Institution of Gas Engineers & Managers

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.

The electrification of final energy uses is a key strategy to reach the desired scenario with zero greenhouse gas emissions. Many of them can be electrified with more or less difficulty but there is a part that is difficult to electrify at a competitive cost: heavy road transport maritime and air transport and some industrial processes are some examples. For this reason the possibility of using other energy vectors rather than electricity should be explored. Hydrogen can be considered a real alternative especially considering that this transition should not be carried out immediately because initially the electrification would be carried out in those energy uses that are considered most feasible for this conversion. The Canary Islands’ government is making considerable efforts to promote a carbon-free energy mix starting with renewable energy for electricity generation. Still in the early–mid 2030s it will be necessary to substitute heavy transport fossil fuel. For this purpose HOMER software was used to analyze the feasibility of hydrogen production using surplus electricity produced by the future electricity system. The results of previous research on the optimal generation MIX for Grand Canary Island based exclusively on renewable sources were used. This previous research considers three possible scenarios where electricity surplus is in the range of 2.3–4.9 TWh/year. Several optimized scenarios using demand-side management techniques were also studied. Therefore based on the electricity surpluses of these scenarios the optimization of hydrogen production and storage systems was carried out always covering at least the final hydrogen demand of the island. As a result it is concluded that it would be possible to produce 3.5 × 104 to 7.68 × 104 t of H2/year. In these scenarios 3.15 × 105 to 6.91 × 105 t of water per year would be required and there could be a potential production of 2.8 × 105 to 6.14 × 105 t of O2 per year.

Hydrogen storage is one of the energy storage methods that can help realization of an emission free future by saving surplus renewable energy for energy deficit periods. Utilization of depleted hydrocarbon reservoirs for large-scale hydrogen storage may be associated with the risk of chemical/biochemical reactions. In the specific case of chalk reservoirs the principal reactions are abiotic calcite dissolution acetogenesis methanogenesis and biological souring. Here we use PHREEQC to evaluate the dynamics and the extent of hydrogen loss by each of these reactions in hydrogen storage scenarios for various Danish North Sea chalk hydrocarbon reservoirs. We find that: (i) Abiotic calcite dissolution does not occur in the temperature range of 40-180◦ C. (ii) If methanogens and acetogens grow as slow as the slowest growing methanogens and acetogens reported in the literature methanogenesis and acetogenesis cannot cause a hydrogen loss more than 0.6% per year. However (iii) if they proceed as fast as the fastest growing methanogens and acetogens reported in the literature a complete loss of all injected hydrogen in less than five years is possible. (iv) Co-injection of CO2 can be employed to inhibit calcite dissolution and keep the produced methane due to methanogenesis carbon neutral. (v) Biological sulfate reduction does not cause significant hydrogen loss during 10 years but it can lead to high hydrogen sulfide concentrations (1015 ppm). Biological sulfate reduction is expected to impact hydrogen storage only in early stages if the only source of sulfur substrates are the dissolved species in the brine and not rock minerals. Considering these findings we suggest that depleted chalk reservoirs may not possess chemical/biochemical risks and be good candidates for large-scale underground hydrogen storage.

The paper explores options for a 2050 carbon free energy future for India. Onshore wind and solar sources are projected as the dominant primary contributions to this objective. The analysis envisages an important role for so-called green hydrogen produced by electrolysis fueled by these carbon free energy sources. This hydrogen source can be used to accommodate for the intrinsic variability of wind and solar complementing opportunities for storage of power by batteries and pumped hydro. The green source of hydrogen can be used also to supplant current industrial uses of grey hydrogen produced in the Indian context largely from natural gas with important related emissions of CO2. The paper explores further options for use of green hydrogen to lower emissions from otherwise difficult to abate sectors of both industry and transport. The analysis is applied to identify the least cost options to meet India’s zero carbon future.

Current safety codes and technical standards related to Japanese hydrogen refueling stations (HRSs) have been established based on qualitative risk assessment and quantitative effectiveness validation of safety measures for more than ten years. In the last decade there has been significant development in the technologies and significant increment in operational experience related to HRSs. We performed a quantitative risk assessment (QRA) of the HRS model representing Japanese HRSs with the latest information in the previous study. The QRA results were obtained by summing risk contours derived from each process unit. They showed that the risk contours of 10-3 and 10-4 per year were confined within the HRS boundaries whereas those of 10-5 and 10-6 per year are still present outside the HRS boundaries. Therefore we analyzed the summation of risk contours derived from each unit and identified the largest risk scenarios outside the station. The HRS model in the previous study did not consider fire and blast protection walls which could reduce the risks outside the station. Therefore we conducted a detailed risk analysis of the identified scenarios using 3D structure modeling. The heat radiation and temperature rise of jet fire scenarios that pose the greatest risk to the physical surroundings in the HRS model were estimated in detail based on computational fluid dynamics with 3D structures including fire protection walls. Results show that the risks spreading outside the north- west- and east-side station boundaries are expected to be acceptable by incorporating the fire protection wall into the Japanese HRS model.

Although electricity storage plays a decisive role for the German “Energiewende” and it has become evident that the successful diffusion of technologies is not only a question of technical feasibility but also of social acceptance research on electricity storage technologies from a social science point of view is still scarce. This study therefore empirically explores laypersons’ mindsets and knowledge related to storage technologies focusing on hydrogen. While the results indicate overall supportive attitudes and trust in hydrogen storage some misconceptions a lack of information as well as concerns were identified which should be addressed in future communication concepts.

