Publications

V-Nb-Mo-Ta-W high-entropy alloy (HEA) one of the refractory HEAs is considered as a next-generation structural material for ultra-high temperature uses. Refractory HEAs have low castability and machinability due to their high melting temperature and low thermal conductivity. Thus powder metallurgy becomes a promising method for fabricating components with refractory HEAs. Therefore in this study we fabricated spherical V-Nb-Mo-Ta-W HEA powder using hydrogen embrittlement and spheroidization by thermal plasma. The HEA ingot was prepared by vacuum arc melting and revealed to have a single body-centered cubic phase. Hydrogen embrittlement which could be achieved by annealing in a hydrogen atmosphere was introduced to get the ingot pulverized easily to a fine powder having an angular shape. Then the powder was annealed in a vacuum atmosphere to eliminate the hydrogen from the hydrogenated HEA resulting in a decrease in the hydrogen concentration from 0.1033 wt% to 0.0003 wt%. The angular shape of the HEA powder was turned into a spherical one by inductively-coupled thermal plasma allowing to fabricate spherical V-Nb-Mo-Ta-W HEA powder with a d50 value of 28.0 μm.

The Philippines is exploring different alternative sources of energy to make the country less dependent on imported fossil fuels and to reduce significantly the country's CO2 emissions. Given the abundance of renewable energy potential in the country green hydrogen from renewables is a promising fuel because it can be utilized as an energy carrier and can provide a source of clean and sustainable energy with no emissions. This paper aims to review the prospects and challenges for the potential use of green hydrogen in several production and utilization pathways in the Philippines. The study identified green hydrogen production routes from available renewable energy sources in the country including geothermal hydropower wind solar biomass and ocean. Opportunities for several utilization pathways include transportation industry utility and energy storage. From the analysis this study proposes a roadmap for a green hydrogen economy in the country by 2050 divided into three phases: green hydrogen as industrial feedstock green hydrogen as fuel cell technology and commercialization of green hydrogen. On the other hand the analysis identified several challenges including technical economic and social aspects as well as the corresponding policy implications for the realization of a green hydrogen economy that can be applied in the Philippines and other developing countries.

A coalition of 40 industrial companies and government organizations financially supported by the FCH JU elaborated a technology neutral and fact-based comparative study on eight different powertrain technologies for urban buses in Europe from 2012 to 2030.<br/>According to the results of the study only fully electric powertrain buses (based on hydrogen batteries or trolley system) have the potential to achieve zero local emissions by drastically reducing well-to-wheel emissions.<br/>Following the positive comparative result for  fuel cell hydrogen  urban buses the FCH JU will  launch a follow-up study that more specifically defines real uptake scenarios for market entry scheduled to starting before summer 2013.

In a report co-authored by Columbia University’s Centre on Global Energy Policy (CGEP) and the Global CCS Institute titled ‘Net Zero and Geospheric Return: Actions today for 2030’ findings reveal that climate finance policies and the development of carbon dioxide removal technologies need to grow rapidly within the next 10 years in order to curb climate change and hit net-zero targets.

The report unveils key climate actions required to avoid climate catastrophe:

With 2020 set to close the hottest decade on record CO2 emissions need to drop by 50% to achieve net-zero climate goals by 2030 The rapid deployment of climate mitigating infrastructure needs to occur including the expansion of CO2 pipelines from the current 8000 km to 43000 km by 2030 Clear climate polices which reduce the financial and regulatory risk of CO2 capture and storage and increase CO2 storage options need to be quickly developed and implemented.

Link to document on Global CCS Institute Website

Ferrosilicon 75 a 50:50 mixture of silicon and iron disilicide has been activated toward hydrogen generation by processing using ball milling allowing a much lower concentration of sodium hydroxide (2 wt %) to be used to generate hydrogen from the silicon in ferrosilicon with a shorter induction time than has been reported previously. An activation energy of 62 kJ/mol was determined for the reaction of ball-milled ferrosilicon powder with sodium hydroxide solution which is around 30 kJ/mol lower than that previously reported for unmilled ferrosilicon. A series of composite powders were also prepared by ball milling ferrosilicon with various additives in order to improve the hydrogen generation properties from ferrosilicon 75 and attempt to activate the silicon in the passivating FeSi2 component. Three different classes of additives were employed: salts polymers and sugars. The effects of these additives on hydrogen generation from the reaction of ferrosilicon with 2 wt% aqueous sodium hydroxide were investigated. It was found that composites formed of ferrosilicon and sodium chloride potassium chloride sodium polyacrylate sodium polystyrene sulfonate-co-maleic acid or fructose showed reduced induction times for hydrogen generation compared to that observed for ferrosilicon alone and all but fructose also led to an increase in the maximum hydrogen generation rate. In light of its low cost and toxicity and beneficial effects sodium chloride is considered to be the most effective of these additives for activating the silicon in ferrosilicon toward hydrogen generation. Materials characterisation showed that neither ball milling on its own nor use of additives was successful in activating the FeSi2 component of ferrosilicon for hydrogen generation and the improvement in rate and shortening of the induction period was attributed to the silicon component of the mixture alone The gravimetric storage capacity for hydrogen in ferrosilicon 75 is therefore maintained at only 3.5% rather than the 10.5% ideally expected for a material containing 75% silicon. In light of these results ferrosilicon 75 does not appear a good candidate for hydrogen production in portable applications.

