Publications

A wind–hydrogen coupled power generation system can effectively reduce the power loss caused by wind power curtailment and further improve the ability of the energy system to accommodate renewable energy. However the feasibility and economy of deploying such a power generation system have not been validated through large‐scale practical applications and the economic comparison between regions and recommendations on construction are still lacking. In order to solve the aforementioned problems this paper establishes an economic analysis model for the wind–hydrogen coupled power generation system and proposes a linear optimisation‐based priority analysis method focusing on the major net present value for regional energy system as well as a cost priority analysis method for hydrogen production within sample power plants. The case study proves the effectiveness of the proposed analysis methods and the potential to develop wind–hydrogen coupled power generation systems in various provinces is compared based on the national wind power data in recent years. This provides recommendations for the future pilot construction and promotion of wind–hydrogen coupled power generation systems in China.

To achieve future emission targets for internal combustion engines the use of hydrogen gas generated by renewable energy sources (known as “green” hydrogen) instead of fossil fuels plays a key role in the development of new combustion-based engine concepts. For new hydrogen engine generations there are different challenges concerning the injector layout and functionality. Especially when talking about direct hydrogen injection the key challenge is to ensure a proper mixing between hydrogen and the combustion air—the mixing of gas with a gas is not trivial as shown in this article. In terms of injector functionality it must be ensured that the requested amount of hydrogen gas needs to be provided in time and on the other hand accurately metered to provide an appropriate mixing formation quality inside the combustion chamber. This contribution discusses deep injector analysis techniques with pneumatic and optical approaches for an improved overall understanding of functionality and effects caused by operation with a gaseous fuel. A metering technique for gas flow characterization and for test simplification a comparison of hydrogen with helium and nitrogen as possible surrogate gases indicate that helium and nitrogen can act as a substitute for hydrogen in functional testing. Furthermore this contribution focuses on the usability of helium instead of hydrogen for the determination of spray properties. This is shown by the comparison of spray propagation images that were observed with the Schlieren technique in a pressure vessel proving comparable spray properties. In a next step the usage of spray-guiding devices to improve the global gas distribution during the injection period is discussed. Here it turns out that the volume increase does obviously not depend on the nozzle design. Thus the advantage of multi-hole guiding-devices is based on its flexible gas-jet orientation.

A numerical study of the energy conversion process occurring in a lean-charge cogenerative engine designed to be powered by natural gas is here conducted to analyze its performances when fueled with mixtures of natural gas and several percentages of hydrogen. The suitability of these blends to ensure engine operations is proven through a zero–one-dimensional engine schematization where an original combustion model is employed to account for the different laminar propagation speeds deriving from the hydrogen addition. Guidelines for engine recalibration are traced thanks to the achieved numerical results. Increasing hydrogen fractions in the blend speeds up the combustion propagation achieving the highest brake power when a 20% of hydrogen fraction is considered. Further increase of this last would reduce the volumetric efficiency by virtue of the lower mixture density. The formation of the NOx pollutants also grows exponentially with the hydrogen fraction. Oppositely the efficiency related to the exploitation of the exhaust gases’ enthalpy reduces with the hydrogen fraction as shorter combustion durations lead to lower temperatures at the exhaust. If the operative conditions are shifted towards leaner air-to-fuel ratios the in-cylinder flame propagation speed decreases because of the lower amount of fuel trapped in the mixture reducing the conversion efficiencies and the emitted nitrogen oxides at the exhaust. The link between brake power and spark timing is also highlighted: a maximum is reached at an ignition timing of 21° before top dead center for hydrogen fractions between 10 and 20%. However the exhaust gases’ temperature also diminishes for retarded spark timings. Lastly an optimization algorithm is implemented to individuate the optimal condition in which the engine is characterized by the highest power production with the minimum fuel consumption and related environmental impact. As a main result hydrogen addition up to 15% in volume to natural gas in real cogeneration systems is proven as a viable route only if engine operations are shifted towards leaner air-to-fuel ratios to avoid rapid pressure rise and excessive production of pollutant emissions.

