Given the discussion above regarding principles and concepts of industrial ecology, it is hopefully relatively simple to see that design is a key feature in the practical implementation of industrial ecology. But what do we know about product design; that is, what are the general
guiding design principles that we might find in industry today? Table 24.1 contains a traditional view of what product designers normally think about when conceiving a product.
Additional Points to Ponder From what you know about green chemistry and green engineering, is there anything that you would change about these traditional design goals?
How might these meet the principles of industrial ecology that we just described?
Given the emphasis on integration and interdependency in an industrial ecosystem that we noted above, one would be hard-pressed to achieve the goals of industrial ecology without significant thought given to the overall design of a product or service we might be thinking about developing. General design considerations for industrial ecology have been adapted from Cohen-Rosenthal12and are shown in the accompanying box. Although design for extended use is generally a good thing in many applications for durable goods, it should be understood that there are some areas where design for extended use can create significant issues, as has been the case for chlorofluorocarbons that were found to be ozone depleting, for plastics that have been found to be effectively nonbiodegradable, for pharmaceuticals that are designed to have stable shelf lives, and for early generations of herbicides and pesticides that were very nonspecific and were designed to remain effective for long periods of time when applied.
GENERAL DESIGN CONSIDERATIONS FOR INDUSTRIAL ECOLOGY Design for extended use
Development of “smart materials”
Design for reuse, repair, and remanufacturing Design for disassembly
Demanufacturing Disassembly
Recycling—material loops
TABLE 24.1 Traditional Product Design Goals
Acronym Meaning Why Do We Do This?
DfM Design for manufacturability Product can be made easily and at reasonable cost
DfL Design for logistics Production and supply activities are well orchestrated
DfT Design for testability Product quality may be checked conveniently
DfP Design for pricing Ensures that product will sell
DfSL Design for safety and liability Product is safe to use and company’s liability risk is reduced
DfR Design for reliability Product works as intended over an extended period
DfS Design for serviceability Maintenance services can be offered at a reasonable cost to the customer and company
Dematerialization Molecules
Chemical reactions Nanochemistry Design for waste
Landfill mining Infill
Energy conversion Pollution control residuals Source:ref.12.
What is in view for extended use are materials such as clothing, other textiles, and material for furniture or building coatings, that are by design long-lived through the application of
“smart,” adaptive, and/or self-repairing mechanisms. These materials would have properties that would change with environmental conditions so as to be more durable or adaptable to changes in temperature, pH, humidity, and so on. As you might imagine, there are not many examples of these sorts of materials in existence, but there is certainly much talk of their development, especially since the advent of recent advances in nanotechnology and biomimicry. One could imagine the development of materials that change color to absorb heat or reflect it, materials that change porosity depending on humidity or temperature, and materials that release certain chemicals that repulse a potential pest.
The next tier of the hierarchy would be to design materials for disassembly, de- manufacturing, or recycling. McDonough and Baumgarten13speak of creatingtechnical nutrientsfor some materials in common use so that they may be used over and over again, being returned to their original state through low-impact processes. A great example of this ethos in action may be found with DuPont’s Petretec process.14DuPont has found a way to take any polyester and unzip the polymer to release the virgin monomer, which may then be reused to make “new” polyester products of many kinds. The process can be used to reclaim monomer from mixed-material streams containing polyester and is readily integrated into existing polyester manufacturing facilities. The overall result is that polyester is diverted from landfills or from waste to energy applications, thereby achieving a lower life cycle environmental impact.
Another example of this attention to recycle and reuse may be found in how modern Xerox machines are developed and marketed. A graphic showing the general outline of the Xerox program for recycle and reuse is shown in Figure 24.4. Xerox uses and reuses electronics, optics, and other components over and over in new products or products that are changed, upgraded, and expanded over time. Materials that cannot be reused are either recycled into other product streams or become raw materials for new parts.
A third area where disassembly, demanufacturing, and recycling are used extensively is automobile, manufacture, where about 95% of the average vehicle is recycled in one form or another, thereby avoiding huge quantities of waste finding their way to landfills. From a chemist’s perspective, Table 24.2 contains recycling options for chemicals, solvents, and materials that would be encountered more frequently.
Design from first principles is where green chemistry and green engineering hold the greatest promise for achieving the objectives of industrial ecology. In the case of demateri- alization, one attempts to use as little material and energy as possible to achieve the desired function in a product or service. Through judicious redesign of materials of construction, or through the development of new materials containing the desired properties for existing or new applications, green chemistry holds great promise for removing toxic materials and larger volumes of materials from current product designs. As has been noted throughout this book, target molecules and the synthetic processes employed to produce those molecules can and should be changed to achieve more sustainable outcomes. We can see that the simple
Raw materials
Fabrication of new parts Product design
Build product Recycle
Delivery to customer inspect
&
parts
Customer use Sort
Recycle materials
Dismantle Alternative uses
End of useful life
Product returned to Xerox Disposal
FIGURE 24.4 XEROX equipment recovery and parts reuse/recycle process.
