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Despite myriads of mathematical and experimental studies using various heat exchanger-metal hydride assemblies, an adept comparison of reactors on standard performance defining parameters, i.e., reactor weight, external energy utilization, and alloy material, are not studied or reported for industrial storage containers and onboard applications. This lacuna is a critical barrier in developing efficacious hydrogen storage reactors for various applications. This article chronicles the 3-D design and optimization of three basic heat exchanger setups of solid-state hydrogen storage systems (shell and tube, spiral tube, and tubular) on critical parameters. For 5 kg LaNi 5 , a tubular design with small tube diameters has resulted in a shorter reaction time (120 s) for 90% saturation at 303 K and 15 bar inlet conditions; however, the reactor's gravimetric density was exceptionally high. In contrast, the reactor with three spiral tubes accomplished an exemplary reaction rate at a reasonable gravimetric density. This spiral arrangement became the base for developing a novel reactor that integrated heat pipes to reduce the sorption time. The proposed design achieved a specific output energy rate of 527 W/kg for 90% saturation in 366 s at a supply pressure of 15 bar, which is 23.7% higher than the reactor without heat pipes. [Display omitted] [ABSTRACT FROM AUTHOR]

• Individual effect of acid blocking AEM and monovalent selective CEM in selective ED was studied. • The recovered acid concentration increased by using acid blocking AEM, but limited by high Cu2+ flux. • Monovalent selective CEM further improved the acid concentration by breaking the H+ transfer balance. • Acid concentration was increased with electric current and dilute volume in SED. • H+ concentration difference plays crucial role in improving the current efficiency of SED. Electrodialysis (ED) could concentrate salt solutions, but the leakage of H+ ions across the anion-exchange membrane (AEM) obstructed their application in waste acid recovery. Selective electrodialysis (SED) with acid blocking AEM and monovalent selective cation-exchange membrane (CEM) has the ability of reclaiming acid with high concentration efficiently. This study investigated the individual effect of the two selective ion-exchange membranes by comparing the acid reclamation performance of configurations with standard AEM and CEM (A-C), acid blocking AEM and standard CEM (SA-C) and acid blocking AEM and monovalent selective CEM (SA-SC) for etching solution treatment after diffusion dialysis. Substituting acid blocking AEMs for the standard ones could significantly increase the recovered acid concentration. An acid concentration plateau was reached quickly, but Cu2+ ions transfer through the CEMs continuously due to the low H+/Cu2+ ratio in the dilute of SA-C configuration. The monovalent selective CEM obstructed the migration of Cu2+ through the CEM and broke the balance of H+ migration into and out of the dilute through CEM and selective AEM individually. The configuration of SA-SC has the highest current efficiency and the configuration of A-C has the lowest. The utilization of selective membranes increased the purity of the recovered acid, and decreased the specific energy consumption simultaneously. The acid concentration could be further improved by higher current or enlarged dilute volume in SA-SC configuration. During the ED process, H+ concentration difference between the concentrate and the dilute plays a crucial role on the current efficiency for acid recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] Ghana has been a pioneer in energy efficiency in the sub-Saharan region, becoming the first country to introduce minimum energy performance standards and energy labelling for lighting, air conditioners and refrigerating appliances in 2008. It also introduced an innovative and not yet widely adopted policy of banning the import of used air conditioners and refrigerating appliances, mostly from Europe. While the impact of this policy package has already been assessed in terms of energy savings in Ghana, it is still unclear whether the import ban on used products makes sense in terms of environmental impact. Ghana's ban may seem surprising given that current European product policies in the context of the Green Deal aim to extend the lifetime of products and encourage their reuse to make them more sustainable. In this paper, different scenarios covering new and used refrigerating appliances as well as different end-of-life management options were examined in a life cycle analysis. The results show that exporting used refrigerators from Europe to West Africa increases their environmental impact per functional unit in many categories, even if it extends the lifetime of the product. The informal end-of-life treatment of refrigerators by open burning has a massive impact on human toxicity. As energy consumption during the use phase is the main determinant of most environmental impacts, energy efficiency policies (minimum energy efficiency performance standards and labelling) combined with an import ban on used refrigerating appliances are the best approach to reduce these impacts. It is therefore recommended that the Ghanaian policy package be replicated in other countries in the region, but also that exporting countries take action, as the fight against environmental dumping is a shared responsibility. • Used refrigerators exported to West Africa increase greenhouse gas emissions. • Energy efficiency reduces the environmental impact of refrigerators. • Import ban on used refrigerating appliances is justified. • Informal end-of-life treatment of refrigerators has a major impact on human toxicity. [ABSTRACT FROM AUTHOR]

