• Energy Research
• 3. Good health close
• GB close
• ES close
• Applied Energy close

Abstract In situ and ex situ spatially-resolved techniques are employed to investigate reactant distribution and its impacts in a polymer electrolyte fuel cell. Temperature distribution data provides further evidence for secondary flows inferred from reactant imaging data, highlighting the contribution of convection in heat as well as reactant distribution. Water build-up from neutron tomography is linked to component degradation, matching the pattern seen in the reactant distribution and thus suggesting that high, non-uniform local current densities shape degradation patterns in fuel cells. The correlations shown between different techniques confirm the use of the versatile reactant imaging technique, which is used to compare commonly used flow field designs. Among serpentine-type designs, the single serpentine is superior in both equivalent current density and reactant distribution, showing large contributions from convective flow. On the other hand, the interdigitated design is shown to produce larger equivalent current densities, while showing a somewhat poorer reactant distribution. Considering the correlations drawn between the techniques, this suggests that the interdigitated design compromises durability in favour of power output. The results highlight how established techniques provide a robust background for the use of a new and flexible imaging technique toward designing advanced flow fields for practical fuel cell applications.

Since the emergence of the virus that causes COVID-19 (the SARS-CoV-2) in Wuhan in December 2019, societies all around the world have had to change their normal life patterns due to the restrictions and lockdowns imposed by governments. These changes in life patterns have a direct reflection on energy consumption. Thanks to Smart Grid technologies, specifically to the Advance Metering Infrastructure at secondary distribution network, this impact can be evaluated even at the customer level. Thus, this paper analyzes the consumption behavior and the impact that this crisis has had using Smart Meter data. The proposed approach includes the selection and normalization of features, automatic clustering, the obtaining of the estimated consumption without considering the crisis (at short and mid-terms) and the impact evaluation. The proposed approach has been tested on a case with a real Smart Meter infrastructure from Manzanilla (Huelva, Spain). The results of this use case showed that residential customers have increased their consumption around 15% during full lockdown and 7.5% during the reopening period. In contrast, globally, non-residential customers have decreased their consumption 38% during full lockdown and 14.5% during the reopening period. However, referring to non-residential customers, five different consumption profiles were found with different short-term and mid-term behaviors during the COVID crisis. The different behavior found shows customers who have maintained their normal consumption during the lockdown, others who have reduced it (to a greater or lesser extent) and have not recovered it after the removal of the restrictions, and others who have reduced the consumption but then they recovered it when the restrictions were removed. The metadata of the customers in each behavior cluster found are highly correlated to the restrictions imposed to control the spread of the virus. This study shows evidence about the proposed approach usefulness to analyze the behavior and the impact at customer level during the COVID-19 crisis.

Abstract The implementation of energy thrift measures in Welsh hospitals has led to significant reductions in energy consumption during the last five years. Much remains to be done, as can be seen by comparison of the performances of the worst offenders—large institutions for acutely ill patients—with the achievements of smaller, traditionally constructed hospitals (for long-stay patients) which in general exhibit better energy performances.

This paper presents an isothermal, single-phase model for direct ethanol fuel cells. The ethanol electro-oxidation reaction is described using a detailed kinetic model that is able to predict anode polarization and product selectivity data. The anode kinetic model is coupled to a one-dimensional (1D) description for mass and charge transport across the membrane electrode assembly, which accounts for the mixed potential induced in the cathode catalyst layer by the crossover of ethanol and acetaldehyde. A simple 1D advection model is used to describe the spatial variation of the concentrations of the different species as well as the output and parasitic current densities along the flow channels. The proposed 1D + 1D model includes two adjustable parameters that are fitted by a genetic algorithm in order to reproduce previous experimental data. The calibrated model is then used to investigate the consumption of ethanol and the production, accumulation and consumption of acetaldehyde along the flow channels, which yields the product selectivity at different channel cross-sections. A parametric study is also presented for varying ethanol feed concentrations and flow rates. The results obtained under ethanol starvation conditions highlight the role of acetaldehyde as main free intermediate, which is first produced and later consumed once ethanol is fully depleted. The detailed kinetic description of the ethanol oxidation reaction enables the computation of the four efficiencies (i.e., theoretical, voltage, faradaic, end energy utilization) that characterize the operation of direct ethanol fuel cells, thus allowing to present overall fuel efficiency vs. cell current density curves for the first time. This work has been supported by Project ENE2015-68703-C2-1-R (MINECO/FEDER, UE). P.A. García-Salaberri also thanks the support from the research grant "Ayudas a la Investigación en Energía y Medio Ambiente" of the Spanish Iberdrola Foundation and the support from the US-Spain Fulbright Commission during his stay at Lawrence Berkeley National Lab.

