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[en] Cogeneration or combined heat and power (CHP) is a thermal power generation cycle with the merit of recovering part or all of the heat that is fatally discarded by such cycles. This merit of higher efficiency is subject of rewarding by public authorities. When the EU enacts CHP promotion in a Directive (1997-2004), crucial measurement and qualification issues remain unsolved. CEN (coordinator of the European Bureaus of Standards) contributes in clarifying the measurement of CHP activities, but shortfalls remain, while CEN bypasses the debate on qualifying CHP performance. This article offers appropriate methods for measuring CHP activities based on design characteristics of the plants. The co-generated electric output is a necessary and sufficient indicator of CHP merit and performance. Regulators can extend this indicator, but should avoid the perverse effects of biased external benchmarking as the EU Directive entails
BackgroundThe research field of energy system analysis is faced with the challenge of increasingly complex systems and their sustainable transition. The challenges are not only on a technical level but also connected to societal aspects. Energy system modelling plays a decisive role in this field, and model properties define how useful it is in regard to the existing challenges. For energy system models, evaluation methods exist, but we argue that many decisions upon properties are rather made on the model generator or framework level. Thus, this paper presents a qualitative approach to evaluate frameworks in a transparent and structured way regarding their suitability to tackle energy system modelling challenges.
MethodsCurrent main challenges and framework properties that potentially contribute to tackle these challenges are derived from a literature review. The resulting contribution matrix and the described application procedure is then applied exemplarily in a case study in which the properties of the Open Energy Modelling Framework are checked for suitability to each challenge.
ResultsWe identified complexity (1), scientific standards (2), utilisation (3), interdisciplinary modelling (4), and uncertainty (5) as the main challenges. We suggest three major property categories of frameworks with regard to their capability to tackle the challenges: open-source philosophy (1), collaborative modelling (2), and structural properties (3).General findings of the detailed mapping of challenges and properties are that an open-source approach is a pre-condition for complying with scientific standards and that approaches to tackle the challenges complexity and uncertainty counteract each other. More research in the field of complexity reduction within energy system models is needed. Furthermore, while framework properties can support to address problems of result communication and interdisciplinary modelling, an important part can only be addressed by communication and organisational structures, thus, on a behavioural and social level.
ConclusionsWe conclude that the relevance of energy system analysis tools needs to be reviewed critically. Their suitability for tackling the identified challenges deserves to be emphasised. The approach presented here is one contribution to improve current evaluation methods by adding this aspect.
[en] Multi-functional energy systems such as polygeneration plants and biorefineries provide significant opportunities to enhance the efficiency of fuel utilization, while simultaneously reducing the intensity of greenhouse emissions. Such systems are able to take advantage of process integration opportunities in order to economically meet deamdns for a specified portfolio of outputs, which can include energy streams (e.g., electricity, heat or cooling) or material streams (e.g., hydrogen, biofuels, chemicals). If a multi-functional energy system is assumed to be comprised of a set of ''black box'' processes characterized only by scale-invariant material and energy balance specifications, then it can be represented by an enterprise input-output model consisting of linear equations. One potential disadvantage of these multi-functional energy systems arises from the inherent interdependencies among process units; the partial or total inoperability of one component can have an indirect effect on the ability of other process units to function properly. In this work, we propose an optimization model to determine the best operational response to process inoperability arising from equipment failure or feedstock shortage. The approach is based on a model used for disaster mitigation purposes. The operational adjustment comes in the form of changes in throughput of individual process units as well as reallocation of process streams. A simple trigeneration case study from literature is used to demonstrate the proposed technique. (author)
[en] Transactive energy systems use principles of value to coordinate responsive supply and demand in energy systems. Work continues within the Transactive Systems Program, which is funded by the U.S. Department of Energy at Pacific Northwest National Laboratory, to understand the value of, understand the theory behind, and simulate the behaviors of transactive energy systems. This report summarizes recent advances made by this program. The main capability advances include a more comprehensive valuation model, including recommended documentation that should make valuation studies of all sorts more transparent, definition of economic metrics with which transactive mechanisms can be evaluated, and multiple improvements to the time-simulation environment that is being used to evaluate transactive scenarios.
