Simulation models and performance assessment of district heating substations

Development of new technologies and methodologies regarding district heating substation operational control strategies are increasingly found nowadays. At the same time a great number of modern buildings are provided with energy monitoring and control systems which supervise and collect operating data from different energy components. Accordingly, an exemplary district heating systems is being implemented in the city of Kortrijk in Belgium, as part of a demonstration zero-carbon neighborhood. This study deals with the energy performance assessment of one of the systems component -the consumer substationinstalled in this low-temperature district heating system. A comparative analysis of the energy performance with several existing district heating substations was carried out. Three different district heating substation models are set up (using TRNsys) for investigation of the gross energy use, energyefficiency and comfort issues. In order to evaluate the performance of the analyzed substations two scenarios concerning the space heating system (radiator or floor heating system) were considered. The study aims to investigate the impact of different operational circumstances on the performance of district heating substations. The study generate understandings for energy saving operational strategies to be developed. Results indicate that the design concept together with a suitable selection of the substation has an important impact on the energy performance of the entire system

Performance assessment of tariff-based air source heat pump load shifting in a UK detached dwelling featuring phase change-enhanced buffering

Using a detailed building simulation model, the amount of thermal buffering, with and without phase change material (PCM), needed to time-shift an air source heat pump's operation to off-peak periods, as defined by the UK 'Economy 10' tariff, was investigated for a typical UK detached dwelling. The performance of the buffered system was compared to the case with no load shifting and with no thermal buffering. Additionally, the load shifting of a population of buffered heat pumps to off-peak periods was simulated and the resulting change in the peak demand on the electricity network was assessed. The results from this study indicate that 1000 L of hot water buffering or 500 L of PCM-enhanced hot water buffering was required to move the operation of the heat pump fully to off-peak periods, without adversely affecting the provision of space heating and hot water for the end user. The work also highlights that buffering and load shifting increased the heat pump's electrical demand by over 60% leading to increased cost to the end user and increased CO2 emissions (depending on the electricity tariff applied and time varying CO2 intensity of the electricity generation mix, respectively). The study also highlights that the load-shifting of populations of buffered heat pumps wholly to off-peak periods using crude instruments such as tariffs increased the peak loading on the electrical network by over 50% rather than reducing it and that careful consideration is needed as to how the load shifting of a group of heat pumps is orchestrated

Ubiquitous energy storage

This paper presents a vision of a future power system with "ubiquitous energy storage", where storage would be utilized at all levels of the electricity system. The growing requirement for storage is reviewed, driven by the expansion of distributed generation. The capabilities and existing applications of various storage technologies are presented, providing a useful review of the state of the art. Energy storage will have to be integrated with the power system and there are various ways in which this may be achieved. Some of these options are discussed, as are commercial and regulatory issues. In two case studies, the costs and benefits of some storage options are assessed. It is concluded that electrical storage is not cost effective but that thermal storage offers attractive opportunities

Distributed generation on rural electricity networks - a lines company perspective : a thesis presented in partial fulfillment of the requirements for the degree of Master of Engineering in Energy Management at Massey University

CD held with Reference copyA number of electricity assets used in rural New Zealand yield a very low return on investment. According to the provisions of the Electricity Act 1992, after 01 April 2013, lines companies may terminate supply to any customer to whom they cannot provide electricity lines services profitably. This research was undertaken to assist the policy makers, lines companies, rural investors on the viability of distributed generation in a rural setting from the point of view of the lines company and the investor as well as to provide recommendations to the problem areas. A dynamic distributed generation model was developed to simulate critical distributed generation scenarios relevant to New Zealand, such as diverse metering arrangements, time dependent electricity prices, peak shaving by load control, peak lopping by dispatchable distributed generation and state subsides, which are not addressed in commercial software. Data required to run the model was collected from a small rural North Island sheep and beef farming community situated at the end of a 26km long radial distribution feeder. Additional operational data were also collected from the community on distributed resources such as solar hot water systems. A number of optimum distributed generation combinations involving a range of technologies under different metering arrangements and price signals were identified for the small and the medium investor. The effect of influencing factors, such as state initiatives and technological growth, on the investor and the lines companies were discussed. Recommendations for future implementation in order to integrate distributed generation on to rural networks were also given. Several key research areas were identified and discussed including low cost micro hydro, wind resource assessment, diversification of the use of the induction generators, voltage flicker and dynamic distributed generation techno-economic forecasting tools

A Three-Step Methodology to Improve Domestic Energy Efficiency

Increasing energy prices and the greenhouse effect lead to more awareness of energy efficiency of electricity supply. During the last years, a lot of technologies have been developed to improve this efficiency. Next to large scale technologies such as windturbine parks, domestic technologies are developed. These domestic technologies can be divided in 1) Distributed Generation (DG), 2) Energy Storage and 3) Demand Side Load Management. Control algorithms optimizing a combination of these techniques can raise the energy reduction potential of the individual techniques. In this paper an overview of current research is given and a general concept is deducted. Based on this concept, a three-step optimization methodology is proposed using 1) offline local prediction, 2) offline global planning and 3) online local scheduling. The paper ends with results of simulations and field tests showing that the methodology is promising.\u

Preliminary design study of a baseline MIUS

Results of a conceptual design study to establish a baseline design for a modular integrated utility system (MIUS) are presented. The system concept developed a basis for evaluating possible projects to demonstrate an MIUS. For the baseline study, climate conditions for the Washington, D.C., area were used. The baseline design is for a high density apartment complex of 496 dwelling units with a planned full occupancy of approximately 1200 residents. Environmental considerations and regulations for the MIUS installation are discussed. Detailed cost data for the baseline MIUS are given together with those for design and operating variations under climate conditions typified by Las Vegas, Nevada, Houston, Texas, and Minneapolis, Minnesota. In addition, results of an investigation of size variation effects, for 300 and 1000 unit apartment complexes, are presented. Only conceptual aspects of the design are discussed. Results regarding energy savings and costs are intended only as trend information and for use in relative comparisons. Alternate heating, ventilation, and air conditioning concepts are considered in the appendix