Nanocomposite Catalyst for High-Performance and Durable Intermediate-Temperature Methane-Fueled Metal-Supported Solid Oxide Fuel Cells.

CH4-fueled metal-supported solid oxide fuel cells (CH4-MS-SOFCs) are propitious as CH4 is low-priced and readily available, and its renewable production is possible, such as biomethane. However, the current CH4-MS-SOFCs suffer from either poor power density or short durable operation, which is ascribed to the low catalytic activity and poor coking tolerance of the metallic anode support. Herein, we have deliberately designed and synthesized a highly active nanocomposite catalyst, Sm-doped CeO2-supported Ni, as the internal steam methane reforming catalyst, to optimize CH4-MS-SOFCs. Both power densities and durability of optimized CH4-MS-SOFCs have been dramatically enhanced compared to the pristine CH4-MS-SOFCs. The optimized CH4-MS-SOFCs deliver the highest performances among all zirconia-based CH4-MS-SOFCs. Furthermore, the operating temperature has been reduced to 600 °C. At 600 °C, a viable peak power density of >350 mW/cm2 is achieved, which is more than three times as high as the pristine CH4-MS-SOFCs. Furthermore, the optimized CH4-MS-SOFC achieves >1000 h of stable operation.

Life cycle flaring emissions mitigation potential of a novel Fischer-Tropsch gas-to-liquid microreactor technology for synthetic crude oil production.

This paper compares the environmental impacts of the operation of a novel Gas-to-Liquid (GtL) process for synthetic crude oil production with conventional crude oil production. This process uses novel microreactor technology (NetMIX) applied in Steam Methane Reforming and Fischer-Tropsch (FT-SMR) for the conversion of associated gas originated on offshore Oil and Gas exploration. Data from literature for Oil and Gas extraction together with data obtained from Aspen Plus ® simulations was used to build the life cycle inventory. An attributional Life Cycle Assessment (LCA) was performed to compare the FT-SMR pathway to conventional crude oil production, using 1 MJ LHV as the functional unit. An additional assessment was also conducted by reporting the impact to 1 barrel. This is done to assess the effect that the add-on technology may have on the impact of current crude production. Converting associated gas using the FT-SMR pathway produces a synthetic crude with negative net GWP impacts. This is because the amount of avoided emissions is larger than the emissions due to the operation of the pathway. The remaining impact categories increase since the FT-SMR has additional intermediary steps, with added fuel energy needs, and additional process emissions. Moreover, the amount of natural gas required to produce 1 MJ of synthetic crude oil (abbreviated in the text as syncrude) results in larger impacts in the extraction phase, than those associated with the extraction of 1 MJ of conventional crude. The obtained syncrude has a GWP impact of -0.34 [-0.62, -0.14] kg CO2 eq/MJ, in comparison to 0.012 [0.009, 0.017] kg CO2 eq/MJ of conventional crude. A reduction of 8% to the impacts per daily barrel of crude (70.3 kg CO2 eq/barrel and 64.6 kg CO2 eq/barrel before and after using the FT-SMR pathway) was observed for a reduction of 34% of the total flared gas mass.

Revisiting the role of steam methane reforming with CO2 capture and storage for long-term hydrogen production.

Road transport is associated with high greenhouse gas emissions due to its current dependence on fossil fuels. In this regard, the implementation of alternative fuels such as hydrogen is expected to play a key role in decarbonising the transport system. Nevertheless, attention should be paid to the suitability of hydrogen production pathways as low-carbon solutions. In this work, an energy systems optimisation model for the prospective assessment of a national hydrogen production mix was upgraded in order to unveil the potential role of grey hydrogen from steam methane reforming (SMR) and blue hydrogen from SMR with CO2 capture and storage (CCS) in satisfying the hydrogen demanded by fuel cell electric vehicles in Spain from 2020 to 2050. This was done by including CCS retrofit of SMR plants in the energy systems model, as a potential strategy within the scope of the European Hydrogen Strategy. Considering three hypothetical years for banning hydrogen from fossil-based plants without CCS (2030, 2035, and 2040), it was found that SMR could satisfy the whole demand for hydrogen for road transport in the short term (2020-2030), while being substituted by water electrolysis in the medium-to-long term (2030-2050). Furthermore, this trend was found to be associated with an appropriate prospective behaviour in terms of carbon footprint.

Potential of microbial protein from hydrogen for preventing mass starvation in catastrophic scenarios.

