Waste management systems remain far from meeting material recovery targets and net-zero decarbonization goals. Their design is inherently challenging since it requires resolving competing environmental, economic, and social objectives across tightly coupled process, control, and regulatory domains, under substantial uncertainty in waste composition, product quality, and market outlets. This lack of integration continues to limit the credibility and practical use of decision-support methods for waste management.In this contribution, we define six technical requirements for a decision-support framework suited to industrial research and development and introduce a tool designed to meet them. The proposed Decision-Support Platform couples Modelica-based process simulation with Python workflows for data handling, life-cycle inventory generation, sustainability assessment, and results analysis. It is specifically designed to support multi-domain, time-dependent modeling of heterogeneous waste systems while ensuring modularity, transparency, and traceability of both models and data. In this way, the platform addresses a persistent methodological gap between detailed process-system representation and life-cycle sustainability assessment of Waste-to-X systems.We demonstrate the platform through a case study of municipal solid waste treatment integrating incineration with energy recovery and optional manual and automatic sorting technologies. Results show that automatic sorting operated at nominal throughput yields the lowest environmental impacts, reducing human health, ecosystem quality, and global warming potential indicators by 31 to 39% relative to the incineration-only reference. Manual sorting, in contrast, does not generate substantial economic gains and shifts burdens in the environmental and social indicators.

The reliability of Life-Cycle Analysis (LCA) applied to waste management systems is hindered by fragmented workflows, limited transparency on inventory completeness, and insufficient uncertainty characterization. A review of existing tool frameworks confirms that none systematically combines dynamic process modeling, process heat integration, explicit Life-Cycle Inventory (LCI) coverage verification, and uncertainty propagation. This work presents methods implemented within a Decision-Support Platform to address these gaps. Waste treatment processes are modeled dynamically as a function of detailed heterogeneous waste compositions, providing a time-resolved foreground LCI. Heat integration is applied to maximize energy recovery and size utilities consistently, considering time variability. A systematic model version check verifies mass balance closure, stream elemental breakdowns, and the completeness of elementary and intermediary flow mapping to LCA databases — screening each flow from its physical definition through chemical identification to database availability, and reporting unmatched items for targeted refinement. Foreground sensitivity and background uncertainty analysis are combined, propagating supply chain data uncertainty through Monte-Carlo simulation. The methods are illustrated on a municipal solid waste incineration system with and without post-combustion amine-based carbon capture. Background uncertainty ranges are shown to determine whether observed environmental performance differences between cases are statistically significant, demonstrating that conclusions drawn without uncertainty analysis may be misleading.

Anaerobic digestion (i.e., biogas plant) converts organic waste into biogas that can directly be used or upgraded to bio-methane for natural gas grid injection. The digestate (residues) from biogas plant has nutrients and unconverted organic matters. The dry digestate can be used to produce hydrogen and methane via thermochemical route. This study has modelled a complete process or value chain for converting digestate into methane and hydrogen. The developed process model includes gasification, water gas shift and methanation as the main conversion units, whereas pressure swing adsorption, membrane separation and amine absorption were used to separate different gaseous mixtures. This study focuses on systematic generation and comparison of digestate valorization options. The formulated optimization problem is a mixed integer linear programming problem, and total annual cost is considered as the performance criterion. Several economic scenarios have been generated based on selling prices of hydrogen and methane, and the optimization problem was solved repeatedly for each scenario. The obtained solutions are divided into three categories: only producing methane, producing methane and hydrogen as main products, and producing hydrogen as main product and methane as side product. As expected, the selection of valorization route and relative production of hydrogen and methane depend upon their selling prices. Finally, use of biogenic carbon dioxide for storing excess renewable electricity has been explored for selected scenario.

Municipal solid waste is a mixture of urban and industrial waste, consisting of biodegradable fractions, such as food waste, waste wood or paper, but also fossil-based fractions, among which plastics, textiles, metals, glass and aluminum. Depending on the type of waste and recovery technique, biogas, biofuels, heat, electricity and metals, are possible value-added products. As both biogenic and fossil carbon are present among waste fractions, the reduction and capture of carbon is crucial in the deployment of sound waste management technologies. There are several physicochemical CO2 capture technologies, and they have their own benefits, challenges and limitations. Some techniques are in the development phase, and they need to be evaluated for their possible integration within waste-to-energy system. We have developed a waste-to-energy superstructure, including digestion, gasification and incineration as the main waste treatment technologies. The latter is the main contributor of CO2 emissions. The developed superstructure includes three options for CO2 capture from flue-gases: amine absorption, temperature swing adsorption and membranes. Amine absorption and membranes are considered for biogas upgradation, whereas pressure swing adsorption and membranes are evaluated for syngas upgradation. This study systematically generates and compares a number of decarbonization options for waste-to-energy system. The formulated optimization problem is a mixed integer linear programming problem, and total annual cost is considered as the performance criterion for generating decarbonizing options. For carbon capture from flue-gases, amine absorption and temperature swing adsorption found to be better options compared to membrane separation

The AC and DC dielectric properties of hydrofluoroethers (HFE) [C3F7OCH3] and fluorinated ketone (FK) [C2F5C(O)CF(CF3)2] have been characterised by dielectric spectroscopy and DC conductivity at different temperatures. Results show that DC conductivity and imaginary permittivity of both fluids are positively correlated with increasing temperature. However, the real permittivity decreases with increasing temperature. The breakdown voltages of HFE and FK at 295 K are ∼10 kV mm−1. Reducing temperature is an effective method to increase the breakdown voltage of the FK coolant, but the breakdown voltage of HFE is less temperature dependent. Finally, as expected repeated breakdown had no significant effect on the AC dielectric strength of both liquids.

