628 research outputs found
Policy Decision Support for Renewables Deployment through Spatially Explicit Practically Optimal Alternatives
No full textDesigning highly renewable power systems involves a number of contested decisions, such as where to locate generation and transmission capacity. Yet, it is common to use a single result from a cost-minimizing energy system model to inform planning. This neglects many more alternative results, which might, for example, avoid problematic concentrations of technology capacity in any one region. To explore such alternatives, we develop a method to generate spatially explicit, practically optimal results (SPORES). Applying SPORES to Italy, we find that only photovoltaic and storage technologies are vital components for decarbonizing the power system by 2050; other decisions, such as locating wind power, allow flexibility of choice. Most alternative configurations are insensitive to cost and demand uncertainty, while dealing with adverse weather requires excess renewable generation and storage capacities. For policymakers, the approach can provide spatially detailed power system transformation options that enable decisions that are socially and politically acceptable. The planning of highly renewable power systems at any scale involves compromise across diverse stakeholders. We develop a method that generates a variety of spatially explicit, alternative system configurations that can be used to balance techno-economic feasibility with social and political goals. The application of our method to Italy reveals flexibility of choice for decisions like where to locate wind power and whether to invest in particular technologies. Technology substitution and complementarity is evident: solar photovoltaic and battery capacities expand together, as do wind and synthetic gas turbine capacities, all of which must notably increase to replace bioenergy's firm capacity. We also see that highly renewable systems rely on regional interconnectivity but that gas infrastructure is only useful at a fraction of current capacity. Our approach can be similarly applied to examine trade-offs in other national systems, as well as those at district and continental scales. We develop a computational method, which shows that there is a flexibility of choice to manage contested decisions arising when planning highly renewable power systems, such as where to locate wind capacity. Within this decision space, problematic technologies, such as bioenergy, are difficult and costly to replace and are not absolute must-haves. Expansion of PV is a must-have, coupled with battery when designed to cope with low-wind conditions. Carbon-neutral gas turbines can contribute to balancing but with a minor role compared with today's use
SM: Regional economic impacts of socio-politically driven net-zero energy in Europe
No full textSupplementary Material (SM): Regional economic impacts of socio-politically driven net-zero energy in Europe
Two zipped folders
(a) Euro-Calliope.zip includes
-Energy system configurations by storyline (market-driven, government-directed, people-powered) and year (2030, 2050).
(b) WEGDYN.zip includes
-Supplementary Material (SM_Regionaleconomiceffects.pdf)
-Processed Euro-Calliope output data to WEGDYN input data (EC2WD_data.xlsx)
-WEGDYN results (WEGDYN_data.xlsx)
-WEGDYN resolution, nesting trees, elasticities (WEGDYN_model.xlsx
Euro-Calliope v1.0.0
No full textA model of the European power system built using Calliope.
This repository contains the workflow routines that automatically build the model from source data. Alternatively to building models yourself, you can use pre-built models that run out-of-the-box.
See README.md for further information.
If you use euro-calliope in an academic publication, please cite the following article:
Tröndle, T., Lilliestam, J., Marelli, S., Pfenninger, S., 2020. Trade-offs between geographic scale, cost, and infrastructure requirements for fully renewable electricity in Europe. Joule
Euro-Calliope: pre-built models
No full textpre-built Euro-Calliope
Ready to use models of the European electricity system built using Calliope. Models are available on three different spatial resolutions: continental, national, and regional.
In addition, euro-calliope models can be built manually which adds more configuration options. To build euro-calliope manually, head over to GitHub.
At a glance
euro-calliope models the European electricity system with each location representing an administrative unit. It is built on three spatial resolutions: on the continental level as a single location, on the national level with 34 locations, and on the regional level with 497 locations. On each node, renewable generation capacities (wind, solar, bioenergy) and balancing capacities (battery, hydrogen) can be built. In addition, hydro electricity and pumped hydro storage capacities can be built up to the extent to which they exist today. All capacities are used to satisfy electricity demand on all locations which is based on historic data. Locations are connected through transmission lines of unrestricted capacity. Using Calliope, the model is formulated as a linear optimisation problem with total monetary cost of all capacities as the minimisation objective. The pre-built models can be manipulated by updating any of the files. In addition to the pre-built models, models can be built manually. Manual builds provide more flexibility in adapting and configuring the model. To build euro-calliope manually, head over to GitHub.
