Singapore

Catalytic decomposition of methane (CDM) is a novel technology for turquoise hydrogen production with solid carbon as the by-product instead of CO2. A computational fluid dynamics model was developed to simulate the CDM process in a 3D fixed bed reactor accounting for the impact of carbon deposition on catalytic activity. The model was validated with experimental data and demonstrated its capability to predict hydrogen concentration and catalyst deactivation time under varying operating temperatures and methane flow rates. The catalyst lifespan was characterized by the maximum carbon yield (i.e. gC/gcat) which is a crucial indicator for determining the cost of hydrogen generation. Parametric studies were performed to analyse the effect of inlet gas composition and operating pressure on CDM performance. Various CH4/H2 ratios were simulated to improve the methane conversion efficiency generating a higher amount of hydrogen while increasing the maximum carbon yield up to 49.5 gC/gcat. Additionally higher operating pressure resulted in higher methane decomposition rates which reflects the nature of the chemical kinetics.

The ten nations of Southeast Asia collectively known as ASEAN emitted 1.65 Gtpa CO2 in 2020 and are among the most vulnerable nations to climate change which is partially caused by anthropogenic CO2 emission. This paper analyzes the history of ASEAN energy consumption and CO2 emission from both fossil and renewable energies in the last two decades. The results show that ASEAN’s renewable energies resources range from low to moderate are unevenly distributed geographically and contributed to only 20% of total primary energy consumption (TPEC) in 2015. The dominant forms of renewable energies are hydropower solar photovoltaic and bioenergy. However both hydropower and bioenergy have substantial sustainability issues. Fossil energies depend heavily on coal and oil and contribute to 80% of TPEC. More importantly renewable energies’ contribution to TPEC has been decreasing in the last two decades despite the increasing installation capacity. This suggests that the current rate of the addition of renewable energy capacity is inadequate to allow ASEAN to reach net-zero by 2050. Therefore fossil energies will continue to be an important part of ASEAN’s energy mix. More tools such as carbon capture and storage (CCS) and hydrogen will be needed for decarbonization. CCS will be needed to decarbonize ASEAN’s fossil power and industrial plants while blue hydrogen will be needed to decarbonize hard-to-decarbonize industrial plants. Based on recent research into regional CO2 source-sink mapping this paper proposes six large-scale CCS projects in four countries which can mitigate up to 300 Mtpa CO2 . Furthermore this paper identifies common pathways for ASEAN decarbonization and their policy implications.

Alternatives to conventional diesel engines in medium/heavy-duty commercial trucks offer promising solutions to decarbonize road freight. We compare the life cycle greenhouse gas (GHG) emissions from diesel battery electric (BEV) and hydrogen fuel cell (FCV) medium-duty urban delivery trucks (gross vehicle weight 3.5 – 7 metric tonnes) in Singapore including the vehicle and fuel production use phase and end-of-life stages. Use phase energy demand was estimated by simulating energy consumption on local real-world driving cycles. BEVs powered by the 2019 electricity mix had up to 11% lower GHG emissions than conventional diesel but doubling battery capacity to meet travel range requirements resulted in up to 12% higher emissions. FCVs using gaseous hydrogen via steam methane reforming achieved 23 – 30% GHG reductions while satisfying range requirements. Efforts in obtaining updated and reliable data on vehicle production remain critical for assessments of emerging technologies and enacting evidence-based policies to decarbonize road freight.

A key building block of the European Green Deal is the development of a hydrogen commodity market which requires a suitable hydrogen market design and the timely introduction of related policy measures. Using exploratory interviews with five expert groups we contribute to this novel research field by outlining the core market design criteria and proposing suitable regulations for the future European hydrogen market. We identify detailed recommendations along three core market design focus areas: Market development policy measures infrastructure regulations as well as hydrogen and certificate trading. Our findings provide an across-industry view of current policy-related key challenges in the hydrogen commodity market development and mitigation approaches. We therefore support policymakers within the EU in the ongoing detailing of their regulatory hydrogen and green energy packages. Further we promote hydrogen market development by assisting current and future industry players in finding a common understanding of the future hydrogen market design.

An energy systems comparison of grid-electricity derived liquid hydrogen (LH2) and liquid ammonia (LNH3) is conducted to assess their relative potential in a low-carbon future. Under various voyage weather conditions their performance is analysed for use in cargo transport energy vectors for low-carbon electricity transport and fuel supply. The analysis relies on literature projections for technological development and grid decarbonisation towards 2050. Various voyages are investigated from regions such as North America (NA) Europe (E) and Latin America (LA) to regions projected to have a higher electricity and fuel grid carbon intensity (CI) (i.e. Asia Pacific Africa the Middle-East and the CIS). In terms of reducing the CI of electricity and fuel at the destination port use of LH2 is predicted to be favourable relative to LNH3 whereas LNH3 is favourable for low-carbon transport of cargo. As targeted by the International Maritime Organisation journeys of LNH3 cargo ships originating in NA E and LA achieve a reduction in volumetric energy efficiency design index (kg-CO2/m3 -km) of at least 70% relative to 2008 levels. The same targets can be met globally if LH2 is supplied to high CI regions for production of LNH3 for cargo transport. A future shipping system thus benefits from the use of both LH2 and LNH3 for different functions. However there are additional challenges associated with the use of LH2. Relative to LNH3 1.6 to 1.7 times the number of LH2 ships are required to deliver the same energy. Even when reliquefaction is employed their success is reliant on the avoidance of rough sea states (i.e. Beaufort Numbers >= 6) where fuel depletion rates during a voyage are impractical.

