Scoring and Ranking Methods for Evaluating the Techno-Economic Competitiveness of Hydrogen Production Technologies

Abstract

This research evaluates four hydrogen (H₂) production technologies via water electrolysis (WE): alkaline water electrolysis (AWE), proton exchange membrane electrolysis (PEME), anion exchange membrane electrolysis (AEME), and solid oxide electrolysis (SOE). Two scoring and ranking methods, the MACBETH method and the Pugh decision matrix, are utilized for this evaluation. The scoring process employs nine decision criteria: capital expenditure (CAPEX), operating expenditure (OPEX), operating efficiency (SOE), startup time (SuT), environmental impact (EI), technology readiness level (TRL), maintenance requirements (MRs), supply chain challenges (SCCs), and levelized cost of H₂ (LCOH). The MACBETH method involves pairwise technology comparisons for each decision criterion using seven qualitative judgment categories, which are converted into quantitative scores via M-MACBETH software (Version 3.2.0). The Pugh decision matrix benchmarks WE technologies using a baseline technology—SMR with CCS—and a three-point scoring scale (0 for the baseline, +1 for better, −1 for worse). Results from both methods indicate AWE as the leading H₂ production technology, which is followed by AEME, PEME, and SOE. AWE excels due to its lowest CAPEX and OPEX, highest TRL, and optimal operational efficiency (at ≈7 bars of pressure), which minimizes LCOH. AEME demonstrates balanced performance across the criteria. While PEME shows advantages in some areas, it requires improvements in others. SOE has the most areas needing enhancement. These insights can direct future R&D efforts toward the most promising H₂ production technologies to achieve the net-zero goal.

1. Introduction

The quest for sustainable and green energy sources has prompted significant interest in H₂ as a viable alternative to conventional fossil fuels. Of particular interest is green H₂ production through environmentally friendly technologies such as water electrolysis (WE) integrated with renewable electricity (RE) sources (viz., wind turbines, solar photovoltaic, and hydropower).

1.1. Literature Review

The current state of published work related to this research can be summarized as follows:

In his NREL report, Ivy (2004) [1] provided a techno-economic analysis (TEA) of electrolytic H₂ production systems, evaluating electrolyzers from five companies and offering critical insights into their cost and performance metrics. Zeng and Zhang (2010) [2] examined water electrolysis technologies for H₂ production, identifying key R&D areas for improving efficiency and reducing costs. Dufour et al. (2011) [3] utilized life cycle assessment (LCA) to evaluate various H₂ production pathways from fossil resources, including steam autothermal reforming, methane thermal decomposition, and coal gasification. They provided a comparative environmental impact assessment of fossil-based H₂ production versus electrolysis. Braga et al. (2013) [4] explored the techno-economic and ecological aspects of H₂ production via biogas-steam reforming, indicating that this technology, if integrated with sustainable feedstocks, could be an environmentally-friendly pathway for H₂ production.

Khalil (2016) [5] provided a comparative analysis of various electricity generation technologies, focusing on their environmental impacts from an LCIA perspective. The technologies assessed included nuclear power, coal-fired, natural gas (NG)-fired, wind, and solar PV power. His analysis highlighted that nuclear power offers significant environmental advantages over coal and NG-fired power generation due to its low GHG emissions and reduced human health impacts. However, challenges such as nuclear waste disposal and high initial capital costs need to be addressed. Hinkley et al. (2016) [6] evaluated the current and future costs of H₂ production from solar PV electricity combined with PEME, estimating a production cost of approximately USD 18.70/kg H₂, considering an uninstalled PEME cost and associated balance of plant (BoP) components at around USD 2285/kW. Kuchshinrichs et al. (2017) [7] examined the economics of AWE technology across Spain, Austria, and Germany, providing insights into its economic feasibility in diverse geographical conditions. Parkinson et al. (2018) [8] performed a TEA comparing SMR with other low-carbon H₂ production technologies, including electrolysis with renewable electricity, hydrocarbons reforming with CCS, and hydrocarbons pyrolysis into carbon and H₂ gas. The IRENA Report (2020) [9] concluded that a combination of government involvement, supportive policies, and private sector efforts to standardize and optimize electrolyzer designs can lead to lower costs and more affordable green hydrogen.

Khalil (2021) [10] quantified the environmental and human health impacts of H₂ production from glycerol, a biodiesel by-product, using three conversion technologies: supercritical water reforming (SCWR), aqueous-phase reforming (APR), and autothermal reforming (ATR). He utilized GaBi and Aspen HYSYS software to develop life cycle inventory data and assess environmental impacts per ISO 14040:2006 standards. The TRACI 2.1 methodology was used to quantify midpoint impact categories such as global warming potential (GWP) and energy consumption. The results indicated that glycerol APR is the most environmentally sustainable method among the three technologies assessed. James et al. (2021) [11] discussed strategies for reducing electrolysis costs at both the stack and system levels, including enhancing stack designs, increasing manufacturing scales, and improving materials management. Badgett et al. (2021) [12] argued that increasing the efficiency and reliability of electrolyzers can significantly reduce the overall cost of H₂ production. They emphasized the importance of enhancing current density, reducing degradation rates, and improving overall system efficiencies for the future of water electrolysis technologies.

Nasser et al. (2022) [13] analyzed hybrid renewable energy systems for H₂ production and storage, emphasizing the importance of using renewable energy sources to achieve decarbonization goals. They highlighted AWE’s technological maturity and described AEME as an emerging technology that combines the benefits of AWE and PEME. Kumar and Lim (2022) [14] evaluated the economic feasibility and environmental impacts of WE technologies, noting that while AWE has a higher TRL compared to PEME, SOE and AEME still require further development to reach commercial viability. Reksten et al. (2022) [15] emphasized the potential of hybrid renewable energy systems for efficient and cost-effective green H₂ production. By leveraging the characteristics of PV panels and wind turbines, these systems can overcome the limitations of single-source arrangements.

Sharma et al. (2023) [16] identified biomass gasification as a key method for sustainable H₂ production, utilizing organic materials to produce H₂ alongside by-products like biochar and syngas. James et al. (2023) [17] emphasized the importance of performing TEA in evaluating WE systems, as TEA aids in modeling and analyzing current and future costs, identifying key cost drivers, and charting pathways for cost reduction. Krishnan et al. (2023) [18] assessed the costs of AWE and PEME stacks, exploring pathways for cost reductions to make green H₂ competitive with blue and gray hydrogen.

