Accounting for human labour in LCA: a novel Input-Output approach

One of the most controversial topic in Life Cycle Assessment (LCA) concerns the evaluation of environmental impact of human labour. The omission of human labour effects may constitute an unfortunate bias, resulting in leaking of environmental effects and, thereby, systematically misin-formed decision-making. In this paper, the innovative Bioeconomic Input-Output model is pro-posed to internalize human labour in LCA. Specifically, the production of human labor is defined as a new productive sector of a given economy: this process absorbs a portion of the national final demand in order to produce working hours. Both the standard and the Bioeconomic models are then applied for the analysis of goods and services produced by the Italian economy in 2010, and results are compared. This model aims at representing a step forward in the process of internalization of human labour externality in LCA

Exergy and Thermoeconomic Analyses of Central Receiver Concentrated Solar Plants Using Air as Heat Transfer Fluid

The latest developments in solar technologies demonstrated that the solar central receiver configuration is the most promising application among concentrated solar power (CSP) plants. In CSPs solar-heated air can be used as the working fluid in a Brayton thermal cycle and as the heat transfer fluid for a Rankine thermal cycle as an alternative to more traditional working fluids thereby reducing maintenance operations and providing the power section with a higher degree of flexibility To supply thermal needs when the solar source is unavailable, an auxiliary burner is requested. This configuration is adopted in the Julich CSP (J-CSP) plant, operating in Germany and characterized by a nominal power of 1.5 MW, the heat transfer fluid (HTF) is air which is heated in the solar tower and used to produce steam for the bottoming Rankine cycle. In this paper, the J-CSP plant with thermal energy storage has been compared with a hybrid CSP plant (H-CSP) using air as the working fluid. Thermodynamic and economic performances of all the simulated plants have been evaluated by applying both exergy analysis and thermoeconomic analysis (TA) to determine the yearly average operation at nominal conditions. The exergy destructions and structure as well as the exergoeconomic costs of products have been derived for all the components of the plants. Based on the obtained results, the thermoeconomic design evaluation and optimization of the plants has been performed, allowing for improvement of the thermodynamic and economic efficiency of the systems as well as decreasing the exergy and exergoeconomic cost of their products

Effects of Waste Cooking Oil Biodiesel Use on Engine Fuel Consumption and Emissions: a Study on the Impact on Oxidation Catalyst and Particulate Filter

Abstract The wide use of biodiesel has been driven by its reduction potential on greenhouse emissions from diesel engines without significant technological modifications. In this study a diesel engine for non-road applications has been fuelled with Waste Cooking Oil biodiesel blended with commercial fossil fuel at 6% and 30% v/v. In line with literature trends, experimental results indicate a significant reduction of PM emissions and only a slight increase in NOx emissions. This study has been focused on diesel emissions and in particular on the analysis of PM/NO2 ratio in presence of the Diesel Oxidation Catalyst (DOC). In fact, although the NO2/NOx ratio on raw exhaust is almost unaffected, the use of biodiesel shows a slight reduction of the NO-NO2 light-off temperature. This reduction can ensure more favorable operating conditions for the Diesel Particulate Filter (DPF), and has a positive effect on fuel consumption reduction. In order to deeply analyze these issues, a numerical model of an Aftertreatment system (AS) representing the a DOC and a DPF has been developed and validated with experimental data

An Off-design Thermoeconomic Input-Output Analysis of a Natural Gas Combined Cycle Power Plant

In the current and forecasted energy scenario, Natural Gas Combined Cycle (NGCC) power plants are requested increasingly flexible operation. The continuous changes in the capacity factor of the power plants and the increasing number and steepness of ramp-ups could largely affect the thermodynamic and economic performance of the plants and undermine their competitiveness. In order for industrial operators to adopt competitive strategies to increase the flexibility of the power plants, the effect that off-design operation has on the cost structure of plant products needs to be addressed. Thermoeconomics provides tools and models to meet such objective. The study presents an application of Thermoeconomic Input-Output Analysis (TIOA) to a NGCC power plant subject to flexible operation in Italy. The on- and off-design performance of the plant is assessed, considering two load control mechanisms for off-design operation: Inlet Guide Vanes (IGVs) with constant Turbine Outlet Temperature (TOT) or constant Turbine Inlet Temperature (TIT). The Input-Output model is derived from a detailed off-design Thermodynamic model designed in Thermoflow Thermoflex™, and it is stand-alone: it computes the cost structure of the plant products and the Thermoeconomic performance indicators as continuous functions of the gas turbine load, independently from the Thermodynamic model. In the first place, the on- and off-design models of the plant are set up. Secondly, the detailed economic cost analysis is performed. Eventually, the stand-alone Input -Output model is derived: the Technical Coefficients and the Input Coefficients are computed from the fuels and products in the Thermodynamic model at different loads; by regression of the obtained values, continuous functions of the load are derived for each coefficient; finally, the stand-alone model is designed, including these functions in the Leontief Inverse matrix. The results provide an evaluation of the off-design performance of the power plant for the two control strategies, and a tool for the choice of the most efficient one. After specialised analysts set up and run the off-design Thermodynamic model, the power plant operators may perform production scenarios and predictions through the stand-alone Input-Output model independently. This may help abate barriers for industrial practitioners, given by the complexity, computational effort and difficult interpretation of off-design thermodynamic and cost models

