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The growing integration of renewable energy sources in the energy grid presents intermittency and negative pricing challenges, necessitating large-scale energy storage solutions. Pumped thermal energy storage (PTES) can address these issues by storing and delivering substantial energy whenever required. High-temperature heat pump development is crucial to deploying PTES for storing heat at sink temperatures that are well above the ambient temperature(>450 °C) to ensure a reasonable round-trip efficiency (RTE). Currently, however, it is not a technological possibility for heat pumps to achieve these temperatures even with the support of freely available heat (200 °C to 400 °C) as source temperatures. This study explores a potential layout of the TI-PTES system that exploits commercially available equipment by storing heat below the ambient temperature while still being able to utilize the freely available heat source (Solar, Waste heat, biomass, etc.) to support the overall RTE. The charging phase employs a well-established CO2-refrigeration cycle to accumulate energy below the ambient temperature in cold thermal storage. While the discharging phase runs a trans-critical CO2 power cycle between the freely available heat source and the cold thermal storage. Overall, offering a practically implementable model for the PTES system with market-available components. The study investigates the design of this innovative system presenting the relevance of different operating and machine parameters as well as the contribution of freely available heat sources to the overall performance. Finally, benchmarking the technology with other long-duration energy storages. [ABSTRACT FROM AUTHOR]

As the International Maritime Organization has set 2030 and 2050 targets to reduce the environmental impact of the maritime sector, it is mandatory to investigate innovative solutions aimed at fuel saving and reduction of ship emissions. In this paper, the integration of Solid Oxide Fuel Cells (SOFC) and Internal Combustion Engine (ICE) is investigated for maritime application, targeting a short-sea ferry as a case study operated by a marine gas engine (MGE) rated 750 kW. The paper aims to model via an in-house tool (WTEMP) the proposed hybrid system and study thermodynamic interaction among the two main energy systems, SOFC and ICE, considering blending anode-off gas from the SOFC with natural gas in the ICE. The results showed relevant efficiency enhancement and fuel/CO2 emission savings if compared with traditional MGE while the main source of exergy loss of the hybrid system is ICE.

Interest in supercritical CO2 power cycles is constantly increasing, showing good efficiency, and promising competitive costs and enhanced flexibility with respect to competing systems. Some project within the EU Horizon 2020 program have studied these systems and aim to demonstrate them in large scale, following the example of the STEP project in US. This work is part of the effort of the SOLARSCO2OL project to build a sCO2-CSP power demo plant at MW scale. A dynamic model of a simple recuperated sCO2 cycle is developed in TRANSEO, using miniREFPROP to compute fluid properties, and table of properties are implemented, when possible, to enhance the performance of the code. Control logics is described and simple controllers implemented. Finally, controllers are tested showing the response of the main parameters of the plant to a ramp variation of the load. Stable compressor inlet pressure is achieved with an inventory control, while a stable turbine inlet temperature allows a high efficiency in part-load operation.

This document presents a study on the use of battery energy storage systems in a proposed renewable energy community in Savona, UNIGE Campus. The study compares the outcomes of cooperative approaches with and without flexibility services to a scenario where users do not cooperate. The study concludes that storage systems of relevant size can create new flexible instruments for the power grid and a powerful tool for citizens, which could make the investment into BESS financially viable. The study also suggests that greater transparency and information on hourly energy sales and purchase prices would facilitate awareness among community members and at the same time stimulate discussion of alternative technologies such as batteries to cover the most expensive nighttime periods for users. Overall, the study highlights the potential of battery systems in renewable energy communities in Italy and provides insights into the importance of coupling flexible services with capacity-building activities and awareness campaigns to promote demand-side-response activities and storage technologies.