In their study, Ajeeb et al. (2024) [19] focused on a green H₂ production project powered equally by solar and wind energy with a capacity of 60 MW and an estimated lifetime of 20 years. They evaluated the environmental impacts of H₂ production using two advanced alkaline electrolysis (ALE) technologies: pressurized alkaline electrolysis (ALE-C) and capillary-fed alkaline electrolysis (ALE-P). They concluded that ALE-C presents lower environmental impacts compared to ALE-P, making it a more sustainable option for H₂ production. Cammann et al. (2024) [20] compared the performance of an AWE plant at two locations: Hollands Kust Zuid (HKZ) and Kjøllefjord (KF). The HKZ plant demonstrated higher efficiency due to greater average wind speeds, while the KF plant showed reduced availability due to a higher frequency of low wind speeds. Song, Kim, and Yang (2024) [21] investigated the integration of small-scale hydropower with optimized AWE to produce green H₂. They concluded that integrating hydropower with AWE significantly reduces the environmental impact compared to conventional H₂ production methods.

Dannappel et al. (2024) [22] presented a mechanistic model of a 24 MW AWE plant powered by a 39 MW wind farm. The model included electrolysis stack characteristics, BoP components, and economic performance analysis. Their case analysis showed that the optimal design pressure is around 8 bar, minimizing the levelized cost of hydrogen (LCOH) to USD 10.45/kg H₂. Emam et al. (2024) [23] underscored the critical role of optimizing various electrolyzer parameters to enhance AWE system performance. By fine-tuning electrode thickness, spacing, roughness, and utilizing induction heating, significant improvements in efficiency and overall system performance can be achieved. These findings contribute to the broader understanding of how to optimize AWE systems for more sustainable and efficient H₂ production. In their study, Krishnan et al. (2024) [24] highlighted the increasing use of H₂ as a clean energy carrier, emphasizing its potential to decarbonize various sectors such as transportation, power generation, and industry. They conducted an LCA to compare the environmental impacts of AWE and PEME.

Khalil (2025) [25] conducted an extensive comparative analysis of different H₂ production technologies, evaluating them based on both quantitative criteria (cost, energy consumption, global warming potential, technology energy efficiency) and qualitative criteria (technology readiness level, availability of supply chain materials). He concluded that water electrolysis and biomass waste valorization represent the most promising near-term solutions for meeting the DOE’s 2021 Hydrogen Shot goal of reducing the cost of clean H₂ production to USD 1/kg within a decade. Sukur et al. (2025) [26] addressed Türkiye’s national energy policy goals, focusing on decarbonization and the use of H₂ as a key solution to meet growing energy demands sustainably. They employed the analytic hierarchy process (AHP) to evaluate the impact of various H₂ production technologies on the Energy Trilemma Index (ETI). Additionally, they reviewed Türkiye’s strategy and roadmap for H₂ technologies (categorized into green, blue, and turquoise H₂ production), examining their potential contributions to energy security, sustainability, and equity by 2053. Kadam et al. (2025) [27] evaluated the environmental impacts and energy consumption associated with various H₂ production methods on an industrial scale of 50 tones/day. They focused on the six-step copper–chlorine (Cu-Cl) cycle, comparing it with sorption-enhanced steam methane reforming (SE-SMR) and PEME. The authors emphasized the environmental and energy efficiency benefits of advanced Cu-Cl cycles. Nemeth et al. (2025) [28] provided an overview of H₂ production technologies and their environmental impact, focusing on global warming potential (GWP). They examined how various H₂ production methods align with the EU’s sustainability goals.

Hoope and Minke (2025) [29] explored the potential for reducing the environmental impacts of AWE through reuse and recycling strategies. Their study focused on the LCA of a 5 MW AWE, evaluating end-of-life (EoL) strategies and material recovery. They indicated that approximately 77% of materials in the AWE can be recycled or reused, demonstrating that using recycled materials instead of virgin materials can lead to a 50% reduction in GWP. Kafle et al. (2025) [30] reviewed research trends in LCA for various H₂ production technologies, highlighting advancements, challenges, and future directions to support sustainable H₂ production initiatives. Qureshi et al. (2025) [31] examined the potential of PEME technology for green H₂ production. They focused on technical advancements, market dynamics, production costs, and critical research on PEME degradation mechanisms, aiming to address gaps and challenges in commercialization. They highlighted the key challenges of PEME technologies, including the performance degradation of iridium-based catalysts under high current density and high temperatures and the need for more robust and cost-effective catalysts.

Reznicek et al. (2025) [32] provided a detailed evaluation of advanced H₂ production technologies, focusing on their techno-economic performance and environmental impacts. The key technologies assessed included PEME, SOE, and methane pyrolysis. They concluded that while each H₂ production technology has distinct advantages, addressing material costs, technological challenges, and environmental impacts is paramount for commercial success. Zhua et al. (2025) [33] highlighted the crucial role of H₂ in decarbonizing hard-to-abate U.S. industries. They explored the opportunities, challenges, and potential emissions savings from using clean H₂ in various industrial sectors. Their review identified eight key industries with significant potential for H₂ use and found that steel, refining, and chemical sectors are the highest emitters, accounting for 37% of U.S. industrial emissions.

Waiyaki et al. (2025) [34] investigated the environmental impact and critical raw material demand associated with scaling up green H₂ production using PEME and provided a comprehensive assessment of green H₂ sustainability. Ajeeb et al. (2025) [35] assessed the environmental impacts of H₂ production via electrolysis using different green energy sources. They compared the sustainability of H₂ production technologies powered by various renewable energy configurations, concluding that the electricity supply contributes ≈98% of the GWP impact in most scenarios considered (grid mix, solar PV, wind turbines, and hydropower). Yang et al. (2025) [36] discussed the advantages and disadvantages of AWE, PEME, and SOE, highlighting aspects that distinguish AWE, including its low capital cost and high maturity.

• Knowledge gaps identified from the literature and addressed in this research

Our critical review of the published work from 2004 to 2025 has identified several knowledge gaps as follows:

(1)

Lack of use of multi-criteria decision analysis (MCDA) tools—The reviewed literature primarily focuses on the TEA, LCA, and LCIA of various H₂ production technologies. However, it lacks discussion on the use of structured MCDA tools like the MACBETH and Pugh methods, which are essential for comprehensive evaluations of H₂ production technologies.

(2)

Absence of a robust and comparative framework—Most published studies focused on specific H₂ production technologies or comparisons among a few alternatives. Accordingly, there is a lack clear of a robust framework for evaluating and comparing multiple H₂ production pathways using a consistent set of decision criteria.

(3)

Combining qualitative judgments with quantitative approaches—The published studies primarily relied on quantitative metrics and overlooked the importance of integrating qualitative judgments of subject matter experts (SMEs) in the evaluation process.

(4)

Simultaneous evaluation of a comprehensive set of decision criteria—While various criteria like CAPEX, OPEX, environmental impacts (EIs), and operating efficiency are discussed in the literature, they are often evaluated in isolation rather than simultaneously.

To address these knowledge gaps, this research simultaneously utilizes the MACBETH and Pugh methods. By blending qualitative and quantitative approaches and employing a comprehensive set of decision criteria, it offers a more holistic and robust evaluation of H₂ production technologies.