Currently global energy transformation and the promotion of renewable energy use are being taken care of to minimize the harm to the environment. However the disadvantage of renewable energy is the random change which leads to the regulation of grid operations which is very difficult when the capacity of renewable energy sources accounts for a large proportion. The hydrogen production technology from wind and solar energy sources is one of the possible methods to minimize adverse impacts on the utility grid and serve the load demand of industrial zones. In this study the photovoltaic (PV) hydrogen production potential for industrial zones in Vietnam is analyzed. The Homer was used to simulate and calculate power output. The results showed that the Hai Duong province has the lowest solar radiation so the solar power output is 3600389 kWh/year and the amount of hydrogen generated is less so it mainly serves the hydrogen load while the fuel cell can only generate very low amounts of electricity of about 4150 kWh/year for direct current (DC) load. The hybrid power systems in the typical industrial plant in Quang Nam province Binh Thuan province Can Tho city can generate about 17386 kg/year to 17422 kg/year to supply the operation of fuel cells based on the value of solar radiation of each province. The better the area with solar potential the lower the net present cost (NPC) cost of energy (COE) and operation cost so the economical and technical efficiency of the PV–Fuel cell hybrid power system will increase.

Waste heat recovery was considered as a promising candidate for energy conservation and emission reduction. Methanol steam reforming was considered to be an effective means for hydrogen production because of its advantages. In this work a micro reactor was constructed and thermoelectric generation coupled with hydrogen production from methanol steam reforming was innovatively used to recycle waste heat which was simulated by hot air from a hot air gun. The waste heat was converted into electricity and hydrogen at the same time. The characteristic of thermoelectric generation coupled with methanol steam reforming was investigated. It was experimentally verified that both the hydrogen production rate and methanol conversion increased with the increasing inlet temperature but thermal efficiency increased firstly and then decreased with the increasing temperature. The methanol steam reforming could effectively maintain cold side temperature distribution of thermoelectric generation. In the case of the thermoelectric module (1) the highest temperature difference of 37 ◦C was determined and the maximum open circuit voltage of 2 V was observed. The highest methanol conversion of 64.26% was achieved at a space velocity of 0.98 h−1 when the temperature was 543 K comprehensively considering the CO content and thermal efficiency.

Meeting the Paris Agreement will most likely require the combination of CO2 capture and biomass in the industrial sector resulting in net negative emissions. CO2 capture within the industry has been extensively investigated. However biomass options have been poorly explored with literature alluding to technical and economic barriers. In addition a lack of consistency among studies makes comparing the performance of CO2 capture and/or biomass use between studies and sectors difficult. These inconsistencies include differences in methodology system boundaries level of integration costs greenhouse gas intensity of feedstock and energy carriers and capital cost estimations. Therefore an integrated evaluation of the techno-economic performance regarding CO2 capture and biomass use was performed for five energy-intensive industrial sub-sectors. Harmonization results indicate that CO2 mitigation potentials vary for each sub-sector resulting in reductions of 1.4–2.7 t CO2/t steel (77%–149%) 0.7 t CO2/t cement (92%) 0.2 t CO2/t crude oil (68%) 1.9 t CO2/t pulp (1663%–2548%) and 34.9 t CO2/t H2 (313%). Negative emissions can be reached in the steel paper and H2 sectors. Novel bio-based production routes might enable net negative emissions in the cement and (petro) chemical sectors as well. All the above-mentioned potentials can be reached for 100 €/t CO2 or less. Implementing mitigation options could reduce industrial CO2 emissions by 10 Gt CO2/y by 2050 easily meeting the targets of the 2 ◦C scenario by the International Energy Agency (1.8 Gt CO2/y reduction) for the industrial sector and even the Beyond 2 ◦C scenario (4.2 Gt CO2/y reduction).

The sustainable development goals concept towards zero carbon emission set forth by the Paris Agreement is the foundation of decarbonisation implemented in most developed countries worldwide. One of the efforts in the decarbonisation of the environment is through hydrogen fuel cell technology. A fuel cell is an energy converter device that produces electricity via the electrochemical reaction with water as the by-product. The application of fuel cells is strongly related to the economic aspect including local and infrastructure costs making it more relevant to be implemented in a developed country. This work presents a short review of the development and progress of hydrogen fuel cells in a developed country such as Japan Germany USA Denmark and China (in transition between developing to developed status); which championed hydrogen fuel cell technology in their region.

