ALBERT

Description: The European Green Deal and its endeavors will make rapid and far-reaching decisions with major implications for the European cement industry in the short- and longer-term. Accordingly, new measures should be dealt with quickly and effectively to minimize the adverse impact on global warming and global climate change by this sector. The aim of this study is to show and assess the measures to be undertaken to reach carbon neutrality by the Spanish cement industry by 2050. They may be categorized into three broad types based on the main materials: clinker, cement, and concrete. The cement sector must implement breakthrough initiatives, inventions, and technologies regarding the clinker and cement production processes. Furthermore, carbon dioxide uptake by cement-based materials must be considered to achieve the carbon neutrality objective. Accordingly, two methodologies named simplified and advanced, consistent with Guidelines for National Greenhouse Gas Inventories elaborated by the Intergovernmental Panel on Climate Change (IPCC), were selected to model the carbon offsetting by mortars and concretes. Finally, the existing climate change mitigation technologies available in Spain are insufficient to reach the net zero carbon footprint. Therefore, breakthrough technologies such as novel and efficient carbon dioxide capture, utilization, and storage (CCUS) technologies should be implemented by the Spanish cement industry to achieve zero carbon dioxide emissions in 2050.

Description: The ongoing evolution of the power system to implement climate action policies is resulting in a continuous increase in the penetration of renewables and the necessity of strengthening the transmission grid to optimize the usage of those sources and contain operation costs. Reinforcing the transmission lines or building new ones is a process that is made difficult due to authorization issues related with environmental and public acceptance concerns. Developing innovative conductors for overhead lines with enhanced performances with respect to the traditional ones would bring benefits in terms of energy efficiency increases in transmission and distribution grids without requiring the substitution of the existing towers. The project CALAJOULE (the genesis of the acronym comes from the union of the Italian verb “calare”-to decrease-to the third person singular, namely “cala” i.e., decreases, and of Joule, obvious reference to the active losses), cofinanced by the Italian Ministry of Economic Development in the framework of the “Ricerca di Sistema” program, aims at proposing innovative solutions for overhead line conductors for the containment of Joule power losses. In this paper, starting from the state-of-the-art of the currently adopted conductors, the main innovative solutions resulting from the project are presented and compared with the traditional ones to evaluate the achievable reduction in Joule losses.

Description: Information technologies (IT) currently represent 2% of CO2 emissions. In recent years, a wide variety of IT solutions have been proposed, focused on increasing the energy efficiency of network data centers. Monitoring is one of the fundamental pillars of these systems, providing the information necessary for adequate decision making. However, today’s monitoring systems (MSs) are partial, specific and highly coupled solutions. This study proposes a model for monitoring data centers that serves as a basis for energy saving systems, offered as a value-added service embedded in a device with low cost and power consumption. The proposal is general in nature, comprehensive, scalable and focused on heterogeneous environments, and it allows quick adaptation to the needs of changing and dynamic environments. Further, a prototype of the system has been implemented in several devices, which has allowed validation of the proposal in addition to identification of the minimum hardware profile required to support the model.

Description: The use of alcohol blends in direct alcohol fuel cells may be a more environmentally friendly and less toxic alternative to the use of methanol alone in direct methanol fuel cells. This paper assesses the behaviour of a direct methanol fuel cell fed with aqueous methanol, aqueous ethanol and aqueous methanol/ethanol blends in a long term experimental study followed by modelling of polarization curves. Fuel cell performance is seen to decrease as the ethanol content rises, and subsequent operation with aqueous methanol only partly reverts this loss of performance. It seems that the difference in the oxidation rate of these alcohols may not be the only factor affecting fuel cell performance.

Description: It is well known that a low level of electrolytes in batteries produces a malfunction or even failure and irreversible damage. There are several kinds of sensors to detect the electrolyte level. Some of them are non-invasive, such as optical sensors of level, while some others are invasive; but both require one sensor per battery. This paper proposes a different approach to detect the low electrolyte level, which neither requires invasive sensors nor one sensor for each battery. The approach is based on the estimation of the internal resistance of an equivalent electrical circuit (EEC) model of the battery. To establish the detection criterion of the low level of electrolytes, a statistical analysis is proposed. To demonstrate the feasibility of this approach to be considered a valid method, multiple experiments were performed. The experiments consisted of determining how the internal resistance is affected at eight different levels of electrolyte at different aging levels of vented lead–acid (VLA) batteries. The results have demonstrated the feasibility of this approach. Hence, this approach has the potential to be used for the reducing of sensors and avoiding invasive methods to determine the low level of electrolytes.

