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Commerce · IV.02 · MMXXVI · daylight

La Bourse  /  Volume IV  /  Nº IV.02  /  Workbook — the student

WORKBOOK — THE STUDENT

Chapter IV.02 · Materials and the Return Loop

For the person studying this alone, or in a seminar, with no plant, no skip and no procurement budget. You have something better for learning this than a firm does: a system small enough that you can measure all four inputs in a fortnight.

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WHY THIS WORKBOOK IS DIFFERENT

The chapter is written for someone who can commission an assay. You probably cannot. It would be easy to conclude that the arithmetic has to wait until you can.

It does not, and the reason is the most useful thing here: the four inputs to the whole chapter — ρc, Y, g, L — are properties of any system that takes material in and lets it go again. A wardrobe. A kitchen. A phone. A bicycle. A shared house. A degree's worth of notes. You can measure all four in a term, on a system you fully control, and the habit of measuring them is the transferable part. The industrial case is simply the one most people meet first.

So do what the executive does, on a system where you are also the only stakeholder — which, for the next decade, is a considerable advantage.

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PART ONE — DISCOVERY

Weeks 1–4: find what already returns

Exercise 1.1 — The five streams (90 minutes)

List everything that leaves your possession in a month and where it goes. Not categories — instances. Then mark each with one of five fates: returned to use (sold, given, repaired, handed on), materially recycled, burned, landfilled, unknown.

The "unknown" column is the finding. Most people's is over half, and it is the same discovery a firm makes on its first pass: the loop is not leaking, it is unmeasured.

Exercise 1.2 — Value density (45 minutes)

For five of those items, write the mass and an honest resale or scrap value. Compute value per kilogram. Rank them.

The chapter's Discovery movement found that every loop that closes without being forced closes because of value density — Brazil recovers close to 98 percent of its aluminium cans with no deposit law, because a can is nearly pure alloy and worth about four times per kilogram what PET is worth. Your ranking will predict, with unnerving accuracy, which of your own things you have ever bothered to sell.

Exercise 1.3 — The clean moment (30 minutes)

For each of the five, name the moment at which it is at its cleanest — the moment of arising, before it joins anything else. A single-material item in your hand is worth more than the same item in a bin bag, and everything after that moment is subtraction.

Write down what it would cost you, in seconds per week, to separate at that moment rather than later. It is usually under two minutes and it is the single highest-leverage action in this entire chapter.

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PART TWO — THE ARITHMETIC

Weeks 5–9: measure your own four inputs

Exercise 2.1 — Your mean product life, L (one evening)

Pick one category — shoes, phones, laptops, jackets, bicycles, cookware. List every instance you have owned and how long each lasted. Take the mean. That is your L, measured rather than assumed, and almost nobody has ever computed theirs.

Exercise 2.2 — Your growth rate, g (one evening)

For the same category, how many did you own five years ago, and how many now? g = (now/then)^(1/5) − 1. If you owned four jackets five years ago and six now, g = (6/4)^(1/5) − 1 = 8.45 percent.

Exercise 2.3 — Your ceiling (20 minutes, and it is the point of the term)

Assume you were a perfect recycler of this category: everything you finish with goes to someone who uses it, ρ = 1.00. Compute:

      c  =  1.00 / (1 + g)^L

With L = 4 years and g = 8.45 percent, c = 1/1.0845^4 = 0.723 — you could supply seventy-two percent of your own demand from your own returns if you were flawless. With g = 0, c = 1.00.

Write the sentence out. At my growth rate, even perfect return leaves me buying N percent new. That sentence is the chapter, and you have just derived it from your own wardrobe.

Exercise 2.4 — Your stock (30 minutes)

      K / D  =  (1 − e^(−gL)) / g

At L = 8 years and g = 0, K/D = 8.00 years of purchases held. At g = 3 percent, K/D = 7.11. At L = 12, g = 2 percent, K/D = 10.67. Count what you actually hold and divide by what you buy a year. Compare. Where the measured and computed disagree, one of your two inputs is wrong — and finding out which is the most instructive hour in this workbook.

