Energy systems across the globe are going through a radical transformation as a result of technological and institutional changes, depletion of fossil fuel resources, and climate change. At the local level, increasing distributed energy resources requires that the centralized energy systems be re-organized. In this paper, the concept of Integrated community energy systems (ICESs) is presented as a modern development to re-organize local energy systems to integrate distributed energy resources and engage local communities. Local energy systems such as ICESs not only ensure self-provision of energy but also provide essential system services to the larger energy system. In this regard, a comparison of different energy system integration option is provided. We review the current energy trends and the associated technological, socio-economic, environmental and institutional issues shaping the development of ICESs. These systems can be applied to both developed and developing countries, however, their objectives, business models as well as composition differs. ICESs can be accepted by different actors such as local governments, communities, energy suppliers and system operators as an effective means to achieve sustainability and thereby will have significant roles in future energy systems.

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Energetic communities for community energy: A review of key issues and trends shaping integrated community energy systems

Exergy, exergoeconomic and environmental analyses and evolutionary algorithm based multi-objective optimization of combined cycle power plants

Paradigm shift in urban energy systems through distributed generation: Methods and models

We present a comprehensive review of modelling approaches and associated software tools that address district-level energy systems. Buildings play an important role in urban energy systems regarding both the demand and supply of energy. It is no longer sufficient to simulate building energy use assuming isolation from the microclimate and energy system in which they operate, or to model an urban energy system without consideration of the buildings that it serves. This review complements previous studies by focussing on models that address district-level interactions in energy systems, and by assessing the capabilities of the software tools available alongside the theory of the modelling approaches used. New models and tools that address these district-level interactions are reviewed and their competences assessed. These are divided into the following sections: district energy systems (including heat networks, multi-energy systems and low-temperature networks), renewable energy generation (including solar, bioenergy, wind and the related topic of seasonal storage), and the urban microclimate as it relates to energy demands. The scope and detail covered by twenty cross-disciplinary tools is summarised in a matrix; many other tools that focus on specific areas are also discussed. We end by summarising the current state of district-scale urban energy modelling as it relates to the built environment, along with our perspective on future challenges and research directions.

A review of modelling approaches and tools for the simulation of district-scale energy systems

This article investigates 40 thermal networks in operation in Europe that are able to cover both the heating and cooling demands of buildings by means of distributed heat pumps installed at the customer substations. The technology of thermal networks that work at a temperature close to the ground, can strongly contribute to the decarbonisation of the heating and cooling sector and furthermore exploit a multitude of low temperature heat sources. Nevertheless, the nomenclature used in literature shows that misinterpretations could easily result when comparing the different concepts of thermal networks that operate at a temperature level lower than traditional district heating. The scope of this work is to revise the definitions encountered and to introduce an unambiguous definition of Fifth-Generation District Heating and Cooling networks. A drawback-benefit analysis is presented to identify the pros and cons of such technology. The survey on the current networks shows that on average three Fifth-Generation District Heating and Cooling systems per year have entered the heating and cooling market in the last decade. Pioneer countries in such technology are Germany and Switzerland. For some networks, the assessed Linear Heating Power Demand Density results are lower than the feasibility threshold adopted in traditional district heating. High performances and low non-renewable primary energy factors are achieved in systems that exploit a very high share of renewable or urban excess heat sources. With respect to traditional district heating, the surveyed pumping energy consumptions result one order of magnitude higher, whereas the implemented control strategies can be completely different, leading the network temperature to float freely.

5th generation district heating and cooling systems: A review of existing cases in Europe

Exergy analysis of renewable energy-based climatisation systems for buildings: A critical view

Low Exergy Systems for High-Performance Buildings and Communities

https://orbit.dtu.dk/files/133956922/1_s2.0_S1876610217322592_main.pdf

Low Temperature District Heating for Future Energy Systems

Development of system concepts for improving the performance of a waste heat district heating network with exergy analysis

The low exergy approach should be the key concept in any long term strategy aiming at creating a sustainable built environment. In recent years, how to build sustainable houses has been a constant source of discussion. A highly efficient usage of energy and all of the potentials in the involved energy flows are undisputable mandatory for that. To find and to quantify further potentials in energy use, the thermodynamic concept of exergy can be beneficial. Energy, which is entirely convertible into other types of energy, is exergy (high valued energy such as electricity and mechanical workload). Energy, which has a very limited convertibility potential, such as heat close to room air temperature, is low valued energy. Low exergy heating and cooling systems use low valued energy, which could also easily be delivered by sustainable energy sources (e.g. by using heat pumps, solar collectors or others). Common energy carriers like fossil fuels deliver high valued energy. Heat emission systems, that are often part of the building construction itself, have a much longer service lifetime than building service equipment, such as boilers or chillers. With appropriate emission systems, the overall system design of a building is flexible in meeting future requirements, and they are open to being supplied by low temperature energy sources, such as renewable ones. There are already a number of different low temperature components, systems and technologies on the market, such as the known hydronic floor heating systems. Examples of buildings equipped with low exergy heating and cooling systems from all over the world and from all kinds of buildings, from newly erected to retrofit, from dwellings to commercial buildings, and also cultural monuments, such as churches and castles are collected during the course of the project.

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Dietrich Schmidt

Papers

Exergy analysis of renewable energy-based climatisation systems for buildings: A critical view

Low Exergy Systems for High-Performance Buildings and Communities

Low Temperature District Heating for Future Energy Systems

Development of system concepts for improving the performance of a waste heat district heating network with exergy analysis

Low Exergy Systems for Heating and Cooling of Buildings