Search

Most energy conversion systems, and especially electricity generation plants, do not operate at nominal conditions throughout their useful life: periodic, semi-periodic and stochastic changes in the availability of the resource affect solar (thermal and PV), wind, hydraulic, and geothermal plants, which in reality operate at off-design conditions for most of their life. To a smaller extent, fossil-fuelled plants may also be plagued by fuel availability problems and no longer easily predictable demand oscillation. In spite of the ever growing net connectivity, since the demand curve in even larger geographic regions displays a typical quasi-sinusoidal shape, fleet load modulation is unavoidable. Naturally, off-design operation and load cycling affect the cost of the generated kWh. This paper presents a general thermoeconomic method to evaluate the economic and environmental effects of energy system integration, taking into account life cycle concerns (supply chains) and the effect of inefficiencies due to off-design operation of the systems. The method here is applied to a realistic case study of an Italian regional utility: an analysis of the implications of the variation of the productive mix between a photovoltaic power plant (PV) and a standard commercial, non-cogenerating gas turbine plant (GT) on the final cost of the electrical kWh. The demand curve is prescribed, and the effect of different mixes is assessed, both on the monetary and on the exergy cost of the electricity. The economic cost assessment is performed by standard thermoeconomic techniques, whereas the exergy costs are evaluated using both the Extended Exergy Accounting (EEA) and the Thermo-Ecological Cost (TEC) methods. The results show that a purely monetary cash flow accounting and thermo-economics lead to contrasting results, and also that the EEA and TEC cost indicators generate different rankings among the studied alternative GT/PV mixes. [ABSTRACT FROM AUTHOR]

Abstract To support the ongoing transition towards smart and decarbonised energy systems, energy models need to expand their scope and predictive capabilities. To this end, this study proposes a multi-layer modelling methodology that soft-links (i) a stochastic bottom-up load curves estimation model, (ii) a technology-rich energy system optimisation model (Calliope) and (iii) a Multi-Regional Input-Output model (Exiobase v.3), and applies it to investigate the economic and environmental consequences entailed by a massive replacement of traditional gas-fired kitchens with induction kitchens within the Italian residential sector. Two scenarios are considered for the analysis: (i) business as usual (BAU, 2015 energy system configuration), and (ii) national energy strategy (SEN, configuration prospected in 2030). The results show how the intervention produces positive net effects on the primary energy balance of the energy sector only when sustained by adequate shares of renewables, as in the SEN (−1.5 TWh∙y−1); otherwise, increased operation of fossil-fuel plants offsets gas savings (BAU, +2 TWh∙y−1). Nonetheless, feedbacks on other productive sectors entail additional energy consumption and emissions, thus counterpoising positive effects obtained within the energy sector even in the SEN scenario. Still, higher renewables penetration reduces overall additional emissions from 2.07 Mton∙y−1 for BAU to 0.88 Mton∙y−1 for the SEN. Highlights • A multi-layer methodology to link energy models and input-output models is proposed. • Italian electricity demand due to massive electrification of cooking devices is assessed. • Change in the Italian power production mix is assessed based on Calliope energy model. • The related economic/environmental implications are assessed with the Exiobase model. [ABSTRACT FROM AUTHOR]

In this work, the primary resources assessment of four different soil erosion remediation technologies, Geo-nets , Bio-mats , Geo-cells and Deep Rooting Plants (DRP), is performed applying the approach of the Exergy Life Cycle Assessment (ELCA). The ELCA provides a comprehensive framework to assess the primary resources requirements of products by means of the conversion of primary flows of energy and raw materials absorbed by a production process into exergy. The soil erosion technologies described in the work are analysed according to two complementary indicators: the annual average soil loss and the life cycle primary exergy requirements. The primary exergy requirement of the different applications is measured by means of three ELCA indicators: the Cumulative Exergy Demand (CExD), the Thermo-Ecological Cost (TEC) and the Cumulative Exergy Extraction from Natural Environment (CEENE). The specific context of the application is a highway slope of the size of 1 hectare situated along the A1 highway, near the town of Fabro (TR), in Italy. The results indicate that DRPs are the most suitable solutions. However, TEC, CExD and CEENE indexes of these technologies suggest the existence of hidden impacts related to land use. The same result characterises also Bio-mats, the technology with the highest contribution of renewable material along the life cycle phases. In conclusion, this work shows that the use of exergy based impact indexes for the environmental impact assessment supplies a wider framework and deeper insights of the environmental performance of production processes and products. [ABSTRACT FROM AUTHOR]

The decarbonisation of residential heat through integration with the power system and deployment of refurbishment policies is at the core of European energy policies. Yet, heat-electricity integration may be challenged, in practice, by the large variability of heat demand across weather years. Current approaches for residential heat demand simulation fail to provide insights about the extent of such variability across many weather years and about the benefits potentially brought about by nearly zero-energy buildings. To fill this gap, this work develops an open-source space-heating demand simulation workflow that is applicable to any country's building stock. The workflow, based on a well-established lumped-parameter thermodynamic model, allows capturing sub-national weather-year variability and the mitigation effects of refurbishment. For Italy, different weather years lead to variations in heat demand up to 2 TWh/day, lasting for several days. Moreover, some weather regimes produce spatial asymmetries that may further complicate heat-electricity integration. The refurbishment of about 55% of buildings constructed before 1975 could substantially mitigate such oscillations, leading to a 31–37% reduction of yearly heat demand, primarily in colder regions. Intra-day heat demand variations, driven by user behaviour, are not substantially impacted by refurbishment, calling for the simultaneous deployment of flexible heat generating technologies. • Heat demand models fail to capture weather variability and refurbishment benefits. • This study provides an open, context-adaptable workflow that allows to do so. • For Italy, large and long-lasting demand variations occur across weather regimes. • Refurbishment can reduce absolute demand by up to 37% and mitigate oscillations. • All such effects vary spatially and must be evaluated at sub-national resolution. [ABSTRACT FROM AUTHOR]