Abstract

Our growing needs for social networks, cloud storage and more recently machine learning have fueled the increasing demand for datacenters (DC). It is estimated that by 2030, in the US alone, datacenter power consumption could more than double from 2022. In Europe, the energy consumption is expected to rise by 28%, from 77TWh to 99TWh. This surge, coupled with the increasing scrutiny imposed on Information and Communication Technology (ICT) from stakeholders, regulators and competition, regarding environmental impacts, and to stay on the path of net-zero, has spotlighted datacenters as key contributors to these environmental concerns. Consequently, companies have set major milestones for the next decades in terms of renewables, energy consumption and water use. This paper aims to shed light on the imperative necessity of revisiting and evaluating various metrics and methodologies used to gauge the impact of datacenters, extending beyond merely assessing sustainability factors. More in detail, we focus on four paramount criteria which encompass the whole datacenter lifecycle and its direct and indirect impacts: environmental impact, economic performance, ecosystem integration and external influence. These are usually evaluated through three types of analysis: single indicators, lifecycle analysis and multi-criteria assessment, all of which are analyzed here.

Abstract

Parameter estimation methods based on recursive least squares (RLS) are extensively used in the online identification of battery models. Forgetting factor RLS (FFRLS), which can track the parameter changes online, has been regarded as an essential solution to real-time model adaptation. However, under the non-persistent excitation condition, the performance of FFRLS will degrade and the covariance windup phenomenon will be triggered, as a consequence, FFRLS will become numerically unstable and lose the capacity to provide reliable estimates. In this paper, a new scheme named exponential resetting RLS (ERRLS) is proposed to overcome the aforementioned shortcoming, the mechanism of information matrix updating is modified to guarantee exponential convergence towards a non-zero matrix under no excitation. This modification will result in a bounded covariance matrix whether the excitation is persistent or not, which implies an improved robustness in comparison with FFRLS. Experimental results indicate that ERRLS can achieve better performance than FFRLS when the persistent excitation condition is violated.

Abstract

Thermal energy requirements in the industrial sector for different process heating applications consume about 35% of the total global fossil fuels. To mitigate the consumption of fossil fuels, solar industrial process heating (SIPH) can be the best possible option. Therefore, in this paper, dynamic simulation and performance analysis of the SIPH system have been carried out for the food industry. The main objective of this study was to investigate the effect of mass flow rate on the outlet temperature of solar thermal collectors by multi-flat plate collectors (m-FPC) industrial process requirements. The methodology has considered data for the food industry of Pakistan to verify its potential quantitatively for different weather conditions (Summer and winter). The investigation revealed that once the desired temperature (T_set) of 60°C was attained at the optimized mass flow rate of 41 kg/s, any additional upsurge in flow rate led to greater energy consumption by the auxiliary heating system. Additionally, the analysis confirmed that the annual thermal energy generated by the solar collector, in conjunction with the supplementary heat provided by the heater, adequately fulfills the process requirements. These findings demonstrate the promising potential of SIPH within the food industry.

Abstract

This research investigates the effect of various storage tank geometries and relief pressure on boil-off losses for liquid hydrogen (LH2). The effect of storage volume of LH2 in the tanks for the various geometries is analyzed as well. The model takes into consideration the heat transfer between the liquid and vapor phases, integrates actual heat transfer mechanisms, and employs variety equations of state to estimate evaporative losses. For this, a software package BoilFAST has been used to investigate the boil-off losses. The model was validated against experimental data available in open literature from NASA. Results showed that the effect of relief pressure on the evaporation of LH2 is very high. The LH2 volume is reduced by 34% in the case of cuboid shape and 22% the for spherical shape of the tank from relief pressure of 111 to 10 kPa. However, the effect of the filled volume of LH2 in the storage tank on the evaporation of LH2 is minimal as the volume is reduced only by less than 5% for all tank shapes. Overall, for various tank geometries, spherical shape showed minimum evaporation losses compared to other tank geometries.

