Eco-Efficient Implementation of Electronic Waste Policies in Practice Jaco Huisman
Ab Stevels
Design for Sustainability Research Program, Delft University of Technology, Delft, The Netherlands
[email protected]
Environmental Competence Centre Philips Consumer Electronics Eindhoven, The Netherlands
[email protected] Boards), capacitors, LCD (Liquid Crystal Display) screens and plastics with brominated flame retardants) [2,3]. In the WEEE Directive (Waste of Electric and Electronic Equipment), there is only limited or no attention on the minimum collection amount strategy (currently 4 kg per inhabitant to be collected per year together for all categories covered) and on the strategy of prescribing minimum outlets of recycling operations. This last strategy means prescribing what the processing destinations and characteristics of the various fractions created, should be as a minimum. The RoHS Directive (Restriction on the use of Hazardous Substance) [3], which addresses the strategy of restricting hazardous substances is mainly left out of the scope of this article.
Abstract—An comprehensive and quantitative eco-efficiency concept for end-of-life consumer electronics is developed at the TU Delft. It addresses the key question in setting up take-back systems for discarded consumer electronics: How much environmental improvement can be realized per amount of money invested? This paper highlights the latest results of applying the concept in practice on the implementation of electronic waste policies like in the European WEEE and RoHS Directives. The outcomes show in general how short, medium and long term developments in applying electronic waste policies should look like. Keywords- Eco-efficiency; End-of-life; Electronics; Waste Policy Strategies
I.
In the next Section 2 the QWERTY/EE concept will be introduced. In Section 3, various results are presented to illustrate the position and consequences of the European WEEE Directive in particular. This includes:
INTRODUCTION
In this paper, the outcomes of the QWERTY/EE concept, (Quotes for environmentally WEighted RecyclabiliTY and Eco-Efficiency) on the current European waste policy situation are discussed. Based on this, generic rules and strategies are presented which are applicable for all countries already dealing or starting in the near future with take-back and recycling of electronic products.
1) The environmental level of re-application Here, an illustration will be presented on the influence of the level of re-application of materials. In this case CRT glass (Cathode Ray Tube) is used as an example and the options considered here are disposal, application in the building industry, application in the ceramic industry, application as secondary material for new screen and cone glass.
With the QWERTY/EE concept, detailed insights are generated on where environmental losses in recycling occur, on what the contribution of the various processes in end-of-life treatment is, on which material to focus on, how to evaluate (re)designs and finally how to come to eco-efficiency waste policy strategies [1]. In general, there are 5 main strategies to improve or enable environmental performance of end-of-life products: 1) 2) 3) 4) 5)
2) Mandatory disassembly of PWB’s This includes analysis of the eco-efficiency of the selective treatment of printed circuit boards as pointed out in the Annex II of the EU WEEE Directive. 3) Plastic recycling and compliance with recycling targets This includes analysis of the eco-efficiency of applying plastic recycling of housings of various sizes in order to achieve compliance with recycling targets.
Weight based recycling and recovery targets Restriction on hazardous substances Treatment rules for recyclers Minimum collection amounts Outlet rules for recyclers
In Section 4, the conclusion out of the eco-efficiency calculations performed on the implementation process of the WEEE Directive are presented as well as the key elements needed to come to effective and efficient take-back systems for electronic products on the present time. Thereafter, a more general roadmap is presented for short, medium and long term development of the electronic waste policies in general and on the implementation in practice. In the last section, conclusions are drawn on rebalancing policy strategies in general.
For the European situation, from these five strategies, the main focus is on the first three items: weight based recycling targets for various products categories, restrictions on the use of specific hazardous materials and specific treatment rules for recyclers like mandatory and selective treatment of certain components (printed wiring boards (PWB’s (Printed Wiring
0-7803-8250-1/04/$20.00 © 2004 IEEE.
243
II.
THE QWERTY/EE CONCEPT
1) Minimum environmental impact and minimum costs These two values (environmental and economic) are corresponding with the theoretical scenario of all materials being recovered completely without any environmental impact or economic costs of end-of-life treatment steps. As such, they are representing the environmental value for substitution of primary materials and the economic value for newly extracted and produced materials. Usually both are negative and theoretical values: in practice there will always appear (environmental) costs connected to separation of materials, energy consumption and transport.
