• Energy Research

This work studies the transformation of energy grids of the European Union (EU) in the frame of the energy transition. Three energy grid types are considered namely the electricity, thermal and gas grids. Regarding electricity grids, we investigate the required reinforcements of the low-voltage networks (e.g. replacing the distribution transformer by one of higher nominal power, replacing cables by cables of larger cross-section) in order to integrate residential low-carbon technologies such as heat pumps, photovoltaic systems and electric vehicles. To do so, we develop a methodology for the quantification of EU low-voltage grid reinforcement costs following residential low-carbon technologies integration. This methodology uses urbanisation data to determine the share of dwellings in rural and urban areas in EU28 countries (EU27 + United Kingdom). It is also based on a model that quantifies the grid reinforcement cost as a function of the low-carbon technologies integration scenario for representative rural and urban grids. This model is composed of three sub-models, namely the dwelling, grid and economic models. We also collected data from 24 open access grids (i.e. grids of which the specifications are freely accessible online) and 23 scientific articles and reports to determine the parameter values of the grid and economic models for EU28 countries. Finally, we provide example applications that illustrate the methodology by computing the grid reinforcement costs from heat pumps and photovoltaic systems integration in Belgium and Italy. Results indicate that, in the largest majority of cases, both for Belgian and Italian grids, the reinforcement cost per dwelling remains below 350 € per dwelling (total cost for the whole lifespan of 33 years). The only case where more significant reinforcement costs occurred (> 350 €/dwelling and up to 1150 €/dwelling) is for the Belgian rural grid with heat pump integration rates larger than 40%. When it comes to thermal grids, we investigate the deployment of district heating, a heat supply technology that by its fundamental idea incorporates energy efficiency and thus can trigger important greenhouse gas emissions reduction. For this purpose, we proposed an approach to map the cost of thermal grids deployment per heat demand unit in the EU. This approach is based on the concept of representative thermal grids which corresponds to a principal equation that defines the distribution capital costs as the ratio of empirically derived specific investments costs and the linear heat density. In the sEEnergies project, this concept is expanded to comprise better cost models based on actual district heating network layouts at the spatial resolution of 1 hectare. While in the Heat Roadmap Europe project, the variables were generated only for the 14 EU Member States with largest annual volumes of building heat demands, the present approach covers all EU27 Member States plus United Kingdom. In this deliverable, we focus on the current year, while the deliverable 4.5 focuses on the future years. Regarding gas grids, we present the key technical and economic characteristics of the existing gas grids and storages in the EU28 countries. We focus not only on infrastructure for natural gas but also for biogas, biomethane, syngas and hydrogen, which could play an important role in the decrease of greenhouse gas emissions. This techno-economic review provides important information to assess the cost of retrofitting and developing gas grids depending on the decarbonisation scenarios. Cite as: Meunier, S., Protopapadaki, C., Persson, U., Sánchez-García, L., Möller, B., Wiechers, E., Schneider, N.C.A, Saelens, D. (2021). Cost and capacity analysis for representative EU energy grids depending on decarbonisation scenarios. Report in the frame of the H2020 EU project sEEnergies.

Abstract This paper evaluates simple metamodels to predict local electricity demand and grid restrictions, in residential neighborhoods with heat pumps and photovoltaics. The procedure and challenges of developing such models are described. Modeling is based on results obtained from detailed simulation of buildings and the grid. Linear and logistic regression models are developed for electricity demand and minimum voltage respectively, as a function of neighborhood characteristics, related to both building and electrical network properties. The paper shows that linear regression can be used for a first evaluation of electricity demand. For voltage violations, logistic regression gives acceptable results; however, more complex models are needed to approximate voltage levels.

