Going on a Resource Diet

by | Apr 21, 2011

In a recent article I was building an argument to try to place products in a space defined by the use vs. make consumption or impact. This would allow us to consider products to consume that require both fewer resources to produce as well as fewer to consume. And I argued that such products were closer to sustainable than others. Except for including it in the figure showing the contribution to lifetime impact in that posting, I did leave out the “post consumer” phase in the discussion. That should be an important consideration also.

We could add that easily. If you are a good visual thinker, you could imagine a third axis on the graph I showed in that article representing End of Life Consumption or Impact. Then, by extension of the argument, products would fall into a “high” or “low” end of life impact based on whether they were essentially fully recyclable (or the materials were fully recovered, and extra points for avoiding downcycling) or not, respectively.

Again, living in the lower left quadrant (or cubic space if a three dimensional plot) is most desirable. Recall the Ricoh Comet circle diagram introduced early on in this blog (see the posting of September 21, 2009). In the circle, the forward (counterclockwise loop) is from materials manufacture through parts manufacture, product manufacturing, through sales to delivery and use. The reverse (clockwise loop at the bottom) is after the consumer is done with the product back through recycling, recovery, and return to material supply chain.

So, relative to the Comet circle, the “top half” is the manufacturing phase and the “bottom half” is the use phase. And, the shortest loops of the circle the extend from the consumer and back to the consumer are the most sustainable in the use phase.

So, what about the material diet?

In a follow-on posting to the use vs make chart and discussion I gave an example of Ditto hangers, made from post consumer recycled paper and cardboard fiber, as a product in the lower left hand corner of the chart. I don’t know all the details about resources used to produce the hangers but I’m finding out.

The re-use of material reduces our appetite for new materials and, essentially, amortizes the initial environmental cost and impact of the first production of the material.

An article in the Christian Science Monitor on March 15th discusses Pepsi’s  plan to move to totally “plant based PET” bottle for packaging their beverage instead of the current oil-based plastic. They plan to start introducing this in 2012 in some markets and it could eventually result in “a switch of billions of bottles sold each year. Of Pepsi’s 19 biggest brands, those that generate more than $1 billion in revenue, 11 are beverage brands that use PET.” According to the article the bottle will be made from “switch grass, pine bark, corn husks and other materials. Ultimately, Pepsi plans to also use orange peels, oat hulls, potato scraps and other leftovers from its food business. One unique feature is that the input to the material is waste from other uses and not plant bio-matter grown specially for this purpose.

Again, as with the hangers, we’ll need to see how much energy and resources go into converting the salad listed above into the bottle and, there is no mention of whether or not this particular bottle will be classified as compostable or recyclable.

Another candidate for the lower left corner?

Now for something completely different (and apologies to Monty Python for borrowing the phrase!) but on the same subject. My friend at Cambridge University, Julian Allwood, just sent me the most recent white paper published from a project titled “WellMet 2050” which is, according to the website, “investigating novel methods of meeting global carbon emissions targets for steel and aluminium that go beyond improving process efficiency by reconsidering the entire product lifecycle.” This recent white paper is titled “Going on a metal diet” (and is available to download).

“Going on a metal diet” discusses means “to use less liquid metal to deliver the same services in order to save energy and carbon.” I have referred to Professor Allwood’s research on this in past postings. He has pointed out in several publications that just trying to recycle metals more efficiently (or more completely) will never allow us to reach the goals of energy and carbon reduction proposed by many governmental agencies and organizations.

In this latest white paper from WellMet, they report on two key strategies for reducing our intake of liquid metal: “designing products that use less metal and improving the ‘yield ratio’ of metals manufacturing.” In this research they used five detailed case studies to examine metal intensive product design. These included: universal beams in construction, food cans, car bodies, reinforcing bars and deep sea oil and gas pipeline.  All real products and large consumers of metal.

The research report states that “in each case, we found we could deliver the same final service with less metal, by pursuing one of four strategies: avoiding over-specification; selecting the best materials; optimising whole products; optimising individual components.”

This is the recipe for eating well while on a diet – ala metals. Let’s look closer:
– avoid overeating (that is use the correct size, thickness, strength of metal needed – not more; this usually relies on quality control to insure materials meet specifications; we’ve discussed this before. Recall the example of tightened tolerances on aerospace components saving weight?)
– choose the right food to eat (or, selecting the right materials; use analysis to get the right ratio of strength to weight, or stiffness to weight, etc. Using software like Granta designs material selection software can help.
– consider the whole meal and its overall balance of ingredients (or, optimizing whole product or system of production; we’ve covered this a lot in the past – thinking of the entire product life cycle)
– read the label on each food item in your meal and choose carefully (or optimize the individual components; recall the “Google earth” view of manufacturing? And we talked there about technology wedges to aid in this optimization. We identified a number of levels that can be analyzed or optimized and improvements can be applied to).

It all makes sense to me. This strategy can be applied to a broad range of materials – not just metals. These can act as the criteria for the creating the technology wedges that we propose to move our products and systems in the green direction.

David Dornfeld is the Will C. Hall Family Chair in Engineering in Mechanical Engineering at University of California Berkeley. He leads the Laboratory for Manufacturing and Sustainability (LMAS), and he writes the Green Manufacturing blog.

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