Berliner Energieagentur (Germany)

District heating is pivotal in urban decarbonization. As cities strive for climate neutrality, understanding emissions across the district heating supply chain is essential. Yet most studies focus on heat generation and fuel supply, while impacts of distribution infrastructure receive far less attention. This study closes that gap by delivering the first system-wide, bottom-up carbon footprint assessment of a metropolitan district heating network using real operational data from Berlin. Results show fuel combustion accounts for about 87% of total emissions, plant construction for 2%, and the distribution network for roughly 11%. Around 70% of network-related emissions stem from civil engineering activities such as excavation and backfilling. When comparing plastic casing pipes and ducted steel pipes, distinct embodied emission profiles emerge. However, civil engineering impacts remain the dominant factor. In addition, road restoration proves critical, as asphalt reinstatement generates nearly twice the emissions of natural stone pavement. Building on this, a scenario analysis indicates that bundling house-connection works can cut emissions by 12.8% by avoiding repeated excavation and transport processes. Looking ahead, as heat generation becomes increasingly decarbonized, the relative importance of infrastructure emissions will rise, making low-carbon construction and planning strategies indispensable. This approach calls for integrating carbon-footprint accounting into heating plans and regulations, prioritizing low-emission materials, and coordinating construction processes. The study offers a system-wide evidence base to help policymakers and utilities design infrastructure strategies aligned with climate-neutral district heating. • Infrastructure construction contribute up to 71% of emissions in the district heating network. • Network construction accounts for 11.2% of CO 2 emissions in the supply chain. • Using asphalt for pipe installation doubles CO 2 emissions compared to using natural stone. • Bundled house connections reduce emissions by 12.8%. • First systematic CO 2 analysis of Berlin’s district heating infrastructure.

We observe defect formation at the metal halide perovskite (MHP)/ALD-NiO x interface, as revealed by HAXPES. Introduction of an organic buffer layer minimizes these defects, leading to improved device performance.

Production of electrolytic hydrogen and its conversion to methane, also known as power-to-gas (PtG), could play a key role in the transition towards a defossilised energy system. Integration of PtG technology with wastewater treatment and co-digestion presents an opportunity to produce low-carbon methane while simultaneously upgrading biogas, recycling biogenic carbon dioxide and utilising process by-products (heat and oxygen). A model of such an integrated system was developed using real plant data to assess the techno-economic performance through simulation of hourly operation and configuration optimisation. The integrated concept was demonstrated to be a promising option for increasing efficiency and reducing costs and emissions in the PtG system. By-product utilisation increased net energy efficiency from 52.3 to 59.7 %HHV, leading to a reduction in levelised cost of PtG (LCOPtG) of 1.0 % and in net specific emissions of 28.3 % and 2.2 % based on average and marginal grid emission factors respectively. Minimum LCOPtG of 194.6 €/MWhCH4 was achieved, which entailed average and marginal net specific emissions of 37.2 and 635.2 gCO2/kWhCH4, respectively. In the investigated conditions, the optimised PtG configuration produced heat in excess, but could not fulfil oxygen demand at the wastewater treatment plant. Heat integration yielded considerable performance improvements, while oxygen integration provided only minor benefits and slightly increased overall production costs. However, improved economic performance of oxygen integration was shown to be possible depending on local conditions. Although integrating several independent systems introduced the challenge of managing fluctuating heat and oxygen demand, alongside the varying supply of biogas and renewable electricity, the difference in magnitude between by-product generation and demand meant that their utilisation had only a minor impact on system operation.

The global energy system is undergoing a major transition, and in energy planning and decision-making across governments, industry and academia, models play a crucial role. Because of their policy relevance and contested nature, the transparency and open availability of energy models and data are of particular importance. Here we provide a practical how-to guide based on the collective experience of members of the Open Energy Modelling Initiative (Openmod). We discuss key steps to consider when opening code and data, including determining intellectual property ownership, choosing a licence and appropriate modelling languages, distributing code and data, and providing support and building communities. After illustrating these decisions with examples and lessons learned from the community, we conclude that even though individual researchers' choices are important, institutional changes are still also necessary for more openness and transparency in energy research.

Abstract An interdisciplinary study was carried out to trace the hydrological changes of the Havel River in northeastern central Europe over the last ca. 2000 years. This research was driven by the hypothesis that the present‐day riverscape is to a large degree a result of medieval and modern human transformation of the drainage system. The river system forms a series of dammed lakes and river sections that were greatly altered through hydraulic engineering in the past. Along the middle course of the Havel, 16 sedimentary sequences available for geoarchaeological and paleoecological research were analyzed in order to reconstruct regional water level dynamics. Chronological control was ensured through a multitude of palynological, dendrochronological, archaeological, and radiocarbon data. The sections upriver from the Brandenburg/H. and Spandau weirs, representing sites with historic watermills, reveal substantial water level changes during the late Holocene. Generally, lower water levels before and higher levels during the medieval German colonization of that area (ca. A.D. 1180/1250) can be inferred. This water level increase, which is primarily attributed to dams constructed for watermills and secondarily due to a multitude of fish weirs, took place rapidly and amounted to a relative height of ca. 1.5 m. It enlarged the river's cross‐sections and increased the size of existing lakes or initiated secondary lakes that previously aggraded, and thus caused flooding of large parts of land. The rising water level even influenced the settlement topography to a large degree. Several medieval rural settlements were abandoned due to flooding. In total, a ca. 150‐km long dammed lake cascade was formed.