In the context of energy conservation and the reduction of CO2 emissions inconsistencies between the inevitable emission of CO2 in traditional hydrogen production methods and eco-friendly targets have become more apparent over time. The catalytic decomposition of methane (CDM) is a novel technology capable of producing hydrogen without releasing CO2 . Since hydrogen produced via CDM is neither blue nor green the term “turquoise” is selected to describe this technology. Notably the by-products of methane cracking are simply carbon deposits with different structures which can offset the cost of hydrogen production cost should they be harvested. However the encapsulation of catalysts by such carbon deposits reduces the contact area between said catalysts and methane throughout the CDM process thereby rendering the continuous production of hydrogen impossible. This paper mainly covers the CDM reaction mechanisms of the three common metal-based catalysts (Ni Co Fe) from experimental and modelling approaches. The by-products of carbon modality and the key parameters that affect the carbon formation mechanisms are also discussed.

The blending of hydrogen gas into natural gas pipelines is an effective way of achieving the goal of carbon neutrality. Due to the large differences in the calorific values of natural gas from different sources the calorific value of natural gas after mixing with hydrogen may not meet the quality requirements of natural gas and the quality of natural gas entering long-distance natural gas and urban gas pipelines also has different requirements. Therefore it is necessary to study the effect of multiple gas sources and different pipe network types on the differences in the calorific values of natural gas following hydrogen admixing. In this regard this study aimed to determine the quality requirements and proportions of hydrogen-mixed gas in natural gas pipelines at home and abroad and systematically determined the quality requirements for natural gas entering both long-distance natural gas and urban gas pipelines in combination with national standards. Taking the real calorific values of the gas supply cycle of seven atmospheric sources as an example the calorific and Wobbe Index values for different hydrogen admixture ratios in a one-year cycle were calculated. The results showed that under the requirement of natural gas interchangeability there were great differences in the proportions of natural gas mixed with hydrogen from different gas sources. When determining the proportion of hydrogen mixed with natural gas both the factors of different gas sources and the factors of the gas supply cycle should be considered.

Rod-like molybdenum carbide (Mo₂C) microcrystals were obtained from the pyrolysis of Mo-containing organic-inorganic hybrid composite. We investigated the photocatalytic H₂ evolution activity of Mo₂C by constructing a Mo₂C-dye sensitizer photocatalyst system. A high quantum efficiency of 29.7% was obtained at 480 nm. Moreover Mo₂C catalyst can be easily recycled by simple filtration.

Liquid hydrogen (LH2) aircraft have the potential to achieve carbon neutrality. However if the hydrogen is produced using electricity grids that utilise fossil fuel they have a non-zero carbon dioxide (CO2) emission associated with their well-to-wing pathway. To assess the potential of LH2 in aviation decarbonisation an energy systems comparison of large commercial LH2 liquified natural gas (LNG) conventional Jet-A and LH2 dual-fuel aircraft is presented. The performance of each aircraft is compared towards 2050 over which three system changes occur: (1) LH2 aircraft technology develops; (2) both world average and region-specific grid electricity which is used to produce the hydrogen decarbonises; and (3) the International Air Transportation Association (IATA) emissions targets which are used to restrict the passenger-range performance of each aircraft tighten. In 2050 the emissions of all aircraft are thus constrained to 0.063 kg-CO2/p-km relative to 0.110 kg-CO2/p-km for the unconstrained Jet A fuelled Boeing 787-8. It is estimated that in this year an LH2 aircraft powered by fuel cells and sourcing world average electricity can travel 6000 km 20% further than the conventional Jet A aircraft that is also constrained to meet the IATA targets but not as far as the LNG aircraft. At its maximum range the LH2 aircraft carries 84% of the Jet A passenger demand. Analysis using region-specific hydrogen indicates that LH2 aircraft can travel further than LNG aircraft in North America only accounting for 17% of the global demand. 1.59 times the current aviation energy consumption is required if all conventional aircraft are replaced with LH2 designs. Under stricter emissions constraints than those outlined by the IATA LH2 outperforms LNG in Europe and the Americas accounting for 41% of the global demand. Also in these regions the range energy consumption and passenger capacity of LH2 aircraft can be improved upon by combining the advantages of LH2 with LNG in dual-fuel aircraft concepts. The use of LH2 is therefore advantageous within several prominent niches of a future decarbonising aviation system.

This paper presents the “Three Gorges Hydrogen Boat No. 1” a novel green hydrogen-powered vessel that has been successfully delivered and is currently sailing. This vessel integrated with a hydrogen production and bunkering station at its dedicated dock achieves zero-carbon emissions. It stores 240 kg of 35 MPa gaseous hydrogen and has a fuel cell system rated at 500 kW. We analysed the engineering details of the marine hydrogen system including hydrogen bunkering storage supply fuel cell and the hybrid power system with lithium-ion batteries. In the first bunkering trial the vessel was safely refuelled with 200 kg of gaseous hydrogen in 156 min via a bunkering station 13 m above the water surface. The maximum hydrogen pressure and temperature recorded during bunkering were 35.05 MPa and 39.04 ◦C respectively demonstrating safe and reliable shore-toship bunkering. For the sea trial the marine hydrogen system operated successfully during a 3-h voyage achieving a maximum speed of 28.15 km/h (15.2 knots) at rated propulsion power. The vessel exhibited minimal noise and vibration and its dynamic response met load change requirements. To prevent rapid load changes to the fuel cells 68 s were used to reach 483 kW from startup and 62 s from 480 kW to zero. The successful bunkering and operation of this hydrogen-powered vessel demonstrates the feasibility of zero-carbon emission maritime transport. However four lessons were identified concerning bunkering speed hydrogen cylinder leakage hydrogen pressure regulator malfunctions and fuel cell room space. The novelty of this work lies in the practical demonstration of a fully operational hydrogen-powered maritime vessel achieving zero emissions encompassing its design building operation and lessons learned. These parameters and findings can be used as a baseline for further engineering research.