Get ready to run the models
You need a Gurobi license installed on your computer. You may as well choose another solver than Gurobi. See Calliope’s documentation to understand how to switch to another solver.
You need to have Calliope and Gurobi installed in your environment. The easiest way to do so is using conda. Using conda, you can create a conda environment from within you can build the model:
conda env create -f environment.yaml
conda activate euro-calliope
Run the models
There are three models in this directory – one for each of the three spatial resolutions continental, national, and regional. You can run all three models out-of-the-box, but you may want to modify the model. By default, the model runs for the first day of January only. To run the example model on the continental resolution type:
$ calliope run ./continental/example-model.yaml
For more information on how to use and modify Calliope models, see Calliope’s documentation.
Manipulating the model using overrides
Calliope overrides allow to easily manipulate models. An override named freeze-hydro-capacities can be used for example in this way:
calliope run build/model/continental/example-model.yaml --scenario=freeze-hydro-capacities
You can define your own overrides to manipulate any model component. The following overrides are built into euro-calliope:
directional-rooftop-pv
By default, euro-calliope contains a single technology for rooftop PV. This technology comprises the total rooftop PV potential in each location, in particular including east-, west-, and north-facing rooftops. While this allows to fully exploit the potential of rooftop PV, it leads to less than optimal capacity factors as long as the potential is not fully exploited. That is because, one would likely first exploit all south-facing rooftop, then east- and west-facing rooftops, and only then – if at all – north-facing rooftops. By default, euro-calliope cannot model that.
When using the directional-rooftop-pv override, there are three instead of just one technologies for rooftop PV. The three technologies comprise (1) south-facing and flat rooftops, (2) east- and west-facing rooftops, and (3) north-facing rooftops. This leads to higher capacity factors of rooftop PV as long as the potential of rooftop PV is not fully exploited. However, this also increases the complexity of the model.
freeze-hydro-capacities
By default, euro-calliope allows capacities of run-of-river hydro, reservoir hydro, and pumped storage hydro capacities up to today’s levels. Alternatively, it’s possible to freeze these capacities to today’s levels using the freeze-hydro-capacities override.
Model components
The models contain the following files. All files in the root directory are independent of the spatial resolution. All files that depend on the spatial resolution are within subfolders named by the resolution.
├── {resolution} <- For each spatial resolution an individual folder.
│ ├── capacityfactors-{technology}.csv <- Timeseries of capacityfactors of all renewables.
│ ├── directional-rooftop.yaml <- Override discriminating rooftop PV by orientation.
│ ├── electricity-demand.csv <- Timeseries of electricity demand on each node.
│ ├── example-model.yaml <- Calliope model definition.
│ ├── link-all-neighbours.yaml <- Connects neighbouring locations with transmission.
│ ├── locations.csv <- Map from Calliope location id to name of location.
│ └── locations.yaml <- Defines all locations and their max capacities.
├── build-metadata.yaml <- Metadata of the build process.
├── demand-techs.yaml <- Definition of demand technologies.
├── environment.yaml <- Conda file defining an environment to run the model in.
├── interest-rate.yaml <- Interest rates of all capacities.
├── link-techs.yaml <- Definition of link technologies.
├── README.md <- The file you are currently looking at.
├── renewable-techs.yaml <- Definition of supply technologies.
└── storage-techs.yaml <- Definition of storage technologies.
Units of quantities
The units of quantities within the models are the following:
power: 100,000 MW
energy: 100,000 MWh
area: 10,000 km2
monetary cost: 1e+09 EUR
These units were chosen in order to minimise numerical issues within the optimisation algorithm.
License and attribution
euro-calliope has been developed and is maintained by Tim Tröndle, IASS Potsdam.
If you use euro-calliope in an academic publication, please cite the following article:
Tröndle, T., Lilliestam, J., Marelli, S., Pfenninger, S., 2020. Trade-offs between geographic scale, cost, and infrastructure requirements for fully renewable electricity in Europe. Joule.
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Contains modified Copernicus Atmosphere Monitoring Service information 2020. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.