A heat exchange interface at subzero temperature in a water vapor environment exhibits high probability of frost formation due to freezing condensation, a factor that markedly decreases the heat transfer efficacy due to the considerable thermal resistance of ice. Here we report a novel strategy to delay ice nucleation on these types of solid-water vapor interfaces. With a process-driven mechanism, a self-generated liquid intervening layer immiscible to water is deposited on a textured superhydrophobic surface and acts as a barrier between the water vapor and the solid substrate. This liquid layer imparts remarkable slippery conditions resulting in high mobility of condensing water droplets. A large increase of the ensuing ice coverage time is shown compared to the cases of standard smooth hydrophilic or textured superhydrophobic surfaces. During deicing of these self-impregnating surfaces we show an impressive tendency of ice fragments to skate expediting defrosting. Robustness of such surfaces is also demonstrated by operating them under subcooling for at least 490 h without a marked degradation. This is attributed to the presence of the liquid intervening layer, which protects the substrate from hydrolyzation, enhancing longevity and sustaining heat transfer efficiency.

Maintaining the non-wetting property of textured hydrophobic surfaces is directly related to the preservation of an intervening fluid layer (gaseous or immiscible liquid) between the droplet and substrate; once displaced, it cannot be recovered spontaneously as the fully penetrated Wenzel wetting state is energetically favorable. Here, we identify pathways for the "lifting"of droplets from the surface texture, enabling a complete Wenzel-to-Cassie-Baxter wetting state transition. This is accomplished by the hemiwicking of a transient (limited lifetime due to evaporation) low surface tension (LST) liquid, which is capable of self-assembling as an intervening underlayer, lifting the droplet from its impaled state and facilitating a skating-like behavior. In the skating phase, a critical substrate tilting angle is identified, up to which underlayer and droplet remain coupled exhibiting a pseudo-Cassie-Baxter state. For greater titling angles, the droplet, driven by inertia, detaches itself from the liquid intervening layer and transitions to a traditional Cassie-Baxter wetting state, thereby accelerating and leaving the underlayer behind. A model is also presented that elucidates the mechanism of mobility recovery. Ultimately, this work provides a better understanding of multiphase mass transfer of immiscible LST liquid-water mixtures with respect to establishing facile methods towards retaining intervening layers.

Transcritical CO2 power systems are being investigated for site independent electro-thermal energy storage (ETES). The storage plant uses electrical energy with a standard vapor-compression heat pump/refrigeration cycle to store thermal energy as hot water and ice over a period of approximately 8 hours during low power demand. The power cycle is then reversed and operated as a simple Rankine cycle to produce ∼100 MWe for about 4.5 hours during peak demand. During the power generation cycle the storage plant uses the heat stored in the hot water tanks, together with ice melting, plus ambient heat rejection for the heat sink. For 100 MWe class power plants, the round trip efficiency is estimated to be up to 60%. CO2 was selected as the working fluid because it improves the ability of the plant to operate with high reversibility. In addition, it is compact and can operate below the freezing point of water. This report describes the major control characteristics of the plant, together with methods, tools, and results of the model. Because the plant is nearly “closed”, it must operate only by consuming electrical energy during the charging cycle and by producing electrical energy plus some waste heat during the discharge cycle. All other heat transfer processes occurs solely within the storage plant itself and consists of either heating or cooling water and by making or melting ice. For the plant to operate continuously, both the water thermal storage and ice storage must be returned to their initial conditions after every 24 hour period. Otherwise, small changes in the thermal environment during waste heat rejection or performance variations of internal components will cause the storage system to drift from its designed operating temperature, pressure and energy storage capability, challenging its ability to operate. The control concept for the storage plant addresses both the operation of the plant during charging and discharging. It also addresses strategies for control during off-design situations or due to disturbances such as load following or changes in ambient heat rejection conditions. The process simulations described in the paper include models for the main physical components of the plant including the turbomachinery, the heat exchanger network, states of charge of the cold and hot storage, and CO2 inventory.