• Research novelty

The following elements highlight the innovation and uniqueness of this research:

• Bridging knowledge gaps—This research addresses existing gaps in the published literature by uniquely employing both the MACBETH and Pugh methods, offering a structured and innovative approach to scoring and ranking H₂ production technologies while considering multiple decision criteria simultaneously.
• Establishing a robust technology evaluation framework—By simultaneously utilizing the MACBETH and Pugh methods, this research establishes a robust framework for the comparative evaluation of various H₂ production technologies, which are all based on a comprehensive set of decision criteria.
• Nuanced insights with MACBETH—The MACBETH method provides nuanced insights that purely quantitative methods might miss, involving pairwise comparisons among H₂ production technologies. It employs a mix of qualitative judgments and quantitative scores. Additionally, the MACBETH tool includes internal functions for consistency checks, ensuring the robustness of the scoring and ranking results.
• Leveraging the Pugh method’s strengths—This research harnesses the unique strengths of the Pugh method, using the same decision criteria as in the MACBETH method. Instead of pairwise technology comparisons, the Pugh method benchmarks each technology against a baseline technology (SMR with CCS). By incorporating the Pugh matrix, this research evaluates the competitive positioning of emerging H₂ technologies.
• Holistic approach—This research evaluates each H₂ production technology using a comprehensive set of nine decision criteria, ensuring a holistic approach that takes into account various dimensions of performance and sustainability.
• By integrating the unique features of both the MACBETH and Pugh methods, this research produces more robust and reliable evaluations of H₂ production technologies, thereby making a meaningful contribution to the knowledge base of this field.

1.2. Research Objectives

This research aims to comprehensively evaluate H₂ production through WE technologies using structured and robust scoring and ranking methods: specifically the MACBETH method and the Pugh decision matrix. The overarching objective is to guide future green H₂ research and development (R&D) efforts to promote the adoption of the most efficient and sustainable technologies.

The rest of this manuscript is structured as follows: Section 2 describes the research methodology used, Section 3 presents the results, Section 4 discusses the findings, and Section 5 offers a summary of the conclusions from this comparative evaluation of H₂ production via water electrolysis. Finally, Section Abbreviations provides a list of the acronyms and abbreviations used in this manuscript.

2. Research Method

Evaluating the performance and sustainability of H₂ production technologies requires robust scoring and ranking tools capable of managing multiple decision criteria. This research employs two prominent methods—the MACBETH method [37] and the Pugh decision matrix—to score and rank WE technologies. Herein, scoring involves assigning values to technologies based on specific attributes or decision criteria, while ranking entails ordering the technologies based on their aggregated scores. Understanding this distinction between these two consecutive steps (scoring and then ranking) is crucial for accurate evaluation and comparison, enabling effective comparisons and supporting informed decision making.

To guide the comparative evaluation of WE technologies, nine decision criteria were utilized, encompassing economic and operational factors, technology readiness levels, and environmental considerations. These criteria are essential for identifying the most promising technology for hydrogen production.

Table 1. Brief description of water electrolysis (WE) technologies.

Water Electrolysis (WE) Technology	Description
Alkaline water electrolysis (AWE)	AWE is one of the most established and widely researched technologies for H2 production. It operates using a liquid alkaline electrolyte, typically potassium hydroxide (KOH) or sodium hydroxide (NaOH). Studies highlight its advantages, including mature technology, robustness, and relatively low capital costs. However, challenges persist with regard to operating efficiency and the need for pressure control to prevent gas crossover.
Anion exchange membrane electrolysis (AEME)	AEME represents a newer approach, combining elements of both AWE and PEME. It utilizes an anion exchange membrane to transfer hydroxide ions. Research suggests that AEME has the potential to offer cost benefits and simpler materials handling compared to PEME. However, the technology is less mature, and further development is needed to enhance its stability, efficiency, and long-term reliability.
Proton exchange membrane electrolysis (PEME)	PEME, another well-studied WE technology, employs a solid polymer electrolyte (SPE) that conducts protons from the anode to the cathode. The literature notes PEME’s higher efficiency and quicker startup compared to AWE. Nevertheless, PEME systems face challenges related to high capital costs and the use of rare earth metals such as platinum group metals (PGMs) * for catalysts.
Solid oxide electrolysis (SOE)	SOE operates at high temperatures (typically 700–1000 °C), using a solid ceramic electrolyte to conduct oxygen ions. This high-temperature operation enables SOE to achieve higher efficiencies particularly when integrated with waste heat recovery systems. The literature points out that SOE is still in the developmental stage with significant research required to address material degradation and long-term operational reliability concerns.

* Platinum group metals (PGMs)—PGMs include platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), and osmium (Os). These metals serve as highly efficient WE electrocatalysts for H₂ production. However, PGMs are rare and predominantly sourced from limited geographical locations, which poses substantial supply chain risks. Their production and extraction processes are energy-intensive and have significant environmental impacts coupled with high costs associated with mining, refining, and processing. Additionally, geopolitical factors can disrupt PGM supply chains, affecting their availability and prices. Consequently, technologies like PEME, which heavily rely on PGMs, encounter critical supply chain challenges.

provides a concise overview of the water electrolysis (WE) technologies examined in this research.

2.1. MACBETH Scoring and Ranking Method

The MACBETH (Measuring Attractiveness by a Categorical-Based Evaluation Technique) scoring and ranking method is a multi-criteria decision analysis (MCDA) tool that uses pairwise comparisons to score and rank selected technologies [37]. The approach involves comparing the alternatives in pairs with respect to each criterion using qualitative judgments, which are then converted into numerical scores by M-MACBETH software [37]. The qualitative judgments evaluate differences of attractiveness using seven semantic categories: no, very weak, weak, moderate, strong, very strong, and extreme. Any inconsistencies in the judgment matrices are identified and resolved using the M-MACBETH software’s built-in tools.

The MACBETH seven attractiveness categories are defined as follows:

No: Means the pairwise technologies being compared have no perceptible difference in attractiveness for the given decision criterion.

Very Weak (VW): There is a very slight difference in attractiveness in favor of one technology over the other for the given criterion.

Weak (W): There is a small difference in attractiveness in favor of one technology over the other for the given criterion.

Moderate (M): There is a noticeable difference in attractiveness in favor of one technology over the other for the given criterion.

Strong (S): There is a significant difference in attractiveness in favor of one technology over the other for the given criterion.

Very Strong (VS): There is a very significant difference in attractiveness in favor of one technology over the other for the given criterion.

Extreme (E): There is a substantial difference in attractiveness in favor of one technology over the other for the given criterion.

With the exception of the “no” category (which represents equal attractiveness), any of the six semantic categories can be selected individually or in sequence of judgements ranging from “very weak” to “extreme” (e.g., moderate to strong, very weak to weak, etc.). Finally, the “no” category cannot be combined with any of the other six attractiveness categories.