Shallow Geothermal Energy (SGE) systems are emerging as an attractive solution to enhance building energy efficiency and contribute to a low-carbon economy. This research investigates a SGE system comprising 40 boreholes installed in a university building located in Aveiro City under Mediterranean climate conditions. Both the building and the underground soil were monitored during the SGE operation, and EnergyPlus® software was subsequently employed for the integrated dynamic simulation. The building energy model was calibrated using field data, and a good agreement between the measured and the simulated temperatures was archived, with a Coefficient of Variance of the Root Mean Square Error (CVRMSE) below 10 %. The case study model performance was analysed and compared to other alternatives. The impact of the climate on the system performance was investigated by analyzing nine Portuguese cities situated in different climate contexts. A sustainability indicator was proposed, and an initial sustainability assessment was conducted. The results emphasize that the SGE system offered advantages compared to other alternative systems, achieving a 55 % reduction in heating and cooling energy consumption, and mitigating climate change by 405.67 ton of CO 2 per 25-year lifespan. This study can guide further implementation of sustainable geothermal systems in Mediterranean climates. [ABSTRACT FROM AUTHOR]

• Onboard eco-driving feedback improves fuel economy by 6.6% on average. • The impact of most onboard feedback tested to-date deteriorates over time. • Eco-driving feedback should include both fine- and course-grained information. • Eco-driving feedback should include performance standards. • Multimodal eco-driving feedback may be more effective than visual only. • Gamification may enhance eco-driving feedback effectiveness. • Interventions should combine eco-driving feedback with education and rewards. Eco-driving refers to suites of behavior a driver can engage in to improve fuel economy. The most common strategy used to promote eco-driving is onboard feedback that conveys information about fuel efficiency to the driver. This paper presents a statistical meta-analysis of eco-driving feedback studies in order to determine a weighted estimate of the average impact of feedback on fuel economy and explore potential moderators of its effectiveness, particularly regarding features of the feedback interface design. The main effect of onboard feedback on fuel economy across the final sample of 17 studies and 23 effect sizes was 6.6% improvement. Feedback that included information about both instantaneous and accumulated performance predicted larger effects. Though not statistically significant, trends in relationships between other feedback design features and fuel economy outcomes aligned with study hypotheses. Length of feedback intervention negatively related to effects, and pairing feedback with instructions or rewards predicted larger effects. [ABSTRACT FROM AUTHOR]

The improvement of energy efficiency of products is a key pillar of climate and energy strategy in the European Union (EU). The first EU product policies were adopted in the late 1970s, and they have evolved to become a coherent set of implementing measures under framework directives that harmonise and refine the regulatory process. After years of weak implementation, considerable progress in terms of scale and ambition has been achieved in the last decade. In 2020, product mandatory measures covered 50% of the EU total final energy consumption, leading to 46 Mtoe energy savings. This paper describes the available policy instruments to promote energy efficiency and remove the market barriers hindering the penetration of the best performing technologies. It offers a review of the progress made over these last 40 years of EU product policies, describing the Energy Labelling, the Minimum Energy Performance Standards (MEPS), the Ecodesign Directive and the voluntary agreements (EU Ecolabel and Green Public Procurement). Moreover, it highlights the remaining challenges and provides policy recommendations to further exploit the EU potential to save energy from products. • Energy efficiency in products is a key pillar of EU climate and energy strategy. • Despite 40 years of EU product policies, their scale has only improved since 2010. • In 2020, mandatory measures covered 50% of the EU final energy consumption. • By 2030, savings expect to reduce the final consumption by 17%. • Policy orientation to further exploit the energy savings of products is provided. [ABSTRACT FROM AUTHOR]