Abstract

Considering diminishing limestone resources and escalating carbon emission regulations, geopolymers are considered to be the third generation of cementitious materials after lime and ordinary Portland cement (OPC). Geopolymers are distinguished by their strong corrosion resistance, freeze-thaw resilience, mechanical strength, and reduced CO2 emissions, positioning them as environmentally friendly alternatives to traditional cement. Metakaolin (MK) based geopolymers typically have a light-colored appearance which contributes to high solar reflectance, thereby reducing heat absorption from sunlight and rendering them beneficial for radiative cooling. Enriched with alumina (Al₂O₃) and silicon dioxide (SiO₂), MK geopolymers possess unique radiative properties, outperforming in radiative cooling experiments with a notable temperature drop of about 6.5˚C. Compared to other green alternatives like slag and fly ash geopolymers, MK geopolymers demonstrate enhanced strength and thermal stability. A life cycle assessment reveals that metakaolin-based geopolymers can mitigate carbon emissions compared to ordinary Portland cement (OPC), underscoring their role as a sustainable solution in the construction industry.

Abstract

Successfully steering the intricate transition to a sustainable energy system entails the inclusion of diverse stakeholders and the evaluation of numerous criteria in a multifaceted decision-making framework. This frequently presents challenges in the realm of data management. This work lays out conceptual considerations for identifying suitable weighting approaches in the context of Multi-Criteria Decision Analysis applied in sustainable energy transitions in the Sahel region.

Abstract

Metal hydrides (MH) are promising solid hydrogen storage materials with significant reaction heat effect applied in reactors. Phase-change materials (PCM) have been used as thermal management media in the MH reactor. To further improve the performance of such reactors, this study proposed a novel PCM-based MH (MgH2) reactor with array layouts, aiming to construct a heat transfer interface with a high specific surface area. A mathematical model was developed to describe the process of heat transfer and absorption reaction. The results showed that an increase in the number of array units significantly increased the heat transfer area and enhanced the heat transfer and hydrogen absorption rate. The array reactor with seven units had a 1.8 times increase in the absorption rate compared to the traditional reactor with only one array unit.

Abstract

Mining is one of the most energy-intensive industries, accounting for almost 10 percent of worldwide energy consumption. This study investigates microwave treatment as a rock pre-conditioning method to improve energy efficiency in mine-to-mill operations. A novel energy-based data analysis is used to evaluate the application of the method, considering the input microwave energy and its corresponding effect on the mining processes. The results show that microwave treatment provides advantageous outcomes such as reducing the strength of rocks, specific crushing energy, field penetration index, and increasing cutter life cycle. The energy-based analysis emphasizes the significance of optimizing microwave power and exposure time as major design criteria. The results show that applying microwave energy can influence multiple mine-to-mill operations simultaneously, which exponentially improves the efficiency of the method. This understanding showcases the potential of microwave treatment in field applications, leading to more energy efficient and sustainable mining.

Abstract

The increasing sophistication of transmission network expansion planning (TNEP) can be attributed to several evolving factors. These include the uncertain nature of renewable energy sources, the introduction of new market regulations and participants, and ongoing demand amplification in line with the increasing integration of electric vehicles and energy storage systems. The TNEP is a complex optimization problem that finds the optimal number and location of new transmission lines to satisfy system demand. In this work, we propose a hybrid-adaptive differential evolution with an iterated local search algorithm to solve this combinatorial problem and evaluate the performance of multiple acceptance criteria for solution selection in the iterative process for an 87-bus north-northeast Brazilian transmission system. Results showed that the HyDE-ILS strategies reduced the total costs by around 5% to 6% compared to HyDE on average.

Abstract

Making the leap toward a clean future can be challenging. Network planning is essential to combat those challenges. This research work focuses on the planning field, dealing with daily uncertainty, energy storage systems, remuneration of distributed resources, and CO2 emissions while considering the impacts of the seasons on the network expansion. In that regard, a multi-stage stochastic optimization model is proposed to minimize all planning costs and CO2 emissions. The model is tested in a 180-bus realistic 30kV medium- voltage distribution network in the Leiria district, Portugal, with high renewable energy penetration, in a 30-year lifetime project.