Restricted dissimination
(Contract XXX)
Analytical review of comparative environmental assessments of incineration and co-incinertaion of waste
final report
Ive Vanderreydt, Ann Van der Linden, Veronique Van Hoof, Karl Vrancken (VITO)
Henrik Wenzel, Nassera Shabeer Ahmed (SDU)
Study accomplished under the authority of EURITS
2008/ECIMS/R/xxx
VITO
February 2009
All rights, amongst which the copyright, on the materials described in this document rest with the Flemish Institute for Technological Research NV (“VITO”), Boeretang 200, BE-2400 Mol, Register of Legal Entities VAT BE 0244.195.916.
The information provided in this document is confidential information of VITO. This document may not be reproduced or brought into circulation without the prior written consent of VITO. Without prior permission in writing from VITO this document may not be used, in whole or in part, for the lodging of claims, for conducting proceedings, for publicity and/or for the benefit or acquisition in a more general sense.
VII
Chapter 1 Introduction
Distribution list
Guido Wauters, Indaver
Andres Van Brecht, Indaver
Ann Van der Linden, VITO
Ive Vanderreydt, VITO
Veronique Van Hoof, VITO
Karl Vrancken, VITO
Henrik Wenzel, SDU
Nassera Shabeer Ahmed, SDU
Table of content
Chapter 1 Introduction 4
1.1 Understanding and goal of the project 4
1.2 Approach 5
Chapter 2 Preliminary case study 7
2.1 Introduction 7
2.2 General review 7
2.2.1 Used method 7
2.2.2 Emission Limit Values 8
2.2.3 Function of the compared systems 9
2.2.4 Course of the study 9
2.3 LCA review 10
2.3.1 Goal and scope definition 10
2.3.2 Life cycle inventory analysis 12
2.3.3 Life cycle impact assessment 13
2.3.4 Interpretation 13
Chapter 3 Literature search 14
3.1 Introduction 14
3.2 Approach 14
3.3 Results 14
Chapter 4 Conclusion 18
4.1 Critical review of one case study 18
4.2 Literature search 18
4.3 The way forward 19
List of abbreviations
CK / Cement kilnDTO / Draai Trommel Oven
ELV / Emission Limit Values
FBC / Fluidised Bed Combustion
LCA / Life Cycle Assessment
PFD / Process Flow Diagram
RKI / Rotary Kiln Incinerator
Chapter 1 Introduction
1.1 Understanding and goal of the project
Various routes exist for the treatment of hazardous wastes. When the waste has a medium or high calorific value, incineration in dedicated waste treatment installations and co-incineration in cement kilns are most often used.
The priority order for waste treatment in the EU Waste Framework Directive prefers recovery of wastes over disposal. As simple as it seems, this priority order leaves a lot of room for interpretation. The incineration of waste can be seen as either a recovery operation (R1 : Use principally as a fuel or other means to generate energy) or as a disposal operation (D10 : incineration on land). This has since long triggered a debate between hazardous waste incineration companies and the cement industry on the environmental benefits of both options. The classification of both routes may result in an adapted waste management policy, using e.g. taxes, to favor one route over another. In Flanders a tax has to be paid for the incineration (dedicated waste incinerator) and co-incineration (in cement kiln, power plant or other industrial installations) of waste. There is no distinction made between both incineration options.
Life Cycle Assessment (LCA) is one of the most widely used and internationally accepted methods for the evaluation of the environmental impacts of products and systems. An LCA is a calculation of the environmental burden of a material, product or service during its lifetime, and ideally performed as a comparison between alternatives.
LCA has been used in the last decade to compare the environmental impacts of different options for the handling of waste. However, the application of LCA to such complex systems presents significant challenges, the most important being whether or not the interactions between a waste system with its surrounding technosphere have been properly characterised. Different assumptions around such interactions have often resulted in LCAs which apparently analyse the same material system but produce very different conclusions. A key objective of a comparative LCA review is therefore to build a greater understanding of the critical factors that determine environmental preferences between waste management options, taking into account overall life cycle impacts and underlying assumptions.