Contains modified data from Renewables.ninja.
Contains modified data from Open Power System Data
Diffusion across particle-laden interfaces in Pickering droplets
No full textEmulsions stabilized by nanoparticles, known as Pickering emulsions, exhibit remarkable stability, which enables applications ranging from encapsulation, to advanced materials, to chemical conversion. The layer of nanoparticles at the interface of Pickering droplets is a semi-permeable barrier between the two liquid phases, which can affect the rate of release of encapsulates, and the interfacial transfer of reactants and products in biphasic chemical conversion. A gap in our fundamental understanding of diffusion in multiphase systems with particle-laden interfaces currently limits the optimal development of these applications. To address this gap, we developed an experimental approach for in situ, real-time quantification of concentration fields in Pickering droplets in a Hele-Shaw geometry and investigated the effect of the layer of nanoparticles on diffusion of solute across a liquid–liquid interface. The experiments did not reveal a significant hindrance on the diffusion of solute across an interface densely covered by nanoparticles. We interpret this result using an unsteady diffusion model to predict the spatio-temporal evolution of the concentration of solute with a particle-laden interface. We find that the concentration field is only affected in the immediate vicinity of the layer of particles, where the area available for diffusion is affected by the particles. This defines a characteristic time scale for the problem, which is the time for diffusion across the layer of particles. The far-field concentration profile evolves towards that of a bare interface. This localized effect of the particle hindrance is not measurable in our experiments, which take place over a much longer time scale. Our model also predicts that the hindrance by particles can be more pronounced depending on the particle size and physicochemical properties of the liquids and can ultimately affect performance in applications.ChemE/Transport Phenomen
Shifting and persosting in the face of failure: Learning from what did not work
No full textSocial justice activism demands coordinated, concentrated efforts to move the needle in a positive direction. In the author's nine years as a social justice educator, he led multiple large- and small-scale projects for social justice within higher education. In many ways, those efforts failed to create a lasting impact. In the higher education ecosystem, they also took away time from the kind of promotable work which would benefit his case for tenure and promotion. Trying - and failing - to effect institutional changes left him emotionally, psychologically, and physically exhausted. Beyond that, he suffered from feelings of loneliness, exclusion, and lack of direction. For a long time, the author blamed himself for the failure to change the institution to be a place in which he felt comfortable. He also failed to cope with these negative experiences and emotions, often seething in frustration or anger or avoiding similar situations of vulnerability or creativity. It took years for him to remember and internalize lessons of persistence and shifting appraisals in order to maintain motivation for action and survive the stressors of working within an oppressive system.Published versio
Board of County Commissioners v. Umbehr: The Inadequacies of Extending Pickering Analysis to Government Contractors
No full textThis Note challenges the restrictive First Amendment free speech protection that the Supreme Court gave to government contractors in Board of County Commissioners v. Umbehr when it applied the Pickering balancing test, developed nearly thirty years ago in Pickering v. Board of Education in the context of government employees. It does so by first questioning whether the First Amendment free speech protections given to government employees should be similar for government contractors. It then explores whether the Pickering balancing test should be applied to cases involving government contractors as it was in Umbehr.
