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MEMORANDUM

To: Clare Lindsay, EPA

From: Lynn Knight and Shelly Schneider, ERG

Date:October 16, 2005

Re:Baseline Electronics Assessment: Overview of Assumptions for Modeling the Flow of Electronic Products

______

EPA is developing a baseline assessment of information related to the end-of-life (EOL) management of electronic products. EPA’s baseline assessment of electronics centers on developing a set of data inputs that will be used to model the flow of electronics products from initial sales through EOL management.

The scope of products that is covered by this analysis includes:

  • Personal computers, including desktops, laptops, computer monitors
  • Televisions
  • Large computer peripherals, including printers, scanners, and fax machines
  • Computer mice and keyboards

These products were chosen because, to date, they have been the focus of electronics recycling initiatives at the Federal, state and local levels. Products from all sectors of the economy (i.e., residential, commercial, institutional) will be addressed in the analysis.

The purpose of this memo is to present some of the key assumptions that will be used in the modeling effort. Since we have been limited to using publicly available data for some assumptions and there are limited data for others, EPA will seek guidance from stakeholders on any adjustments that should be made to increase the accuracy of the data. Comments should be sent to Jenny Stephenson at EPA. [

To date, data have been developed to support assumptions for the following key factors:

  • Average weight of historic products
  • Life span of products (i.e., how long do people keep products before they are ready for EOL management)
  • Per capita recovery rates observed by existing electronics collection programs

The following sections will present the preliminary assumptions developed for each of these factors.

Average Weight of Products

Two data sets were reviewed to develop historic average weight figures by product for this analysis. The first data set was developed from electronics collection data obtained from the Florida DEP[1]. The second data set was ERG’s in-house data used for the EPA MSW Characterization report series.[2] ERG developed average weight figures using either data set or combining data from both depending on how robust the data for the specific products were, as well as our professional judgment as to how representative the data were. Tables 1 and 2 present the average weight estimates for each product type.

Life Span of Selected Electronic Products

One of the most critical assumptions for the modeling effort is life span of the products—the time period that lapses between the time of purchase and the time when the owner of the product is ready to discard it. The total life span of any particular product will encompass several stages of use. The “first use” is the time period that the product was considered functional to the first purchaser. After the first use, the computer may be discarded or recycled, but if it is in working order it will more likely be given to someone else either within the same household, or given or sold to someone outside the household. It also could be stored in a closet or basement for varying periods of time. There are many combinations of use, reuse, and storage scenarios underlying the time period before which any electronic product is ready for EOL management.

The state of Florida has been providing grants to its counties for electronic collection programs for a number of years. For 12 months, beginning April 2004, the Florida DEP conducted a study in which the individual units in the loads from these collection programs were sorted and the product type, brand, weight, and age were recorded. These loads represent collections from residential and small business sources that are generally served by county recycling or thrift store donation services. At the time of this analysis, the data set from this project had vintage information for 12,801 units. We analyzed these data to investigate the age distribution of each type of product collected. Although we cannot say with any degree of certainty that the Florida results are representative of the nation as a whole, it is the largest available detailed data set accounting for the age of electronic products collected.

To develop the assumptions for life span to use in the modeling effort, we examined the age distribution of each product type and decided on an approach that would best represent the distribution for that product. In general, the life span assumptions for each product are based on the median of each of the quartiles. (For example, 25 percent of desktop computers are used for the length of time represented by the median of the 1st quartile; another 25 percent are assumed to be used for the length of time represented by the median of the 2nd quartile; etc.) Thus, for most product types, there are four life span assumptions, one for each 25 percent of products sold in any given year.

For some products, such as laptop computers, keyboards, LCD monitors, console TVs and projection TVs, we took a different approach to best represent the distribution because there was a relatively small number of observations in these data sets. In these cases we used the mean, mode, or chose specific quartiles to represent the distribution. For computer peripherals, we conducted statistical tests to determine whether or not the individual age distributions for printers, fax machines, multifunction devises, and scanners were similar. Using the Kruskal-Wallis Test, we found that there was no statistically significant difference in the age distribution among the 4 product types. Therefore, we combined the data for computer peripherals and used the median of each quartile to represent the life spans of these products. Table 3 lists the life span assumptions and basis for each assumption by product type. Appendix A displays the distributions graphically.

