Green Informants

Should electronics manufacturers test competitor’s products for hazardous materials compliance? This question is investigated in the paper Green Production through Competitive Testing by E. Plambeck and T.A. Taylor, which can be found here. The rationale would be that a detected violation disclosed to regulators could then lead to blockage of the competitor’s products. The paper models this scenario from an economics angle and includes results from numerical experiments. Added to References.

Paper on WEEE returns strategy

The paper summarized below is part of an upcoming EJOR issue on closed-loop supply chains, mentioned earlier. It includes an integer program and connects to cradle-to-cradle ideas with its emphasis on “Design for Dissassembly and Recovery”.

Strategic response to EEE returns: Product eco-design or new recovery processes?
R. Zuidwijk and H. Krikke
in European Journal of Operational Research
doi:10.1016/j.ejor.2007.08.004
Notes: This paper looks at possible strategic responses of electronics industry firms to WEEE. As the title suggests, strategic approaches are divided into product design and processing of recovered products. Strategies to handle WEEE can be implemented at either end, or both simultaneously. On the design side (or “eco-design” as the authors label it), “Design for Disassembly and Recovery (DfX)” and “Product Data Management (PDM)” are considered. The inclusion of DfX is what links the paper to the cradle-to-cradle philosophy. For instance, one of the goals of DfX listed in the paper is “to make material fractions more homogeneous so they can be separated more easily”. Under PDM, products maintain information about themselves over their life-cycles, providing industry with data on the installed base and consequently on the recovered products.

After a nice overview of WEEE, the authors outline the strategic responses and discuss some background literature. X-ray technology is mentioned as one of the methods used to assess the content of recovered products (this was also mentioned in the batteries paper summarized here). The authors claim that a key contribution of the paper is that it considers the integration of eco-design and advanced process technologies. They make the interesting observation that a reason the overlap has not been studied much may be that, both in industry and academia, these two areas are studied/managed by people in different disciplines/locations in the supply chain.

Within product/module/component recovery, the basic decision to be made is between recycling and remanufacturing. The problem is modeled in different ways depending on the level of product information being assumed. Under full product information, the problem is posed as an integer program. The objective is to maximize profit, which consists of remanufacturing and recycling revenue (some of which may be negative) minus disassembly costs. Constraints are primarily flow balances from products to modules to components across the various processes, but also include WEEE recovery quotas for given materials. Under partial information, the IP is replaced by a set of decision rules. In the absence of any information, a “default strategy” is used.

The models are applied to the recovery of computer monitors under differing levels of information and with different combinations of strategies on both the design and recovery ends. As might be expected, DfX comes out favorably because it aids in remanufacturing as well as in reducing recycling costs because of its better separation of materials. It reduces the importance of complex processing technologies and information tracking. The authors point on that the IP is fairly generic and can be adapted to other industries.

WEEE and OR

An important keyword at the OR/Sustainability intersection is WEEE (Waste Electrical and Electronic Equipment), which is a directive of the European Union aimed at reducing the amount of waste from such equipment. WEEE puts much of the burden on the manufacturer. Here is an excerpt from a WEEE page on the European Commission’s Environmental site:

Producers will be responsible for taking back and recycling electrical and electronic equipment. This will provide incentives to design electrical and electronic equipment in an environmentally more efficient way, which takes waste management aspects fully into account. Consumers will be able to return their equipment free of charge.

The EURO 2006 program makes no mention of WEEE, but there were 3 talks concerning WEEE in EURO 2007 (see this page). A rather critical view of such legislative intervention on the environment’s behalf was taken in a 2003 issue of Interfaces (see this page, scroll down).

WEEE-like activity is happening in the US to a lesser extent. I described one instance here.

Lastly, this interesting story in Computing is about how more emphasis should be placed on re-using computers than on recycling them. It mentions a study claiming that about three times as much fossil fuel is used in manufacturing a PC than by the PC in its lifetime. (The study appears to be Energy intensity of computer manufacturing: hybrid analysis combining process and economic input-output methods, E. Williams, Environmental Science & Technology 38(22), 6166 - 6174 (2004). See also this related volume. Note the series name of the volume: Eco-Efficiency in Industry and Science series of Kluwer Academic Publishers: Computers and the Environment.)