The thermal treatment of wastes in dedicated incinerators and in cement kilns has been the topic of several LCA studies, each using its own system borders and assumptions. In this review of comparative LCAs we will study the parallels and differences between the various LCA studies. From this we will provide insight in the key assumptions that govern the environmental performance of both waste treatment scenarios. In a final step we will give advice on how the key assumptions should be set to reflect the real life situation.
1.2 Approach
The project is performed in two phases, each phase having 2 tasks:
· Phase 1: Setting the scene:
o Task 1.1 : preliminary case study
o Task 1.2 : literature search
· Phase 2: Analytical review and evaluation of comparative LCAs
o Task 2.1 : analysis and identification of key issues and robustness of conclusions
o Task 2.2 : definition of the right assumptions on selected key issues
The project follows a phased approach with an evaluation and go/no-go decision after phase 1. On basis of the results of phase 1, the extent of the analysis (i.e. total number of LCA studies to evaluate) will be clear. At this stage an evaluation of the budget proposal for the remaining phases will be done. The budget for phase 2 will be determined on basis of the number of cases for evaluation.
This report covers Phase 1 of the approach, with Chapter 2 focusing on the preliminary case study and 0 on the literature search.
3
Chapter 1 Introduction
Chapter 2 Preliminary case study
2.1 Introduction
In order to provide insight in the possible key issues for an assessment, a critical review of a LCA study is performed as part of phase 1. This review will help to decide on the selection of relevant LCAs for further study and will discuss, using an example, how a variation in key issues can affect the final conclusions of a comparative LCA study.
The study ‘LCA of thermal treatment of waste streams in cement clinker kilns in Belgium, comparison to alternative treatment options’ (Annex A, [15]) will be used as an example case. In the critical review we refer to this study as “the study”.
The critical review consist of two parts, a general part and a LCA-part. In the general review we make a overall evaluation of the study and the way it was conducted. In the LCA review we make a critical review on whether the study is conform the ISO 14040 an 14044 [ISO, 2006].
2.2 General review
2.2.1 Used method
In the reviewed study the method of marginal changes is used to compare the two systems. The marginal approach is used when allocation problems in life cycle assessment occur [EKVALL, 1999] and allocates environmental burdens to each function in proportion to the extent to which the total modeled environmental burdens of the multi-function system are affected by a marginal change in that function. The results from a successful application of this approach will reflect the consequences of actions that affect the production volume of one of the functional outputs while the other functions remain unaffected. In the study the marginal change is the treatment of one extra ton of waste in either system.
ISO 14044 states that wherever possible, allocation should be avoided by
§ Dividing the unit process to be allocated into two or more sub-processes and collecting the input and output data related to these sub-processes, or
§ Expanding the product system to include the additional functions related to the co-products, taking the requirements of system boundaries into account.
We believe that in this case the latter method should have been used. Important key issues of the comparison between incineration and co-combustion relate to the products and systems replaced by the co-product outputs from the waste management, i.e. heat and electricity. In not applying system expansion on these, significant errors can be made.
2.2.2 Emission Limit Values
Both incinerators are submitted to the European directive 2000/76 on the incineration of waste. In this directive different emission limit values (ELV) are given for the incineration of waste and the co-incineration of waste in specific industrial sectors. One of these specific industrial sectors is the cement industry. For a number of parameters less strict ELV apply for these installations. Furthermore the directive states that exemptions may be authorized by the competent authority for some pollutants.
For instance, the ELV for dust an NOx are respectively 10 and 200 mg/Nm³ (oxygen content of 11%) for incineration and 30 and 500 (to 800) mg/Nm³ (with an oxygen content of 10%). This difference in ELV has as a consequence that less investments have to be made in flue gas cleaning installations by the cement industry. Besides that, both the emissions in concentration (mg/m³) and the pollution load (kg/year) are higher for co-incineration in the cement industry compared to incineration in a dedicated installation[1].
