SCCER JA-RED - A list of possible ancillary services for enhanced grid operation and implementation of the most effective ones at the RE demo site - Deliverable 1.2.3

There is a need by distribution system operators and power suppliers to propose ancillary services to enhanced grid operation allowing the optimal deployment of photovoltaic panels, cogeneration technologies and distributed storage. This deliverable therefore proposes and evaluates the impact of a list of possible ancillary services for the injection of local renewable energy in the future low voltage grid. The novelty of the proposed building to district and district to grid approaches lies in the ability to generate a wide range of optimal energy transition scenarios using multi-objective optimisation techniques both at building and district level. The proposed approach differs from previous work by integrating ancillary services by optimizing simultaneously both sizing and operation of the district energy technologies. This deliverable demonstrates, on the reference case (TR3716), the implementation of voltage control ancillary services to integrate more renewable energy to the low voltage grid. In particular it exposes how advanced electricity tariffs can influence energy system design and operation to decrease stress induced by high PV penetration on the grid. The proposed implementation can be deployed in control boxes developed using open-source standards, such as mikrobus. Moreover, considering the transformer’s area as a relevant scale for the implementation of ancillary services, this work pave the way to the definition of a new geographical division for territorial energy planning aiming at the integration more renewable energy resources in urban areas.

Potential of Photovoltaic Panels on Building Envelopes for Decentralized District Energy Systems

Francesco Baldi, Luc Girardin, François Maréchal, Luise Middelhauve

The expected increase of the penetration of distributed renewable energy technologies into the electricity grid is expected to lead to major challenges. As a main stakeholder, authorities often lack the appropriate tools to frame and encourage the transition and monitor the impact of energy transition policies. This paper aims at combining relatively detailed modeling of the PV generation potential on the building's envelope while retaining the energy system optimization approach. The problem is addressed as a multiobjective, mixed-integer linear programming problem. Compared to the existing literature in the field, the proposed approach combines advanced modeling of the energy generation potential from PV panels with detailed representation of the district energy systems, thus allowing an accurate representation of the interaction between the energy generation from PV and the rest of the system. The proposed approach was applied to a typical residential district in Switzerland. The results of the application of the proposed method show that the district can achieve carbon neutrality based on PV energy alone, but this requires covering all the available district's rooftops and part of the district's facades. Whereas facades are generally disregarded due to their lower generation potential, the results also allow concluding that facade PV can be economically convenient for a wide range of electricity prices, including those currently used by the Swiss grid operators. Achieving self-sufficiency at district scale is challenging: it can be achieved by covering approximately 42-100% of the available surface when the round-trip efficiency decreases from 100 to 50%. The results underline the importance of storage for achieving self-sufficiency: even with 100%, round-trip efficiency for the storage, very large capacities are required. However, energy demand reduction through renovation would allow reaching self-sufficiency with half of the PV and storage capacity required.

2021

Optimisation of Urban Form by the Evaluation of the Solar Potential

Marylène Montavon

What will the cities of tomorrow look like? This is a crucial question because in the four and a half billion years of its existence, the Earth has never been so threatened, as it is today. Since 2008 half of the world's population has lived in towns – more than 70% in rich nations. Three quarters of CO2 emissions are produced in towns, 75% of the world's energy is consumed in towns. The battle for our climate, for the continuation of our species and all other life, will be largely waged in cities. Will it be possible to create the ideal ecological town? The objective of this study is to compare actual and theoretical urban forms in order to explore the diverse effects of daylighting and solar potential on densely built-up sites. Indeed, the search for ideal solar orientations has been a persistent problem from the 19th century until the beginning of the 20th. Even today, for all our scientific knowledge and empirical experience of solar energy, making the correct choice has still not crossed the boundary from an enigmatic, tricky art into the field of an exact science. As a first step, six existing urban sites in Switzerland and Brazil, as well as two projects in the United Kingdom, a few generic models and a utopian city, were modelled and analyzed. The goal was not merely the construction of new, exemplary districts but also the transformation of existing towns. The findings have been used to assess the potential of façades and roofs located in urban areas for active and passive solar heating, photovoltaic electricity generation and daylighting. The results obtained from these different case studies revealed large variations of the potential for solar energy collection on the buildings' façades and roofs. Ideally, these investigations are expected to help architects and town planners understand how to optimise solar collection on buildings design. In addition, a study was made of the Contemporary City of Three Million Inhabitants created by Le Corbusier. According to the latter, the Contemporary City could increase the urban capacity and at the same time improve the urban environment and the efficiency of the city. Therefore the present study extracted the solar potential of this utopian city in order to assess Le Corbusier's propositions. Since 1922, Le Corbusier's studies have influenced architects and town-planners in their choice of orientations and urban forms: it was therefore crucial to discover if this reliance on Le Corbusier was justified. Solar irradiation and illuminance values obtained through numerical simulations form the core part of the method. The method adopted for the entire set of computer simulations consisted in modelling — via a computer-aided drawing piece of software, namely AutoCAD — the digital model of each building or group of buildings prior to exporting them to an urban performance analysis software (PPF/RADIANCE software package). Spatial distributions of solar irradiation and daylight fluxes over the overall building façades and roofs were calculated using ray-tracing simulation techniques to determine the appropriate placement of different solar technologies (passive and active solar, photovoltaic and daylighting). Performance indicators were used to assess the solar utilisation potential of the urban sites (e.g. statistics of sky view factors and daylight factors) in order to determine the optimal solar strategies for a given urban context. In addition, various works and sun-related recommendations that have appeared mainly since the end of the nineteenth century, together with the various scientific models and software tools pertaining to this topic, are presented in this study.

EPFL2010

SCCER JA-RED - Detailed evaluation of the grid operation bottlenecks and load shifting potential for the reference system - Deliverable 1.2.2

Lionel Benjamin Bloch, Luc Girardin, Jordan Holweger, Luise Middelhauve, Paul Michael Stadler

Based on the analysis of the reference case, models developed at the PVLAB-EPFL and IPESEEPFL have been valued and improved to assess the impact of distributed generation and ancillary services on REel demonstrator. The models are used to evaluate solutions capable to cope with the variability and uncertainty of renewable energy generation, avoiding curtailment and reliably supplying all the demanded energy to customers. The database compiled by the JA-RED partners [10], have been enhanced and converted into an essential tool to support communication and strategic decisions among the REel Demonstrator Community. This database contains for each building the typology, the actual energy agents, an estimation of the energy demand, the relation with the injection point of the energy distribution networks and the actual usage and potential of renewable energy such as the solar PV potential. In order to evaluate the energy flow in the grid with sufficient precision, skills have been developed in the allocation of stochastic load profiles from aggregated measurements. Moreover, the profiles for PV generation have been refined considering the optimal roof’s area and orienta tion. Methods to assess the power grid flexibility are based on both consumers behaviour and technical and operational flexibility. The assessment of the latest relies on a model recently developed for the generation optimal design and operation of energy technologies in buildings [17]. Finally, the limits imposed by the existing power supply infrastructure have been identified using a power flow algorithm to conduct grid stability assessment and detect the bo􀆩lenecks in the power grid. For this task, the stochastic nature of the proposed load profile allocation model is fundamental.

2019