Thursday, February 11, 2010

Pro Choice for Green


Or ... go climb a hill!

I hesitate to use such a provocative title but, relative to the posting last week, I believe it is the only way to go. I'll get to why in a bit.

Recall that last week we discussed the problem of reducing the complexities of determining whether one process was "more green" (or less impactful) than another. And I referred to this as the "paper or plastic" question.  I said that the phrase "paper or plastic" points out the often confusing choices we are faced with when trying to do the right thing. I then gave a great example of this from a Brazilian colleague who was comparing grinding versus machining in a manufacturing example.

So, relative to those kinds of decisions - I am definitely "pro choice". Let me explain.

Depending how large you draw the control volume (meaning, how much of reality you want to include in your analysis) you can get some different pictures of the impact of a process (or product) compared to another. This was the basis of the paper vs plastic dilemma. Some say that, because the plastic bag weighs a lot less than a paper bag (and since transportation is often the biggest contributor to the impact of plastic bags) you can transport many many more plastic bags for the same volume of paper bags. So, on a "per use basis" (and there are other considerations of course but let's keep it simple for the moment) the plastic bag has less impact. Of course, others cite issues with recycling (paper is usually easier) or litter (you rarely see paper bags flapping in the breeze on fences along the freeway) as considerations that tip the balance towards paper. And then there are reusable bags (paper or plastic). People can honestly choose one over the other and argue, with some scientific evidence on their side, that their choice is "best." But, this always depends on the control volume. How wide are you willing to cast your net to include all the important bits of data in impact? But you have to make a choice.

I often use a simple example with students (told to me in a seminar a decade ago by an early environmental engineer for a major consumer product company). He posed the question: which is better - to make your orange juice from a frozen concentrate (or at least liquid container) or to squeeze locally purchased oranges yourself to get the juice? Berkeley students almost always went for the "squeeze it yourself" option since is sounds more green. Of course that is not correct (unless you have an orange tree in your backyard that is). Since transportation is the major source of "orange juice environmental impact", the density of shipping concentrate or liquid OJ is so much greater than the juice content in the orange as shipped - there is no comparison. Of course, we don't consider taste here.

The important point is that you have to carefully consider the key information when making the decision - information like:

- how much of the process chain (or supply chain) do you want to include?
- how much of the intangibles should be included (meaning, as in the OJ case, taste or more generally the non-quantitative aspects of the decision making like litter in the paper or plastic case)?
- how do you want to value the future (meaning what is your time horizon and do you need to worry about - the next 10 years, 100 years, 1000 years)?
- what do you do about data you don't have or can't get hold of easily (meaning, for example for many materials, the data sheets are non-existent or very sparsely populated, or the business practice of that small supplier to you in some distant part of the world is not apparent)?
- how sure am I that the information I am using today is going to be valid tomorrow (or the next quarter, or fiscal year; meaning prices change, vendor practices change, markets change, etc.)?
- how do I know what the state, federal, international regulations are going to be in the future?

And so on.

Fortunately, the situation is not insolvable. I am an engineer. Engineers have been confronting these types of "uncertainties" for centuries. Mostly we made great progress with few mistakes. Sometimes we made really big mistakes (see Tacoma Narrows Bridge, Challenger Space shuttle, New Coke - well ... let's not burden engineers with this one!) but we always learned from these and made progress. Same situation for the "paper or plastic" question.

We can make a choice, and feel comfortable with it, if we have done our due diligence in attempting to understand a reasonable range of the process or supply chain we have the most influence over (and that we believe captures the most of the impact) and use our best judgement to fill in the pieces we don't know well or at all or can't find information on. This gives us a start. We can go through the other information uncertainties listed above in the same way.

If we feel we are on really thin ice then we need to update our analysis or decision frequently to see if better information is available. We need to keep asking questions and "fill in the blanks" as we gain experience with our system. It's sort of like one of these Sudoku puzzles ... but sometimes with only a few numbers filled in to start with.

When I was a graduate student I took a course on a statistical methodology called "response surface methodology" or RSM. This was intuitively very easy to understand. Relative to the problem we were solving, it assumed that the world could be represented as a hill. The optimum place to be was on top of the hill. We were not able to see the whole hill but could, from our present position, reach out in four directions and try to "feel the slope." You did that by running some experiments over a range of conditions, or some simulations, or other testing (think Taguchi). Then, based on the results of that, plan a next move in the direction of steepest ascent. By repeating this we eventually climbed to the top. (And don't ask what happens if the "hill" is just a small bump on the side of the real hill - that, of course, complicates things).

Decision making in green manufacturing is a bit like that. We make our decision (or our choice of paper vs plastic, frozen or squeezed, and so on) based on where we think we are on the hill and how we feel the slope of our situation. We need to collect enough information to get a reasonable feel for where we are and what is the likely direction to climb the hill. If we can do that, we can feel comfortable that we are making progress.

In some of the previous postings I've reviewed ways to "feel the slope of our situation". These can be helpful in our decision making. Not making a decision is, after all, " a decision"!

We all have to choose to either stay with what we have or look at alternatives that can offer green solutions to our processes and systems. And in choosing those alternatives we need to go with what we can discern and where we feel the slope is steepest.

So, make your choice and happy climbing!

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