The steps of the MACBETH scoring and ranking method are as follows:

• Decision criteria identification and definitions relevant to the intended evaluation.
• Pairwise comparisons of the alternatives with respect to each criterion to determine the relative attractiveness (no, very weak, weak, moderate, strong, very strong, and extreme).
• Consistency checking to ensure that the qualitative judgments are consistent across all pairwise comparisons. This feature is internal in M-MACBETH software.
• Scores calculations which convert the qualitative judgments into a numerical scale to rank the alternatives. This feature is internal in M-MACBETH software.

In this research, we employed the MACBETH scoring and ranking method to systematically compare each WE technology against the others across the nine decision criteria. The resulting scores are provided in tables and visualizations (graphs) for evaluating the attractiveness of the selected H₂ production technologies.

2.2. The Pugh Decision Matrix Scoring and Ranking Method

The Pugh decision matrix method is another scoring and ranking method that uses a baseline technology for benchmarking purposes [38]. This method involves evaluating alternatives against a set of decision criteria by comparing each alternative to the baseline technology, typically a conventional and mature technology. The steps in the Pugh decision matrix method are as follows:

• Selection of baseline technology: choosing a reference technology against which all other alternatives will be compared.
• Decision criteria definition: identifying and defining decision criteria relevant to the evaluation.
• Scoring: evaluating each alternative against the baseline for each criterion using a three-point scoring scale: −1 for worse than baseline, 0 for same as baseline, +1 for better than the baseline.
• Summation: algebraically summing the scores to determine and rank the overall performance of each alternative relative to the baseline.

This research employs the Pugh decision matrix method [38] in addition to the MACBETH scoring method [37], and the ranking results of both methods are then compared to generate useful insights for making informed and balanced decisions for selection of the most promising H₂ production technology based on the selected multidimensional criteria.

2.3. MACBETH Method vs. Pugh Decision Matrix

Table 2. Attributes of MACBETH vs. Pugh scoring and ranking methods.

Attribute	MACBETH Method	Pugh Decision Matrix
Methodology	Uses qualitative judgments of differences in attractiveness (namely: no; very weak; weak; moderate; strong; very strong; and extreme) of the pairwise alternatives comparisons.	- Employs qualitative scoring against a benchmark technology using a 3-point scale (+, −, 0). - Other scales can also be used such as the five-point scale: ++, +, 0, −, −−.
Decision-Making Basis	Determines global attractiveness values to rank each of the technology alternatives.	Evaluates relative merit of alternatives compared to a baseline technology.
Scoring	Pairwise comparisons of attractiveness without the need for a baseline technology for benchmarking.	Direct comparison to a baseline for each decision criterion and alternative technology.
Weighting Factors	- Varying weights for the decision criteria to reflect their relative attractiveness. - Weights can be varied for performing sensitivity studies.	Optional weighting factors for the decision criteria to reflect their importance.
Ranking	Ranking is about ordering the evaluated technologies based on their calculated scores.

shows the salient attributes that distinguish the two scoring and ranking methods including their unique approaches to scoring. Both methods, however, utilize the generated scores to establish a ranking of the technology alternatives, ordering them from the most to the least favorable.

2.4. Multidimensional Decision Criteria

A set of multidimensional criteria that are deemed effective have been identified to guide the MACBETH and Pugh’s scoring and ranking methods. The nine selected decision criteria are outlined below:

• Capital expenditure (CAPEX);
• Operating expenditure (OPEX);
• System operating efficiency (OE);
• System startup time (SuT);
• Environmental impact (EI);
• Technology readiness level (TRL);
• Maintenance requirements (MRs);
• Supply chain challenges (SCCs);
• Levelized cost of hydrogen (LCOH).

Note that for the WE technologies, CAPEX can be represented by Equation (1):

CAPEX = Electrolyzer Purchasing Cost + Installation Cost

(1)

WE technologies OPEX can be represented by Equation (2) assuming that the KOH cost is small relative to the other operating costs:

OPEX = Stack O&M Costs + Stack Replacement Cost + Electricity Cost + Water Cost

(2)

The use of the levelized cost of H₂ (LCOH) as a decision criterion is pivotal in evaluating the economic feasibility of H₂ production technologies. The LCOH is influenced not only by the CAPEX and OPEX of the electrolyzer systems but also by the costs associated with the source of electricity. Specifically, the use of RE sources like wind turbines and solar PV tends to lower the LCOH due to their decreasing cost trends. Moreover, LCOH is also impacted by the electrolyzer’s operating pressure and temperature. Specifically, electrolyzer operation at moderate pressures (≈7 to 8 bar) and moderate temperatures (60–80 °C compared to 700–1000 °C in PEME) can reduce LCOH. Thus, striking the right balance between operational efficiency and cost savings from using moderate operating conditions is a critical factor to consider. The stack startup time is also an important decision criterion particularly for fast on-demand H₂ production applications.

2.5. Rationale for Baseline Technology (SMR + CCS) Selection in Pugh Method

• Technology Readiness Level—(TRL)—SME with CCS is a well-established and widely used technology for H₂ production. Additionally, it has been extensively studied, thus providing a reliable reference point for comparing other H₂ production technologies [39].
• Performance metrics—SMR with CCS is considered a conventional technology with well-documented performance metrics, including capital expenditure (CAPEX), operating expenditure (OPEX), carbon footprint, and overall efficiency. These characteristics make it an appropriate choice benchmarking purpose [39].

2.6. Renewable Electricity (RE) Sources

The integration of RE sources such as wind power into H₂ production processes is a vital step toward achieving sustainable and greener H₂ production. Accordingly, integration with RE, in addition to using moderate operating temperatures and pressures, can maximize the environmental benefits of H₂ production from water electrolysis (WE). Also, it should be noted that the electrolyzer’s operating pressure not only impacts the efficiency and cost but also impact safety of H₂ production as safety risks increase due to potential H₂ leaks and the gas-crossover in high-pressure systems.

3. Results

This section is divided into two sections, Section 3.1 and Section 3.2, which summarize the MACBETH and Pugh scoring and ranking results of H₂ production technology alternatives. As shown by the results, both methods ranked AWE as the leading and most promising H₂ production technology via water electrolysis.

3.1. MACBETH Scoring and Ranking of H₂ Production Technology Alternatives

First, the four WE technologies (AWE; AEME; PEME; and SOE) are defined in the M-MACBETH tool. Then, the pairwise differences in attractiveness among these technologies with respect to each decision criterion are then are judged qualitatively using the M-MACBETH tool, which generates the qualitative judgment matrices (as shown in Figures 3–11). Any inconsistencies in judgments are identified and resolved using the software’s built-in tools. The numerical scores are then derived from the qualitative judgments using the M-MACBETH built-in value function which is designed to convert qualitative judgements into numerical scores.