Per Capita Recovery Rates Observed in Existing Electronics Collection Programs

ERG analyzed data from existing collection programs. Unfortunately, we do not have access to collection data from a large number of existing, electronics recycling programs in the United States. However, we were able to obtain data from a handful of programs for this analysis. Programs selected for the analysis had to meet the following criteria:

  • The program serves a discrete and quantifiable population. Examples include state programs available to all state residents, collections at county or municipal waste management facilities, and curbside collections within a specific city or county.
  • The program involves regular daily, weekly, or monthly collection—not sporadic collection events.
  • The program tracks recovery rates by product type, at least for the major categories, such as TVs, computers (CPUs), and monitors.
  • Data are available that are representative of an annual collection rate. If a program did not cover exactly one year, the data were scaled so that the final results reflected an annual recovery rate.

Table 4 presents annual per capita recovery rates for the programs for which we had data. Further analyses of these data will be conducted to determine a recovery rate that is reasonably representative of what might be expected on a national average basis if a well-established, reasonably advertised system for recycling waste electronics were available. EPA is seeking additional data that would be appropriate to add to this analysis.

Table 1


Table 2

Average Weight of Computer and Other Equipment Units

(Pounds)


Table 3. Life Span Assumptions By Product Type

(Number of Years Before Collection)

Product Type / Assumption / Basis
Computers – desktop / 25% - 7 years
25% - 10 years
25% - 14 years
25% - 18 years / Median of each quartile
Computers – laptop / 50% - 5 years
50% - 8 years / 1st and 3rd quartile
Monitors – CRT / 25% - 5 years
25% - 8 years
25% - 10 years
25% - 13 years / Median of each quartile
Monitors - LCD / 100% - 9.3 / Mean
Printers, scanners, fax, MFDs / 25% - 4 years
25% - 7 years
25% - 10 years
25% - 14 years / Median of each quartile
Keyboards / 100% - 5 years / Median
TV <19” / 25% - 8 years
25% - 13 years
25% - 17 years
25% - 23 years / Median of each quartile
TV >19” / 25% - 7 years
25% - 12 years
25% - 15 years
25% - 20 years / Median of each quartile
TV – console / 50% - 11.5 years
50% - 17 years / 2nd and 3rd quartiles
TV – projection / 100% - 8 years / Mean

Source: Assumptions were based on statistical analyses conducted by ERG of data from Florida. Florida Department of Environmental Protection. Database accessed 8/22/05.

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Table 4

Annual Per Capita Recovery Rates By Product for Selected Programs

(Pounds per capita)

Product Type / Hennepin Co., MN (2004) / Branford, CT (2004) / Delaware (2004) / Waukesha Co., WI (2004) / Florida (county programs, 2002)
Broward / Charlotte / Citrus / Lee / Miami-Dade / Polk / Sarasota
Computer (CPU) / 0.35 / ** / 0.30 / 0.15 / 0.04 / 0.07 / 0.21 / 0.05 / 0.01 / 0.01 / 0.05
Total CRTs / 2.61 / 2.61 / 1.10 / 0.23 / 0.12 / 0.15 / 1.26 / 0.14 / 0.16 / 0.30 / 0.37
Monitor / 0.60 / ** / 0.65 / 0.23 / 0.07 / 0.08 / 0.47 / 0.09 / 0.03 / 0.03 / 0.13
TV / 2.00 / ** / 0.45 / *** / 0.05 / 0.07 / 0.79 / 0.05 / 0.13 / 0.27 / 0.24
Printer / 0.16 / ** / 0.25 / 0.07 / 0.02 / * / * / 0.03 / 0.01 / 0.01 / 0.03
Laptop / 0.01 / ** / ** / ** / ** / ** / ** / 0.00 / ** / ** / 0.00
Total / 3.12 / 2.61 / 1.65 / 0.45 / 0.18 / 0.22 / 1.47 / 0.21 / 0.19 / 0.32 / 0.45
* Charlotte and CitrusCounties reported totals for peripheral devices, but did not break these down by type of device.
** Not reported.
*** The WaukeshaCounty program collects computers and not TVs.

Note: Assumes the following weights per unit in pounds: TVs – 63; Desktops – 22; Laptops – 9; Printers – 21; CRT monitors – 30.

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APPENDIX A

AGE DISTRIBUTION OF ELECTRONIC PRODUCTS

BASED ON ANALYSES OF DATA FROM

THE FLORIDA STATE DEPARTMENT OF ENVIRONMENTAL PROTECTION






[1] Florida Department of Environmental Protection. Database accessed 8/22/05.

[2]Municipal Solid Waste in The United States: 2003 Facts and Figures and previous years.