On Thursday, 15.04.2021, our third NEQ-Works session took place – due to pandemics once again virtually! And even though we are all used to Zoom and Co by now: we can hardly wait to meet again in person sometime in the (hopefully not too distant) future! After a short discussion of several organizational topics, we went straight to work.

While the last session focused on the exchange with partners from practice, we – the doctoral students – had a lot of time to talk among ourselves about the individual dissertations. For this purpose, we were divided into different small groups, just like last time – because it definitely works better in groups of three or four than in a plenary session. After about an hour, there was a short coffee break before we went into the second round with newly mixed groups.

In the individual break-out sessions, the participants each gave a short insight into the status of their dissertations, so that a discussion about various topics arose. For example, there were discussions about data sources and different possibilities for data collection, as well as about methodologies and software for analysis. References to helpful literature, if any, were also brought forth. In addition, at least in some groups, the schedules of the PhDs were in focus, because things are going more or less well everywhere, but thanks to the pandemic definitely not always according to plan!

With a good hour of discussion time per break-out session, there was – in addition to the interdisciplinary exchange – fortunately also the one or other minute to simply get the problems in the everyday life of scientific employees during a pandemic off their chest! It was really good to hear that most of us are going through a similar situation and that we are not alone with our problems and worries!

Finally, there was unanimous positive feedback to our two coordinators for the successful format of virtual discourse! We would like to take this opportunity to thank Canan and Christine once again for their work and effort in bringing us back to the exchange in different ways!

29.10.2020 Workshop// Post by Antonia Stratmann and Christian Thommessen

CIRED (Congrès International des Réseaux Electriques de Distribution) is a major international conference in the field of power supply systems. Since the early 1970s, the conference has been held every two years at different venues throughout Europe and is characterised in particular by its proximity to industry and its focus on distribution networks.

In 2019, the conference was held in Madrid and, over a total of four days, dealt with almost all current issues in the field of electricity supply. In six technical sessions, current research results and developments in the fields of plant engineering, planning, operation and control of electrical networks and many other topics were presented.

The opening of the conference was thematically determined by the EU legislative package Clean Energy for All Europeans. The legislative package comprises four directives as well as four regulations and, together with other legislative acts, constitutes the framework for the implementation of the Energy Union and the European climate and energy targets until 2030. In a panel discussion, representatives of various interest groups debated the challenges and opportunities of the new legal acts. In particular, the future role of prosumers was intensively discussed. Prosumer is a portmanteau word made up of the terms producer and consumer and describes an agent who can both purchase electricity and generate it and then consume it individually or feed it into the grid. The lively debate provided impulses for further work on the research questions of the NEQ Graduate School.

All in all, attending the CIRED 2019 conference provided exciting insights into a broad spectrum of practice-oriented content, and through direct contact with experts it was possible to gain valuable advice on planned examinations.

District Heating (DH) is based on the fundamental idea of using local fuel or heat resources – which would otherwise be wasted – to satisfy local customer demands for heating. Hereby, a heat distribution network of pipes act as a local market place. Traditionally, excess heat resources have their origin in other energy sectors, i.e. combined heat and power (CHP) plants for generating electricity generation or industrial processes. Today, there is an additional interest in the use of renewables in DH systems, e.g. geothermal, solar thermal, biomass. A combination of providing recycled or renewable heat is the focus for future DH systems. As a result ordinary primary energy supply for heat demands will be substituted and lower environmental impact will be achieved.

Globally, DH systems able to fulfil the fundamental idea are very different regarding their market penetration, use of resources, network size, as well as environmental impact. However, the main merit of DH is always similar: there are lower heating costs in (high) dense urban areas with concentrated heat demands, especially in times with high international fuel prices. The costs for heat generation, distribution and consumption are even lower when considering damage costs for climate impacts in the form of e.g. taxes.

In some countries DH systems provide heat to about half of the national building stocks, whereas there are other countries with only a few systems because of lower awareness or competitiveness. Commercial DH was introduced in the American cities of Lockport and New York in the late 19^th century. Thereafter, the progress of DH has taken different directions across Europe. Most countries developed DH in response to minimize the importation of fuels. However, the first European DH systems were introduced in Germany in the 1920’s. The very first German DH system was operated in the city of Hamburg, because of a war straff: after the First World War France rose up the price on coal (in the Ruhr area). As a result, DH was a cheaper and more efficient solution for heating buildings. During both oil crises in the 1970’s, the international oil price rose so high that as a reaction, the general interest in DH and its optimization increased significantly. Utilities in Germany found that DH was the best way of using the energy from municipal waste, which is today an important part of DH schemes (e.g. in Vienna or Copenhagen).

The Scandinavian and German DH industries spent a lot of time and money on research and development to support the technological process. Improved energy efficiency and several (upcoming) fuel changes in the electricity sector, make CHP generation attractive. DH temperatures are crucial to the overall system efficiency. Current DH research focuses on optimizing supply and return temperatures, as well as optimizing CHP plant operation considering both, the electricity and the heating sector and markets, respectively. Hereby, thermal storages enable the DH to be supplied at the lowest costs and to bridge the time between heat generation and distribution. Furthermore, the development of better piping technology for the DH networks is ongoing. Pre-insulated piping systems are state-of-the-art since the 1960’s, but there are improvements needed in order to become the reliable, cost-efficient basis of novel DH schemes with lower temperatures. Finally, the mature technology of surveillance systems, sophisticated controls and heat meters needs to evolve and make DH smart in the sense of digitalization. Operating DH temperatures will be much lower than in the past (i.e. well below 100 °C), so that heat loss reduction and an efficient heat generation become crucial.

All in all DH technology is improving so that DH becomes a significant element of several heating markets in European countries, especially in Germany. Today, district energy systems are analyzed and planned in a more holistic way than in the past. In order to encompass several sectors (i.e. electricity, heating and transportation) DH is increasingly seen as an integral part of the overall energy system. In Germany DH can be an essential element to enable the usage of the increasing intermittent renewable electricity. This results in a more efficient usage of fossil fuels for residual loads and lower greenhouse gas or carbon emissions. In high-dense urban cities DH will be the form of heating with the lowest costs due to its ability to use a range of (locally available) heat sources, especially waste heat from CHP plants and industrial processes, as well as renewable heat. DH is a major benefit in increasing supply diversity and reducing dependence on imported fuels by third parties.