized Hydrogen in the US Power and Industrial Sectors: Identifying and Incentivizing Opportunities to Lower Emissions. Report 20-25. Resources for the Future; 2020. https://media.rff.org/docum ents/RFF_Report_20-25_Decar boniz ed_Hydro gen.pdf. Accessed April 1, 2021.
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Analyzing Future Demand, Supply, and Transport of Hydrogen. European Hydrogen Backbone in cooperation with Gas for Climate
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Boundary Dam 3 Coal Plant Achieves Goal of Capturing 4 Million Metric Tons of CO 2 but Reaches the Goal Two Years Late
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