Analysis of different typologies of natural insulation materials with economic and performances evaluation of the same in building

Considering the significant impact that the residential sector has on energy consumption, it is particularly important to implement policies aimed at improving energy efficiency in buildings for saving primary energy, and also to spread the concept of sustainable development through the use of appropriate technology and proper project criteria both for new constructions and for the rehabilitation of existing ones. It is in this context and in an attempt to reduce as much as possible the consumption of resources that fits the possibility of utilizing "natural" materials for the insulation of buildings. In this work they have been analyzed the natural insulation materials present on the Italian building market, where for "natural" it is meant the ones that are derived from renewable materials, which emit no pollutants and that are recyclable or biodegradable. Then it has been created a database which highlights the physical and thermohygrometrical characteristics (density, conductivity, specific heat, vapor permeability, etc.), as well as the possible applications (ceiling, wall, roof). Then it has been carried out a performing and economic comparison related to the replacement of the traditional insulation of a residential building located in Perugia (Central Italy) with the majority of the insulating materials identified in relation to its type of use. The synthetic insulating materials have been replaced in order to reach, for the analysed building, the same thermal performances obtained with the application of traditional insulators. From the analysis of dynamic thermal parameters has been deduced that the building envelope insulated with natural products has better thermal summer performances compared to the same insulated with traditional materials such as XPS, with the same thermal winter performances. This improvement is mainly due to the high value of the specific heat characteristic of the natural insulators. Finally, it has been carried out an economic comparison between the two types of insulation from which it has been possible to deduce that the utilize of natural insulation products have meant an increase in the costs which is widely variable depending on the type of natural insulator used

Multi-criteria investigation of a pumped thermal electricity storage (PTES) system with thermal integration and sensible heat storage

In the present paper a multicriteria analysis of a Rankine Pumped Thermal Electricity Storage (PTES) system with low-grade thermal energy integration is performed. The system is composed by an ORC for the discharging phase and a high-temperature heat pump for the charging phase. As previously demonstrated, the low-grade thermal energy can be provided at the heat pump evaporator to boost the PTES performances. As it regards the multi-criteria analysis, a tradeoff is required when electric-to-electric energy ratio ηrt, total exergy exploitation efficiency ψut and energy density ρen, are maximized concurrently. By means of multi-objective optimization, theoretical performances of the system are derived in two different layouts, which are differentiated by the presence, or not, of internal regeneration in charge and discharge subsystems. Results showed that regeneration can be very effective, as it relaxes the tradeoff between the objectives, thus yielding better global performances. Pareto fronts are built and explored to characterize the PTES system. Configurations of interest are proposed, and PTES performances are compared with other storage technologies. Theoretical results showed that, by exploiting thermal energy at temperature lower than 80 °C, ηrt ≈ 0.55 and ρen ≈ 15 kWh/m3 can be concurrently achieved. This can be done at the cost of an inefficient exploitation of the thermal source, as ψut ≈ 0.05. If higher total exergy utilization efficiency is required, storage density can still be maintained high, but ηrt must drop down to 0.4

Rankine carnot batteries with the integration of thermal energy sources: A review

This paper provides an overview of a novel electric energy storage technology. The Thermally Integrated Pumped Thermal Electricity Storage (TI-PTES) stores electric energy as thermal exergy. Compared to standard PTES, TI-PTES takes advantage of both electric and low-temperature heat inputs. Therefore, TI-PTES is a hybrid technology between storage and electric production from low-temperature heat. TI-PTES belongs to a technology group informally referred to as Carnot Batteries (CBs). As the TI-PTES grows in popularity, several configurations have been proposed, with different claimed performances, but no standard has emerged to date. The study provides an overview of the component and operating fluid selection, and it describes the configurations proposed in the literature. Some issues regarding the performance, the ratio between thermal and electrical inputs, and the actual TI-PTES utilisation in realistic scenarios are discussed. As a result, some guidelines are defined. The configurations that utilise high-temperature thermal reservoirs are more extensively studied, due to their superior thermodynamic performance. However, low-temperature TI-PTES may achieve similar performance and have easier access to latent heat storage in the form of water ice. Finally, to achieve satisfactory performance, TI-PTES must absorb a thermal input several times larger than the electric one. This limits TI-PTES to small-scale applications

An energy saving solution applied to the final use of electrical and lighting systems of school buildings managed by Perugia Province

In this paper, a study and design of energy conservation actions and the obtention of Energy Efficiency Titles, according to the Italian Ministerial Decree 20th July 2004, applied to lighting and electrical systems in a school district managed by Perugia Province (Italy), is presented. Specifically, the analysis regarded the replacement of neon lamps with high efficiency ones, and the power factor correction of the electrical system with a lower value. The work was carried out through an energy audit of some school buildings. From the results of this energy audit, project solutions were developed and a technical and economical feasibility study was made. This study was then extended to the whole school building fleet managed by Perugia Province. The results of this work were validated by a commercial feasibility assessment through an ESCo

Dynamic control strategies for distributed microgeneration and waste heat recovery power plants

In this paper the modeling activity on a waste heat recovery microgeneration ORC plant is presented together with the results of the application of two different load diagrams and three different control strategies. The overall energy production and the average efficiency were compared and a proper control strategy was evaluated to optimize the energy recovery process as well as the dynamic response of the plant

Techno-economic assessment of an industrial carbon capture hub sharing a cement rotary kiln as sorbent regenerator