This paper presents the design of a solid oxide fuel cell (SOFC) tri-generation system that consists of an SOFC-combined heat and power subsystem an adsorption refrigeration subsystem and coupling devices between the two subsystems. Whereas typical extant designs use absorption techniques the proposed design employs adsorption refrigeration. In this paper the dynamics of adsorption refrigeration are reported in detail to evaluate the feasibility of the tri-generation system design. The design of the coupling devices and instrumentation strategies of the overall system are discussed in detail. Simulation results indicate that the proposed SOFC trigeneration system can output 4.35 kW of electrical power 2.448 kW of exhaust heat power and 1.348 kW of cooling power. The energy efficiency is 64.9% and the coefficient of performance of the refrigeration is 0.32. Varying the electrical output power results in the variation of exhaust heat power but not the cooling power; varying the cooling power affects the exhaust heat power but not the electrical power. These favorable features can be attributed to the proposed heat exchange sequence and active temperature controls of the system.

In order to reduce anthropogenic global warming governments around the world have decided to reduce CO₂ emissions from fossil fuels dramatically within the next decades. In moderate and cold climates large amounts of fossil fuels are used for space heating and domestic hot water production in winter. Although on an annual base solar energy is available in large quantities in these regions least of the solar resource is available in winter when most of the energy is needed. Therefore solutions are needed to store and transfer renewable energy from summer to winter. In this paper a seasonal energy storage based on the aluminium redox cycle (Al3+→Al→ Al3+) is proposed. For charging electricity from solar or other renewable sources is used to convert aluminium oxide or aluminium hydroxide to elementary aluminium (Al3+→Al). In the discharging process aluminium is oxidized (Al→Al3+) releasing hydrogen heat and aluminium hydroxide or aluminium oxide as a by-product. Hydrogen is used in a fuel cell to produce electricity. Heat produced from the aluminium oxidation process and by the fuel cell is used for domestic hot water production and space heating. The chemical reactions and energy balances are presented and simulation results are shown for a system that covers the entire energy demand for electricity space heating and domestic hot water of a new multi-family building with rooftop photovoltaic energy in combination with the seasonal Al energy storage cycle. It shows that 7–11 kWp of photovoltaic installations and 350–530 kg Al would be needed per apartment for different Swiss climates. Environmental life cycle data shows that the global warming potential and non-renewable primary energy consumption can be reduced significantly compared to today's common practice of heating with natural gas and using electricity from the ENTSO-E network. The presumptive cost were estimated and indicate a possible cost-competitiveness for this system in the near future.

Hydrogen remains an important option for long-term decarbonisation of energy and transport systems. However studying the possible transition paths and development prospects for a hydrogen energy system is challenging. The long-term nature of technological transitions inevitably means profound uncertainties diverging perspectives and contested priorities. Both modelling approaches and narrative storyline scenarios are widely used to explore the possible future of hydrogen energy but each approach has shortcomings.<br/>This paper presents a hybrid approach to assessing hydrogen transitions in the UK by confronting qualitative socio-technical scenarios with quantitative energy systems modelling through a process of ‘dialogue’ between scenario and model. Three possible transition pathways are explored each exploring different uncertainties and possible decision points. Conclusions are drawn for both the future of hydrogen and on the value of an approach that brings quantitative formal models and narrative scenario techniques into dialogue.

The Fuel Cells and Hydrogen Joint Undertaking (FCH JU) has the ambitious objective to place Europe at the forefront of the development commercialization and deployment of fuel cells and hydrogen technologies as of 2015. About €470 million over a six year period have been granted by the European Union to achieve this and private funds are being attracted to support the same ambition as part of the global European effort embedded in the multi-annual implementation plan MAIP (2008-2013).

In this work CdS/SiC/TiO₂ tri-composite photocatalysts that exploit electron- and hole-transfer processes were fabricated using an easy two-step method in the liquid phase. The photocatalyst with a 1:1:1 M ratio of CdS/SiC/TiO₂ exhibited a rate of hydrogen evolution from an aqueous solution of sodium sulfite and sodium sulfide under visible light of 137 μmol h⁻¹ g⁻¹ which is 9.5 times that of pure CdS. β-SiC can act as a sink for the photogenerated holes because the valence band level of β-SiC is higher than the corresponding bands in CdS and TiO2. In addition the level of the conduction band of TiO2 is lower than those of CdS and β-SiC so TiO₂ can act as the acceptor of the photogenerated electrons. Our results demonstrate that hole transfer and absorption in the visible light region lead to an effective hydrogen-production scheme.