A. A comprehensive approach Until now, recyclability of products has mostly been calculated on a weight basis only, which is a poor yardstick from an environmental perspective and which is scientifically very inaccurate. The general focus on ‘weight’ can lead to incorrect conclusions regarding the initial ‘environmental’ goals of waste policies. Calculations based on weight-based recyclability are likely to lead to incorrect decisions, especially when materials are present in low amounts, but with high environmental and economic values like precious metals [1,4]. This notion has led to the development of the QWERTY concept for calculating product recyclability on a real environmental basis instead of on a weight basis only [4]. Before discussing the methodology developed in detail, the starting points, boundary conditions and elements needed, are discussed shortly: The starting point of the QWERTY analysis is the point of disposal by consumers. From there, the product, its components and materials can follow different directions. The general directions are re-use, refurbishment and material recycling as well as disposal with MSW (Municipal Solid Waste). Whereas the QWERTY approach is primarily focused on material recycling, the re-use and refurbishment option are regarded as out of scope of this article. The environmental calculations as shown later on in this paper are based on LCA (Life-Cycle Assessment), but with one important difference: the calculations are starting with the end-of-life phase followed with the destinations of materials into new products or to disposal options only. The most important elements required for environmental validation and integral costs connected to this (which are needed for the eco-efficiency part) are all included in the calculations. These are: collection and transport characteristics after discarding, the individual behavior of products in dismantling and, or shredding and separation operations, modeling of the secondary material processing and disposal routes like emissions at landfill and incineration and an environmental validation method producing environmental scores. The resulting modeling is very comprehensive and covering all main environmental and cost aspects [5].
2) Maximum environmental impact and maximum costs These two values are defined as the theoretical scenario of every material ending up in the worst possible (realistic) endof-life route, including the environmental burden plus costs of pre-treatment: collection, transport, disassembly and shredding and separation into fractions. The ‘realistic’ end-of-life scenarios under consideration are controlled and uncontrolled landfill, incineration with or without energy recovery and all subsequent treatment steps for material fractions, like copper, ferro and aluminum smelting, glass oven and plastic recycler. Also this theoretical value cannot easily be exceeded: only under extreme disposal conditions, which are normally forbidden by law. 3) Actual environmental impacts and costs These values are based on the actual environmental and economic performance of the end-of-life scenario under consideration and are compared with the two boundary conditions above and finally expressed as percentages. These actual values are obtained by tracking the behavior of all materials over all end-of-life routes and by taking into account all costs and environmental effects connected to this. All detailed backgrounds and formulas to calculate QWERTY values can be found in [1,4,5]. The environmental values can be calculated with different LCA methods. As a default method however, the Eco-Indicator’99 method is used [6]. C. Eco-efficiency In order to enhance the ‘eco-efficiency over the total endof-life chain’, the outcomes of the eco-efficiency calculations support the stakeholder and enablers involved in take-back and recycling. These stakeholders are: authorities by helping formulating criteria for collection of disposed products and monitoring end-of-life performance of take-back systems. It enables producers to calculate economical and environmental values on forehand. Furthermore it supports recyclers in finding the right avenues of future technology application and investments. At last, from a consumer or society point of view it helps getting insights in the environmental impacts per amount of money being spent, directly or indirectly, whereas the consumers pay the environmental and economic bill in the end.
B. QWERTY Based on the modeling of the end-of-life chain, environmental and economic calculations are based on three values as displayed in Fig. 1. All materials recovered, best case
Minimum environmental impact
100% QWERTYloss
Actual environmental impact
QWERTY score
QWERTY
In Fig. 2, the four main eco-efficiency directions are shown in a two-dimensional eco-efficiency graph. The Y-axis represents the absolute environmental outcomes of the QWERTY calculations (in environmental millipoints), the Xaxis represents the economic outcomes (in €, representing the
Maximum environmental impact
0%
All materials to worst case end-of-life route
Figure 1. Calculating QWERTY values
This research is executed in commission of the Dutch Ministry of Environment, Division Non Hazardous Waste (VROM), The Stichting Nederlandse Verwijdering Metalektro Producten (NVMP, Dutch take-back system) and Philips Consumer Electronics, Environmental Competence Centre (PCE-ECC)
0-7803-8250-1/04/$20.00 © 2004 IEEE.
