42,292 research outputs found
Duration-differentiated Energy Services with a Continuum of Loads
As the proportion of total power supplied by renewable sources increases, it
gets more costly to use reserve generation to compensate for the variability of
renewables like solar and wind. Hence attention has been drawn to exploiting
flexibility in demand as a substitute for reserve generation. Flexibility has
different attributes. In this paper we consider loads requiring a constant
power for a specified duration (within say one day), whose flexibility resides
in the fact that power may be delivered at any time so long as the total
duration of service equals the load's specified duration. We give conditions
under which a variable power supply is adequate to meet these flexible loads,
and describe how to allocate the power to the loads. We also characterize the
additional power needed when the supply is inadequate. We study the problem of
allocating the available power to loads to maximize welfare, and show that the
welfare optimum can be sustained as a competitive equilibrium in a forward
market in which electricity is sold as service contracts differentiated by the
duration of service and power level. We compare this forward market with a spot
market in their ability to capture the flexiblity inherent in
duration-differentiated loads
Smart Grid for the Smart City
Modern cities are embracing cutting-edge technologies to improve the services they offer to the citizens from traffic control to the reduction of greenhouse gases and energy provisioning. In this chapter, we look at the energy sector advocating how Information and Communication Technologies (ICT) and signal processing techniques can be integrated into next generation power grids for an increased effectiveness in terms of: electrical stability, distribution, improved communication security, energy production, and utilization. In particular, we deliberate about the use of these techniques within new demand response paradigms, where communities of prosumers (e.g., households, generating part of their electricity consumption) contribute to the satisfaction of the energy demand through load balancing and peak shaving. Our discussion also covers the use of big data analytics for demand response and serious games as a tool to promote energy-efficient behaviors from end users
A Discrete-time Scheduling Model for Continuous Power-intensive Processes Considering Fatigue of Equipment
In the light of the growing renewable energy generation, matching of electricity supply and demand has become increasingly challenging. By participating in demand side management programs, industry can contribute to counter this challenge. However, the frequent adjustment of operation conditions according to volatile electricity prices leads to additional dynamic loads for the equipment. In this work, a mixed-integer linear programming based discrete-time model is proposed for scheduling of a single air separation unit, explicitly considering fatigue of equipment occurring during transient operation. Besides constraints for describing the feasible region and the process dynamics, this model includes constraints for considering mechanical fatigue of some key equipment. The resulting model is applied to investigate the impact of mechanical constraints on the potentials of demand side management.BMBF, 03SFK3X1, Verbundvorhaben SynErgie: Synchronisierte und energieadaptive Produktionstechnik zur flexiblen Ausrichtung von Industrieprozessen auf eine fluktuierende Energieversorgung. X1_Linde: Erforschung und Demonstration von Industrieprozessen und Produktionssystemen im Hinblick auf energetische NachfrageflexibilitÀ
Union Mediation and Adaptation to Reciprocal Loyalty Arrangements
This study assesses the industrial relations application of the âloyalty-exit-voiceâ proposition. The loyalty concept is linked to reciprocal employer-employee arrangements and examined as a job attribute in a vignette questionnaire distributed to low and medium-skilled employees. The responses provided by employees in three European countries indicate that reciprocal loyalty arrangements, which involve the exchange of higher effort for job security, are one of the most desirable job attributes. This attribute exerts a higher impact on the job evaluations provided by unionised workers, compared to their non-union counterparts. This pattern is robust to a number of methodological considerations. It appears to be an outcome of adaptation to union mediated cooperation. Overall the evidence suggests that the loyalty-job evaluation profiles of unionised workers are receptive to repeated interaction and negative shocks, such as unemployment experience. This is not the case for the non-union workers. Finally, unionised workers appear to âvoiceâ a lower job satisfaction, but exhibit low âexitâ intentions, compared to the non-unionised labour.EPICURUS, a project supported by the European Commission through the 5th Framework Programme âImproving Human Potentialâ (contract number: HPSE-CT-2002-00143
Machine learning for identifying demand patterns of home energy management systems with dynamic electricity pricing
Energy management plays a crucial role in providing necessary system flexibility to deal with the ongoing integration of volatile and intermittent energy sources. Demand Response (DR) programs enhance demand flexibility by communicating energy market price volatility to the end-consumer. In such environments, home energy management systems assist the use of flexible end-appliances, based upon the individual consumer's personal preferences and beliefs. However, with the latter heterogeneously distributed, not all dynamic pricing schemes are equally adequate for the individual needs of households. We conduct one of the first large scale natural experiments, with multiple dynamic pricing schemes for end consumers, allowing us to analyze different demand behavior in relation with household attri
Source-tracking cadmium in New Zealand agricultural soils: a stable isotope approach
Cadmium (Cd) is a toxic heavy metal, which is accumulated by plants and animals and therefore enters the human food chain. In New Zealand (NZ), where Cd mainly originates from the application of phosphate fertilisers, stable isotopes can be used to trace the fate of Cd in soils and potentially the wider environment due to the limited number of sources in this setting. Prior to 1997, extraneous Cd added to soils in P fertilisers was essentially limited to a single source, the small pacific island of Nauru. Analysis of Cd isotope ratios (É114/110Cd) in Nauru rock phosphate, pre-1997 superphosphate fertilisers, and Canterbury (Lismore Stony Silt Loam) topsoils (Winchmore Research Farm) has demonstrated their close similarity with respect to É114/110Cd.
We report a consistent É114/110Cd signature in fertiliser-derived Cd throughout the latter twentieth century. This finding is useful because it allows the application of mixing models to determine the proportions of fertiliser-derived Cd in the wider environment. We believe this approach has good potential because we also found the É114/110Cd in fertilisers to be distinct from unfertilised Canterbury subsoils. In our analysis of the Winchmore topsoil series (1949-2015), the É114/110Cd remained quite
constant following the change from Nauru to other rock
phosphate sources in 1997, despite a corresponding
shift in fertiliser É114/110Cd at this time.
We can conclude that to the present day, the Cd in topsoil at Winchmore still mainly originates from historical phosphate fertilisers. One implication of this finding is that the current applications of P fertiliser are not resulting in further Cd accumulation. We aim to continue our research into Cd fate, mobility and transformations in the NZ environment by applying Cd isotopes in soils and aquatic environments across the country
ANGELAH: A Framework for Assisting Elders At Home
The ever growing percentage of elderly people within modern societies poses welfare systems under relevant stress. In fact, partial and progressive loss of motor, sensorial, and/or cognitive skills renders elders unable to live autonomously, eventually leading to their hospitalization. This results in both relevant emotional and economic costs. Ubiquitous computing technologies can offer interesting opportunities for in-house safety and autonomy. However, existing systems partially address in-house safety requirements and typically focus on only elder monitoring and emergency detection. The paper presents ANGELAH, a middleware-level solution integrating both âelder monitoring and emergency detectionâ solutions and networking solutions. ANGELAH has two main features: i) it enables efficient integration between a variety of sensors and actuators deployed at home for emergency detection and ii) provides a solid framework for creating and managing rescue teams composed of individuals willing to promptly assist elders in case of emergency situations. A prototype of ANGELAH, designed for a case study for helping elders with vision impairments, is developed and interesting results are obtained from both computer simulations and a real-network testbed
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