The concept of CCS cluster brings together multiple CO2 industrial emitters using shared capture and/or transportation infrastructure and offers several advantages for network partners compared with point-to-point individual projects. It reduces costs for CCS, and enables CO2 capture from small volume industrial facilities. The proposed concept connects a cluster of industrial sites with significant heat demands with a cement plant through the implementation of a Ca-looping CCS system. This system treats the flue gas from all the industrial emitters in independent boiler/carbonators while uses the kiln furnace as calciner for the cement and the capture plant. The carbonator reactors located in each one of the industry sites are fed by CaO from the cement plant to capture the CO2 content of their own flue gas. After carbonation reaction, the exhaust sorbent is transported back to the cement plant for regeneration in the kiln furnace. The aim of this work is to analyse the techno-economic feasibility of the proposed Ca-looping CCS cluster. The economic assessment, assuming 20 euro/ton CaO and carbon market 30 euro/ton CO2 points out the feasibility of this kind of centralized carbon capture system to handle the carbon from small emitters. Results show that the operating costs of small companies that use coal or natural gas reduce from 21.3 Meuro to 18.8 Meuro or from 25.5 to 23.0 Meuro. For the cement industry this income lessens its operating costs 1.9 Meuro lower than a reference situation where CCS is only implemented in cement plant

SOFC Micro-CHP integration in residential buildings

SOFC technology has reached many of the performance goals that where indicated by scientific society and is providing several application that permits market penetration. One of the main targets is related to Micro Cogeneration Heat and Power (μ-CHP) for residential application. The integration of this system with a residential house has to be deeply investigated to individuate market targets in terms of costs and efficiency. This study evaluates the Italian market condition and analyzes the integration possibility with both thermal and electrical systems. Different solutions are investigated evaluating thermal and electrical driven logic for μ-CHP SOFC based unit and the opportunity of integration with local electrical grid. Evaluation on heat and electricity storage was also considered as integration strategy. The study is based on electrical and thermal loads in typical residential users and the evaluation is based on Italian technical standards and guidelines. Several operating conditions were evaluated and compared to obtain an optimized size and integration of μHP SOFC based solution

A co-located solar receiver and thermal storage concept using silicate glass at 1000°C and above: Experiments and modeling in the optically-thick regime

This work presents the exploratory experimental results of a co-located solar receiver and thermal energy storage (TES) concept based on a pool of molten glass contained in a cavity, serving as solar receiver and TES medium simultaneously. Distinctive features of the system are the direct and volumetric absorption of solar radiation by the semi-transparent glass and a stationary TES medium. Only the charge cycle was studied, without a heat-removal system. Recycled soda-lime-silica (SLS) container glass of various colors was adopted as working medium in a setup tested at the ETH's High Flux Solar Simulator (HFSS). A steady 3D heat transfer model of the experimental apparatus, which couples Monte-Carlo ray-tracing and CFD techniques, was developed and validated against the experimental results. The tests used the HFSS as the only energy source, with maximum radiative fluxes of 1.2 MWm-2 and power input of 1.5 kW directly absorbed by the glass, which reached measured temperatures of 1300 °C, while the maximum temperatures –as predicted by the model– exceeded 1500 °C. Such conditions were maintained for 5 to 10 h and no technical problems were encountered with the containment of the hot glass melt. These preliminary results demonstrate that silicate glasses are effective volumetric absorbers of solar radiation up to temperatures exceeding 1300 °C

impact of consumption profile discontinuities on the feasibility of a pv plant

Abstract The revenues of a grid-connected photovoltaic plant are strongly related to the local climatic conditions. In addition, since self-consumed electricity is much more valuable than that traded with the main power grid, also consumption profile plays a key role in the profitability of a PV system. Self-consumption to total PV production ratio depends on the temporal mismatch between energy generation and demand. The amount of energy that is not self-consumed may be very high in the case of a consumption profile with several discontinuities. This study is focused on the analysis of a grid-connected PV system serving a compressed natural gas (CNG) fueling station. These facilities are energy-intensive users, characterized by high variability of electricity demand due to intermittent operation of gas compressors: in a few seconds the total load may change from 100% to 5% and vice versa very frequently during the day. The analysis was based on data acquired on the field for the compression station and those already present in the literature for solar irradiation. The influence on plant design of the time step used for the analysis was studied in detail. The outcomes showed that the typical and well-assessed design approaches of a PV pant may lead to errors when used for the design of systems with several consumption profile discontinuities

Life cycle assessment of synthetic natural gas production from different CO2 sources: A cradle⇂to-gate study

Fuel production from hydrogen and carbon dioxide is considered an attractive solution as long‐term storage of electric energy and as temporary storage of carbon dioxide. A large variety of CO2 sources are suitable for Carbon Capture Utilization (CCU), and the process energy intensity depends on the separation technology and, ultimately, on the CO2 concentration in the flue gas. Since the carbon capture process emits more CO2 than the expected demand for CO2 utilization, the most sustainable CO2 sources must be selected. This work aimed at modeling a Power‐to‐Gas (PtG) plant and assessing the most suitable carbon sources from a Life Cycle Assessment (LCA) perspective. The PtG plant was supplied by electricity from a 2030 scenario for Italian electricity generation. The plant impacts were assessed using data from the ecoinvent database version 3.5, for different CO2 sources (e.g., air, cement, iron, and steel plants). A detailed discussion on how to handle multi‐functionality was also carried out. The results showed that capturing CO2 from hydrogen production plants and integrated pulp and paper mills led to the lowest impacts concerning all investigated indicators. The choice of how to handle multi‐functional activities had a crucial impact on the assessment