Abstract Conventional solid oxide fuel cells (SOFCs) could suffer from carbon deposition when fueled with hydrocarbons. For comparison, a new type of SOFC with porous electrolyte can resist carbon deposition because it allows oxygen molecules to transport from the cathode to the anode. As the transport of O2 to the anode lowers the fuel cell performance and causes the risk of explosion, the rate of O2 transport must be well controlled to ensure efficient and safe operation. Following our previous model, this paper focuses on electrolyte porosity optimization under various inlet methane mole fractions, inlet oxygen mole fractions and inlet gas flow rates. Furthermore, a new design with a partial porous electrolyte is proposed and numerically evaluated. The new design significantly improves the electrochemical performance compared with all-porous one. A conversion rate >90% from methane to syngas is achieved at the 0.33 inlet CH4 mole fraction with the new design. The results enhance the understanding of all porous solid oxide fuel cells and the mechanism underlying, inspiring novel designs of solid oxide fuel cells.

Abstract This paper reports a computational demonstration and analysis of an innovative counter-flow-based microfluidic unit and its upscaling network, which is compatible with previously developed dual-electrolyte protocols and numerous other electrochemical applications. This design consists of multidimensional T-shaped microchannels that allow the effective formation of primary and secondary counter-flow patterns, which are beneficial for both high-performance regenerative H2/O2 redox cells and flow batteries at a low electrolyte flow-rate operation. This novel design demonstrates the potential to achieve high overall energy throughput and reactivity because of the full utilization of all available reaction sites. A computational study on energy and pressure loss mechanism during scale-out is also examined, thereby advancing the realization of an economical electrolyte-recycling scheme.

Abstract Chlorofluorocarbons have been among the most useful chemical compounds ever developed. However, after more than forty years of a continuously increasing rate of worldwide use in the industrial and domestic sectors, unequivocal evidence has indicated that, if released into Earth's atmosphere, they are amongst the most devastating of pollutants that could threaten the quality of life for future generations. Thus it is not surprising that, for nearly two decades, this dichotomy of interests has been a prominent issue. This report presents the scientific evidence available concerning the impacts of chlorofluorocarbons on the ambient environment. Regional, national and international policies adopted to try to curb their emissions into the atmosphere are summarised. Economic and social consequences of these policies are discussed, together with some of the available and recommended technological solutions to the environmental problem. It is believed that agreements reached internationally to date are insufficient to ensure the adequate protection of the environment. Even an immediate total ban on the production and use of such chemical compounds would not lead to a reversal of the environmental degradation for at least a century, due to the chlorofluorocarbons already in the atmosphere.

COVID-19 has caused great challenges to the energy industry. Potential new practices and social forms being facilitated by the pandemics are having impacts on energy demand and consumption. Spatial and temporal heterogeneities of impacts appear gradually due to the dynamics of pandemics and mitigation measures. This paper overviews the impacts and challenges of COVID-19 pandemics on energy demand and consumption and highlights energy-related lessons and emerging opportunities. The discussion on energy-related issues is divided into four main sections: emergency situation and its impacts, environmental impacts and stabilising energy demand, recovering energy demand, and lessons and emerging opportunities. The changes in energy requirements are compared and analysed from multiple perspectives according to available data and information. In general, although the overall energy demand declines, the spatial and temporal variations are complicated. The energy intensity has presented apparent changes, the extra energy for COVID-19 fighting is non-negligible for stabilising energy demand, and the energy recovery in different regions presents significant differences. A crucial issue has been to allocate and find energy-related emerging opportunities for the post pandemics. This study could offer a direction in opening new avenues for increasing energy efficiency and promoting energy saving.