Hydrogen (H2) produced using renewable energy could be used to reduce greenhouse gas (GHG) emissions in industrial sectors such as steel chemicals transportation and energy storage. Knowing the delivered cost of renewable H2 is essential to decisionmakers looking to utilize it. The cheapest location to source it from as well as the transport method and medium are also crucial information. This study presents a Monte Carlo simulation to determine the delivered cost for renewable H2 for any usage location globally as well as the most cost-effective production location and transport route from nearly 6000 global locations. Several industrially dense locations are selected for case studies the primary two being Cologne Germany and Houston United States. The minimum delivered H2 cost to Cologne is 9.4 €/kg for small scale (no pipelines considered) shipped from northern Egypt as a liquid organic hydrogen carrier (LOHC) and 7.6 €/kg piped directly as H2 gas from southern France for large scale (pipelines considered). For smallscale H2 in Houston the minimum delivered cost is 8.6 €/kg trucked as H2 gas from the western Gulf of Mexico and 7.6 €/kg for large-scale demand piped as H2 gas from southern California. The south-west United States and Mexico northern Chile the Middle East and north Africa south-west Africa and north-west Australia are identified as the regions with the lowest renewable H2 cost potential with production costs ranging from 6.7—7.8 €/kg in these regions. Each is able to supply differing industrially dominant areas. Furthermore the effect of parameters such as year of construction electrolyser and H2 demand is analysed. For the case studies in Houston and Cologne the delivered H2 cost is expected to reduce to about 7.8 €/kg by 2050 in Cologne (no pipelines considered PEM electrolyser) and 6.8 €/kg in Houston.

The design of future energy systems requires the efficient use of all available renewable resources. Biomass can complement variable renewable energy sources by ensuring energy system flexibility and providing a reliable feedstock to produce renewable fuels. We identify biomass gasification suitable to utilise the limited biomass resources efficiently. In this study we inquire about its role in a 100% renewable energy system for Denmark and a net-zero energy system for Europe in the year 2050 using hourly energy system analysis. The results indicate bio-electrofuels produced from biomass gasification and electricity to enhance the utilisation of wind and electrolysis and reduce the energy system costs and fuels costs compared to CO2-electrofuels from carbon capture and utilisation. Despite the extensive biomass use overall biomass consumption would be higher without biomass gasification. The production of electromethanol shows low biomass consumption and costs while Fischer-Tropsch electrofuels may be an alternative for aviation. Syngas from biomass gasification can supplement biogas in stationary applications as power plants district heat or industry but future energy systems must meet a balance between producing transport fuels and syngas for stationary units. CO2-electrofuels are found complementary to bio-electrofuels depending on biomass availability and remaining non-fossil CO2 emitters

Hydrogen supplementation in diesel Compression Ignition (CI) engines is gaining more attention since it is considered as a feasible solution to tackle the challenges that are related to the emission regulations that will be applied in the forthcoming years. Such a solution is very attractive because it requires only limited modifications to the existing technology of internal combustion CI engines. To this end numerous work on the investigation of an engine’s performance and the effects of emissions when hydrogen is supplied in the engine’s cylinders has been completed by researchers. However contradictory results were found among these studies regarding the efficiency of the engine and the emission characteristics achieved compared to the diesel-only operation. The different conclusions might be attributed to the different characteristics and technology level of the engines that were utilized as well as on the chosen operational parameters. This paper aims to present an overview of the experimental studies that have examined the effects of hydrogen addition in CI four-stroke diesel engines reporting the characteristics of the utilized engines the quantities of hydrogen tested the method of hydrogen induction used as well as the operational conditions tested in order to help interested researchers to easily identify relevant and appropriate studies to perform comparisons or validations by repeating certain cases. The presented data do not include any results or conclusions from these studies. Furthermore an experimental configuration along with the appropriate modifications on a heavy-duty auxiliary generator-set engine that was recently developed by the authors for the purposes of the HYMAR project is presented.

This paper proposes a multi-objective model predictive control (MPC) designed for the power management of a multi-stack fuel cell (FC) system integrated into a renewable sources-based microgrid. The main advantage of MPC is the fact that it allows the current timeslot to be optimized while taking future timeslots into account. The multi-objective function solves the problem related to the power dispatch at time that includes criteria to reduce the multi-stack FC degradation operating and maintenance costs as well as hydrogen consumption. Regarding the scientific literature the novelty of this paper lies in the proposal of a generalized MPC controller for a multi-stack FC that can be used independently of the number of stacks that make it up. Although all the stacks that make up the modular FC system are identical their levels of degradation in general will not be. Thus over time each stack can present a different behavior. Therefore the power control strategy cannot be based on an equal distribution according to the nominal power of each stack. On the contrary the control algorithm should take advantage of the characteristics of the multi-stack FC concept distributing operation across all the stacks regarding their capacity to produce power/energy and optimizing the overall performance.

