ITT (Germany)

The accelerating global demand for renewable heating, cooling and electricity, driven by climate change and rising living standards, presents both a challenge and an opportunity for sustainable energy transitions. This paper introduces the Initial-Aid Cashback (IAC) model, an innovative business model designed to finance renewable energy solutions, with a focus on space cooling, by leveraging citizen participation and collaborative financing mechanisms. The model incentivizes private investors through discounted energy prices, while system operators benefit from reduced upfront capital requirements and minimised financial risk. Through two case studies, an office building in Romania (small-scale case) and the application of the REGEN-BY-2 technology in a mixed housing–office area (large-scale case), the paper demonstrates the model’s potential to accelerate the adoption of renewable cooling technologies, enhance profitability for operators, and provide attractive returns for investors. The findings highlight the model’s adaptability to diverse stakeholder needs, its scalability, and its role in fostering the clean energy transition (CET). However, challenges such as the need for a minimum number of investors, legal complexities, and trust-building among stakeholders are identified as critical barriers to implementation. The paper concludes that the IAC model offers a promising pathway to integrate citizens and small investors into the CET, while emphasising the importance of supportive policies, clear governance structures, and practical testing to ensure its success.

Abstract The increasing demand for space cooling poses a major challenge to energy systems and buildings, both residential and commercial applications. Cost-effective and easily deployable solutions are widely needed to tackle this challenge. Heat emitted to the indoor from equipment is critical, particularly cooling units such as refrigerators and freezers. The impact of heat rejected from refrigerators on the indoor climate of small shops and supermarkets have been widely overlooked. This study presents and investigates an innovative and low-tech solution to control the heat dissipation of indoor cooling units, leading to increased comfort and reduced cooling demand. The solution, designed to be installed as a retrofit measure, controls the exhaust air ducting. Thus, it does not provide cooling, but manages the waste heat from refrigerators. This study includes the monitoring of an actual kiosk in Stuttgart, Germany, to meter refrigerators’ power consumption, a lab-scale prototype testing to prove the methodology of the solution and additionally dynamic thermal simulations via TRNSYS18 for different climates to analyze the performance and impact of the novel solution. The prototype showed the effectiveness of the control strategy during the lab-testing. The simulation results for Stuttgart show that controlled heat dissipation can reduce overheating degree hours by up to 97%, resulting in a potential cooling demand reduction of up to 83%. Overall, the findings reveal an underutilized potential in existing appliances to contribute to energy-efficient building operation and lay the groundwork for future research into optimization, control strategies, and broader application of such hybrid concepts. Graphical Abstract

Field-weakening is an established technique for exceeding motor base speeds while maintaining constant input power. To improve energy efficiency of emergency ventilators, this paper presents a methodology for reducing torque to lower the input power of brushless DC (BLDC) motors. Using the Clarke-Park transformation, the operating point is obtained by minimizing the voltage and then applied as phase-advance angle and modulation index in the voltage model. A proof-of-concept experimental setup yields power savings of up to 40% using field-weakening compared to conventional field-oriented control approaches, demonstrating its feasibility for energy savings in BLDC motors.

El pez blanco Chirostoma estor es una especie con alto potencial de cultivo y calidad nutricional. A pesar de los avances en su cultivo y alimentación, aún no se cuenta con una alimento balanceado que permita el buen crecimiento obtenido con el alimento vivo. En este trabajo se estudió el desarrollo de la actividad digestiva en la especie, desde la eclosión hasta los 150 días, usando solo alimento vivo para evitar afectar la maduración digestiva. Los análisis de actividad se realizaron con técnicas fluorómetricas (enzimas pancreáticas) y espectofotométricas (enzimas intestinales) validadas para evaluar maduración digestiva. El crecimiento observado fue comparable con el obtenido utilizando luz contínua y microdietas con proteína soluble y consorcio bacteriano. Se evidenció la necesidad de incluir rotíferos y nauplios de Artemia en los primeros estadíos. Los indicadores de maduración digestiva evidenciaron que C. estor sigue el modelo descrito para peces gástricos, con las particularidades de ser tardío -posterior a los 5 meses de vida-, presentar niveles muy elevados de actividad citosólica intestinal (leucin alanin peptidasa) y mantener esta actividad y la anclada a la membrana de los enterocitos durante el estadio juvenil. Por consiguiente, se recomienda un destete posterior al primer mes de vida, induciendo una maduración temprana.

Meteorological drought is a climatic phenomenon that affects all global climates with social, political, and economic impacts. Consequently, it is essential to develop drought forecasting tools to minimize the impacts on communities. Here, probabilistic models based on Markov chains (first and second order) and Bayesian networks (first and second order) were explored to generate forecasts of meteorological drought events. A Ranked Probability Score (RPS) metric selected the best-performing model. Long-term precipitation data from Liberia Airport in Guanacaste, Costa Rica, from 1937 to 2020 were used to estimate the 1-month Standardized Precipitation Index (SPI-1) characterizing four meteorological drought states (no drought, moderate drought, severe drought, and extreme drought). The validation results showed that both models could reflect the climatic seasonality of the dry and rainy seasons without mistaking 4–5 months of the rain-free dry season for a drought. Bayesian networks outperformed Markov chains in terms of the RPS at both reproducing probabilities of drought states in the rainy season and when compared to the months in which a drought state was observed. Considering the forecasting capability of the latter method, we conclude that these models can help predict meteorological drought with a 1-month lead time in an operational early warning system.

