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Swindon, United Kingdom

Evangelisti S.,University College London | Tagliaferri C.,University College London | Clift R.,University of Surrey | Lettieri P.,University College London | And 2 more authors.
Waste Management | Year: 2015

In the past, almost all residual municipal waste in the UK was landfilled without treatment. Recent European waste management directives have promoted the uptake of more sustainable treatment technologies, especially for biodegradable waste. Local authorities have started considering other options for dealing with residual waste. In this study, a life cycle assessment of a future 20. MWe plant using an advanced two-stage gasification and plasma technology is undertaken. This plant can thermally treat waste feedstocks with different composition and heating value to produce electricity, steam and a vitrified product. The objective of the study is to analyse the environmental impacts of the process when fed with seven different feedstocks (including municipal solid waste, solid refuse fuel, reuse-derived fuel, wood biomass and commercial & industrial waste) and identify the process steps which contribute more to the environmental burden. A scenario analysis on key processes, such as oxygen production technology, metal recovery and the appropriate choice for the secondary market aggregate material, is performed. The influence of accounting for the biogenic carbon content in the waste from the calculations of the global warming potential is also shown. Results show that the treatment of the refuse-derived fuel has the lowest impact in terms of both global warming potential and acidification potential because of its high heating value. For all the other impact categories analysed, the two-stage gasification and plasma process shows a negative impact for all the waste streams considered, mainly due to the avoided burdens associated with the production of electricity from the plant. The plasma convertor, key characteristic of the thermal process investigated, although utilising electricity shows a relatively small contribution to the overall environmental impact of the plant. The results do not significantly vary in the scenario analysis. Accounting for biogenic carbon enhanced the performance of biomass and refuse-derived fuel in terms of global warming potential. The main analysis of this study has been performed from a waste management perspective, using 1. ton of waste as functional unit. A comparison of the results when 1. kWhe of electricity produced is used as functional unit shows similar trends for the environmental impact categories considered. © 2015 Elsevier Ltd. Source


Tagliaferri C.,University College London | Evangelisti S.,University College London | Clift R.,University of Surrey | Lettieri P.,University College London | And 2 more authors.
Journal of Cleaner Production | Year: 2016

This study integrates the Life Cycle Assessment (LCA) of thermal and biological technologies for municipal solid waste management within the context of renewable resource use for methane production. Five different scenarios are analysed for the UK, the main focus being on advanced gasification-plasma technology for Bio Substitute natural gas (Bio-SNG) production, anaerobic digestion and incineration. Firstly, a waste management perspective has been taken and a functional unit of 1 kg of waste to be disposed was used; secondly, according to an energy production perspective a functional unit of 1 MJ of renewable methane produced was considered. The first perspective demonstrates that when the current energy mix is used in the analysis (i.e. strongly based on fossil resources), processes with higher electric efficiency determine lower global warming potential (GWP). However, as the electricity mix in the UK becomes less carbon intensive and the natural gas mix increases the carbon intensity, processes with higher Bio-SNG yield are shown to achieve a lower global warming impact within the next 20 years. When the perspective of energy production is taken, more efficient technologies for renewable methane production give a lower GWP for both current and future energy mix. All other LCA indicators are also analysed and the hot spot of the anaerobic digestion process is performed. © 2016 Elsevier Ltd. All rights reserved. Source


Ray R.,Advanced Plasma Power Applied | Taylor R.,Advanced Plasma Power Applied | Chapman C.,Advanced Plasma Power Applied
Process Safety and Environmental Protection | Year: 2012

The Gasplasma ® process developed by APP is an advanced thermal conversion (ATC) technology which has been developed for the treatment of household and trade wastes and has also been successfully applied to the handling of wastes derived from landfill and would be capable of achieving effective energy conversion when utilised as an integrated part of the Enhanced Landfill Mining (ELFM) concept. The core Gasplasma ® technology comprises a two-stage thermal treatment system - firstly, a fluidizing bed gasifier which converts the wastes to a crude syngas using oxy-steam and, secondly, a plasma converter that efficiently cracks problematic tars in the raw syngas to produce a reformed and clean syngas suitable for generating electrical power in gas engines and also recovering an environmentally stable vitrified product for use as a secondary aggregate material. The utilization of oxy-steam as a gasifying agent greatly reduces the syngas volume compared to other ATC processes and incineration and hence reduces the cost of the gas cleaning system while improving the efficiency of the process. By adopting this two-stage approach, high energy conversion (74-90%) and carbon conversion (95 ± 1.6%) efficiencies were achieved with the Gasplasma ® plant that compare favourably with published efficiencies data. The calculated net exportable power generation efficiency for a commercial scale plant is significantly in excess of 25%. This compares well with the published figures of 17.7-23% for fluidized bed technologies processing MSW. © 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Source


Taylor R.,Advanced Plasma Power Applied | Ray R.,Advanced Plasma Power Applied | Chapman C.,Advanced Plasma Power Applied
Fuel | Year: 2013

The disposal of End-of-Life Vehicles (ELVs) results in a highly heterogeneous polymeric waste stream of Automobile shredder residue (ASR). Within Europe, strict legislation, such as the End-of-Life Vehicle Directive and the Landfill Directive, has imposed targets for reducing this waste stream and diverting the material away from landfill. One pathway open to recyclers is to thermally process these wastes, but the presence of chlorine and metallic species can present challenges to traditional incineration technologies. This paper discusses the use of Gasplasma®, an advanced thermal treatment technology, comprising fluidised bed oxy-steam gasification followed by plasma treatment, for ASR, refuse derived fuel (RDF) and blends of ASR and RDF wastes. The work demonstrates the ability to process these highly heterogeneous materials achieving high energy conversion (87-94%) and virtually complete carbon conversion, producing a calorific synthetic gas (syngas) capable of being used for power generation or as a chemical feedstock. The actual conversion efficiency achieved is dependent on feed chemistry and properties. The study also shows that ash components of the feed material can be transformed into an environmentally stable vitrified product. © 2012 Elsevier Ltd. All rights reserved. Source

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