This paper presents analysis of CO2 turbomachinely for the electro-thermal energy storage (ETES) concept for site-independent bulk (grid-scale) electric energy storage. In charging mode, ETES operates as a transcritical CO2 heat pump, consuming electric energy which is converted into thermal energy stored in the form of hot water and ice on the hot and cold side of the cycle, respectively. On demand, the CO2 cycle is reversed for discharging during which ETES operates as transcritical CO2 power generation plant, consuming the stored hot and cold sources. The target capacity of the ETES system is of the order of units of MW electric to 100 MW electric, with typical daily cycles and 4 to 8 hours of storage. The estimated electric-to-electric round trip efficiency of ETES is about 60%.A companion paper [1] presents the control concept of the ETES plant and discusses several issues specific to the ETES plant design and operation. This paper analyzes these particular requirements from the perspective of the CO2 turbomachinery required for the storage plant, presenting the selection of the turbomachinery types and their shaft arrangement suitable for the ETES. The expected performance, main design features and challenges are discussed, together with questions related to the scalability of the turbomachines towards high power targets. Impacts of the turbomachinery designs on the ETES system performance, such as the sensitivity of the system electric-to-electric round trip efficiency on the turbomachinery efficiency are discussed

The conceptual design of a thermo-electric energy storage (TEES) system for large scale electricity storage is discussed in this work by showing the results of the thermoeconomic optimization of three different system configurations that were identified in previous works. The system is based on transcritical CO2 cycles, water storage and salt-water ice storage and is designed for a capacity of 2 h discharge and equal charge and discharge power of 50 MW. A two-step optimization procedure is used. The system intensive design parameters are optimized at the master level through a genetic algorithm. The optimal cycle mass flow rates are calculated in a nested linear programming step where the heat integration between the cycles is optimized subject to the heat transfer feasibility imposed through Pinch Analysis cascade calculations. The synthesis of the heat exchanger network and of the storage tank systems was solved through a set of heuristic rules. Equipment purchasing costs were estimated by means of cost functions that were built upon vendors quotations. The results are discussed by showing the Pareto fronts of the three optimization cases and the trends of the decision variables along each optimal front. Nine solutions are discussed in more detail by showing the values of the design parameters and the process flow diagrams including storage and heat exchanger layouts. Design guidelines are then formulated which can be used in future works for detail plant design. The topological features that are found to maximize the system performance at the minimum costs are: superheating before the CO2 heat pump, two independent systems of hot water storage tanks above and below the ambient temperature, and air cooling at the heat pump side. The design parameters that affect significantly the costs and performances are the cycle pressures. These are in fact directly associated with temperature differences both at the cold and hot storage sides which should be carefully optimized to obtain the best trade-off between exergy losses and costs for heat exchangers. Due to the change in specific heat of the supercritical CO2 along the temperature range of hot water storage, a system of multiple storage tanks was used. Intermediate storage tanks help reduce significantly the temperature differences at the hot storage side and therefore their number represent another critical design parameter that must be optimized to achieve the best trade-off between costs and performances. (C) 2013 Elsevier Ltd. All rights reserved.

A novel type of bulk electricity storage - electrothermal energy storage (ETES) - is presented. The concept is based on heat pump and heat engine technologies utilizing transcritical CO2 cycles, storage of pumped heat in hot water, and ice generation and melting at the cold end of the cycles. The paper first describes the growing need for large scale electrical energy storage and the role of storage in the integration of renewable intermittent generation such as wind energy into the electricity network. The background and a short review on ETES is given and the main principles of (i) reversible(1) heat pumping using vapor compression, (ii) thermal energy storage, and finally (iii) back conversion of thermal energy into electricity via a thermal engine are explained. Following the introduction of ETES as a general concept, the transcritical CO2 based system is presented by providing a description of the thermodynamic cycles and the corresponding operating conditions. Next the overview of an envisioned transcritical ETES plant is given with information on the main equipment including the turbomachines such as compressor and turbine, high pressure plate heat exchangers, and ice storage. Key properties of the proposed transcritical ETES system are then reviewed with an emphasis on energy storage efficiency, scalability, site-independence, and minimal environmental impact. Information about the operating characteristics such as start-up and standby times and storage duration of the proposed system is also given. The paper is concluded by discussing the future perspectives for the proposed system mainly by focusing on potential technology improvements for the CO2 machines and the storage materials for both hot and cold ends of the system. (C) 2012 Elsevier Ltd. All rights reserved.

L'invention porte sur un systeme et un procede pour le stockage d'energie thermoelectrique. Le systeme comprend un cycle de chargement (10) servant a apporter de l'energie thermique a un dispositif de stockage thermique chaud (18, 20, 22) et un dispositif de stockage a glace a evaporation (24), et un cycle de dechargement (30) pour generer de l'electricite en recuperant l'energie thermique. Le dispositif de stockage de glace a evaporation (24) comprend un echangeur de chaleur (14, 36), un reservoir de stockage de suspension de glace (26), une chambre d'evaporation a vide (28) et un echangeur de chaleur de suspension (40). Le dispositif de stockage de glace a evaporation (24) de la presente invention se comporte comme un stockage de froid dedie pour le systeme de stockage d'energie thermoelectrique. Le stockage de froid est realise par la production d'un melange glace-eau pendant le chargement du stockage, et par utilisation du melange glace-eau stocke pour condenser le fluide travaillant pendant le cycle de dechargement (30). L'utilisation de cet agencement a evaporation a point sub-triple a pour effet d'ameliorer le rendement de circuit ferme du systeme TEES en reduisant au minimum la difference maximale de temperature entre le fluide travaillant et le milieu de stockage thermique pendant les cycles de fonctionnement.