The Emschergenossenschaft is the oldest and biggest public German water board, („Wasserwirtschaftsverband”) located in Essen (North Rhine-Westphalia/Germany) and responsible for the 865 km2 Emscher catchment with 2.2 million citizens. The main tasks are wastewater discharge and treatment, flood protection, groundwater management, settlement of claims caused by hard coal mining, river restoration and protection of ecosystems..
Freshwater ecosystems are vital for biodiversity and human well-being, but remain amongst the most degraded globally. Nature-based Solutions (NbS) offer a promising pathway to restoration, yet implementation remains fragmented and often limited in scale. This paper synthesises insights from 18 demonstration cases across Europe, carried out under the EU Horizon 2020 MERLIN project, to identify key factors enabling the systemic upscaling of freshwater restoration through NbS. Drawing on practical experiences, five interdependent “building blocks” are proposed: (1) comprehensive status review; (2) narratives of the future; (3) evidence-informed approach; (4) resource management and (5) stakeholder engagement. These dimensions reflect cross-cutting challenges and capacities — such as context-sensitive planning, adaptive learning, financing strategies and inclusive governance. While grounded in diverse local contexts, the framework offers a strategic orientation for scientists, practitioners and policy-makers working to align restoration efforts with the ambitions of the European Green Deal and Nature Restoration Regulation. Rather than prescribing uniform solutions, the paper provides practice-informed guidance for embedding restoration in complex social–ecological systems. Highlights Synthesises lessons from 18 diverse freshwater restoration cases across Europe under the MERLIN project;Proposes five strategic building blocks for scaling Nature-based Solutions: system understanding, shared vision, evidence use, resource management and stakeholder engagement;Emphasises the interdependence of ecological, institutional and societal dimensions in upscaling restoration;Demonstrates the value of transdisciplinary collaboration, adaptive planning and embedded implementation;Offers practice-orientated insights aligned with the European Green Deal and Nature Restoration Regulation.
An integrated biogas-to-methanol (B2M) conversion system combining autothermal reforming (ATR) with regenerative methanol (MeOH) synthesis, integrating both oxygen (O2) and hydrogen (H2) from water electrolysis, is designed, commissioned and investigated operationally. The pilot plant is operated under real world conditions at a wastewater treatment plant in western Germany to demonstrate the process using sewage-derived biogas and to investigate its applicability and suitability for decentralized, efficient value-added bio-chemical production from renewable feedstock. The studies conducted at the test plant evaluate system effectiveness by optimizing operational parameters for both ATR (steam-to-carbon ratio [S/C], oxygen-to-fuel ratio [lambda]) and the methanol (MeOH) synthesis process (stoichiometric number [SN], reaction temperature and gas space velocity [GHSV]). Additionally, stable start-up procedures are developed for reliable operation under dynamic conditions, as is expectable in industrial process application. To compare different MeOH synthesis pathways, regenerative synthesis gas-based MeOH-production is set against direct CO2-to-MeOH conversion. Results demonstrate that ATR of biogas produces CO2-rich synthesis gas (SynGas) with excellent methane (CH4) conversion and extremely low soot formation at relatively low reforming temperatures below 750 degrees C. Although the high CO2-content reformate requires substantial H2 injection for stoichiometric MeOH synthesis SynGas conditions, the H2-enhanced SynGas route proves superior to CO2-only operation of the pilot plant, highlighting possible synergies in oxygen-injected ATR and MeOH-synthesis applications. The combined ATR-H2-injection approach yields higher MeOH yields with reduced water formation and improved conversion. The findings from this study support the technical feasibility of the integrated B2M-system and provide operational foundations for economically viable decentralized MeOH-production at biogas facilities and future system scale-up.