Hydrogen is an attractive clean sustainable energy source primarily produced via industry. At present most reviews on hydrogen mainly focus on the preparation and storage of hydrogen while the development and utilization of natural hydrogen will greatly reduce its cost. Natural hydrogen has been discovered in many geological environments. Therefore based on extensive literature research in this study the distribution and sources of natural hydrogen were systematically sorted and the identification method and occurrence state of natural hydrogen were examined and summarized. The results of this research show that hydrogen has been discovered in oceanic spreading centers transform faults passive margins convergent margins and intraplate settings. The primary sources of the hydrogen include alterations in Fe(II)-containing rocks the radiolysis of water degassed magma and the reaction of water- and silica-containing rocks during the mechanical fracturing. Hydrogen can appear in free gas it can be adsorbed and trapped in inclusions. Currently natural hydrogen exploration is in its infancy. This systematic review helps to understand the origin distribution and occurrence pattern of natural hydrogen. In addition it facilitates the exploration and development of natural hydrogen deposits thus enabling the production of low-cost hydrogen.

The shipping industry is a major enabler of globalization trade commerce and human welfare. But it is still heavily served by fossil fuels which make it one of the foremost greenhouse gas emitting sectors operational today. It is also one of the hardest to abate segments of the transport industry. As part of the economy-wide climate change mitigation and adaptation efforts it is necessary to consider a low carbon energy transition for this segment as well. This study examines the potential role of nuclear power and cogeneration towards greening this sector and identifies the associated techno-commercial and policy challenges associated with the transition. Quantitative estimates of the economics and investments associated with some of the possible routes are also presented. Alternatives such as nuclear-powered ships along commercial maritime trading routes ships working on nuclear derived green hydrogen ammonia or other sustainable power fuels will enable not only decarbonization of the shipping industry but also allow further diversification of the nuclear industry through non-electric applications of nuclear power and new sector coupling opportunities. In the run-up to the UNFCCC-COP28 meeting in 2023 in UAE nuclear equipped nations heavily engaged in and dependent on maritime trade and commerce should definitely consider nuclear driven decarbonization of shipping and some of the options presented here as part of their climate action strategies.

This paper contributes to the climate policy discussion by focusing on the challenges and opportunities of reaching net zero emissions by 2050 in Italy. To support Italian energy planning we developed energy roadmaps towards national climate neutrality consistent with the Paris Agreement objectives and the IPCC goal of limiting the increase in global surface temperature to 1.5 ◦C. Starting from the Italian framework these scenarios identify the correlations among the main pillars for the change of the energy paradigm towards net emissions by 2050. The energy scenarios were developed using TIMES-RSE a partial equilibrium and technology-rich optimization model of the entire Italian energy system. Subsequently an in-depth analysis was developed with the sMTISIM a long-term simulator of power system and electricity markets. The results show that to achieve climate neutrality by 2050 the Italian energy system will have to experience profound transformations on multiple and strongly related dimensions. A predominantly renewable-based energy mix (at least 80–90% by 2050) is essential to decarbonize most of the final energy consumption. However the strong increase of non-programmable renewable sources requires particular attention to new flexibility resources needed for the power system such as Power-to-X. The green fuels produced from renewables via Power-to-X will be a vital energy source for those sectors where electrification faces technical and economic barriers. The paper’s findings also confirm that the European “energy efficiency first” principle represents the very first step on the road to climate neutrality.

Alkaline electrolyzers are the most widespread technology due to their maturity low cost and large capacity in generating hydrogen. However compared to proton exchange membrane (PEM) electrolyzers they request the use of potassium hydroxide (KOH) or sodium hydroxide (NaOH) since the electrolyte relies on a liquid solution. For this reason the performances of alkaline electrolyzers are governed by the electrolyte concentration and operating temperature. Due to the growing development of the water electrolysis process based on alkaline electrolyzers to generate green hydrogen from renewable energy sources the main purpose of this paper is to carry out a comprehensive survey on alkaline electrolyzers and more specifically about their electrical domain and specific electrolytic conductivity. Besides this survey will allow emphasizing the remaining key issues from the modeling point of view.

The Green Deal Industrial Plan aims to boost the competitiveness of Europe’s net-zero industry and to accelerate the transition to climate neutrality. The Plan is based on four pillars: (1) a predictable and simplified regulatory environment; (2) faster access to funding; (3) developing skills for net-zero industry; and (4) open trade for resilient supply chains.