Twin-screw pumps due to their particular capabilities, offer u nique b enefits in comparison to other types of pumps. They can also recover wasted energy from the fluid system when run in a reversed way, i.e., in turbine mode. In this study, the possibility of benefiting twin-screw machines instead of conventional control valves in order to recover energy is investigated. Flow physics and energy recovery are analyzed experimentally and by 3D flow simulations in both, pump and turbine mode. Pump and turbine characteristics under different operating points are experimentally measured for low and high viscous fluids, i.e., water and oil, respectively. It is observed that for higher viscosity the dependency of volume flow rate on the pressure difference imposed on the pump is reduced. This observation indicates the significant effect of viscosity on the gap flow. Based on a simulation method by means of overset grid technique, unsteady 3D flow simulations with a high grid quality and a high spatial resolution particularly in gap regions in terms of y + < 1 are conducted and results are validated against experiments. The profound assessment of gap flow based on the simulation results shows that for highly viscous fluids such a soil, the rotational speed of spindles as well as the direction of rotation have a significant effect on gap flow characteristics and consequently on the pump and turbine performance. From the experiments, it is clarified that with a lower rotational speed of spindles and a higher pressure difference, a higher amount of energy up to about 50% of the fluid energy in the piping system can be recovered instead of being dissipated by a conventional control valve.

Il presente contributo tratta dei flussi migratori stagionali che tra fine Ottocento e inizi Novecento si diressero dalla montagna veneta verso i territori dell’Europa centro-orientale. Soprattutto il Bellunese fu interessato a partire dalla metà dell’Ottocento da una considerevole migrazione stagionale verso l’Europa centro-orientale, che, in inverno, trovò impiego nella ristrutturazione stradale e ferroviaria o nei lavori connessi al taglio delle piante. Nei mesi estivi se ne aggiunse, tuttavia, un’altra di venditori ambulanti di dolciumi, a cui subentrò in seguito la vendita del gelato. Tracce di entrambi i flussi si rinvengono nei racconti orali del mio campione che riferisce di una forma singolare e tuttora attiva di emigrazione stagionale. Praticata dal lontano 1880 da intere vallate dell’Alto Veneto, essa si rivolse inizialmente a Vienna e ai territori limitrofi dell’Impero asburgico e, subito dopo la II guerra mondiale, soprattutto alla Germania. Il materiale qui proposto, desunto dalla mia tesi di dottorato dal titolo I gelatieri veneti in Germania. Un’indagine sociolinguistica, pubblicata nel 2006 dalla Peter Lang di Francoforte sul Meno, si fonda su un’indagine quantitativa e qualitativa. Grazie alle testimonianze autentiche sarà, pertanto, possibile intraprendere un “viaggio” nella memoria di intere vallate montane, “consacrate” da secoli, all’emigrazione stagionale artigianale.

Algeria’s energy needs are actually satisfied mainly through the use of hydrocarbons. Demand for energy is growing exponentially because the population is growing massively and the building sector is in full expansion in order to address and solve the problems of housing, health and education. In 2011, Algeria initiated a dynamic green energy program by launching an ambitious development project aims at developing a renewable energy power source of 22000 MW and to save more than 60 Million TOE in energy efficiency by the year 2030. Our research topic is linked to the energy efficiency program initiated in Algeria. The objective of this article in to present a study carried out on the thermal performance of Phase Change Materials (PCMs) and their integration in buildings in order to achieve thermal comfort and to reduce the energy consumption. Then, an investigation on the capacity of using (PCMs) in Algeria is presented for a sustainable development and rational energy consumption.

This paper presents a Cubature Kalman Filter (CKF) based speed and position observer for a Permanent Magnet Synchronous Motor (PMSM). CKF is a new variety of Kalman filter which uses a third degree spherical-radial cubature rule to numerically compute multivariate moment integrals. Unlike in an Extended Kalman Filter(EKF), mean and covariance are propagated through the non-linear system, which minimizes the errors due to linearization. The proposed observer is incorporated in the sensorless control of an IPMSM of 1.5kW, 3000rpm rating. For the CKF algorithm, PMSM is modeled in stationary αβ reference frame. To get comparatively better transient performance and convergence of the CKF for a non-zero initial rotor position, system covariance matrix Q is chosen adaptively. Simulation results for a VSI fed IPMSM are presented and the convergence of CKF is shown for a variation of stator resistance. Performance of the proposed observer is compared with that of an EKF observer.