244
Dutch situation, 1 € = $ 1,29 at 18-2-2004). The points in the graph are representing various end-of-life scenarios for one and the same product (or an individual component, assembly, fraction or product stream). The scenarios are based on changes in technology, design or system organization. Examples of such changes are for instance saving more products from the landfill (increasing collection rates), increasing plastic recycling and glass recycling, the effects of Design for Environment activities or logistics changes.
the Dutch take-back system with relatively short transport distances. Economies of scale are realized for all examples and improvement options. Costs for consumers for handing in products are excluded from the integral costs unless stated otherwise. For all example products, chemical analysis of the PWB’s is performed. Data for all other components are obtained from environmental benchmarks [7]. The two combined result in full product compositions. For the other products without chemical analysis of PWB’s, good estimates are available based on the types of PWB materials, the level of integration of components and the amounts and types of components attached to the boards. The Eco-Indicator '99, Philips Best-Estimate, Hierarchic Perspective, Average Weighting set, weighting factor Resource Depletion – Minerals adjusted to 5%, is used as a default environmental assessment model [6]. All fractions sent to a subsequent process fall under the acceptance criteria applicable for this process or operation. The environmental effects of final waste disposal are obtained from [8]. All further underlying data for all process steps and stages and the environmental validation methods are published in [1,4,5].
In order to achieve a higher eco-efficiency compared to an existing recycling scenario, one should move into the direction of the upper right part of the graph (a ‘plus’ for environment and a ‘plus’ for economy). Besides this direction, the opposite direction (minus, minus) should be avoided and the (minus, plus) and (plus, minus) should be balanced or ranked. Revenues “Higher” eco-effic iency
A III.
(€)
C D
B “Low er” eco-effic iency
A. The environmental level of re-application for CRT glass Currently, glass fractions from CRT containing appliances can be send to different outlets like landfill, as replacement of sand in the building industry, as replacement of Feldspar in the ceramic industry or as application as secondary material for new screen and cone glass. In the WEEE Directive, all of these applications (except the landfill of course) are counted as a useful re-application and therefore as ‘recycled’. Recyclers are likely to send their fractions to the cheapest outlet with the highest recovery rate. Fig. 3 shows the environmental level of re-application versus the recovery percentage of the glass replacement options under consideration.
Costs Environmental burden
(mPts)
Environmental gain
Figure 2. The four eco-efficiency quadrants
Based on Fig.2, application of the eco-efficiency method to analyze take-back and recycling includes two important steps: Step 1 is application of a ‘vector approach’ as sketched above. This means that in first instance four quadrants are selected. A ‘positive eco-efficiency’ is realized when for example the resulting vector is directed to the first quadrant (e.g. point A) of Fig. 2 compared to the original situation (reference point). The opposite counts for the third quadrant. Options and directions is this case should be avoided from both an environmental as an economic point of view.
Level of re-application (%)
100%
Step 2 includes calculation of environmental gain over costs ratios and ranking of the ‘quotient’ for the second and fourth quadrant. This is applied when an environmental improvement is realized and financial investments are needed to obtain this or in reverse. In general, when multiple options are appearing in the fourth quadrant, the ‘quotient approach’ can be applied to determine how much absolute environmental improvement (mPts) is realized per amount of money invested (€).
Primary CRT glass
80% 60%
Secondary CRT glass (replacing new glass)
40%
Replacing Feldspar (ceramic industry)
20%
Replacing sand (building industry)
0% 0%
20%
40%
60%
80%
100%
Recovery (%)
Figure 3. The environmental level of re-application of CRT glass
The points in the graph represent the environmental level of re-application (Y-axis) versus the ‘recovery’ percentage (this is not the WEEE definition but the amount of material really reapplied in a ‘new product’). The initial value for primary CRT glass (100%) can not be reached due to transport, cleaning operations and energy needed for processing secondary glass. The graph shows that the lower levels of re-application result in higher WEEE recycling percentages. An important outcome
D. Assumptions and data All data, results and graphs presented in the next sections are based on the following important assumptions and starting points: State-of-the-art recycling is based on best available shredding and separation techniques [1]. Data are representing
0-7803-8250-1/04/$20.00 © 2004 IEEE.
RESULTS
245
from this graph is that all secondary options contribute equally to the WEEE recycling targets and that they are in reality not equally contributing to the environmental results. The conclusion on this issue is that lack of prescriptive ‘output’ rules results in the effect that the environmental intent of the WEEE Directive is not served.
more in proportion compared to 50 seconds for 50 grams (factor 10). In the WEEE Directive, no real distinction is made in the recycling targets for small, medium and large sized products. Especially for small plastic dominated products, the recycling targets can only be achieved by applying plastics recycling. In this respect, the actual costs for take-back and recycling will be dependent on how strict monitoring (and this will be different per individual EU member state) will take place by authorities.