Building energy consumption forecasting is crucial for energy managers and policymakers. However, acutely predicting the energy consumption of any building is more important in energy efficiency benchmarking of buildings. Energy benchmarking is a precise technique for measuring, tracking, and reducing end-use energy usage of buildings by employing comparative scenarios. Bottom-Up energy consumption assessment has been used in several studies to evaluate a collection of buildings' energy performance to a standard. Traditionally, researchers have used a single approach to predict the energy use of buildings and to conduct benchmarking. However, it has been found that doing so frequently compromises the accuracy of the predicted energy use of buildings. It also has an adverse effect on the buildings' energy benchmarking framework results. This paper will provide an energy benchmarking framework for residential buildings based on the blending techniques of multiple approaches. Over 3000 datasets were gathered from the Indian city of Jaipur. In order to analyse the trends in energy consumption, the data were divided into categories based on economic levels. The data is then subjected to some fundamental statistical analysis, along with several approaches are blended to forecast the energy consumption of the buildings with the highest accuracy. These benchmark levels set guidelines for assessing and recognising strong performance while also identifying underperforming buildings and giving them more priority for energy efficiency improvement. The technique may be used for different metropolitan levels and climatic conditions. [ABSTRACT FROM AUTHOR]

This article serves as an update to the manuscript with the same title published back in 2010. Since then, Malaysia has seen some major changes in its energy and electricity generation scene. The country is now in the 11th Malaysian Plan (11MP) and its final thrust towards the high-income status targeted by 2020. Keeping to the scope in addressing the country's energy security and sustainability through non-renewable and renewable energy (RE), this article shall update on the existing and new significant energy-related events that have taken place and how they have affected the energy landscape of the country. In addition to that, the important role of the various energy efficiency (EE) and conservation practices set in place to ensure sustainable demand growth is also highlighted. The removal of fuel subsidy by the Malaysian government in 2014, although as unpopular as it may seem, was necessary as part of its energy reform to implement a more common energy regulatory framework involving all relevant agencies to safeguard a secured and sustainable energy future is also covered here. Lastly, latest development and issues surrounding the nuclear dream that the government is currently pursuing will also be discussed. [ABSTRACT FROM AUTHOR]

This study designed and fabricated a novel top-lit downdraft gasifier stove (TLDDGS), which was compared with a traditional top-lit updraft gasifier stove (TLUDGS) in terms of modeling and performance. The experimental and simulation results demonstrated that the novel TLDDGS exhibits a downward-flow configuration. The average fuel consumption measured in the experiments was 4.57 ± 0.933 g/min. The average flame temperature from the experiment was 608 ± 43 °C. The TLDDGS mean flame temperature remained stable throughout the experiment. The O 2 , H 2 , CO 2 , CO, CH 4 , and N 2 in the diluted syngas from the experiment were 16.07, 0.33, 0.66, 2.56, 0.34, and 80.04% by volume, respectively. The total suspended particulates and CO in TLDDGS and TLUDGS were 15 and 28 mg/m3 and 335 and 69 ppm, respectively, which are within the limits specified by the local standard. Thus, the developed TLDDGS is a promising alternative for sophisticated cooking applications because of its superior performance in terms of flame stability. • The new design of top-lit downdraft gasifier stove has a partial syngas downward flow direction. • The top-lit downdraft gasifier stove has superior flame stability than the conventional stove. • The top-lit downdraft gasifier stove has less total suspended particulates than the conventional stove. • The top-lit downdraft gasifier stove has emission performance according to the standard. • The simulation well explained the mechanism of the top-lit downdraft gasifier stove. [ABSTRACT FROM AUTHOR]

