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Supplementary material for the publication " Agricultural biogas plants as a hub to foster circular economy and bioenergy: An assessment using material substance and energy flow analysis" Burg, V., b, Rolli, C., Schnorf, V., Scharfy, D., Anspach, V., Bowman, G. Today's agro-food system is typically based on linear fluxes (e.g. mineral fertilizers importation), when a circular approach should be privileged. The production of biogas as a renewable energy source and digestate, used as an organic fertilizer, is essential for the circular economy in the agricultural sector. This study investigates the current utilization of wet biomass in agricultural anaerobic digestion plants in Switzerland in terms of mass, nutrients, and energy flows, to see how biomass use contributes to circular economy and climate change mitigation through the substitution effect of mineral fertilizers and fossil fuels. We quantify the system and its benefits in details and examine future developments of agricultural biogas plants using different scenarios. Our results demonstrate that agricultural anaerobic digestion could be largely increased, as it could provide ten times more biogas by 2050, while saving significant amounts of mineral fertilizer and GHG emissions.

The expansion of irrigated agriculture has increased global crop production but resulted in widespread stress to freshwater resources. Ensuring that increases in irrigated production only occur in places where water is relatively abundant is a key objective of sustainable agriculture, and knowledge of how irrigated land has evolved is important for measuring progress towards water sustainability. Yet a spatially detailed understanding of the evolution of global area equipped for irrigation (AEI) is missing. Here we utilize the latest sub-national irrigation statistics (covering 17298 administrative units) from various official sources to develop a gridded (5 arc-min resolution) global product of AEI for the years 2000, 2005, 2010, and 2015. We find that AEI increased by 11% from 2000 (297 Mha) to 2015 (330 Mha) with locations of both substantial expansion (e.g., northwest India, northeast China) and decline (e.g., Russia). Combining these outputs with information on green (i.e., rainfall) and blue (i.e., surface and ground) water stress, we also examine to what extent irrigation has expanded unsustainably (i.e., in places already experiencing water stress). We find that more than half (52%) of irrigation expansion has taken place in regions that were already water stressed, with India alone accounting for 36% of global unsustainable expansion. These findings provide new insights into the evolving patterns of global irrigation with important implications for global water sustainability and food security. Recommended citation: Mehta, P., Siebert, S., Kummu, M. et al. Half of twenty-first century global irrigation expansion has been in water-stressed regions. Nat Water (2024). https://doi.org/10.1038/s44221-024-00206-9 Open-access peer reviewed publication available at https://www.nature.com/articles/s44221-024-00206-9 Files G_AEI_*.ASC were produced using the GMIA dataset[https://data.apps.fao.org/catalog/iso/f79213a0-88fd-11da-a88f-000d939bc5d8]. Files MEIER_G_AEI_*.ASC were produced using Meier et al. (2018) dataset [https://doi.pangaea.de/10.1594/PANGAEA.884744].

UNEP/GRID-Geneva established the Global Sand Observatory initiative as a direct response to requests to identify knowledge gaps under the UNEA-4 Mineral Resource Resolution (UNEP/EA.4/Res.19). Sand resource governance is complex, spanning policy domains, stakeholders and sectors. Establishing consensus on key terms on the sand and sustainability topic is therefore key, and requires reviewing language, definitions and terminology. This will be important to initiate cross-sectoral and multi-actor discussions to define problems and update goals and key results in implementing policies and laws governing sand resources. This document is version 1 of what will be a living repository of terms and definitions being adopted as we explore themes in sand and sustainability at UNEP/GRID-Geneva following the UNEA-5 Minerals and Metals Management Resolution (UNEP/EA.5/Res.12). UNEP/GRID-Geneva shares this working research product openly in the spirit of open science, giving free access for all and seeking feedback and corrections.

Abstract: Waste heat energy discharged into the atmosphere is one of the largest sources of clean, fuel-free and inexpensive energy available. Although technologies such as thermoelectric and thermo-electrochemical cells have been around for a long time, there is still no environmentally sustainable and efficient technology platform available for viable harvesting of low-grade waste heat. The central aim of our project (TRANSLATE) is to develop a nanofluidic platform technology based on large ion flux in nanochannels under a thermal gradient. This technology utilises Earth-abundant materials such as anodic aluminum oxide (AAO) and cellulose membranes for the development of a versatile and sustainable energy harvesting and storage platform. This presentation will provide an overview of the project on low-grade waste heat harvesting in ionic nanofluidic membranes. A key enabler for achieving greater waste heat to electrical energy conversion efficiencies is the overlap of electric double layers (EDLs) in very narrow channels. These overlapping EDLs cause a surge of ions (ion flux) into the ‘hot entrances’ of the nanochannels resulting in an enhanced thermovoltage, i.e. high waste heat conversion. The nanochannels with a diameter of ~10 nm and a length ranging from a few micrometers to several millimeters are created by two-stage aluminum anodization (for AAO), chemical treatment of natural wood (for cellulose). To increase the charge density, the surface of the nanochannels is functionalized, which leads to the appearance of overlapping EDL. We will present initial experimental results with aqueous electrolytes (KCl, NaCl etc.) that are capable of converting low-grade heat with thermopowers up to 1–3 mV/K, which is higher than that of conventional solid-state thermoelectric converters. Variation of the geometric parameters of the nanochannels, the type and concentration of the electrolyte, as well as the surface charge density of the nanochannels can result in a much higher ionic thermovoltage. With such a high thermopower, ionic nanofluidic membranes can be a game changer in the field of thermoelectric power conversion. Additional Information: Dr Subhajit Biswas presented at the HZDR NanoNet+ workshop on 4-6 October 2022 in Görlitz, Germany. TRANSLATE is a €3.4 million EU-funded research project that aims to develop a new nanofluidic platform technology to effectively convert waste heat to electricity. This technology has the potential to improve the energy efficiency of many devices and systems, and provide a radically new zero-emission power source. The TRANSLATE project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement number 964251, for the action of 'The Recycling of waste heat through the Application of Nanofluidic ChannelS: Advances in the Conversion of Thermal to Electrical energy’. More information can be be found on the TRANSLATE project website: https://translate-energy.eu/

