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Fiorese G.,Polytechnic of Milan | Fiorese G.,LEAP Laboratorio Energia Ambiente Piacenza | Fiorese G.,European Commission - Joint Research Center Ispra | Gatto M.,Polytechnic of Milan | Guariso G.,Polytechnic of Milan
Biomass and Bioenergy | Year: 2013

A method to assess the energy balance and environmental and economic feasibility of a biomass-based energy supply system is presented. Biomass production, harvesting and transportation are considered together with capital investment and operating costs, for both thermal and cogenerative energy production. The location of plants and the definition of collection basins are optimised according to different criteria and allocation strategies: a district-wide planning vs. an incremental allocation. System performances are also compared under alternative technological choices. A case study in the province of Cremona, a major farming area in Northern Italy, is presented. Biomass exploitation has positive returns in terms of energy produced, emissions avoided and investment payback.© 2013 Elsevier Ltd.

Bogale W.,Polytechnic of Milan | Bogale W.,LEAP Laboratorio Energia Ambiente Piacenza | Vigano F.,Polytechnic of Milan | Vigano F.,LEAP Laboratorio Energia Ambiente Piacenza
Energy Procedia | Year: 2014

When looking for sustainable energy systems, Waste-to-Energy plants play a relevant role. Therefore performance evaluation of these plants in order to increase their efficiency is of great relevance to the field of engineering. In the present paper, highly efficient Waste-to-Energy plants are modeled and analyzed from the thermodynamic and technological points of view. Four existing plants constructed in Amsterdam/the Netherlands, Reo Nord/Denmark, Brescia/Italy and Germany were considered. The different methods aiming at increasing the efficiency adopted in these plants have been discussed and compared by using available data in the literature. The performance evaluation was carried out using a proprietary code developed at Politecnico di Milano. A sensitivity analysis was performed to investigate the effects of the plant size, condenser pressure, oxygen content and flue gas temperature at boiler exit on the efficiency of the plants. The results show that adopting a new configuration for steam cycle increases the efficiency of the plant, thus also reducing the corrosion of boiler tubes. It is also demonstrated that the proposed configuration leads to a net lower heating value efficiency of 33%. © 2013 The Authors.

Vigano F.,Polytechnic of Milan | Vigano F.,LEAP Laboratorio Energia Ambiente Piacenza | Consonni S.,Polytechnic of Milan | Consonni S.,LEAP Laboratorio Energia Ambiente Piacenza | And 2 more authors.
Waste Management | Year: 2010

Shredding is the common end-of-life treatment in Europe for dismantled car wrecks. It produces the so-called Automotive Shredded Residue (ASR), usually disposed of in landfill. This paper summarizes the outcome of a study carried out by Politecnico di Milano and LEAP with the support of Actelios SpA on the prospects of a technology based on sequential gasification and combustion of this specific waste stream. Its application to the treatment of ASR allows the recovery of large fractions of metals as non-oxidized, easily marketable secondary raw materials, the vitrification of most of the ash content and the production of power via a steam cycle. Results show that despite the unfavourable characteristics of ASR, the proposed technology can reach appealing energy performances. Three of four environmental impact indicators and the cumulative energy demand index are favourable, the main positive contributes being electricity production and metal recovery (mainly aluminium and copper). The only unfavourable indicator is the global warming index because, since most of the carbon in ASR comes from fossil sources, the carbon dioxide emissions at the stack of the thermal treatment plant are mainly non-renewable and, at the same time, the avoided biogas production from the alternative disposal route of landfilling is minor. © 2009 Elsevier Ltd. All rights reserved.

Consonni S.,Polytechnic of Milan | Consonni S.,LEAP Laboratorio Energia Ambiente Piacenza | Vigano F.,Polytechnic of Milan | Vigano F.,LEAP Laboratorio Energia Ambiente Piacenza
Waste Management | Year: 2012

A number of waste gasification technologies are currently proposed as an alternative to conventional Waste-to-Energy (WtE) plants. Assessing their potential is made difficult by the scarce operating experience and the fragmentary data available. After defining a conceptual framework to classify and assess waste gasification technologies, this paper compares two of the proposed technologies with conventional WtE plants. Performances are evaluated by proprietary software developed at Politecnico di Milano and compared on the basis of a coherent set of assumptions. Since the two gasification technologies are configured as "two-step oxidation" processes, their energy performances are very similar to those of conventional plants. The potential benefits that may justify their adoption relate to material recovery and operation/emission control: recovery of metals in non-oxidized form; collection of ashes in inert, vitrified form; combustion control; lower generation of some pollutants. © 2012 Elsevier Ltd.

Consonni S.,Polytechnic of Milan | Consonni S.,LEAP Laboratorio Energia Ambiente Piacenza | Vigano F.,Polytechnic of Milan | Vigano F.,LEAP Laboratorio Energia Ambiente Piacenza
Waste Management | Year: 2011

This article is part of a set of six coordinated papers reporting the main findings of a research project carried out by five Italian universities on " Material and energy recovery in Integrated Waste Management Systems (IWMS)" An overview of the project and a summary of the most relevant results can be found in the introductory article of the series. This paper describes the work related to the evaluation of mass and energy balances, which has consisted of three major efforts (i) development of a model for quantifying the energy content and the elemental compositions of the waste streams appearing in a IWMS; (ii) upgrade of an earlier model to predict the performances of Waste-to-Energy (WtE) plants; (iii) evaluation of mass and energy balances of all the scenarios and the recovery paths considered in the project.Results show that not only the amount of material available for energy recovery is significantly higher than the Unsorted Residual Waste (URW) left after Separate Collection (SC), because selection and recycling generate significant amounts of residues, but its heating value is higher than that of the original, gross waste. Therefore, the energy potential of what is left after recycling is always higher than the complement to 100% of the Source Separation Level (SSL). Also, increasing SSL has marginal effects on the potential for energy recovery: nearly doubling SSL (from 35% to 65%) reduces the energy potential only by one fourth. Consequently, even at high SSL energy recovery is a fundamental step of a sustainable waste management system.Variations of SSL do bring about variations of the composition, heating value and moisture content of the material fed to WtE plants, but these variations (i) are smaller than one can expect; (ii) have marginal effects on the performances of the WtE plant. These considerations suggest that the mere value of SSL is not a good indicator of the quality of the waste management system, nor of its energy and environmental outcome.Given the well-known dependence of the efficiency of steam power plants with their power output, the efficiency of energy recovery crucially depends on the size of the IWMS served by the WtE plant. A fivefold increase of the amount of gross waste handled in the IWMS (from 150,000 to 750,000 tons per year of gross waste) allows increasing the electric efficiencies of the WtE plant by about 6-7 percentage points (from 21-23% to 28.5% circa). © 2011 Elsevier Ltd.

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