Given the significance of carbon emissions from the existing building stock, this paper aims to provide an international comparative analysis of pioneering policies on minimum energy efficiency standards in the Scottish, English/Welsh, Dutch and French commercial real estate sectors. These are the four national policy regimes to employ these policy instruments to date with varied timelines spanning from 2009 to 2050. The methodological approach employs a document review of policy texts produced by policy makers and other stakeholders. The four policy regimes are evaluated in terms of their policy design focussing on minimum performance standards, forward guidance, scope and exemptions. A key finding is that, given the range of intervening factors, side-effects and uncertainties, there are difficult choices in striking a balance between phasing implementation, providing forward guidance and adjusting policy in response to evaluation. Whilst it was initially expected that most European Union jurisdictions would default to an Energy Performance Certificate related standard, our findings show that there has been a shift towards standards that are linked to actual rather than modelled energy consumption. However, for leased stock where the owner may have limited operational control, the separation of owners' responsibility for compliance and the users' responsibility for operations makes designing consumption-based instruments more challenging. It is concluded that a central issue in policy design has been the trade-off between minimising the financial costs to property owners and occupiers of complying with performance thresholds and maximising reductions in energy consumption. There is growing recognition that regulatory economies of scale may be achieved by targeting large properties which allows for a large proportion of the total area of the stock to be covered whilst exempting a large proportion of transactions or properties. • Policy makers use MEES to improve the energy efficiency of the worst building stock. • Significant policy divergence is observed across the four national policy regimes to date. • MEES should be based on actual energy consumption rather than design-based metrics. • The separation of ownership and use is a barrier to MEES linked to actual consumption. • Regulatory economies of scale may be achieved by targeting large properties. [ABSTRACT FROM AUTHOR]

Application of the best practice of setting minimum energy performance standards (MEPS) in technically disadvantaged countries (TDCs) faces many barriers. The best practice of determining MEPS has a comprehensive analytical framework including engineering-economic analysis, life-cycle cost-benefit analysis, as well stakeholders’ and market impact assessments. However, TDCs usually are lack of reference product classes, market data, and other necessary inputs data. This study demonstrated how to overcome those barriers to apply the best practice to TDCs using the actual experience in setting initial MEPS for Air Conditioners (ACs) in Brunei from scratch with limited secondary data as an example. The series of application works include definition of the product classes and the baseline group; collection of market data; formulation of cost-efficiency relationship from the market data; examination of the economic, environmental, and financial impacts of various MEPS options; revealing of the consumers’ willingness to pay; and analysis of the impacts and responses from the industry and consumers. The coordination with the compliance of the Montreal Protocol was also considered. The methodology should also be applicable to setting MEPF for other appliances in any TDCs. [ABSTRACT FROM AUTHOR]

In 2007 was settled the first minimum energy performance standards for air conditioners in Brazil. After more than 14 years since the first regulations and looking upon future perspectives, this paper presents a review of regulatory developments in the country and an assessment based on scenario simulation to verify potential impacts of new minimum energy performance standards for air conditioners. The methodology employed is a bottom-up approach designed to estimate the energy consumption of air conditioners. A spreadsheet-based computational tool was developed to perform sensitivity analysis of key parameters such as ownership rate, average temperature and cooling degree days. The results show a significant energy savings potential that could be captured through a minimum energy performance standards revision. For the scenarios simulated these savings potential would reach up to 417 TWh, with respective greenhouse gases emissions reduction that would be 249 million tons, over the period from 2023 to 2040. An economic analysis of minimum energy performance standards impact is also provided and indicate that even in conditions that involve higher costs and discount rates, new more restrictive minimum energy performance standards allow capturing significant benefits for the society as a whole and for consumers individually. Reviewing the minimum energy performance standards is a critical and urgent issue for Brazil and the methodology presented in this paper can be useful in the process of decision-making related to new regulatory developments. • More restrictive MEPS for air conditioners is urgently needed in Brazil. • The synergy between the CGIEE, Procel and PBE/INMETRO should be improved. • The methodology presented in the paper can support the process of MEPS revisions. • Energy, economic and environmental benefits of more stringent MEPS can be very significant. [ABSTRACT FROM AUTHOR]