Climate change in temperate mountain systems and associated increase in temperature and decrease in precipitation are expected to have strong implications for vegetation productivity, species diversity and carbon turnover in subalpine grasslands. Little is known, however, about the interaction between the effects of climate change and those of local land use management and possible changes in landscape structure. Pasture woodlands in the Swiss Jura Mountains are a traditional landscape, resulting from a long-lived sustainable use of grasslands and woodlands, and as such provide a suite of important ecosystem services to human society. These range from carbon sequestration and biodiversity preservation, to provision of timber and forage for livestock, and last but not least an aesthetic value, much appreciated by tourism. In this thesis various aspects of ecosystem functioning have been studied, investigating the combined effects of experimental climate change and land use on structurally different wooded pastures. An altitudinal gradient method has been used to simulate future climate change conditions, by imposing warmer and drier climate on subalpine turfs transplanted at lower elevation. The resulting gradient in mean annual temperature and precipitation – ranging from cold and wet in the subalpine zone, to warm and dry in the colline zone – has allowed for the detection of tipping points and altered states of ecosystem functioning in response to the treatments. The method employed provided also the possibility for a direct comparison of three land use types: unwooded pastures, sparsely wooded pastures, and densely wooded pastures (the result of pasture management intensity), in their response to climate perturbation. During the four years of experimental work, a series of observations have been made at the plot scale (square metre) in terms of plant performance and biogeochemical cycles, as well as at the landscape scale (hectare) in terms of forage production. A general threshold level for ecosystem resistance to experimental climate change was detected between the moderate IPCC scenario (+2 K mean annual temperature; -20 % annual precipitation) and the intensive IPCC scenario (+4 K mean annual temperature; -40 % annual precipitation). A concomitant gradient in ecosystem response to climate change was observed across the three land use types. The intensively managed unwooded pasture type was consistently more affected by the experimental treatment and rarely exhibited signs of resistance, especially under the intense climate change scenario. A drastic loss of plant species diversity, reduction of herbaceous biomass, impaired litter decomposition and soil microbial metabolic activity have all contributed to the altered state of ecosystem functioning. In contrast, the two extensively managed wooded pasture types showed considerable resistance to climate perturbation in terms of both above and belowground ecosystem processes. The reported inter-annual variation in herbaceous diversity and biomass production within these land use types demonstrated their resilience (recovery) potential too. Using a modelling approach for upscaling these results to the heterogeneous landscape of pasture woodlands in the Swiss Jura Mountains, has proven that extensively used wooded pastures could grant sustainable ecosystem services in terms of forage provision for cattle under climate change. Considering that the two experimental climate change intensities implemented this study are the projected ‘best’ and ‘worst’ case scenarios for the coming decades, the reported resistance of wooded pastures to climate change has to be embraced, and sustainable land use set as a goal in high altitude mountain pastures.

Distributed power generation and cogeneration of heat and power is an attractive way toward a more rational conversion of fossil and bio fuels. Solid oxide fuel cell (SOFC) – gas turbine (GT) hybrid systems are emerging as the most promising candidates enabling the achievement of a cleaner and more efficient conversion of a large variety of resources across a broad power range covering from small to medium scale applications. This thesis introduces an innovative concept of SOFC-GT hybrid system that allows reaching efficiencies higher than the state of the art while enabling the carbon dioxide separation and avoiding fuel cell pressurisation technical issues. Several hybrid system design alternatives based on this concept are analysed through a thermodynamic optimisation approach combining process modelling, advanced process integration techniques and multi-objective optimisation. A number of optimal hybrid system configurations are determined for different design targets. The results consistently demonstrate the higher energy conversion performance and flexibility enabled with respect to the state of the art. The innovative concept analysis is extended to two applications for which SOFC-GT hybrid cycles are expected to provide the most significant impact toward sustainability: the small scale distributed generation and the conversion of renewable resources. A simplified version of the new hybrid system layout is especially developed for small scale distributed generation, typical of residential building applications (5-10 kWel). Experimental data are used to prove the technical feasibility of the system and to assess the performance potentially achievable with currently feasible technologies. The results of the analysis underline that energy conversion efficiencies higher than traditional centralised power generation can be achieved even at such a small scale. A systematic process integration and optimisation approach is used to assess the energy conversion performance of the original SOFC-GT hybrid cycle fuelled with hydrothermally gasified wet waste biomass. The analysis highlights the considerable potential of the integrated system that allows for converting wet waste biomass into electricity with First Law efficiency higher than 60% while simultaneously enabling the separation of the biogenic carbon dioxide.