The author concludes that the Court improperly restricted the First Amendment free speech rights of government contractors by failing to take into account the numerous modifications the Court has made to the Pickering balancing test that have gradually eroded the broader protections of Pickering and by failing to account for the potentially significant differences between public employees and government contractors. The author thus proposes a new test that would both incorporate the Court\u27s views regarding the free speech rights of government employees and account for the potentially significant differences between public employees and government contractors
Fabrication of edible biocompatible carbohydrate particle-based Pickering emulsions
No full textDifferent from conventional emulsions, Pickering emulsions are stabilized by interfacially-adsorbed solid particles. Pickering emulsions have gained great interest in the past decades due to their high stability against coalescence, Ostwald ripening, and the possibility to avoid the deleterious effects linked to emulsifiers used in conventional emulsions. To fulfill the strong market trend of formulating products that are not only edible in theory, but also maintain the consumer perception of being natural, “clean label” and “green”, this study was dedicated to developing particles from biomass-based resources to form Pickering emulsions with potential application in food, cosmetic and pharmaceutic products. As a simple, organic solvent-free process, media-milling was applied to modify two major biomass materials, native starch and cellulose. Three maize starches (normal maize starch, high-amylose maize starch and waxy maize starch) with different amylose/amylopectin ratios were physically modified through media milling process to form milled starch particles. The physiochemical properties of these starches during milling process, including particle size, crystallinity and gelatinization properties were studied. Emulsions stabilized by milled starch particles with different amylose/amylopectin ratios exhibited significant difference in terms of stabilization capability and rheological properties. Milled high-amylose maize starch particles have the best stabilization ability, followed by milled normal maize starch particles. Furthermore, the stabilization capacity of the milled starch particles improves with the increase of milling time. To investigate the feasibility of Pickering emulsions stabilized by milled starch as a novel food-grade formulation for encapsulation and delivery of lipophilic bioactive compounds, curcumin was selected as model delivery target and encapsulated in the oil phase of Pickering emulsion. The digestion profile of curcumin-loaded Pickering emulsion was studied using three in vitro digestion models, simulated static small intestinal digestion model, pH-stat lipolysis model and TNO’s gastrointestinal model (TIM-1). Simulated static small intestinal digestion model and pH-stat model indicated that the bioaccessibility of curcumin encapsulated in Pickering emulsion was enhanced compared with free curcumin suspended in bulk oil phase. A significant improvement of curcumin bioaccessbility was also observed in an emulsion system vs in bulk oil when using TIM-1 model, which simulates the entire human GI tract. Overall, the study's findings showed that curcumin encapsulated in Pickering emulsion stabilized by milled starch possesses benign stability against harsh gastric conditions as well as improved dissolution profiles in small intestinal tract. All are suggested that Pickering emulsion stabilized by milled starch exhibit high potential as encapsulate and delivery system for lipophilic bioactive compounds. Milled cellulose particles of sizes ranging from 38 nm to 671 nm with rod-like shapes have also been successfully fabricated using media milling. Media milling process led to a notable decrease in the particle size and crystallinity of milled cellulose particles with the increase of milling time. The milled cellulose particles were irreversibly adsorbed at the oil/water interface and formed stable emulsions with droplet size around 60~42 µm, which exhibited benign stability over a month storage. Milled cellulose stabilized emulsions also exhibited good stability against a wide range of pH (3, 5, 7, 9) and salt conditions (0.1~100 mM) with slight change in the droplet size. The rheological tests indicated the formation of gel network in the emulsions, which promoted the stability of the emulsions. The in vitro digestion profile and phase behavior of Pickering emulsions stabilized by milled cellulose were evaluated to investigate their feasibility for encapsulation and delivery of lipophilic bioactive compounds. Curcumin encapsulated in Pickering emulsions exhibited benign stability with less than 50% degraded after storage of 30 days. The digestion behavior of emulsions under simulated small intestinal conditions was characterized using a pH-stat lipolysis model. The digestion profiles of emulsions were markedly dependent on the type of lipid and digestion buffer employed in lipid digestion experiments. The rate and extent of lipolysis of emulsions with medium chain triglycerides (MCT) was greater than emulsions with long chain triglycerides (soy bean and canola oil), reaching complete hydrolysis during lipolysis process independent of bile salt and phospholipids concentration. The structure changes of emulsions during digestion were analyzed using optical and fluorescent imaging. Although the initial digestion rate of curcumin encapsulated in Pickering emulsions with soy bean and canola oil was slower than the corresponding conventional emulsions stabilized by Tween/Span, their total extent of lipolysis was higher than that of conventional emulsions under both fasted and fed intestinal digestion conditions. The bioaccessibility of curcumin encapsulated