Battery Recycling and OR

Paper Summary: Closed-Loop Supply Chains for Spent Batteries by F. Schultmann, B. Engels, and O. Renz, Interfaces, November-December 2003

Germany has a “battery decree” that puts the responsibility on manufacturers and importers of collecting, sorting, and, if possible, reprocessing spent batteries. This paper focuses on portable batteries, as opposed to car batteries, industrial batteries, etc. The paper consists of two parts:
1. a flow-sheeting process model to study the impact of using spent batteries in the production of steel
2. a two-stage facility-location problem to optimize the reverse logistics for the spent batteries

The authors state that after sorting batteries, many companies are storing them in “special waste deposits”, not recycling them. This motivates the first part of the paper. Flow-sheeting allows for the simulation of chemical engineering processes including metallurgical ones. So this modeling tool is more from the engineering side than the OR side. Using it, the authors study the impact of increasing the amount of spent batteries fed into a type of steel production (EAF) on technical workings, emissions, and economics. They conclude that such recycling is feasible and will lead to higher steel production costs. They state that the increased costs are comparable to the disposal costs for the batteries, making recycling an appealing option. This claim seems to be a key finding of the paper, but the authors do not provide any supporting information. Details of the simulation are not included though some results are plotted.

The reverse logistics part of the paper contains a nice use of the facility-location problem, wherein spent batteries flow from collection points to sorting facilities to recycling facilities. The paper contains the details of the model in the Appendix (two-stage, mixed-integer linear program) along with maps of Germany indicating the locations of the solutions. Two scenarios are considered, the second of which lays out strategic solutions anticipating future needs.

Some other points:

The authors characterize this as “high-quality” recycling as opposed to “down-cycling”, since the batteries are being recycled into steel. But if the quality of the steel is reduced by incorporating batteries, and if the batteries contain rare metals that are then lost to future isolated use, I’m not sure if this is technically correct. See the book Cradle to Cradle (summarized on this site here) for more on these ideas.

In Germany in 2000, the number of batteries taken back was equal to 31% of the number of batteries sold. (Some batteries taken back that year may have been sold in previous years.) This has got to be at least ten times the level in the US.

The paper does not deal with the forward supply network at all.

Batteries can be sorted automatically to some extent, using various battery attributes, using a UV pigment found on many mercury-free batteries, with x-rays, etc.

To sum up, the operations research content of this paper is concentrated mainly in the formulation of a recycling collection process as a facility-location problem. This is a logical way to formulate the problem. Nothing specific to the recycling plays a role here; no application-driven methodology is introduced. It was interesting to learn about the flow-sheeting process model and concerns therein, though they may have been outside the normal domain of OR. In sum, I found it to be quite an interesting paper and would be interested to learn about what has happened since the paper was published in 2003.

Some quick scanning reveals that 1) the portable battery recycling rate in Germany increased to 39% in 2002, and 2) the EU is following suit with its own version of the legislation, effective 2008.

Energy Star Computers

New tighter US energy star computer specifications were recently released.

Among the key specifications for desktops:
Standby (Off Mode): <= 2.0 W
Sleep Mode: <= 4.0 W
Idle State:
Category A: <= 50.0 W
Category B: <= 65.0 W
Category C: <= 95.0 W
Basically the higher the category, the more of a workhorse the machine is (more RAM or more than 1 hard drive etc.)

These idle state powers are on the order of regular household incandescent light bulbs.

Not directly tied to OR, but not hard to imagine how it could be, particularly in light of the usage of computers at various institutions. For example, some institutions require all computers be kept on all the time for the occassional system update via the network. Watt metering “survey” to come…

Local E-cycling

Connecticut (USA) recently enacted a law aimed at reducing electronics waste. It places the burden of “e-cycling” on manufacturers who will have to register with the state Department of Enviromental Protection (DEP), paying an annual fee used by the DEP to administer the program. No OR content here, but see the posts pertaining to clsc, and the bit about Cisco in the INFORMS roundtable post.

Link to the bill, worth a closer look.

A little more depth on the business angle from this informative Hartford Business Journal article. In the past, state plans like this have either charged the manufacturer with the costs of recycling the electronics they produce, or charged the consumer by adding a fee to the retail cost of the item. The latter is alarming to retailers. I’m wondering if retailers are more vocal in a Statehouse than manufacturers, since they are more local.