The industrial sector is a major source of wealth, producing about one-quarter of the global gross product. However, industry is also a major emitter of CO and it represents a key challenge toward achieving the worldwide CO2 emission reduction targets. Nowadays, about 22% of the overall energy demand is heating for the industrial sector, generating about 40% of the global CO2 emissions. Additionally, 30% of the final energy demand of the industrial sector is electricity. Solutions to decarbonize the industrial sector are needed. This work presents the techno-economic assessment of four different molten salts-based power-to-heat-to-heat and power solutions aiming at decarbonizing the industrial sector, requiring medium temperature heat. The systems are studied under different electric markets. Dispatch strategies and system sizing are identified to ensure optimal techno-economic performance. The main performance indicators investigated are the levelized cost of heat and electricity (LCoH and LCoE), the operational expenditure, and the attainable savings with respect to alternative business as usual solutions. The results highlight that the proposed system can be cost-competitive, particularly in markets characterized by low electricity prices and high daily price fluctuations, such as Finland. In these locations, LCoE as low as 100 €/MWh and LCoH lower than 55 €/MWh can be attained by the base system configuration. The introduction of high temperature heat pumps can provide further LCoH reduction of about 50%. This study sets the ground for further power-to-heat-to-heat and power techno-economic investigations addressing different industrial sectors and identifies main system design strategies. [ABSTRACT FROM AUTHOR]

Ocean Thermal Energy Conversion (OTEC) is a promising technology to provide sustainable and dispatchable energy supply to oceanic coastal areas and islands. It exploits the temperature difference between deep cold ocean water and warm tropical surface water in an Organic RankineCycle (ORC), guaranteeing a continuous and dispatchable electric production, overcoming one ofthe most critical issue of renewable generators such as PV or wind turbines. Despite the technological maturity of ORC application to OTEC systems, it still presents technical and economicbarriers mainly related to their economic feasibility, large initial investments as well as heavy and time demanding civil installation works. To overcome such issues, multipurpose OTEC plants are proposed, producing electrical power as well as other products, such as useful thermal power (e.g. ambient cooling) and desalinated water. Since OTEC engineering is still at a lowdegree of maturity, there are no widespread and established tools to facilitate OTEC feasibility studies and to allow performance and cost optimization. Therefore, in this paper, a new tool for techno-economic analysis and optimization of multipurpose OTEC plants is presented. Starting from a detailed database of local water temperature and depth, the approach allows to provide a quantitative insight on the achievable performance, required investment, and expected economic returns, allowing for a preliminary but robust assessment of site potential as well as plant size. After the description of the techno-economic approach and related performance and cost functions, the tool is applied to an OTEC power plant case study in the range of 1 MW gross electrical power, including a preliminary assessment of scaling-up effects.

The increasing share of electricity produced from renewable energy sources (RES), with the consequent strong penetration in the current energy network, is causing a growing need of balancing power to compensate power supply from such fluctuating sources. For these reasons, nowadays the power plants are requested to improve their operational flexibility, together with their global efficiency in part-load operation, for ancillary services and to sustain the grid operability. A possible solution for flexibility enhancement is characterized by a highly efficient heat pump integrated in a conventional natural gas combined cycle (CC). Such concept can be applied both to power oriented combined cycle (POCC), to modify the compressor intake temperature with a consequent increase or decrease of the power production, and both to cogeneration CC in association with District Heating Network (DHN). In this work, a statistical analysis of climatic data and their correlations with energy market condition will be performed considering Italian context, to understand which the more suitable conditions for such integrated system are. The analysis will be performed on seasonal and daily basis. The final aim of this work is to identify how such integrated system can be operated at its best in the different Italian markets and climatic frames.