In the modern world zero-carbon society has become a new buzzword of the era. Many projects have been initiated to develop alternatives not only to the environmental crisis but also to the shortage of fossil fuels. With successful projects in automobile technology hydrogen fuel is now being tested and utilized as a sustainable green fuel in the aviation sector which will lead to zero carbon emission in the future. From the mid-20th century to the early 21st numerous countries and companies have funded multimillion projects to develop hydrogen-fueled aircraft. Empirical data show positive results for various projects. Consequently large companies are investing in various innovations undertaken by researchers under their supervision. Over time the efficiency of hydrogen-fueled aircraft has improved but the lack of refueling stations large production cost and consolidated carbon market share have impeded the path of hydrogen fuel being commercialized. In addition the Unmanned Aerial Vehicle (UAV) is another important element of the Aviation industry Hydrogen started to be commonly used as an alternative fuel for heavy-duty drones using fuel cell technology. The purpose of this paper is to provide an overview of the chronological development of hydrogen-powered aircraft technology and potential aviation applications for hydrogen and fuel cell technology. Furthermore the major barriers to widespread adoption of hydrogen technology in aviation are identified as are future research opportunities.

Underground Hydrogen Storage (UHS) has received significant attention over the past few years as hydrogen seems well-suited for adjusting seasonal energy gaps. We present an integrated reservoir-well model for “Viking A00 the depleted gas field in the North Sea as a potential site for UHS. Our findings show that utilizing the integrated model results in more reasonable predictions as the gas composition changes over time. Sensitivity analyses show that the lighter the cushion gas the more production can be obtained. However the purity of the produced hydrogen will be affected to some extent which can be enhanced by increasing the fill-up period and the injection rate. The results also show that even though hydrogen diffuses into the reservoir and mixes up with the native fluids (mainly methane) the impact of hydrogen diffusion is marginal. All these factors will potentially influence the project's economics.

The Japanese government has announced a commitment to net-zero greenhouse gas emissions by 2050. It envisages an important role for hydrogen in the nation’s future energy economy. This paper explores the possibility that a significant source for this hydrogen could be produced by electrolysis fueled by power generated from offshore wind in China. Hydrogen could be delivered to Japan either as liquid or bound to a chemical carrier such as toluene or as a component of ammonia. The paper presents an analysis of factors determining the ultimate cost for this hydrogen including expenses for production storage conversion transport and treatment at the destination. It concludes that the Chinese source could be delivered at a volume and cost consistent with Japan’s idealized future projections.

Hydrogen as fuel has been a promising technology toward climate change mitigation efforts. To this end in this paper we analyze the contribution of hydrogen technology to our future environmental goals. It is assumed that hydrogen is being produced in higher efficiency across time and this is simulated on Global Change Assessment Model (GCAM). The environmental restrictions applied are the expected emissions representative concentration pathways (RCP) 2.6 4.5 and 6.0. Our results have shown increasing hydrogen production as the environmental constraints become stricter and hydrogen more efficient in being produced. This increase has been quantified and provided on open access as Supporting Information to this manuscript.

Hydrogen fuel cell vehicle industry is in a rapid development stage. Studying the domestic spatial distribution of hydrogen fuel cell vehicle industry across a country especially the spatio-temporal evolution of the innovation level and position of each region in innovation network will help to understand the industry’s development trends and characteristics and avoid repeated construction. This article uses social network analysis and patent citation information of 2971 hydrogen fuel cell vehicle related invention patents owned by 218 micro-innovators across 25 provinces of China from 2001 to 2020 to construct China’s hydrogen fuel cell vehicle innovation network. Based on the dimensions of knowledge production knowledge consumption and network broker the network positions of sample provinces in three periods divided by four main national policies are classified. The main findings are as follows. 1) In China the total sales of hydrogen fuel cell vehicle and the development of supporting infrastructure are balanced and a series of national and local industrial development polices have been issued. 2) China’s hydrogen fuel cell vehicle innovation network density the proportion of universities and research institutes among the innovators and the active degree of the eastern provinces are all becoming higher. 3) The provinces in optimal network position are all from the eastern region. Shanghai and Liaoning are gradually replaced by Beijing and Jiangsu. 4) Sichuan in the western region is the only network broker based on knowledge consumption. 5) Although Zhejiang Tianjin Hebei Guangdong and Hubei are not yet in the optimal position they are outstanding knowledge producers. Specifically Guangdong is likely to climb to the optimal network position in the next period. The conclusions will help China’s provinces to formulate relevant development policies to optimize industry layout and enhance collaborative innovation in the hydrogen fuel cell vehicle industry.