In following table an overview is given of the average emissions to air for the Belgian Cement industry and the dedicated waste installation (DTO (or RKI) of Indaver). For the cement industry these figures are based on “the annual environmental report of the Belgian cement industry, 2006”. The emission levels given in the table are calculated using the percentage given in the report and the ELV of the waste incineration directive. These emission levels refer to the year 2005. More recent figures were not found by VITO. For SOx an ELV of 50 mg/Nm³ is used and for NOx 800 mg/Nm³. For the DTO of Indaver these emission levels are based on the information given on the website. They refer to the year 2007. These emission levels are the combined emissions of both DTO’s and the static furnace at the Antwerp site of Indaver.
Table 1: overview average emission values for the Belgian cement industry(2005) and for the DTO and static furnace of Indaver (2007)
mg/Nm³, dioxins and furans ng TEQ/Nm³ / Cement kilns / Dedicated hazardous waste incinerationCO / nda / 14,3
dust / 11,55 / 0,53
HCl / 6,07 / 0,56
HF / 0,219 / nda
NOx / 512 / 139
SOx / 19,5 / 7,13
TOC / nda / 1,29
Cd-Tl / 0,0058 / < 0,01
Hg / 0,0195 / < 0,004
Heavy metals / 0,04 / < 0,004
dioxins en furans / 0,0376 / 0,006
nda = no data available.
These figures show that the emission levels of the dedicated incinerator are lower compared to the emission levels of the Belgian cement kilns.
The data that are used in the TNO-study for the waste incineration plant are based on several different sources, creating an installation that is non-existing. In addition, the majority of the emission data are based on a Swiss incineration plant. These installations are therefore not subjected to the EU-directive on waste incineration.
2.2.3 Function of the compared systems
Besides their differences in environmental performance both systems also have a different social function. The function of a waste incinerator is to destroy waste. In that function waste incinerators are important to society, and economic motives are often of minor importance. The function of a cement kiln is to produce cement. For this sector the main motive is to produce high-grade cement at a competitive price, and their impact on society is of secondary importance.
Because of their specific function waste incinerators are designed to be able to process different types of (hazardous) waste, within certain limits, conform the ELV. Cement kilns can process different types of (hazardous) waste taking certain conditions into account (see also Annex A, [37]) :
§ maximum 15% of the minerals used in the clinker can come from wastes replacing fuels,
§ at least 10% of the used fuels need to be high calorific,
§ the suitability of types of waste is determined by the need for energy and specific raw materials (e.g. Si, Al, ,…) of the process,
§ some elements (e.g. Cl, P2O5, Hg, Tl, …) have a negative effect on the process, product or installation. The use of wastes containing these elements are therefore undesirable in cement kilns.
By only evaluating in the LCA those waste streams that can be processed by the cement industry, the social function of the waste incinerator is not accounted for. Dedicated waste incinerators have to deal with waste, regardless it’s composition and calorific value.
A standard LCA study provides answers for one pillar of sustainability : the environmental pillar. The two other pillars of sustainability, social and economic, are not evaluated in these types of studies, although they also have to be considered in discussion related to waste hierarchy (as stated in Article 4 of the Waste Framework Directive). To evaluate these issues other types of impact assessments need to be conducted.
Finally, the conditions that need to be taken into account by the cement kilns concerning the total amounts of waste that can be processed are not taken into account in the study. These restrictions should at least be mentioned in the study.
2.2.4 Course of the study
The chairman of the expert panel, who should have been present at all the meetings has only attended the last meeting. He was replaced during the first three meetings by the commissioner of the study. This means that there is a conflict of interest.
According to VITO, the minutes of the meeting do not reflect the content of the meetings.
The distribution coefficients that are used for incinerators where sent to the expert panel after the deadline to formulate fundamental comments. So the quality of these data is not checked by the expert panel.
Several comments given by members of the expert panel were not taken into account.
2.3 LCA review
In “the study” is stated that ‘to follow the ISO guidelines for LCA and to improve the quality of the LCA study, an expert panel was consulted four times during the performance of the study”, (pg. 8). Therefore we assume that TNO had the intention to conduct this study according to the ISO guidelines. For that reason we use ISO 14040 [ISO, 2006] to evaluate the LCA study.