• Energy Research
• Restricted close
• Embargo close
• ES close
• EU close
• AU close

Capítulos en libros This paper assesses the scalability and replicability of smart grid projects, by means of the identification of limitations and barriers faced by these projects. Factors have been identified that impact a project s scalability and replicability by means of a review of demonstration projects. The factors are of technical, economic, regulatory and social acceptance nature, and they describe requirements for scalability and replicability. Data was collected from ongoing European smart grid demonstration projects through the use of an elaborated questionnaire on the identified factors. Which allowed to quantify the status quo to what extent projects have taken these factors into account. Dew to their nature the derived factors can be categorized in technical, economic and regulatory & stakeholder related factor areas The obtained results allowed the identification of barriers, i.e. limitations regarding the scalability and replicability of smart grid projects. In particular projects face barriers regarding the absence of standards, the physical limits of the existing infrastructure, the absence of cost-benefit analyses, the neglect of varying macro-economic factors, stakeholder involvement and from the dependency of projects on regional or national regulatory frameworks and market designs. info:eu-repo/semantics/publishedVersion

A literature review was conducted aiming at investigating the use of Sustainability, Lean, Green and eco-efficiency concepts, as well as meaningful combinations of those, on the field of Production and Operations Management. The study reports on the scientific papers published in all major journals in the field over the period 2001–2015. A set of 83 papers from 40 journals were selected for further analyzes, aiming at uncovering the existing level of awareness and use of the synergic and symbiotic relationship between Lean Manufacturing and Green Production. The findings show that a modest share of papers, about 30 %, explicitly recognize the Lean-Green joint approach. The same study testifies a clear growth pattern, which is patently reinforced in the last two and a half years, on the number of papers that behold a combined approach towards more efficient and cleaner production activities. The research has highlighted that the Lean-Green link does, in fact, exist and is gaining momentum, but requires further reinforcements from the scientific community, as well as from the companies, to deliver excelled and environmentally sound production systems. FCT Strategic Project PEst2015-2020, reference UID/CEC/00319/2013. info:eu-repo/semantics/publishedVersion

Artículos en revistas Security-constrained unit commitment (SCUC) problem is one of the necessary tools for system operators to make operational planning and real-time operation. The internalization of transmission-network and security constraints (e.g. N-1 criterion) could lead to different decisions in the generation dispatch. However, the computational burden of this problem is challenging mainly due to its inherent large problem size. Therefore, this paper proposes an N-1 security constrained formulation based on the Line Outage Distribution Factors (LODF) instead of the one based on Injection Sensitivity Factors (ISF). This formulation is at the same time more compact than analogous formulations for contingency constraints; hence, it presents a lower computational burden. The computational efficiency of the proposed formulation is shown by solving the SCUC of the IEEE 118 bus system with LODF and ISF. Additionally, an iterative methodology for filtering the active N-1 congestion constraints is detailed, and its implementation for large-scale systems is described. The results show that the proposed filter reduces the computational time by approximately 70% in comparison to the complete formulation of N-1 constraints in SCUC. info:eu-repo/semantics/publishedVersion

Abstract The use of phase change materials (PCMs) for thermal storage in buildings was one of the first applications studied, together with typical storage tanks. An interesting possibility in building application is the impregnation of PCMs into porous construction materials, such as plasterboard or concrete, to increase thermal mass. The thermal improvements in a building due to the inclusion of PCMs depend on the climate, design and orientation of the construction, but also to the amount and type of PCM. Therefore, these projects require a complete simulation of the thermal behaviour of the designed space in the conditions of use established a priori. In this paper a simple methodology for the energetic simulation of buildings including elements with PCMs using the program TRNSYS is presented and validated. This procedure does not aim a simulation of the real transfer processes inside the materials with PCM, but to evaluate the influence of walls/ceiling/floor with PCM in the whole energy balance of a building. The key parameter in the simulations is the equivalent heat transfer coefficient which has to be determined for each material. Experimental evaluation of the coefficient is presented. The methodology is applied in a building such as a prototype room built with concrete panels with PCM.

Artículos en revistas This paper presents the principles of a centralized underfrequency load-shedding (UFLS) scheme based on a frequency stability boundary curve suitable for small isolated power systems. The centralized UFLS scheme is illustrated in case of two small isolated Spanish power systems. info:eu-repo/semantics/publishedVersion

Shallow Geothermal Systems (SGS) are widely used to provide low-cost heating and cooling of residential and commercial buildings. SGS can be an economically-viable solution even for commercial buildings, where controlled temperature is fundamental for the production processes. To assess the thermal resistance of the soil and the performance of a SGS, Thermal Response Tests (TRT) must be performed. TRT machines are today designed mainly for short term monitoring, for relatively deep SGS (up to 200 m) and for being used by expert operators. Lightweight, low-cost machines for both fast and long term, reliable and unattended TRT for very Shallow Geothermal Systems (vSGS) are not available today. This paper describes the design of a micro-TRT machine (mTRT) for vSGS, which is gaining interest in the civil engineering, environmental, energy and food chain sectors. The paper describes the features of the wireless monitoring system, the design choices to achieve the required accuracy and the software developed for adding remote control capability. Experimental validation in a real test field demonstrates the quality of measurements collected for analysing the TRT data.

Common hornbeam (Carpinus betulus) is one of the most important spring pollen allergens widespread in the Czech Republic. This study evaluates the changes in Carpinus betulus flowering and the length of the blooming period in the Czech Republic during 1991-2020. Temporal and spatial evaluations in the timing of the flowering and the length of the blooming period were investigated at different altitudinal levels. Moreover, the changes in mean air temperature and precipitation total in spring months (March-April-May) were assessed, including the correlation with phenological data. Geographic Information System methods, the Mann-Kendall test and Pearson's correlation coefficient were used for processing. The flowering of Carpinus betulus changed significantly over time during the 1991-2020 period. The linear models predicted early flowering in Carpinus betulus at different altitudes (27 days at > 701 m 18 days at 501-700 m and 13 days at 301-500 m) significantly (p<0.001) over the last three decades. Furthermore, the length of the blooming period of Carpinus betulus has been shortened (4 days) at the 301-500 m a.s.l. altitudinal level significantly (p<0.05). The strongest correlation was predominantly observed between flowering and the mean air temperature (March-April-May).

Nordhaus (1973) has in his seminal contribution addressed two emerging questions in the field of energy economics. First, how do current market prices of natural resources reflect true scarcity fro...