Figure 1 shows the value tree created using the M-MACBETH tool. The tree’s root node is called the “Overall” node, and the created nine decision criteria nodes (Figure 2) against which the four technologies (AWE; AEME; PEME and SOE) are evaluated are below. The M-MACBETH tool uses a built-in value function that converts the qualitative judgments into numerical scores that reflect the attractiveness (or desirability) of each of the four technologies (pairwise) with respect to each of the nine decision criteria. To eliminate any unintended consequences of biases that may arise from subjectively assigning different weighting factors to the selected criteria, we assumed equal weights for all factors.

Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10 and Figure 11 show the judgment matrices of the pairwise comparisons of technology alternatives for H₂ production via water electrolysis for each of the selected decision criteria: CAPEX; OPEX; operating efficiency (OE); environmental impact (EI); technology readiness level (TRL); maintenance requirements (MRs); startup time (SuT); supply chain challenges (SCCs); and levelized cost of H₂ (LCOH) production.

In each of the pairwise comparison matrices (Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10 and Figure 11), each element [i, j] in the matrix represents the qualitative judgment of how attractive the alternative in row [i] is compared to the alternative in column [j] for a specific criterion (note that for the rows, i runs from 1 to 4, and for the columns, j runs from 1 to 4).

As illustrative examples in Figure 3, the element [i = 1, j = 4] is assigned ‘S’, signifying the strong relative attractiveness of the alternative ‘AWE’ (row i = 1) compared to the alternative ‘SOE’ (column j = 4). Similarly, the element [i = 2, j = 3] is assigned ‘W’, which signifies a weak relative attractiveness of the alternative ‘AEME’ (in row i = 2) compared to the alternative ‘PEME’ in column j = 3.

Note: For Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10 and Figure 11: W = weak; VW = very weak; M = moderate; S = strong; VS = very strong; E = extreme.

The M-MACBETH tool converts these qualitative judgment matrices into the following aggregate numerical scores and rankings. To eliminate any biases that may arise from assigning different weighting factors to the selected criteria, we assumed equal weights for all factors. Figure 12 shows MACBETH aggregated scores for the four water electrolysis technologies.

Also, as can be seen in

Table 3. MACBETH rankings of the four water electrolysis (WE) technologies.

CAPEX	OPEX	OE	EI	TRL	MR	SUT	SCC	LCOH
AWE	AWE	AWE	AWE	AWE	AWE	AWE	AWE	AWE
AEME	AEME	AEME	AEME	AEME	AEME	AEME	AEME	AEME
PEME	PEME	PEME	PEME	PEME	PEME	PEME	PEME	PEME
SOE	SOE	SOE	SOE	SOE	SOE	SOE	SOE	SOE

, the MACBETH tool has consistently ranked AWE as the most promising technology for each of the nine decision criteria.

Based on the insights from Figure 12 for aggregated scores and Table 3 for rankings, the four technologies can be expressed in the following order (in Equation (3)) from the most promising technology (AWE) to the least promising (SOE):

AWE > AEME > PEME > SOE

(3)

Equation (3) shows that AWE emerges as the leading H₂ production technology, which is followed by AEME. Both PEME and SOE currently appear to be the least attractive technologies. However, with future improvements in stack design to reduce capital costs, the new discovery of cheaper electrolyzer materials to replace rare earth metals used in PEME and the high-temperature materials used in SOE, these two electrolyzer types could have better prospects for H₂ production.

3.2. Pugh’s Decision Matrix for Scoring and Ranking H₂ Production Technology Alternatives

For this scoring and ranking method, steam-methane reforming (SMR) with carbon capture and storage (CCS) has been chosen as the baseline technology for benchmarking purposes. The nine decision criteria are the same as those used in the MACBETH method, namely, the following: capital cost (CAPEX); operating costs (OPEX); operating efficiency (OE); environmental impact (EI); technology readiness level (TRL); maintenance requirements (MR); startup time (SuT); supply chain challenges (SCC); and levelized cost of H₂ (LCOH) production. Also, the three-point scoring scale has been selected as follows:

• 0: Baseline (namely SMR with CCS);
• +1: Better than the baseline;
• −1: Worse than the baseline.

Table 4. Summary of results of the Pugh decision matrix.

Criteria	AWE	AEME	PEME	SOE	Baseline (SMR with CCS)
Capital expenditure (CAPEX)	+1	+1	−1	−1	0
Operating expenditure (OPEX)	+1	+1	−1	−1	0
Operating efficiency (OE)	0	+1	+1	+1	0
Environmental impact (EI)	+1	+1	+1	+1	0
Technology readiness level (TRL)	+1	0	+1	−1	0
Maintenance requirements (MRs)	0	0	−1	−1	0
Startup Time (SuT)	−1	−1	+1	−1	0
Supply chain challenges (SCCs)	+1	0	−1	−1	0
Levelized cost of H2 (LCOH)	+1	+1	−1	−1	0
Total score	+5	+4	−1	−5	0
Technology ranking	1st (Most favorable)	2nd	3rd	4th (Least favorable)	Baseline

summarizes the scoring and ranking results of the Pugh decision matrix for the selected WE technologies based on the aforementioned nine decision criteria (same as those used the MACBETH method).

The scoring results of the Pugh decision matrix method are as follows:

• Capital expenditure (CAPEX):

• AWE: +1 (lower capital costs);
• AEME: +1 (lower capital costs);
• PEME: −1 (higher capital costs);
• SOE: −1 (highest capital costs);
• SMR with CCS: 0 (baseline technology).

• Operating expenditure (OPEX):

• AWE: +1 (moderate operating costs);
• AEME: +1 (moderate operating costs);
• PEME: −1 (higher operating costs);
• SOE: −1 (highest operating costs);
• SMR with CCS: 0 (baseline technology).

• Operating Efficiency (OE):

• AWE: 0 (comparable to baseline);
• AEME: +1 (potentially better as a new technology);
• PEME: +1 (higher efficiency);
• SOE: +1 (highest efficiency);
• SMR with CCS: 0 (baseline technology).

• Environmental Impact (EI):

• AWE: +1 (lower environmental impact particularly when driven by renewable electricity);
• AEME: +1 (lower environmental impact with renewables);
• PEME: +1 (lower environmental impact with renewables);
• SOE: +1 (lowest environmental impact with renewables);
• SMR with CCS: 0 (baseline technology).

• Technology Readiness Level (TRL):

• AWE: +1 (high TRL);
• AEME: 0 (moderate TRL, emerging technology);
• PEME: +1 (high TRL);
• SOE: −1 (lower TRL, developing technology);
• SMR with CCS: 0 (baseline technology).

• Maintenance Requirements (MRs):

• AWE: 0 (moderate);
• AEME: 0 (moderate but evolving);
• PEME: −1 (higher maintenance);
• SOE: −1 (highest maintenance);
• SMR with CCS: 0 (baseline technology).

