Conserve Complexity
Embedded entropy and complexity must be viewed as an investment when making design choices on recycle, reuse, or beneficial disposition.
Contributed by Dr. Michael A. Gonzalez, Senior Chemist, US Environmental Protection Agency, Office of Research and Development, Cincinnati, Ohio
The evolution of nature’s products, systems and life forms has taken billions of years and still is an evolving system. Embedded in this evolution is a series of networks and larger systems that offer a level of complexity that we are just beginning to understand and experience their interconnectedness. It is with this new understanding of tradeoffs, unintended consequences and the implications of our actions that has established the scientific areas of sustainability and resilience and the contributing fields of green chemistry and green engineering, to name a few.
As continued innovations and advancements are being made by applying the tenants of green chemistry and green engineering, linkages regarding the impacts of these novel developments are being demonstrated daily. It is in these crossovers where important improvements made in one discipline cannot be lost or minimized when transitioned into another discipline. This rationale needs to be followed when applied in both the forward and reverse directions. A simple example of the need for this thinking is demonstrated when improvements achieved on a bench-scale chemical reaction are no longer being applied at the process-level due to difficulties associated with the scale-up. Thus, the improvement is no longer relevant and there is no net gain, or even a loss, in the overall performance results. This concept can also be extended when needing to retain the embedded complexity between your beginning and ending states.
The complexity in a beginning state depends on factors such as the number of atoms and/or functional groups present in a molecule, the type, quality and quantity of energy within a system, and the economic value in a starting material or process. Historically, when discussing retaining the value of a starting material throughout a process, ‘value’ has generally been implied to mean only a material’s economic value. This concept is very easy to understand in practice because it would not appear sustainable to have a method/process that operates by taking a material of high economic value and transforming it into one with a lower value. This is the same as having a business model that operates at a loss. If you were to have a business that did this, you would not be in business very long. Unless you like losing money.
This concept of retaining complexity can also be applied to the end-of–life (EOL) considerations for products. We have seen tremendous efforts placed on the design of chemicals and products that have reduced or minimized impact to the environment and human health during the use-phase of their life cycle. This has resulted in significant strides in identifying and providing alternatives to more impactful chemicals and products in use. Recently, this concept has been further extended by considering the EOL phase and focusing on the design of products to breakdown naturally or be designed for reuse, recycle and repurposing.
It is generally understood products which require high-entropic substances, greater mass and number of materials, more energy and time for their construction and the use of exotic manufacture techniques are defined as complex. Current approaches for recycling these complex products comes at an economic, environmental and societal price. Additionally, the embedded complexity, either natural or man-made, in the product is reduced, sacrificed and results in a down-cycled product (one with reduced complexity). Additionally, the high-level of embedded complexity in these products make them less attractive for recycling and limits their second life to reuse only. This is problematic as eventually their usable life time will be reached and then society has to address its disposal, the resulting waste and the entrainment of high-complexity materials that we cannot easily access for additional uses.
Because of these concerns, attention is being directed towards designing products with characteristic that are favorable for recycle, reuse and repurposing. Such approaches include products made with construction techniques that allow for easy, fast and safe disassembly, use of materials that have minimal complexity and are abundant, modular structures that allow for upgrades of the technical components without the need to entirely replace the product, and utilization of the fewest number and least different types of materials. While this is only one approach for EOL considerations in product design, this approach clearly demonstrates the application of holistic thinking.
As we, scientists and engineers, move forward in our individual research areas, it is important we think holistically and be mindful of the upstream and downstream considerations of our discoveries. We also need to remember and realize that while a chemical or product may not appear complex, there has been a considerable amount of time, energy (solar and thermal) and materials utilized in its production, either by nature or man, and it is our responsibility to ensure we utilize these embedded qualities efficiently and effectively. These actions will allow our discoveries and designs to be readily available for their next use or purpose with minimal altering and loss of complexity.