The hydrogen storage pressure in fuel cell vehicles has been increased from 35 MPa to 70 MPa in order to accommodate longer driving range. On the downside such pressure increase results in significant temperature rise inside the hydrogen tank during fast filling at a fueling station which may pose safety issues. Installation of a chiller often mitigates this concern because it cools the hydrogen gas before its deposition into the tank. To address both the energy efficiency improvement and safety concerns this paper proposed an on-board cold thermal energy storage (CTES) system cooled by expanded hydrogen. During the driving cycle the proposed system uses an expander instead of a pressure regulator to generate additional power and cold hydrogen gas. Moreover CTES is equipped with phase change materials (PCM) to recover the cold energy of the expanded hydrogen gas which is later used in the next filling to cool the high-pressure hydrogen gas from the fueling station.

The development of a hydrogen energy-based society is becoming the solution for more and more countries. Fuel cell electric vehicles are the best carriers for developing a hydrogen energy-based society. The current research on hydrogen leakage and the diffusion of fuel cell electric vehicles has been sufficient. However the study of hydrogen safety has not reduced the safety concerns for society and government management departments concerning the large-scale promotion of fuel cell electric vehicles. Hydrogen safety is both a technical and psychological issue. This paper aims to provide a comprehensive overview of fuel cell electric vehicles’ hydrogen dispersion and the burning behavior and introduce the relevant work of international standardization and global technical regulations. The CFD simulations in tunnels underground car parks and multistory car parks show that the hydrogen escape performance is excellent. At the same time the research verifies that the flow the direction of leakage and the vehicle itself are the most critical factors affecting hydrogen distribution. The impact of the leakage location and leakage pore size is much smaller. The relevant studies also show that the risk is still controllable even if the hydrogen leakage rate is increased ten times the limit of GTR 13 to 1000 NL/min and then ignited. Multi-vehicle combustion tests of fuel cell electric vehicles showed that adjacent vehicles were not ignited by the hydrogen. This shows that as long as the appropriate measures are taken the risk of a hydrogen leak or the combustion of fuel cell electric vehicles is controllable. The introduction of relevant standards and regulations also indirectly proves this point. This paper will provide product design guidelines for R&D personnel offer the latest knowledge and guidance to the regulatory agencies and increase the public’s acceptance of fuel cell electric vehicles.

Based on the energy strategy of the Republic of Kosovo from 2017–2026 the increase in the integration of renewable energy sources (RES) in the national energy system was aimed at. However the hydrogen potential was not mentioned. In this work a roadmap toward the introduction of hydrogen in the energy system with the main focus on the transportation sector through three phases is proposed. In the first phase (until 2024) the integration of hydrogen in the transportation sector produced via water electrolysis from the grid electricity with the increase of up to a 0.5% share of fuel cell vehicles is intended. In the second phase (2025–2030) the hydrogen integration in the transportation sector is increased by including renewable hydrogen where the share of fuel cell electric vehicles (FCEVs) will be around 4% while in the third phase (2031–2050) around an 8% share of FCEVs in the transportation was planned. The technical and environmental analysis of hydrogen integration is focused on both the impact of hydrogen in the decarbonization of the transportation sector and the energy system. To model the Kosovo energy system the hourly deterministic EnergyPLAN model was used. This research describes the methodology based on EnergyPLAN modeling that can be used for any energy system to provide a clear path of RES and hydrogen implementation needed to achieve a zero-emission goal which was also set by various other countries. The predicted decrease in GHG emissions from 8 Mt in the referent year 2017 amounts to 7 Mt at the end of the first phase 2024 and 4.4 Mt at the end of the second phase 2030 to achieve 0 Mt by 2050. In order to achieve it the required amount of hydrogen by 2030 resulted in 31840 kg/year and by 2050 around 89731 kg/year. The results show the concrete impact of hydrogen on transport system stabilization and its influence on greenhouse gas (GHG) emissions reduction.

This research work is the novel state-of-the-art technology performed on multi-cylinder SI engine fueled compressed natural gas emulsified fuel and hydrogen as dual fuel. This work predicts the overall features of performance combustion and exhaust emissions of individual fuels based on AVL Boost simulation technology. Three types of alternative fuels have been compared and analyzed. The results show that hydrogen produces 20% more brake power than CNG and 25% more power than micro-emulsion fuel at 1500 r/min which further increases the brake power of hydrogen CNG and micro-emulsions in the range of 25% 20% and 15% at higher engine speeds of 2500–4000 r/min respectively. In addition the brake-specific fuel consumption is the lowest for 100% hydrogen followed by CNG 100% and then micro-emulsions at 1500 r/min. At 2500– 5000 r/min there is a significant drop in brake-specific fuel consumption due to a lean mixture at higher engine speeds. The CO HC and NOx emissions significantly improve for hydrogen CNG and micro-emulsion fuel. Hydrogen fuel shows zero CO and HC emissions and is the main objective of this research to produce 0% carbon-based emissions with a slight increase in NOx emissions and CNG shows 30% lower CO emissions than micro-emulsions and 21.5% less hydrocarbon emissions than micro-emulsion fuel at stoichiometric air/fuel ratio.