• Observation of spray of biodiesel is done to correlate with engine performance. • Mass of fuel molecules of B100 are found to be heavier than B0 and B50. • Mass of fuel molecules of B50 and B0 are found to be similar. • Satuer mean diameters of fuel molecules of B50 and B100 are larger than diesel. • Penetration lengths of vapour of B50 and B100 are 6.28% and 13.75% longer. • Combustion duration B0, B50 and B100 are 52°CA, 57°CA and 59°CA, respectively. Palm oil diesel (POD) is derived from palm oil using an esterification process. POD has similar physicochemical properties to fossil diesel, and this allows POD to be the primary substitute to diesel. However, existing research has found that the combustion of POD in CI engines produce lower performance standards than pure diesel. This is due to POD having a higher viscosity, density and presence of heavier molecules resulting in poor evaporation and mixing with the air leading to higher brake specific fuel consumption (BSFC) and reduced power. This research aims to observe the fuel spray behaviors inside the combustion chamber and corelate these with the lower performance of POD than diesel. POD is tested at 100% (B100) and, blended with diesel at a ratio of 50/50 (B50) by volume to reduce the viscosity. The study of spray properties in real engines is expensive and difficult, with most studies being performed in constant volume transparent chambers using Mie-scattering and Schlieren imaging techniques. Therefore, the engine simulation is conducted using ANSYS Forte software to observe the in-cylinder spray behaviors. A 26-kW diesel engine used in a generator is modelled using SolidWorks with respective performance parameters noted from simulation data. The CHEMKIN-PRO software is used to create POD by solving thousands of reaction combinations. Spray analysis of fuels shows longer penetration lengths with POD, higher Sauter Mean Diameter (SMD) and heavier mass of fuel molecules than diesel. These along with a lower calorific value of POD resulted in lower power and a higher brake specific fuel consumption than diesel. Furthermore, B50 performs better than B100. [ABSTRACT FROM AUTHOR]

Frequency regulation (FR) is the electric grid service responsible for maintaining the system frequency at its nominal value of 60 Hz in the United States — an indicator of energy balance on the grid. In cases of mismatch between power supply and demand, FR resources either on the generation or the demand side, responding rapidly to restore system frequency to its nominal value. Due to the limited responsiveness of generators, fast and accurate demand side resources (DSR) have recently been encouraged to participate in FR. However, the tested DSRs typically require high initial equipment investment (e.g., flywheels and batteries). Large commercial buildings can provide effective load shaping with little impact to occupants’ comfort and have significant amount of available capacity for FR participation. In addition, commercial buildings are characterized by numerous interdependent HVAC subsystems and control systems. Therefore, a high-level supervisory control strategy is needed that directs the interdependent HVAC systems for FR with strengthened interactions and depressed counteractions. Simulation results suggest that large commercial buildings can provide significant FR capacity and high performance scores. Dynamic building-to-grid integration automatically and continuously provides solutions maintaining energy balance on the gird. The benefit to the power system reliability would be significant. [ABSTRACT FROM AUTHOR]

Highlights: [•] We have modeled the influence of the increase of efficiency of motors. [•] The amount of saved energy is estimated. [•] The work deals with the “measurement” of a non-consumed energy. [•] The influence of the motor useful life is taken into account. [•] The influence of efficiency decrease along the motor life is also taken into account. [Copyright &y& Elsevier]

Abstract: This paper presents the online test and evaluation of the performance of five practical control strategies (fixed set-point control method, fixed approach control method, two near optimal strategies and one optimal strategy) for building cooling water systems to identify the best strategy for future field validation. All of these strategies were tested and evaluated in a simulated virtual environment similar to the situation when they are actually implemented in practice. A virtual building system representing the real building and its central chilling system was developed and used to test the operational performance of the system controlled by different strategies. The packages of each control strategy are separately computed by the application program of Matlab, as the control optimizers to identify the necessary control settings for the given condition based on the collected operation data. The data exchanger between the virtual building system and the control optimizer was managed by a software platform through a communication interface. The results showed that the optimal control strategy is more energy efficient and cost effective than the other strategies, and its computational cost is manageable and can satisfy the requirements of practical applications. This strategy is being implemented in a super high-rise building for field validation. [Copyright &y& Elsevier]

The residential sector is the third largest electricity user in Taiwan. A clear understanding of the rapid growth in its electricity consumption is crucial to the formulation of policy. This study applied the Logarithmic Mean Divisia Index (LMDI) to a decomposition of Taiwan's residential electricity consumption based on eighteen electrical appliances. Data was obtained from questionnaire surveys conducted in 7677 households. Note that this study was conducted at various disaggregation levels in order to characterize the consumption of electricity in terms of the factors that contribute to specific end-uses. Climate was identified as the primary factor driving growth in the residential electricity consumption, accounting for an increase of 2.03 billion kWh between 2014 and 2017. In Taiwan, climatic effects manifest primarily as a substantial increase in the use of air-conditioners for cooling. Thus, efforts should be made to accelerate the replacement of low energy-efficiency air conditioners. The same methods could also be used to promote energy upgrades in existing buildings. Our analysis of specific end-uses revealed that the inefficiency of personal computers and dehumidifiers is an important factor in residential electricity consumption. Thus, minimum energy performance standards (MEPS) should be expanded to include these appliances. • This study identified factors influencing electricity consumption in the residential sector. • The electricity consumption for specific end-uses is decomposed into corresponding factors. • Contribution from climate effect is investigated by considering cooling degree days. • Four policy implications are proposed by analyzing the driving factors in depth. [ABSTRACT FROM AUTHOR]