Description: This paper deals with a battery energy storage system (BESS) in only one of its multiple operating modes, that is when the BESS is charging the battery bank and with the focus on the control scheme design for the BESS input stage, which is a three-phase LCL-filter PWM rectifier. The rectifier's main requirements comprise output voltage regulation, power factor control, and low input current harmonic distortion, even in the presence of input voltage variations. Typically, these objectives are modeled by using a dq model with its corresponding two-loop controller architecture, including an outer voltage loop and a current internal loop. This paper outlines an alternative approach to tackle the problem by using not only an input–output map linearization controller, with the aim of a single-loop current control, but also by avoiding the dq modeling. In this case, the voltage is indirectly controlled by computing the current references based on the converter power balance. The mathematical model of the three-phase LCL-filter PWM rectifier is defined based on the delta connection of the filter, which accomplishes the requirements of a 100 kW BESS module. Extensive simulation results are included to confirm the performance of the proposed closed-loop control in practical applications.

Description: The valorization and sustainable management of historic centers is a topic relevant to the cultural identity and heritage of European cities. A rational strategy to preserve the centers must consider both energy and environmental retrofitting, even if this is a complex issue requiring interdisciplinary approaches, dedicated diagnostic procedures, and specific tools. Within this context, this paper proposes an integrated method for energy and environmental analysis specifically devoted to historical building retrofit. Attention is focused on cases in which building management is not interested in renovation or in a deep conservation project, but instead in green management and maintenance overhaul. The basis of the procedure is the Leadership in Energy and Environmental Design for Existing Buildings: Operations and Maintenance (LEED O+M) rating protocol. The global goal was the definition of an intervention strategy indicating the principal direction of action. The first step is identifying critical issues in the operation of the building through energy diagnosis and dynamic thermophysical simulations. The second step is defining a panel of appropriate retrofit measures. The third step is choosing between alternatives to increase the sustainability performance following an environmental assessment scheme. Ca’ Rezzonico in Venice (Italy), a 17th-century palace, nowadays the seat of a museum, was used as a case study to apply the proposed methodology.

Description: This article assesses the costs and benefits of incorporating battery energy storage systems (BESS) in transmission network expansion planning (TEP) over multiple time periods. We propose a mixed-integer programming model (MIP) for joint planning of the installation of battery energy storage systems (BESS) and construction of new transmission lines in multiple periods of time. The mathematical formulation of the presented model is based on the strategies of the agents of a transmission network to maximize their benefit, and on the operational restrictions of the power flows in transmission networks. This analysis is performed for the Garver 6 node test system takes into account the power losses in the lines and the restrictions for the energy stored in BESS. The power flows obtained with the MIP model are compared with AC power flows generated with specialized software for flows in power systems. This allows us to demonstrate the potential of models based on DC power flows to achieve approximate results applicable to the behavior and characteristics of real transmission networks. The results show that the BESS increase the net profit in the transmission networks and reduce their power losses.

Description: The transition from traditional energy to cleaner energy sources has raised concerns from companies and investors regarding, among other things, the impact on financial downside risk. This article implements backtesting techniques to estimate and validate the value-at-risk (VaR) and expected shortfall (ES) in order to compare their performance among four renewable energy stocks and four traditional energy stocks from the WilderHill New Energy Global Innovation and the Bloomberg World Energy for the period 2005-2016. The models used to estimate VaR and ES are AR(1)-GARCH(1,1), AR(1)-EGARCH(1,1), and AR(1)-APARCH(1,1), all of them under either normal, skew-normal, Student’s t, skewed-t, Generalized Error or Skew-Generalized Error distributed innovations. Backtesting performance is tested through traditional Kupiec and Christoffersen tests for VaR, but also through recent backtesting ES techniques. The paper extends these tests to the skewed-t, skew-normal and Skew-Generalized Error distributions and applies it for the first time in traditional and renewable energy markets showing that the skewed-t and the Generalized Error distribution are an accurate tool for risk management in those markets. Our findings have important implications for portfolio managers and regulators in terms of capital allocation in renewable and traditional energy stocks, mainly to reduce the impact of possible extreme loss events.

Description: The Modular Multilevel Matrix Converter is a relatively new power converter topology appropriate for high-power Alternating Current (AC) to AC purposes. Several publications in the literature have highlighted the converter capabilities such as modularity, control flexibility, the possibility to include redundancy, and power quality. Nevertheless, the topology and control of this converter are relatively complex to design and implement, considering that the converter has a large number of cells and floating capacitors. Therefore multilayer nested control systems are required to maintain the capacitor voltage of each cell regulated within an acceptable range. There are no other review papers where the modelling, control systems and applications of the Modular Multilevel Matrix Converter are discussed. Hence, this paper aims to facilitate further research by presenting the technology related to the Modular Multilevel Matrix Converter, focusing on a comprehensive revision of the modelling and control strategies.