Human civilization's food production system is currently unprepared for catastrophes that would reduce global food production by 10% or more, such as nuclear winter, supervolcanic eruptions or asteroid impacts. Alternative foods that do not require much or any sunlight have been proposed as a more cost-effective solution than increasing food stockpiles, given the long duration of many global catastrophic risks (GCRs) that could hamper conventional agriculture for 5 to 10 years. Microbial food from single cell protein (SCP) produced via hydrogen from both gasification and electrolysis is analyzed in this study as alternative food for the most severe food shock scenario: a sun-blocking catastrophe. Capital costs, resource requirements and ramp up rates are quantified to determine its viability. Potential bottlenecks to fast deployment of the technology are reviewed. The ramp up speed of food production for 24/7 construction of the facilities over 6 years is estimated to be lower than other alternatives (3-10% of the global protein requirements could be fulfilled at end of first year), but the nutritional quality of the microbial protein is higher than for most other alternative foods for catastrophes. Results suggest that investment in SCP ramp up should be limited to the production capacity that is needed to fulfill only the minimum recommended protein requirements of humanity during the catastrophe. Further research is needed into more uncertain concerns such as transferability of labor and equipment production. This could help reduce the negative impact of potential food-related GCRs.

Comparative life cycle sustainability assessment of renewable and conventional hydrogen.

Hydrogen is gaining interest as a strategic element towards a sustainable economy. In this sense, sound decision-making processes in the field of hydrogen energy require thorough analyses integrating economic, environmental and social indicators from a life-cycle perspective. For this purpose, Life Cycle Sustainability Assessment (LCSA) constitutes an appropriate methodology jointly handling indicators related to the three traditional dimensions of the sustainability concept. In this work, the sustainability performance of renewable hydrogen from both wind-powered electrolysis and biomass gasification was benchmarked against that of conventional hydrogen from steam methane reforming under a set of five life-cycle indicators: global warming, acidification, levelised cost, child labour, and health expenditure. The results led to identify the stage of driving-energy/biomass production as the main source of impact. When compared to conventional hydrogen, the life-cycle sustainability performance of renewable hydrogen was found to underperform under social and economic aspects. Nevertheless, the expected enhancement in process efficiency would significantly improve the future performance of renewable hydrogen in each of the three main sustainability dimensions.

Prospective carbon footprint comparison of hydrogen options.

The Life Cycle Assessment methodology is often used to evaluate the environmental performance of hydrogen energy systems. However, even though hydrogen is usually seen as a strategic energy carrier for the future energy sector, there is a lack of case studies assessing its prospective life-cycle performance. In order to contribute to filling this gap, this work addresses a carbon footprint comparison of hydrogen options from a prospective standpoint. Four relevant hydrogen production pathways (steam methane reforming, grid-powered alkaline electrolysis, wind-powered alkaline electrolysis, and biomass gasification) under three time scenarios (reference, year 2030, and year 2050) are assessed, taking into account the expected evolution of key technical parameters such as efficiencies, lifespans, and the grid electricity mix. The results show a favourable carbon footprint of renewable hydrogen from biomass gasification and wind electrolysis, with a relatively steady near-zero carbon footprint. Despite the unfavourable carbon footprint results of conventional hydrogen from steam methane reforming and hydrogen from grid electrolysis, the latter is associated with a rapid trend towards a suitable long-term carbon footprint.

Model Development and Exergy Analysis of a Microreactor for the Steam Methane Reforming Process in a CFD Environment.

Steam methane reforming (SMR) is a dominant technology for hydrogen production. For the highly energy-efficient operation, robust energy analysis is crucial. In particular, exergy analysis has received the attention of researchers due to its advantage over the conventional energy analysis. In this work, an exergy analysis based on the computational fluid dynamics (CFD)-based method was applied to a monolith microreactor of SMR. Initially, a CFD model of SMR was developed using literature data. Then, the design and operating conditions of the microreactor were optimized based on the developed CFD model to achieve higher conversion efficiency and shorter length. Exergy analysis of the optimized microreactor was performed using the custom field function (CFF) integrated with the CFD environment. The optimized catalytic monolith microreactor of SMR achieved higher conversion efficiency at a smaller consumption of energy, catalyst, and material of construction than the reactor reported in the literature. The exergy analysis algorithm helped in evaluating length-wise profiles of all three types of exergy, namely, physical exergy, chemical exergy, and mixing exergy, in the microreactor.