• Startup Time (SuT):

• AWE: −1 (longer startup);
• AEME: −1 (longer startup);
• PEME: +1 (fast startup);
• SOE: −1 (long startup);
• SMR with CCS: 0 (baseline technology).

• Supply Chain Challenges (SCCs):

• AWE: +1 (non-previous metals, fewer challenges);
• AEME: 0 (moderate challenges, evolving);
• PEME: −1 (precious metals, higher challenges);
• SOE: −1 (advanced ceramics, highest challenges);
• SMR with CCS: 0 (baseline technology).

• Levelized Cost of H₂ (LCOH) Production:

• AWE: +1 (lower LCOH);
• AEME: +1 (lower LCOH);
• PEME: −1 (higher LCOH);
• SOE: −1 (highest LCOH);
• SMR with CCS: 0 (baseline technology).

• Insights from Pugh’s decision matrix results:
• AWE:
• Total score: +5
• Conclusion: AWE emerges as the most promising technology compared to the baseline technology (viz., SMR with CCS) with distinguished advantages in CAPEX, OPEX, EI, TRL, SCC, and LCOH production. The stack SuT is less favorable for this technology.
• AEME:
• Total score: +4
• Conclusion: AEME shows favorable performance, especially in CAPEX, OPEX, EI, and LCOH production, but it has some emerging challenges in TRL, SuT, and SCC.
• PEME:
• Total score: −1
• Conclusion: PEME has strengths in OE, EI, and SuT but faces high costs, maintenance requirements issues, and supply chain challenges.
• SOE:
• Total score: −5
• Conclusion: SOE has high operating efficiency (OE) and low environmental impact (EI) but is currently disadvantaged by high CAPEX, OPEX, TRL, maintenance requirements (MRs), and supply chain challenges (SCCs).

Overall, the results of the Pugh decision matrix clearly identify AWE as the leading H₂ production technology. AWE outperforms both the baseline technology (SMR with CCS) and the other water electrolysis technologies, namely, AEME, PEME, and SOE.

4. Discussion

In this section,

Table 5. Capital expenditure (CAPEX) as a decision criterion for scoring and ranking H₂ production technology alternatives.

Water Electrolysis (WE) Technology	CAPEX	Comments
Alkaline water electrolysis (AWE)	USD 400–900 per kW	Lower capital costs due to technology maturity and use of non-precious metal catalysts.
Anion exchange membrane electrolysis (AEME)	USD 500–1000 per kW	Higher capital costs than AWE, emerging technology with potential cost benefits as it matures.
Proton exchange membrane electrolysis (PEME)	USD 1000–2500 per kW	Higher capital costs due to use of expensive materials (e.g., platinum catalysts) and advanced membranes.
Solid oxide electrolysis (SOE)	USD 2000–4500 per kW	Highest capital costs, requires high-temperature materials and complex designs to accommodate stack heat removal and recovery.

Table 5 data sources: [11,14,16,17,18,19,25,32,34].

,

Table 6. Operating expenditure (OPEX) as a decision criterion for scoring and ranking H₂ production technology alternatives.

Water Electrolysis (WE) Technology	OPEX	Comments
Alkaline water electrolysis (AWE)	Moderate	Low to moderate energy consumption, regular maintenance of electrodes and moderate O&M costs.
Anion exchange membrane electrolysis (AEME)	Moderate	Moderate energy consumption, membrane maintenance, moderate O&M costs, and potential for future costs reduction.
Proton exchange membrane electrolysis (PEME)	High	Low energy consumption due to higher operating efficiency, high costs of catalysts (previous metals) and membranes, frequent maintenance.
Solid oxide electrolysis (SOE)	Moderate to High	Low energy consumption due to higher operating efficiency, high-temperature material costs, frequent maintenance of high-temperature components.

Table 6 data sources: [11,14,16,17,18,19,25,32,34].

,

Table 7. Operating efficiency (OE) as a decision criterion for scoring and ranking H₂ production technology alternatives.

Water Electrolysis (WE) Technology	OE	Comments
Alkaline water electrolysis (AWE)	60–78%	Moderate OE limited by higher electrical/ohmic resistance and slower ion migration though the electrolyte (KOH solution).
Anion exchange membrane electrolysis (AEME)	60–70%	Comparable to AWE, needs improvement in membrane stability.
Proton exchange membrane electrolysis (PEME)	70–80%	Higher OE than AWE and AEME due to lower internal resistance and effective proton conductivity.
Solid oxide electrolysis (SOE)	80–90%	Very high OE and faster reaction kinetics at high temperatures (700–1000 °C) but come with challenging material stability and shorter long-term reliability.

Table 7 data sources: [11,14,16,17,18,19,23,24,32,34].

,

Table 8. Startup time (SuT) as a decision criterion for scoring and ranking H₂ production technology alternatives.

Water Electrolysis (WE) Technology	SuT	Comments
Alkaline water electrolysis (AWE)	Moderate (several minutes to an hour)	Requires time to reach the operating temperature (60–85 °C) and establish steady-state conditions.
Anion exchange membrane electrolysis (AEME)	Moderate to fast (a few minutes)	Quicker startup than AWE, benefiting from efficient anion exchange membranes.
Proton exchange membrane electrolysis (PEME)	Fast (less than a minute)	Rapid response due to the solid polymer electrolyte membrane; suitable for quick on-demand H2 production.
Solid oxide electrolysis (SOE)	Slow (several hours)	Requires time to reach high operating temperatures (700–1000 °C) to stabilize the solid oxide electrolyte.

Table 8 data sources: [11,14,16,17,18,19,32,34].

,

Table 9. Environmental impact (EI) as a criterion for scoring and ranking H₂ production technology alternatives.

Water Electrolysis (WE) Technology	EI	Comments
Alkaline water electrolysis (AWE)	Low to moderate	Moderate GHG emissions (but lower with renewable electricity), moderate resource depletion, significant water usage.
Anion exchange membrane electrolysis (AEME)	Low to moderate	Low to moderate GHG emissions, lower resource depletion, similar water usage to AWE.
Proton exchange membrane electrolysis (PEME)	Low (with renewables electricity), High with respect to extraction of rare-earth metals	Low GHG emissions (with renewables), high resource depletion (precious metals), moderate to low water usage.
Solid oxide electrolysis (SOE)	Very low (with renewable electricity), high with respect to resources	Very low GHG emissions (with renewable electricity), high resource depletion (advanced ceramics), lower water usage.

Table 9 data sources: [5,11,14,16,17,18,19,23,24,25,26,28,30,32,34].

,

Table 10. Technology readiness level (TRL) as a decision criterion for scoring and ranking H₂ production technology alternatives.