B. Mandatory disassembly of PWB’s Another example of a chosen policy strategy in the WEEE Directive is the prescription of treatment rules for recyclers: The Annex II regards ‘selective treatment’ of certain components like printed circuit boards larger than 10 cm2. It is shown that the basic environmental benefit of disassembling PWB’s from discarded products lies in avoiding that valuable and environmentally relevant materials are lost in shredding and separation [1]. However, only for products with relatively high concentrations of precious metals like cellular phones, the resulting eco-efficiency of the disassembly step is significant. This is illustrated in Fig.4. It shows the concentration (not the amount!) of gold on circuit boards (X-axis) versus the ecoefficiency in mPts per € (Y-axis).
-300
Eco-efficiency (mPts/€)
-250
Large sized
-200 -150
Medium sized -100
Small sized
-50 0 0,0
Environmental gain (mPts/€
100 80
Precious metal dominated, high end
60
Precious metal dominated, average
40
Plastic dominated
20
Metal dominated, average
0 0
200
400
600
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
Weight housings (kg)
Figure 5. Plastic recycling versus size of housings
IV.
ROADMAP FOR ECO-EFFICIENT IMPLEMENTATION OF WEEE
The consequences of the above examples on the short term development process of implementation of the WEEE Directive in Europe will be discussed in this section. This includes a roadmap towards a more eco-efficient and long term revising of the European Directive and also learning material for those countries still without electronic waste regulations. However, before starting with the roadmap, three important and key-elements which are required for eco-efficient takeback systems for the present situation are discussed. These are important to consider and needed to start with take-back system ‘construction’ or further development on basis of current best practices.
800 1000
Gold concentration (in ppm)
Figure 4. Eco-efficiency of disassembly of PWB’s versus gold concentration
The graph shows an eco-efficiency which is very low for ‘regular’ consumer electronic products and low for products with a gold concentration above 400 ppm (see next section for a comparison with other eco-efficiency outcomes). However, the general strategy of not losing valuable material for the ‘most valuable’ products to other fractions than the fraction can also be obtained by sorting these products out of the larger products streams collected, followed by sending them directly to a copper smelter. Besides similar environmental outcomes, such operation would also lead to a change towards the first ‘WIN-WIN’ quadrant of Fig.2 and should be encouraged by waste policies instead of discouraged.
A. Start on basis of best practice: key elements . These elements are presented in order of importance: Economies of scale is contributing the most, followed by ‘outlet management’ and with Design for End-of-life at last. 1) Economies of scale Achieving economies of scale is the number one element for cost efficient take-back systems. Relatively high costs occur when product streams collected or recycled are too small. As a consequence, recyclers might process multiple product streams from the 10 WEEE categories within the same process at the same time. As a result, certain monitoring problems could occur for instance on determining whether the recycling and recovery targets are achieved per WEEE category or not. This is due to mixing multiple categories (like treating TV’s and Monitors from two individual categories on the same disassembly line).
C. Plastic recycling and compliance with recycling targets Another example, related to recycling targets being prescribed, is the recycling of plastic housings from various products. In Fig.5, the eco-efficiency (in mPts/€) are presented on the Y-axis, the size of housings are displayed on the X-axis. The points in this graph represent the eco-efficiency of plastics recycling of the housings from various electronic products. The distinction between large, medium and small sized housings is due to the disassembly time needed for obtaining recyclable plastics. Spending 500 seconds for 5 kg of plastics is much
0-7803-8250-1/04/$20.00 © 2004 IEEE.
0,5
246
which are already disassembled due to the presence of a CRT (-encourage or prescribe that the output of those fractions is plastic recycling!). However, this direction is only possible for well-defined plastics, without contaminations, flame-retardants, stickers and metal inserts and in case that an outlet or market is available for the recycled content.
2) Manage outlets and markets for secondary materials For recyclers, despite all prerequisites of the WEEE Directive, it is recommended to search for those outlet options first which have the highest level of re-application. This applies specifically for glass, residue and plastic fractions. (For metal fractions, the obvious destination is the corresponding available and preferably modern metal smelter). This issue is further discussed in the next part of this section on short term implementation and effective and efficient monitoring.
2) Avoid ‘LOSS – LOSS’ situations Changes or configurations that lead to LOSS-LOSS outcomes should be avoided. Examples of this are the incineration of plastic or residue fractions without energy recovery compared to incineration with energy recovery (=output). In simple words: Always get the energy back. However, fractions that have a relatively low plastic content, but a high metal content should not be incinerated in a cement kiln without sophisticated flue gas cleaning, due to the emissions of metals to air.