TABLE 24.2 Recycling Options for Various Materials Class of
Nonrenewable Material
Recycling Technically
Feasible?
Recycling Economically
Feasible? Examples
I Yes Yes Catalysts, some
solvents, most industrial metals
II Yes No Refrigerants, some
solvents, packaging materials
III No No Coatings, pigments,
fuels, lubricants, pesticides, herbicides, fertilizers, reagents, explosives, detergents Source:ref.15.
to design from first principles and realize the goals of industrial ecology. Table 24.3 contains additional design goals, normally referred to as design for the environment goals, and these may help to get us a bit closer to the objectives of industrial ecology. The table is not exhaustive but is illustrative of the types of things that we should be thinking about when we think about design for the environment.
TABLE 24.3 Goals in Design for the Environment
Acronym Meaning Why Do We Do This?
DfM Design for manufacturability To enable pollution prevention/source reduction during manufacturing through use of:
Less material Fewer materials
Safer materials and processes
DfEE Design for energy efficiency To achieve reductions in energy consumption during the use of products or services:
Promote flexible energy use
Design that promotes renewable energy Design for reduced life cycle emissions Design for carbon neutrality
DfZT Design for zero toxics To remove toxic materials from the supply chain and in products:
Reduce incidence of acute and chronic human and environmental risks
Reduce management costs for high-hazard materials
Reduce potential for product liability
DfD Design for dematerialization To reduce embodied material and energy intensity of a product or service:
Less material per unit produced
DfP Design for packaging To minimize amount of packaging required so there is less:
Material used to ensure robust sales Nonrecylcable packaging
Impactful (toxic, nonbiodegradable or reusable, etc.) packaging
Life cycle impact DfL Design for logistics Arrange supply chain to:
Use locally manufactured materials Require less or lower-impact (e.g., rail) transportation of components and/or products DfL Design for longevity Design for modularity to ease:
Upgrading and delay ultimate need for complete replacement
Serviceability and, later, disassembly Design for serviceability to ease:
Repairs that lead to longer life Recapture of used and/or broken parts DfD Design for disassembly To promote reuse of components:
(continued)
If you have spent any time in industry or have read technical or industrial journals, or perhaps have seen items in the popular press, you have no doubt heard of the idea of achieving zero waste. As the rhetoric goes, you need a goal, a goal should challenge us, and a goal to produce zero waste may not be achievable, but if we don’t strive for perfection, we are admitting defeat. Fortunately, as scientists and engineers we know a little something about the laws of thermodynamics,16and if we just think about it for a few minutes, we realize that zero waste is not an achievable goal. In the general design goals we saw from Cohen- Rosenthal above, he included a design for waste goal. This is arguably a good thing to think about because waste is something we still produce in abundance!
Although it is not discussed routinely, landfills do, in fact, hold large quantities of high- quality plastics, metals, and other materials whose recovery and reentry into our raw material supplies may at some point become economically attractive, especially as we are confronted by the fact that minerals are both dwindling and increasingly difficult to obtain. Moreover, even though we continue to develop our capability to recycle, downcycle (i.e., reuse a material not as virgin material but to convert it to another use that is of inherently lower value), and reuse materials, we are invariably left with something that is truly waste. In some instances these residuals may be feedstocks for waste-to-energy facilities, and that may provide some benefit to society. Unfortunately, these residuals, together with pollution TABLE 24.3 (Continued)
Acronym Meaning Why Do We Do This?
Quicker and cheaper disassembly More complete disassembly Dismantling by simple tools DfR Design for recycling To promote greater materials recovery:
Increase content of recyclable materials Increase content of no- or low-toxicity materials Reduce variety of different materials
Use materials that can be locally recycled Provide easier materials identification
Ensure easy separability of nonrecyclables so that they may be disposed of safely
DfC Design for compostability In appropriate applications, increase content of materials that are:
Biodegradable over short periods of time Contain no or few toxic materials
DfER Design for energy recovery To promote greater energy recovery, increase content of materials that:
May be incinerated safely
Produce low- or no-toxicity residues
Allow for composting of residues or alternative productive uses
DfC Design for compliance So that materials do not:
Fall under stringent regulatory requirements Require special handling, storage, and management So that you are ahead of future regulatory constraints
these residuals may be sequestered in a material such as concrete and reused, or they may be stabilized in some fashion and used as infill for roads or other construction projects.
Therefore, it is imperative that during the design phase we should be thinking about our potential for creating waste so as to avoid it to the greatest extent possible. When all other options for recycle and reuse fail, we must find ways of minimizing the societal and environmental impacts of our waste.
Additional Points to Ponder With all these design considerations to keep in mind, how would you determine which design consideration is likely to be the most important? Can you imagine a situation where pursuit of one design consideration actually interferes with the achievement of another?