The transition from fossil-based primary steel production to a low-emission alternative has gained increasing attention in recent years. Various schemes including Carbon Capture and Utilization (CCU) and Carbon Direct Avoidance (CDA) via hydrogen-based as well as electrochemical routes have been proposed. With multiple technical analyses being available and technical feasibility being proven by first pilot plants pathways towards commercial market entry are of increasing interest. While multiple publications on the economic feasibility of CCU are available data on CDA approaches is scarce. In this work an economic model for the quantification of production cost as well as CO2 emission mitigation cost is presented. The approach is characterized by a seamless integration with a flowsheet-based process model of a direct reduction-based crude steel production plant detailed in a previous work and allows for the investigation of multiple economic aspects. Firstly the gradual transition from the natural gas-based state-of-the-art direct reduction towards a fossil-free hydrogen-based reduction is analyzed. Furthermore a comparison between the more mature technology of low-temperature electrolysis and a potentially more efficient solid oxide electrolysis (SOEL) is given highlighting the potential of SOEL technology. The conducted forecast to 2050 shows that SOEL-based CDA offers lower production cost when technological maturity is reached. Based on the results of the economic assessment possible legislative support mechanisms are studied showing that legislative actions are necessary to allow for market entry as well as for sustainable and economically feasible operation of fossil-free direct reduction plants.

This review focuses on the reduction of iron oxides using hydrogen as a reducing agent. Due to increasing requirements from environmental issues a change of process concepts in the iron and steel industry is necessary within the next few years. Currently crude steel production is mainly based on fossil fuels and emitting of the climate-relevant gas carbon dioxide is integral. One opportunity to avoid or reduce greenhouse gas emissions is substituting hydrogen for carbon as an energy source and reducing agent. Hydrogen produced via renewable energies allows carbon-free reduction and avoids forming harmful greenhouse gases during the reduction process. The thermodynamic and kinetic behaviors of reduction with hydrogen are summarized and discussed in this review. The effects of influencing parameters such as temperature type of iron oxide grain size etc. are shown and compared with the reduction behavior of iron oxides with carbon monoxide. Different methods to describe the kinetics of the reduction progress and the role of the apparent activation energy are shown and proofed regarding their plausibility.

Fuel cells are electrochemical devices that are conventionally used to convert the chemical energy of fuels into electricity while producing heat as a byproduct. High temperature fuel cells such as molten carbonate fuel cells and solid oxide fuel cells produce significant amounts of heat that can be used for internal reforming of fuels such as natural gas to produce gas mixtures which are rich in hydrogen while also producing electricity. This opens up the possibility of using high temperature fuel cells in systems designed for flexible coproduction of hydrogen and power at very high system efficiency. In a previous study the flowsheet software Cycle-Tempo has been used to determine the technical feasibility of a solid oxide fuel cell system for flexible coproduction of hydrogen and power by running the system at different fuel utilization factors (between 60 and 95%). Lower utilization factors correspond to higher hydrogen production while at a higher fuel utilization standard fuel cell operation is achieved. This study uses the same basis to investigate how a system with molten carbonate fuel cells performs in identical conditions also using Cycle-Tempo. A comparison is made with the results from the solid oxide fuel cell study.

Proton-exchange membrane fuel cells (PEMFCs) are low-temperature fuel cells that have excellent starting performance due to their low operating temperature can respond quickly to frequent load fluctuations and can be manufactured in small packages. Unlike existing studies that mainly used hydrogen as fuel for PEMFCs in this study methane is used as fuel for PEMFCs to investigate its performance and economy. Methane is a major component of natural gas which is more economically competitive than hydrogen. In this study methane gas is reformed by the steam reforming method and is applied to the following five gas post-treatment systems: (a) Case 1—water– gas shift only (WGS) (b) Case 2—partial oxidation reforming only (PROX) (c) Case 3—methanation only (d) Case 4—WGS + methanation (e) Case 5—WGS + PROX. In the evaluation the carbon monoxide concentration in the gas did not exceed 10 ppm and the methane component which has a very large greenhouse effect was not regenerated in the post-treated exhaust gas. As a result Case 5 (WGS and PROX) is the only case that satisfied both criteria. Therefore we propose Case 5 as an optimized post-treatment system for methane reforming gas in ship PEMFCs.