Climate change is threatening the well-being of both humans and nature, and new efficient strategies are needed to engage individuals in quickly adopting a more sustainable lifestyle. The present thesis addresses if Mental Accounting, as a central decision mechanism, can be used for designing behavioral interventions which are based on modifications of the choice architecture (“nudges”). Presenting evidence for such central mechanisms in the context of energy conservation, our findings reveal that individuals ascribe dissimilar environmental behaviors to different mental accounts, and are more likely to spend money labelled in a green context on pro-environmental purchases that is in accordance with the dedicated purpose of its account. We further indicate that mental accounts are dynamic and can be refined by a knowledge intervention which teaches the specific environmental impact of a series of energy-relevant behaviors. These mechanisms could be integrated into intervention strategies to increase energy conservation.

Perovskite solar cells have been established as a disruptive technology in the domain of photo-voltaics. Their facile, low-temperature processing and high-power conversion efficiency make them stand-out among other mature solar technologies. The performance of perovskite solar cells is pro-foundly tied to an interplay of material properties of singular thin films that are assembled to form the photovoltaic device stack. An understanding of optoelectronic, morphological, and other key charac-teristics of each layer and its interfaces is instrumental in advancing the science of perovskite solar cells. Since their inception after just over a decade, much work on perovskite solar cell has been stag-nant to bring the technology to the market. The long-term stability remains foremostly the main hin-drance to facilitating technology transfer. Therefore, the work presented in this thesis explores multi-ple interface and compositional approaches to promote stability and other photovoltaic parameters of perovskite solar cells. In the second chapter of the thesis, a light-soaking exploration was done on perovskite sam-ples that utilize single (TiO2 and SnO2) and bilayered (TiO2/SnO2) electron transporting materials. The work aims to expand consensus on the optoelectronic and morphological features of light-soaked samples and link them with long-term stability. Upon preliminary testing, maximum power point tracking on each sample reveals efficiency preservation of SnO2 and TiO2/SnO2 samples over the course of 1000 hours while prominent degradation was revealed for the TiO2 sample. On a secondary investigation, light-soaking characterizations were performed where fresh and light-soaked samples were characterized to obtain photoluminescence, microscopic, and crystallographic features. The work reveals the added benefit of employing TiO2/SnO2 transporting bilayers to improve both the stability and power conversion efficiency of a perovskite solar cell. Building on an effort to understand TiO2/SnO2 bilayer behaviors, the third chapter investigates the role of halide passivating elements in SnO2 on the performance of perovskite solar cells. The study utilizes three metalorganic precursors based on acetylacetone complexes with chloride and bromide groups to fabricate SnO2 layers at different annealing temperatures. Upon thermal and elemental in-vestigations, the study clearly links the presence of amorphous halide elements in SnO2 to the power conversion efficiency of perovskite solar cells. More-in-depth, the optimal SnO2 annealing tempera-ture for bromide containing samples 250 ï °C compared with 220 ï °C for chloride containing samples. The higher temperature tolerance tendency was correlated to bromideâ s lower sublimation sensitivity. Overall, the study highlights the importance of amorphous passivating elements in SnO2 for high per-forming planar perovskite solar cells. Finally, the fourth chapter involves a novel cation mixing approach for 2D perovskites at the interface of the 3D perovskite and the hole transporting layer. Alkyl ammonium halides have been widely used to form light-stable 2D perovskite films upon interaction with excess PbI2. In this study, different alkyl chain cations (propylammonium iodide and octylammonium iodide) were mixed in one solution to form a novel 2D perovskite crystal lattice. Photoluminescence and x-ray diffraction spec-troscopy investigations reveal a unique crystal lattice and a uniform quasi-2

In this dissertation, I develop three essays on sustainable finance. In Chapter 1, I examine whether and why corporate water management affects the valuations of manufacturing firms. I document that good water management is associated with an increase in firm value and a decrease in operating costs during droughts, which suggests that water management allows firms to mitigate the cost of droughts. In Chapter 2, my coauthor and I examine the real and financial effects of a regulation that mandates publicly listed firms to disclose their carbon emissions in a standardized way in their annual reports. We show that the disclosure regulation affects the future costs of high emissions and leads to a significant reduction in firm-level carbon emissions. In Chapter 3, we show that a small university endowment can elicit greater corporate carbon emissions disclosure through shareholder engagement.