in Pickering emulsions was higher than in corresponding surfactant stabilized conventional emulsions. High-amylose maize starch with different fatty acids (C12:0, C14:0, C16:0, C18:0, C18:1) were complexed using two heat-moisture methods. The structure properties of different starch-fatty acid complexes, including size and shapes of nanoscale supramolecular structures formed, through heat and moisture treatment, were studied. Optical microscope and SEM analysis showed that starch-fatty acid complexes retained the Maltese cross and granular morphology of native starch. X-ray diffraction revealed the crystalline morphology of starch-fatty acid complexes with B- and V-type crystallinity. And the crystallinity of the complexes varied depending on the fatty acids and methods used. USAXS/SAXS experiments demonstrated that fatty acid chain length and level of saturation affected both the lamellar structure as well as the B-type crystalline of the complexes. Moreover, the processing methods also exhibited major influence on the nanostructure of complexes. The resistance of these starch complexes against enzymatic hydrolysis was increased based on the in vitro digestion measurements. And the hydrophobicity of these complexes was enhanced. This was manifested by increased contact angles. The capacity of these starch-fatty acid complexes to form Pickering emulsions was characterized. Starch-saturated fatty acid complexes were able to form stable emulsions that endured heat treatment of 60, 80 and 100℃. However, starch-unsaturated fatty acid complexes could not form stable emulsions. The barrier properties of these emulsions could be adjusted by heat treatment, which led to swelling of starches. Lipolysis profile of PMFs loaded emulsions suggested that certain heat treatment could reduce the accessibility of lipase towards oil droplets and release of PMFs during lipolysis by enhancing the coverage of granules onto the oil-water interface. In conclusion, particles derived from biomass resources starch and cellulose have been successfully fabricated to form Pickering emulsions using simple, environmental-friendly procedures. The resulting formulations were edible, ‘green’, have exhibited exceptional stability and a practical potential to encapsulate and control release of lipophilic ingredients, making them suitable for various applications in cosmetic, food and pharmaceutical industry.Ph.D.Includes bibliographical referencesby Xuanxuan L
An investigation of the drying process in pickering foams
No full textPickering foams, aqueous foams stabilized by solid particles, can be used as a precursor to fabricate solid porous polymers, ceramics, and composite materials. The fabrication process usually comprises of two subsequent steps of drying and solidification (e.g. sintering) after foam is prepared. Drying (or aging) in aqueous Pickering foams is a complex transport process which involves evaporation and drainage (induced by gravity) of the excess liquid along with deformation of the foam and possible formation of cracks caused by capillary-induced stresses. Crack formation is therefore depended on the drying conditions and the mechanical properties of sample. A comprehensive understanding of the drying process can provide us with predictive tools to select efficient process parameters (e.g. required drying time prior to sintering) as well as providing input prameters for developing numerical models. In this thesis, we first provide experimental data (end of drying time, average moisture content, and effective moisture diffusivity) on drying of Pickering foams stabilized by polymer particles under controlled conditions (i.e. relative humidity and temperature). Drying curves are presented for samples of various initial thicknesses and shapes on substrates of different hydrophobicity and temperatures. Moisture transport is represented via calculating the effective moisture diffusivity coefficients using method of slope. Also, we investigate drying for a bi-component Pickering foam prepared using Multi-walled Carbon Nanotubes (MWCNTs) and polymer particles. We show that the effective moisture diffusivity increases as the average moisture content decreases for all trials and that all data can be collapsed on a master curve. Also, effective moisture diffusivity increased as initial sample thickness as well as substrate temperature increase. On the other hand, effective moisture diffusivity does not depend strongly on the sample shape and MWCNTs concentration. In next part, we explore the effect of initial sample thickness and shape, substrate temperature and wettability, as well as MWCNTs concentration on the crack formations in the samples. We demonstrate that substrate wettability, initial sample thickness, and MWCNTs concentration have a strong influence on the formation and propagation of cracks. We found that decreasing the wettability of the substrate reduces crack formation. Also, increasing the initial sample thickness reduces crack formation. On the contrary, increasing the MWCNTs concentration increases crack formation for all types of substrates. We demonstrate that substrate temperature and sample shape do not seem to influence crack formation but these parameters influence the crack patterns. Such information can be beneficial in using these foams as a precursor to fabricate porous composite porous materials.Ph.D.Includes bibliographical referencesby Omer S. Alabidalkree
Life after Whitehall: The career moves of British special advisers
No full textsponsorship: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publica-tion of this article: Thanks to the Flanders Research Foundation (FWO) grant number G079619N and KU Leuven, Belgium, for supporting the participation of Heath Pickering in this work. (Flanders Research Foundation (FWO), KU Leuven, Belgium|G079619N)status: Publishe
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