PRACTICAL APPROACHES FOR THE APPLICATION OF EXERGY COST THEORY TO ENERGY CONVERSION SYSTEMS

The Exergy Cost Theory (ECT) was proposed as a complete and formalized method to account for the exergy cost of system products, defining criteria for optimization and diagnosis purposes. In this paper, different practical approaches for the application of the Exergy Cost Analysis are presented and comparatively applied to the CGAM problem. An emphasis has been specially put on the possible approaches to define and to solve the system of exergy cost balances, including the definition of auxiliary relations and the reallocation of the exergy cost of residues. It is found that the definition of the functional diagram and the numerical solution of the system through Input-Output analysis seems to be preferable with respect to other approaches

Off-Design Modeling of Natural Gas Combined Cycle Power Plants: An Order Reduction by Means of Thermoeconomic Input–Output Analysis

In a European context characterized by growing need for operational flexibility across the electricity sector, the combined cycle power plants are increasingly subjected to cyclic operation. These new operation profiles cause an increase of production costs and decrease of revenues, which undermines the competitiveness of the combined cycles. Power plant operators need tools to predict the effect of off-design operation and control mechanisms on the performance of the power plant. Traditional Thermodynamic or Thermoeconomic models may be unpractical for the operators, due to their complexity and the computational effort they require. This study proposes a Thermoeconomic Input–Output Analysis model for the on- and off-design performance prediction of energy systems, and applies it to La Casella Natural Gas Combined Cycle (NGCC) power plant, in Italy. It represents a stand-alone, reduced order model, where the cost structure of the plant products and the Thermoeconomic performance indicators are derived for on- and off-design conditions as functions of the load and of different control mechanisms, independently from the Thermodynamic model. The results of the application show that the Thermoeconomic Input–Output Analysis model is a suitable tool for power plant operators, able to derive the same information coming from traditional Thermoeconomic Analysis with reduced complexity and computational effort

Control Strategy Influence on the Efficiency of a Hybrid Photovoltaic-Battery-Fuel Cell System Distributed Generation System for Domestic Applications☆

AbstractThe full exploitation of locally available renewable resources together with the reduction of system installation and management costs are key issues of diffused Distributed Generation (DG). In the given context, hybrid systems are already at an advanced stage of development which typically integrate several sub-systems. In such hybrid systems, Renewable Energy Sources generation systems (e.g. photovoltaic panels) are coupled to energy storage devices (electric batteries) and with programmable generators (a diesel generator or, more recently, with a sub-system based on fuel cells) allowing stable operations under a wide range of conditions. In this paper a solution which uses hydrogen and fuel cells as a programmable source is presented and is studied by means of a mixed experimental and numerical: a Hardware-In-Loop test bench designed and realized at the Department lab, able to reproduce the behavior of a hybrid system for domestic applications. The system is controlled by means of a rule-based control strategy acting on the common DC-bus whose optimization has a significant influence both on system design and on its overall system energy performances. Results show that Rule-Based strategy have a great potential towards cost reduction and components lifetime increase, while energy efficiency mainly depends on correct system sizing

analysis of standard and innovative methods for allocating upstream and refinery ghg emissions to oil products

Alternative fuel policies need accurate and transparent methods to find the embedded carbon intensity of individual refinery products. This study investigates different ways of allocating greenhouse gases emissions deriving from refining and upstream crude oil supply. Allocation methods based on mass, energy content, economic value and, innovatively, added-value, are compared with the marginal refining emissions calculated by CONCAWE's linear-programming model to the average EU refinery, which has been adopted as reference in EU legislation. Beside the most important transportation fuels (gasoline, diesel, kerosene/jet fuel and heavy fuel oil), the analysis extends to petroleum coke and refinery hydrogen. Moreover, novel criteria, based on the implications due to hydrogen usage by each fuel pathway, have been introduced to test the consistency of the analyzed approaches

MARIO: A Versatile and User-Friendly Software for Building Input-Output Models

MARIO (Multi-Regional Analysis of Regions through Input-Output) is a Python-based framework for building input-output models. It automates the parsing of well-known databases (e.g. EXIOBASE, EORA, Eurostat) and of customized tables. With respect to similar tools, like pymrio, it broadens the scope of application to supply-use tables and handles both monetary and physical units. Employing an intuitive Excel-based API, it facilitates advanced table manipulations and allows for modelling additional supply chains through a hybrid LCA approach. It provides built-in functions for footprinting and scenario analyses as well as for visualizations of model outcomes. Results are exportable into various formats, possibly supplemented by a metadata file tracking the full history of applied changes. MARIO comes with extensive documentation and is available on Zenodo, GitHub, or installable via PyPI