3) Design for end-of-life Besides the strategies which increase environmental performance of products in end-of-life, as a starting principle, the environmental life-cycle perspective should be taken into account. In other words: sound ecodesign in general should focus on reducing environmental burden of products throughout the life-cycle: in the production, use and disposal phase. In this respect, in [9] it is shown that replacing plastic housings of products by metal housings enables better compliance and environmental performance of electronic products in end-of-life. But, this is achieved at the ‘environmental cost’ of putting more environmental value in the products considered in the production phase and is leading to worsened overall environmental results.
3) Balance ‘WIN-LOSS’ situations Take into account the eco-efficiency of those options that appear in the fourth quadrant of Fig.2. In this case, there has to be paid to obtain a certain environmental improvement. (Obviously, this direction appears the most frequent). In Fig.6, all main options investigated in [1] are presented.
Within existing limits of the above life-cycle perspective and other practical limits like functionality demands, health and safety, appearance and looks, the degree of freedom to apply design for end-of-life activities is limited to the following options:
Increase collection metal dominated products Separate coll. precious metal dom. prod. (low precious metal content) Increase glass recycling 15% to 70% Increase collection rates glass dominated products Dedicated treatment metal dominated products (low plastic content)
1) Improve connections, better unlocking properties 2) Avoid certain materials and materials combinations 3) Reduce disassembly times These options are further discussed with actual redesign examples of electronic products in [9].
Plastic recycling medium sized housings (1-2,5 kg) Prevention residue fractions to cement kiln (high plastic content) Pick-up on demand collection at households Plastic recycling small sized housings (0-1kg) Disassembly PWBs and treatment with copper fraction* 0
B. Short term: effective and efficient monitoring Within the EU there are large differences in the development of take-back systems for electronic waste. Due to the previous analysis on where the most eco-efficient and the most eco-inefficient lie, it is recommended to be flexible development of take-back system on the short term. The key element enabling higher eco-efficiencies is monitoring by authorities. Within the different protocols that have to be developed by EU member states individually, the measuring and reporting of the inputs and outputs of recyclers (instead of their treatment activities themselves!) enables controlling the system performance. In this respect, the various and in most cases, still to be developed monitoring protocols should encourage, avoid or balance the following three directions:
1000
1500
2000
2500
3000
Figure 6. . Ranking of several eco-efficient improvement options
In Fig.6, the results of analyzing many different improvement options and configurations in end-of-life processing are presented. These options are presented on the vertical axis. On the horizontal axis, the eco-efficiency in mPts/€ are displayed. The ranking shows that certain options contribute more to the development of eco-efficient take-back system than others. The conclusion out of this is that ideally, waste legislators or authorities should draw a line for the ‘WIN’– ‘LOSS’ directions and prioritize in order to explore the most eco-efficiency options first and to avoid inefficiency. It should be notice that plastic recycling of small sized housings and a mandatory disassembly of PWB’s (=treatment) are the most inefficient options. Increasing collection rates of metal dominated products and enabling CRT glass recycling (=prescribe a minimum amount to be recycled =output) result in the highest environmental returns on investments.
1) Encourage ‘WIN – WIN’ situations Encourage those changes or configurations that have a positive eco-efficiency for the system as a whole. This includes for instance increasing collection rates (=inputs) of those products with a relatively high value (precious metal dominated products). For these products, also separate sorting out of the larger waste streams, followed by direct treatment in a copper smelter appears in the WIN-WIN quadrant of Fig.2. The same counts for plastic recycling of large sized housings
0-7803-8250-1/04/$20.00 © 2004 IEEE.
500
Environmental gain (mPts/€ invested)
Generally speaking, the main available avenue for increasing eco-efficient take-back system performance within
247
the boundaries of the already enacted WEEE Directive is by monitoring and steering the inputs and outputs of recyclers. This could be combined with auditing recyclers on basis of their inputs and outputs by the methodology presented in the second section of this article.
rules used in the WEEE Directive. Prescribing which fractions should follow which secondary treatment routes as a minimum is also very practical because the take-back systems are controlled better this way (in particular this applies on the destinations of plastic, glass and residue fractions) 3) Support industry, system organizers and recyclers It is recommended for system organizers and authorities to enable the exploration of the previous most eco-efficient options first. This is also needed to stimulate further technological developments on the long term. This issue specifically applies in the fields of automated disassembly, efficient identification and sorting techniques for different materials and components (plastics) and the development of secondary outlets or markets for secondary materials, for instance in finding useful thermal applications for shredder residue fractions. For producers there are (limited) ecoefficiency improvement options possible in Design for End-ofLife related to expected end-of-life treatment configurations [9].