[en] A regional forecast of useful energy demand in seven Norwegian regions is calculated based on an earlier work with a national forecast. This forecast will be input to the energy system model TIMES-Norway and analyses will result in forecasts of energy use of different energy carriers with varying external conditions (not included in this report). The forecast presented here describes the methodology used and the resulting forecast of useful energy. lt is based on information of the long-term development of the economy by the Ministry of Finance, projections of population growths from Statistics Norway and several other studies. The definition of a forecast of useful energy demand is not absolute, but depends on the purpose. One has to be careful not to include parts that are a part of the energy system model, such as energy efficiency measures. In the forecast presented here the influence of new building regulations and the prohibition of production of incandescent light bulbs in EU etc. are included. Other energy efficiency measures such as energy management, heat pumps, tightening of leaks etc. are modelled as technologies to invest in and are included in the TIMES-Norway model. The elasticity between different energy carriers are handled by the TIMES-Norway model and some elasticity is also included as the possibility to invest in energy efficiency measures. The forecast results in an increase of the total useful energy from 2006 to 2050 by 18 o/o. The growth is expected to be highest in the regions South and East. The industry remains at a constant level in the base case and increased or reduced energy demand is analysed as different scenarios with the TIMES-Norway model. The most important driver is the population growth. Together with the assumptions made it results in increased useful energy demand in the household and service sectors of 25 o/o and 57 % respectively.(au)
[en] The aim of this paper is to discuss the period of energy privatisation and liberalisation which began in the 1980s within its wider historical context. The key issues are what has been learned from this recent period, and how significant is it in the light of an energy transition to low carbon energy system by 2050? Energy liberalisation has led to positive and globally widespread but modest efficiency gains but a lack of clearly visible direct benefits to households in many countries. It has significantly improved the governance of monopoly utilities (via independent regulators), the prospects for competition and innovation, and the quality of policy instruments for environmental emissions control (through the emergence of trading mechanisms). We conclude that it is not liberalisation per se that will determine the movement towards a low carbon energy transition, but the willingness of societies to bear the cost, which will be significant no matter what the extent of liberalisation. - Highlights: ► We discuss the period of energy privatisation and liberalisation within its wider historical context. ► Energy liberalisation has led to positive but modest efficiency gains. ► Liberalisation has significantly improved regulation, competition and innovation, and emissions control. ► We conclude that liberalisation per se is not a significant energy transition.
[en] Main output of a NESA: • Identification of gaps ('Gap' = INPRO methodology criterion not met) in existing or planned or planned nuclear energy systems (NES). • Definition of follow up actions to close these gaps. • Note: Even if in assessed NES gaps are found, it may be a good interim NES, if path sustainable system has been defined.
[en] Highlights: • Future optimized scenarios are identified by considering future demands and costs. • Optimized scenarios are identified for three different time-horizons. • A method is proposed for selecting target scenarios from optimized ones. • A technique is proposed to design a smooth transition path. • Best suited transient scenarios are chosen from the selected scenarios. - Abstract: Designing future energy scenarios is an important topic to energy planners. As designing future optimized scenarios is a multi-objective optimization problem; therefore, it is required to identify trade-off scenarios (Pareto-front) in order to optimize conflicting objectives. In this study, three Pareto-fronts are identified for designing future scenarios for Val di Non (VdN) for three different time horizons. As the community has to reach different emission targets in different time horizons, it is require to select the optimized scenarios that fulfill the targets. In this regards, we propose a new approach for selecting scenarios based on maximizing decision space diversity in order to provide a diverse set of scenarios to the decision makers. The technique is tested on optimized scenarios of VdN and three sets containing 10 diverse scenarios for different time horizons are selected. Moreover, a smooth transition (in terms of decision variables) is desirable when having a transition from a scenario from one time horizon to a consecutive time horizon. A novel method is proposed to choose scenarios from the sets for a smooth transition based on minimizing distances among the scenarios. The approach is applied on VdN where transient scenarios are identified among different possible optimized scenarios.