Water Electrolysis (WE) Technology	TRL	Comments
Alkaline water electrolysis (AWE)	9	Fully mature technology with widespread industrial application and continuous operation capabilities.
Anion exchange membrane electrolysis (AEME)	4–6	Emerging technology with ongoing development and demonstration projects, aiming for commercial readiness sometime in the future.
Proton exchange membrane electrolysis (PEME)	7–8	Advanced technology with potential for commercial applications, and ongoing cost reduction efforts.
Solid oxide electrolysis (SOE)	4–6	Early-stage technology with active R&D and initial pilot projects, requiring further validation and optimization for commercialization.

Table 10 data sources: [11,14,16,17,18,19,23,24,25,30,32,34].

,

Table 11. Maintenance requirements (MR) as a decision criterion for scoring and ranking H₂ production technology alternatives.

Water Electrolysis (WE) Technology	MR	Comments
Alkaline water electrolysis (AWE)	Low to moderate	Routine maintenance involves electrodes cleaning and or replacing electrodes if damaged.
Anion exchange membrane electrolysis (AEME)	Moderate	Regular checks and membrane replacements. Maintenance is moderate and improving with technology improvements.
Proton exchange membrane electrolysis (PEME)	High	Frequent monitoring and replacement of sensitive materials like membranes and catalysts. High MR due to material cost and sensitivity.
Solid oxide electrolysis (SOE)	High	Maintenance is critical due to high-temperature operation, frequent checks, and replacements of ceramic electrolytes and heating elements.

Table 11 data sources: [11,14,16,17,18,19,25,30,32,34].

,

Table 12. Supply chain challenges as a decision criterion for scoring and ranking H₂ production technology alternatives.

Electrolysis Technology	Supply Chain Challenges	Comments
Alkaline water electrolysis (AWE)	Low to moderate	Uses common and non-precious materials (such as nickel and stainless steel) and, hence, fewer supply chain challenges.
Anion exchange membrane electrolysis (AEME)	Moderate	Emerging technology with specialized membrane requirements; limited production volumes; moderate risk.
Proton exchange membrane electrolysis (PEME)	High	Highly reliant on precious metals such as platinum (Pt) and iridium (Ir); significant supply chain risks and cost volatility.
Solid oxide electrolysis (SOE)	High	Requires advanced ceramics * and precision manufacturing; expensive and challenging supply chain.

Table 12 data sources: [11,14,16,17,18,19,23,24,25,30,32,34]. * Advanced ceramics in SOE such as perovskites (LSCF, LSM, and Ni/YSZ) where LSCF (lanthanum, strontium, cobalt ferrite) is a highly conductive and catalytically active material, LSM (lanthanum, strontium, manganite) is a stable and conductive material, and YSZ (yttria-stabilized zirconia) is a zirconium oxide-based ceramic electrolyte with high ionic conductivity.

and

Table 13. Levelized cost of hydrogen (LCOH) as a criterion for scoring and ranking H₂ production technology alternatives.

Water Electrolysis (WE) Technology	LCOH ** (USD/kg H2)	Comments
Alkaline water electrolysis (AWE)	USD 2.50–6.00	Lower due to being a mature technology and less expensive non-precious materials such as nickel (Ni), steel, and aluminum (Al).
Anion exchange membrane electrolysis (AEME)	USD 3.00–7.50	Higher due to being an emerging technology with specialized membranes, expected to decrease with scaling and maturity.
Proton exchange membrane electrolysis (PEME)	USD 3.50–8.50	Higher due to use of expensive rare-earth metals like platinum (Pt) and Iridium (Ir) catalysts, improvements are ongoing for cost reduction.
Solid oxide electrolysis (SOE)	USD 4.00–9.50	Highest due to high initial investment and complex ceramic materials. However, there is a potential for cost reductions with advancements in R&D.

Table 13 data sources: [11,14,16,17,18,19,25,30,32,34] ** LCOH results can also be benchmarked against industry targets (e.g., the U.S. Department of Energy’s Hydrogen Shot goal of USD 1/kg H₂ by 2030) to evaluate the competitiveness of each technology.

provide supporting justifications and rationale for the scoring and ranking results presented in Section 3, which were derived from the application of the MACBETH method and the Pugh decision matrix.

$$\mathrm{L}\mathrm{C}\mathrm{O}\mathrm{H}\left({\displaystyle \frac{\mathrm{\$}}{\mathrm{k}\mathrm{g} {\mathrm{H}}_2}}\right)={\displaystyle \frac{\mathrm{Total}\mathrm{Annualized}\mathrm{Costs}\mathrm{of}{\mathrm{H}}_2\mathrm{Production} (\frac{\mathrm{\$}}{\mathrm{year}})}{\mathrm{Annual}{\mathrm{H}}_2\mathrm{Production} (\frac{\mathrm{kg}}{\mathrm{year}})}}$$

(4)

• Additional key insights

AWE: This technology benefits from (a) its low CAPEX, OPEX and readily available no-precious materials, thus making its supply chain more robust and less risky; (b) being the most mature technology (TRL = 9) and with established manufacturing processes, and (c) its high long-term reliability and service life.

AEME: This technology is evolving and holds promise, but it still faces moderate supply chain risks and challenges associated with innovation in materials and manufacturing processes.

With the ongoing R&D effort, it is expected that AEME technology will improve in efficiency and stack costs (CAPEX and OPEX) reduction.

PEME: This technology faces significant supply chain challenges due to its high dependence on critical rare-earth metals, particularly platinum group metals (PMGs). Also, PEME has high manufacturing complexity and environmental impact associated with the extraction of raw materials, but it benefits from higher operational efficiency compared to AWE.

SOE: The need for high-temperature materials in SOE results in high costs and complex manufacturing processes. Also, while SOE offers higher operational efficiency, its material requirements and environmental impact pose considerable supply chain risks.

• Alignment and divergence of MACBETH and Pugh scoring and ranking methods
• Alignment:
  • Multi-criteria decision analysis (MCDA):

    -

    Both the MACBETH and Pugh methods utilize multi-criteria decision analysis to evaluate alternative H₂ production pathways. They systematically compare multiple alternatives against a set of decision criteria, facilitating a holistic evaluation process.

    -

    Decision criteria in both methods can include aspects such as operating efficiency, cost, environmental impact, and scalability, ensuring comprehensive assessments of the technologies.

  • Structured comparison framework:

    -

    Both methods provide structured and transparent frameworks for decision making. They enable the careful documentation of judgments and preferences, making it easier to understand and justify the final selection of technologies.

    -

    This structured approach helps with identifying the strengths and weaknesses of each technology, guiding stakeholders in making informed decisions.

• Divergence:
  • Qualitative vs. quantitative judgments:

    -

    MACBETH Method: Primarily relies on qualitative pairwise comparisons that are converted into numerical values via the MACBETH software. This method emphasizes the relative attractiveness of alternatives based on subjective judgments, which are then validated and quantified.