• EU policy efforts on energy efficiency in buildings stared in the 1970s in response to the oil crisis. • The first comprehensive EU policy was the SAVE directive in 1992, introducing policy actions still relevant today. • A major step forward was the Energy Performance of Buildings Directive in 2002 and its subsequent amendments. • Mandatory energy performance standards are progressively converging towards near zero energy buildings. • Additional policies and financing are needed for the full decarbonisation of the building stock. The reduction of energy demand in buildings through the adoption of energy efficiency policy is a key pillar of the European Union (EU) climate and energy strategy. Energy efficiency first emerged in the EU energy policy agenda in the 1970s and was progressively transformed with shifting global and EU energy and climate policies and priorities. The paper offers a review of EU energy policies spanning over the last half century with a focus on policy instruments to encourage measures on energy efficiency in new and existing buildings. Starting from early policies set by the EU in response to the Oil Embargo in the 1973, the paper discusses the impact of EU policies in stimulating energy efficiency improvements in the building sector ranging from the SAVE Directive to the recently 2018 updated Energy Performance of Buildings Directive and Energy Efficiency Directive. The review explores the progress made over the last 50 years in addressing energy efficiency in buildings and highlights successes as well as remaining challenges. It discusses the impact of political priorities in reshaping how energy efficiency is addressed by EU policymakers, leading to a holistic approach to buildings, and provides insights and suggestions on how to further exploit the EU potential to save energy from buildings. [ABSTRACT FROM AUTHOR]

• Variable speed units provide cost-effective solution to improve efficiency. • Fixed speed units are not economically competitive at higher efficiency ratings. • New standard brings accumulative CO 2 reductions of 12.8% between 2019 and 2050. • Accumulative bill saving is 2620 billion RMB between 2019 and 2050. • Continuous revision of the new standard could more than double the overall impact. China is the world's largest consumer of room air conditioners, and it contributes about a quarter of global space cooling CO 2 emissions. We model the costs and benefits of recently proposed new room air conditioner minimum energy performance standards (MEPS) in China. Our results suggest that newly proposed MEPS brings accumulative CO 2 emissions reductions of 12.8% between 2019 and 2050, and accumulative bill saving of 2620 billion RMB to China's consumers. The benefits of the proposed MEPS decrease with longer MEPS revision intervals and increase with shorter intervals—indicating that the intervals should be balanced to maximize benefits while accommodating constraints due to air conditioner manufacturer design cycles. We also model potential nationwide benefits from higher MEPS. Across two increasingly aggressive MEPS scenarios, China's room air conditioner electricity consumption and CO 2 emissions in 2050 are both reduced by 15–53% compared to the proposed MEPS. The highest-efficiency scenario (reaching MEPS of annual performance factor 5.4 in 2025) provides the largest long-term national benefits. These results could inform development of a Chinese regulatory regime that effectively updates room air conditioner MEPS. Because China is the world's largest manufacturer of room air conditioners, the economic, energy, and emissions benefits resulting from higher Chinese MEPS could also have a global reach. [ABSTRACT FROM AUTHOR]

Energy efficiency can get us about half of the way to long-term climate goals. Traditional energy efficiency strategies — vehicle and appliance efficiency standards, building energy codes, utility energy efficiency programs and Energy Star — can provide about half the achievable efficiency savings (i.e., savings of about one-quarter of projected 2050 energy use). However, these strategies can benefit from a variety of improvements, and other programs and policies addressing buildings, transportation and industry can achieve substantial additional savings. These efficiency policies can be combined with strategies involving no- and low-carbon energy sources to put the United States on a trajectory toward meeting long-term energy and climate targets. [ABSTRACT FROM AUTHOR]