C. Long term review However, in the long term legislative development of WEEE, but also for waste policies in general, the following revision can be made which based on the eco-efficiency analysis: 1) Collect more data and insights In order to come to a more eco-efficient and practical legislation at the same time, it is needed that more information on the end-of-life chain of products as a whole becomes available. Recycling is a very complex field with many stakeholders (legislators, industry, consumers, recyclers, secondary material processors, final waste processors, takeback system organizers); and also connected with many different stages of product life-cycles (design, production, disposal, transport, collection, shredding and dismantling, treatment and secondary material processing). Information on the eco-efficiency ‘behavior’ of products should be treated in a comprehensive way and methodology as shown above, in order to optimize product life-cycles in general and the end-of-life phase in particular. Based on such future and developing insights, waste policies should be evaluated and rebalanced:
V.
The quantitative eco-efficiency concept as presented in this paper is proven to be very useful in stakeholder discussions on implementing take-back systems in general and for finding the most eco-efficient balance in take-back and recycling regulations on the short, medium and long term. REFERENCES
2) Rebalance policy strategies Already now, general directions on how to alter policies strategies on the long term become clear:
[1]
a) Adapt weight based recyclability targets Weight based recycling targets should or be discarded completely or being replaced by more accurate (and streamlined) environmental equivalents.
[2]
b) Modified treatment rules Treatment rules, except those necessary for Health and Safety reasons, can also be discarded, whereas in most cases environmental and economic optimization of recycling operations is directed similarly and thus can be left to the recyclers themselves. This also avoids many monitoring problems in practice, which can be done more effectively by following and measuring the inputs and outputs of recyclers:
[3]
[4]
[5]
c) Differentiate in collection targets Some products are more worth being recycled from both an environmental as an economic perspective. One general collection minimum per inhabitant should be differentiated: More focus should be given on (precious) metal dominated products, medium priority on glass dominated products and lower priority on small plastic dominated products. Summarized: differentiate and control the inputs of the systems better.
[6]
[7]
[8]
d) Focus on ‘outlet rules’ The example of the re-application of glass (and others) shows that by monitoring the outputs of recyclers, much higher eco-efficiencies can be achieved than the current set of
0-7803-8250-1/04/$20.00 © 2004 IEEE.
CONCLUSIONS
[9]
248
Huisman, J., “The QWERTY/EE concept, Quantifying Recyclability and Eco-Efficiency for End-of-Life Treatment of Consumer Electronic Products”. Ph.D. thesis, University of Technology Delft, The Netherlands, ISBN 90-5155-017-0 Commission of the European Communities, Directive 2002/95/EC of the European Parliament and of the Council on the restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS), Official Journal of the European Union, Brussels, February 13, 2003 Commission of the European Communities, Directive 2002/96/EC of the European Parliament and of the Council on waste electrical and electronic equipment (WEEE), Official Journal of the European Union, Brussels, February 13, 2003, Huisman J, Boks C.B, Stevels A.L.N., “Quotes for Environmentally Weighted Recyclability (QWERTY), The concept of describing product recyclability in terms of environmental value”, International Journal of Production Research, 41 (16): 3649-3665 Huisman, J., Stevels, A.L.N., Stobbe, I., “Eco-efficiency considerations on the end-of-life of consumer electronic products”, IEEE Transactions on Electronics Packaging Manufacturing, in press. Goedkoop, M., Spriensma, R., The Eco Indicator '99, a damage-oriented method for Life Cycle Impact Assessment. Final Report, National Reuse of Waste Research Program. Pré Consultants, Amersfoort, The Netherlands Philips Consumer Eletronics, Multiple environmental benchmarks 1998 – 2004, Philips Consumer Electronics, Environmental Competence Centre, Eindhoven, The Netherlands Ansems, A.M.M., van Gijlswijk, R., Huisman, J., End of Life control and management of heavy metals out of electronics, Proceedings of the 2002 International Symposium of Electronics and the Environment, San Francisco 2002 Huisman, J., Stevels, A.L.N., Balancing Design Strategies and End-ofLife Processing, Proceedings of the Ecodesign 2003 Conference, Tokyo Japan, Dec. 2003