    -

    Pugh Method: Uses a different ranking and scoring system where alternatives are compared to a baseline technology. The scoring system typically involves assigning values such as +1, 0, or −1 based on whether the alternative is better, the same, or worse than the baseline, respectively.

  • Weighting of criteria and sensitivity analysis:

    -

    MACBETH Method: Involves detailed analysis of weights for each decision criterion. To eliminate this source of subjectivity on the final rankings, we used equal weights for the different decision criteria. In our future research, we plan to perform sensitivity analysis to understand the impact of varying weights on the final rankings.

    -

    Pugh Method: The use of weighting factors is optional, and the primary focus is on direct comparisons to the baseline technology.

• Implications for selecting hydrogen production pathways

While both the MACBETH and Pugh methods serve as valuable tools in the evaluation of H₂ production pathways, their alignment in structured decision-making and multi-criteria analysis, supplemented by their divergence in handling qualitative vs. quantitative judgments and weighting, provide complementary strengths.

5. Conclusions

In this research, both the MACBETH method and Pugh decision matrix method were employed to score and rank H₂ production technologies using water electrolysis based on nine decision criteria. The evaluation results from both methods identified alkaline water electrolysis (AWE) as the leading and most promising technology, while solid oxide electrolysis (SOE) was ranked as the least promising. Anion exchange membrane electrolysis (AEME) and proton exchange membrane electrolysis (PEME) occupied the intermediate ranks between AWE and SOE. However, continued innovation in stack design, the use of sustainable material sourcing, and increased reliance on renewable electricity will be crucial for improving the technology readiness level (TRL) and commercialization prospects of AEME, PEME, and SOE.

The comparison between MACBETH and Pugh methods underscores the importance of employing multi-criteria decision analysis (MCDA) tools in selecting optimal H₂ production pathways. The robustness of MACBETH’s detailed analyses and its ability to handle qualitative judgments provide nuanced insights, while the Pugh method offers a more efficient benchmarking process against a known baseline technology. These complementary strengths facilitate thorough and transparent evaluations, aiding hydrogen technologies stakeholders in making informed decisions.

• Influence on policy, investment, and technology adoption:
  • Policy influence:

    -

    Guiding strategic initiatives: The insights garnered from the evaluations of this research can inform government policies aimed at promoting sustainable H₂ production. By identifying and validating the most promising technologies, policymakers can allocate resources and incentives more effectively.

    -

    Setting standards and regulations: The detailed analysis of this research can help set standards and regulations for H₂ production technologies, ensuring that they meet desired efficiency, cost, and environmental benchmarks. This aligns with global decarbonization goals, such as those outlined in the Paris Agreement.

  • Investment decisions:

    -

    Prioritizing funding: Investors can use our research findings to prioritize funding for technologies that show the highest potential for scalability as well as reassurance about long-term viability and returns on investment.

    -

    Risk management: Investors can better manage risks associated with funding new and emerging H₂ production techniques.

  • Technology adoption at scale:

    -

    Commercialization strategies: The evaluative methods employed in this research can highlight pathways for reducing costs and improving operational efficiencies, aiding in the development of commercialization strategies for promising H₂ production technologies. This is crucial for achieving economies of scale.

    -

    Meeting quantitative targets: Incorporating specific trends and targets, such as those set by the International Energy Agency (IEA) and the U.S. Department of Energy (DOE), can provide quantifiable goals for technology adoption. For example, the IEA’s Hydrogen Technology Roadmap aims to reduce the cost of clean hydrogen to USD 2/kg by 2030. These targets can guide focus areas for R&D and deployment efforts. Also, the U.S. DOE aims for H₂ production cost of USD 1/kg by 2030.

• Future Outlook:
  • Specific trends:

    -

    Increasing emphasis on decarbonization and integration with renewable energy sources is expected.

    -

    Innovations in materials used for electrolysis, such as catalysts and membrane technologies, will drive efficiency improvement and cost reduction.

  • Projected cost evolution:

    -

    The cost trajectory for various H₂ production pathways including water electrolysis is expected to see significant cost reductions and performance improvements as these technologies scale and mature. For more detailed strategies on reducing electrolyzer costs at both the stack and system levels, as well as the pathway to scaling up green H₂ technologies, interested readers are referred to the IRENA 2020 report [9].

  • For electrolyzers cost trajectories:
    • In its 2024 hydrogen shot water electrolysis technology assessment report, the DOE discussed the cost trajectory of each electrolyzer type as follows:
    • For AWE
    • Current Costs: The CAPEX for AWE electrolyzers ranges from USD 500/kW to USD 750/kW.
    • Cost reduction strategies: Potential reductions can be achieved by enhancing system performance and efficiency while maintaining durability.
    • For PEME
    • Current Costs: The CAPEX of PEM electrolyzer systems is estimated to be USD 700 to USD 1100/kW based on current manufacturing volumes. Achieving the DOE target of USD 1/kg-H₂ requires capital cost reductions to ≈USD 150/kW.
    • Cost Reduction Opportunities: Key approaches include reducing precious metal catalyst loading, developing thinner membranes, manufacturing at scale, and optimizing BOP components, particularly power electronics.
    • For AEME
    • Though still at a lower technology readiness level (TRL), AEME electrolyzers show potential for low-cost H₂ production due to the use of non-precious-metal catalysts and inexpensive components. Preliminary estimates suggest that AEME stacks could achieve costs as low as USD 200/kW with higher manufacturing volumes.
    • R&D Needs: Focus on developing durable membranes and ionomers, optimizing electrolyte feed configurations, and improving the overall stability and performance of the stacks.
    • For SOE
    • Current CAPEX is estimated at USD 2000 to USD 2500/kW, which could be reduced to about USD 950/kW when achieving manufacturing scales of 1 GW per year.
    • These electrolyzers benefit from high efficiencies enabled by high operating temperatures, but improvements in stack durability, integration with heat sources, and system designs are needed for cost reduction.
  • EU hydrogen strategy
    • Similar to the U.S. DOE goals for clean H₂ production via water electrolysis, the EU’s H₂ strategy lays out the European Commission’s vision vis-à-vis H₂ and its role as an energy carrier in a European-integrated energy system.
    • Under this EU strategy, (a) renewable H₂ technologies should reach maturity and be deployed at large scales to reach all hard-to-decarbonize sectors where other alternatives might not be feasible or have higher costs, and (b) about 25% of the EU’s renewable electricity production will be used for H₂ production, which in turn would account for about 23% of the EU’s 2050 energy mix.
  • Other insights
    • As renewable electricity (RE) costs continue to decrease and electrolyzer technologies become more operationally efficient and cost-effective, renewable H₂ production via water electrolysis (WE) is expected to become economically competitive with steam methane reforming (SMR) integrated with carbon capture and storage (CCS).
    • Hydrogen production from sustainable sources, such as water electrolysis powered by renewable electricity, offers significant environmental benefits and aligns with global decarbonization and net-zero goals.