The present research study aims at analysing technical and economic feasible solutions for heat pumps integration in energy districts for polygeneration purpose and particularly to store excess of electricity via Power-to-heat schemes considering that, from previous researchers’ works, thermal storage has been identified as the most remunerative and easy to handle storage technology to maximise self-consumption in polygeneration grids. This technology is already developed and currently employed for conditioning of residential, commercial and industrial buildings. However, studies regarding the analysis of heat pumps’ integration in energy districts for distributed generation are still limited. The potential advantages of its employment in this context are fuel savings, a lower emission level and the possibility to couple it with local renewable energy sources (i.e. solar panels, wind turbines) and traditional generators (i.e. engines, micro gas turbines) in order to increase flexibility in operational terms. In this paper, a performance analysis of the poly-generation energy district installed at the University of Genoa Campus, located in Savona, is analysed throughout a whole year: the model is implemented using a dedicated software tool, developed by Thermochemical Power Group. Different solutions for the integration of the heat pump, including size optimization, are investigated, considering the real data related to the University of Genoa Campus: the final aim of the analysis is to determinate the best operational strategy, minimizing variable costs (i.e. fuel) and evaluating the economic feasibility of heat pump installation in the energy district. This work has been also redacted as a preliminary analysis for solar-coupled HP integration (from a optimized management point of view) to be performed in the demonstration campaign of H2020 ENVISION Project*, where both RINA Consulting and University of Genova collaborate.

There are several small energy sources that can be exploited to provide useful energy: small temperature differences, mechanical vibrations, flow variations, latent exhausts are just some examples. The recovery of such common and small energy sources, usually wasted, for example with the conversion into useful amounts of electrical energy, is called energy harvesting. Energy harvesting allows low-power embedded devices to be powered from naturally-occurring or unwanted environmental energy (e.g. pressure or temperature difference). The main aim in the last years of researches in such field, was the increasing of the efficiency of such components, with a higher power output and a smaller size. At present, a wide range of systems incorporating energy harvesters are now available commercially, all of them specific to certain types of energy source. Energy harvesting from dissipation processes such as fluid lamination is a challenge for many different applications. In addition, control valves to dissipate overpressures are common usage of many plants and systems. This paper surveys the market opportunities of such harvesting systems, considering the trade-offs affecting their efficiency, their applicability, and ease of deployment. Particular attention will be devoted to small energy harvesters than can exploit small expansions, such as from lamination valves or to systems that can feed mini sensors from small pressure drops, promising compactness, efficiency and cost effectiveness.

SHIP2FAIR is a H2020 European funded project†, which aim to foster the integration of solar heat in industrial processes from the agro-food sector facilitating the integration of solar heat production in low temperature processes. Based on the assessment of the industrial process for the production of different spirits and the local solar potential in Pessione plant (TO) of Martini & Rossi – one of the four demosite of the project -, the preliminary results that guided the choice of the most suitable solar collectors (Fresnel) and the definition of the thermo-economic parameters for the solar plant are hereby presented. The preliminary assessment takes into account different perspectives from the industrial and economic point of view: the availability of suitable surfaces, the economics of the investment and the best processes to be fed by solar produced steam towards a preliminary techno-economic feasibility study. The starting points for the analysis have been the characterization of the thermal demand in terms of necessary temperature level (°C), overall consumption and time distribution. The following step has been the identification of the suitable collectors to be installed taking into account the thermal parameters presented before, the boundary conditions of the industrial facility (e.g. space available, orientation, etc.), the technical characteristics of the collector itself and the solar irradiation available considering the plant’s location. Moreover, the complex thermal facility in the factory, constituted by multiple (3) gas boilers and a Combined Heat and Power (CHP) plant in two different but linked pressurized steam loops, is taken into account for the definition of the solar collectors configuration and their integration via the proper management of heat generators and storage. The calculations are based on the expected thermal (steam) production guaranteed by the solar collectors and avoided GHG based on the reduction of gas fired boilers consumption.

Solar energy has been considered as one of the promising solutions to replace the fossil fuels. To generate electricity beyond normal daylight hours, thermal energy storage systems (TES) play a vital role in concentrated solar power (CSP) plants. Thus, a significant focus has been given on the improvement of TES systems from the past few decades. In this study, a numerical model is developed to obtain the detailed heat transfer characteristics of lab-scale latent thermal energy storage system, which consists of molten salt encapsulated spherical capsules and air. The melting process and the corresponding temperature and velocity distributions in every capsule of the system are predicted. The enthalpy-porosity approach is used to model the phase change region. The model is validated with the reported experimental results. Influence of initial condition on the thermal performance of the TES system is predicted.