Abstract Integrating low-carbon technologies (e.g. heat pumps, photovoltaic systems) in buildings influences the stability of the low-voltage grid, which therefore often requires to be reinforced. This article proposes a techno-economic methodology to identify the reinforcements needed to maintain grid stability at the lowest life-cycle cost. Novel contributions include the consideration of three-phase connection of low-carbon technologies as a reinforcement option and the fact that we study to what extent grid reinforcements can mitigate voltage unbalance issues. Additionally, to reduce computing time, a dummy island approach is used, whereby one feeder is modelled in detail and the remainder of the distribution island is represented by an aggregated load. Finally, random repetitions are proposed, to consider uncertainties related to building properties, occupants and the location of low-carbon technologies in the feeders. The methodology is applied to investigate the integration of heat pumps and photovoltaic systems in typical Belgian rural and urban grids. For the rural grid, heat pumps may lead to significant reinforcement costs (up to 1230 €/dwelling), mainly due to voltage stability problems. For the urban grid, heat pump and photovoltaic integration causes low reinforcement cost (

Abstract Heating electrification powered by distributed renewable energy generation is considered among potential solutions towards mitigation of greenhouse gas emissions. Roadmaps propose a wide deployment of heat pumps and photovoltaics in the residential sector. Since current distribution grids are not designed to accommodate these loads, potential benefits of such policies might be compromised. However, in large-scale analyses, often grid constraints are neglected. On the other hand, grid impact of heat pumps and photovoltaics has been investigated without considering the influence of building characteristics. This paper aims to assess and quantify in a probabilistic way the impact of these technologies on the low-voltage distribution grid, as a function of building and district properties. The Monte Carlo approach is used to simulate an assortment of Belgian residential feeders, with varying size, cable type, heat pump and PV penetration rates, and buildings of different geometry and insulation quality. Modelica-based models simulate the dynamic behavior of both buildings and heating systems, as well as three-phase unbalanced loading of the network. Additionally, stochastic occupant behavior is taken into account. Analysis of neighborhood load profiles puts into perspective the importance of demand diversity in terms of building characteristics and load simultaneity, highlighting the crucial role of back-up electrical loads. It is shown that air-source heat pumps have a greater impact on the studied feeders than PV, in terms of loading and voltage magnitude. Furthermore, rural feeders are more prone to overloading and under-voltage problems than urban ones. For large rural feeders, cable overloading can be expected already from 30% heat pump penetration, depending on the cable, while voltage problems start usually at slightly higher percentages. Additionally, building characteristics show high correlations with the examined grid performance indicators, revealing promising potential for statistical modeling of the studied indicators. Further work will be directed to the assessment of meta-modeling techniques for this purpose. The presented models and methodology can easily incorporate other technologies or scenarios and could be used in support of policy making or network design.

State-of-the-art Modelica tools for modelling and simulating multi-physical systems have reached certain maturity among the building physics community. Hence, simulation is widely used for control,...

Heat pumps are widely recognized as a key technology to reduce CO2 emissions in the residential building sector, especially when the electricity-generation system is to decarbonize by means of large-scale introduction of renewable electric power generation sources. If heat pumps would be installed in large numbers in the future, the question arises whether all building types show equal benefits and thus should be given the same priority for deployment. This paper aims at answering this question by determining the CO2-abatement cost of installing a heat pump instead of a condensing gas boiler for residential space heating and domestic hot-water production. The electricity system, as well as the building types, are based on a possible future Belgian setting in 2030 with high RES penetration at the electricity-generation side. The added value of this work compared to the current scientific literature lies in the integrated approach, taking both the electricity-generation system and a bottom up building stock model into account. Furthermore, this paper analyzes the possible benefits of active demand response in this framework. The results show that the main drivers for determining the CO2-abatement cost are the renovation level of the building and the type of heat pump installed. For thoroughly insulated buildings, an air-coupled heat pump combined with floor heating is the most economic heating system in terms of CO2-abatement cost. Finally, performing active demand response shows clear benefits in reducing costs. Substantial peak shaving can be achieved, making peak capacity at the electricity generation side superfluous, hence lowering the overall CO2-abatement cost.