Exercise 2.5 — The dilution problem, at human scale (30 minutes)

The blending inequality says a mixture can never be cleaner than its cleanest input. Find one place where this is true of something you do: a shared kitchen, a group project, a playlist, a reading list. Compute the dilution honestly:

      f  =  (C_actual − C_target) / (C_target − C_clean)

Then decide, as the steel industry did, whether you are going to dilute or whether you are going to aim at a looser specification. Both are respectable. Pretending there is a third option is not.

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PART THREE — DESIGN

Weeks 10–12: build one loop

Exercise 3.1 — Choose a stream and write its specification (2 hours)

One stream. Write, on one page: what it is, how much arises per month, its condition, its contaminants, who would take it, and at what quality. That page is an assay specification, and it is the document the whole industrial chapter hangs on. You have now written one.

Exercise 3.2 — Find the holder's reason (1 hour)

Who else has to act for this loop to close, and what do they get? A price, a deposit, a saved trip, a favour, a repair they wanted anyway. Write the reason in their words, not yours. The question is never "will they return it"; it is "what do they get".

Exercise 3.3 — The off-take (2 hours)

Find the person or organisation who will take the output, before you build anything. A repair café, a maker space, a charity shop with a specific need, a neighbour, a resale platform with a real bid. Get a yes with a quality condition attached. A recovery plant without an off-take is a warehouse; a student project without one is a pile in a corridor.

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PART FOUR — DESTINY

Weeks 13–15: make it survive you

A loop you maintain by attention is a chore, and chores end. The chapter names three things that make an industrial loop self-sustaining; all three translate.

It has a price, not a principle. The stream that keeps returning is the one where returning is worth more than not returning, to the person holding it. If your loop depends on your remembering, it has already failed. Put a number on it: what does each return earn or save, and for whom?

It has a standing place, not a standing intention. Industrial loops die at collection, never at sorting. The domestic equivalent is a box by a door. The single most effective intervention in every case in the Discovery movement was making the return trivial — a coin, a machine, a shop you were walking past.

It has a second person. One person maintaining a loop is a habit; two is a practice. Recruit yours by handing them the credit for the first result, which is exactly what the executive workbook advises a director to do.

Exercise 4.1 — The decay test (30 minutes). Write down what would have to happen for your loop to stop: a price fall, a moved flatmate, a closed shop, a changed timetable. For each, write the one sentence that would keep it running. If you cannot write that sentence, the loop has a date on it, and knowing the date is better than being surprised by it.

Exercise 4.2 — The drift check (15 minutes a month). Industrial loops fail silently when the reported number stops tracking the physical one — typically when new scrap gets counted as recycling and every report stays green. Set yourself one physical count a month: not what you intended to return, what actually left. The gap between intention and count is the only number in this workbook that will surprise you twice.

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SEMINAR VERSION

If you are studying this with other people

Session one — the denominator argument (90 minutes). Split the room. One half defends the Circularity Gap Report's metric as published; the other half defends the returnable-fraction version. Both sides must compute their own number from the 2005 account — 62.0 Gt processed, 37 percent to stock, 44 percent dissipated, 4.0 Gt recycled — before speaking. The discovery, every time, is that the disagreement is not about arithmetic.

Session two — the assay auction (60 minutes). Everyone brings one object. Each person writes a one-paragraph specification for what it would yield if disassembled. Then everyone bids, in play money, on everyone else's stream having read only the specification. The specifications that attract no bid are the lesson: a stream with no assay has no price, which is precisely why so much industrial material is landfilled by people who would happily have sold it.

Session three — the threshold defence (90 minutes). Assign each person one route from Brief 9 and have them argue for or against building it. The rule: no argument is admissible that does not name a yield and a threshold. This is harder than it sounds and it is the single best preparation for a real technical meeting that this chapter can give you.

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FIVE ERRORS THIS TERM WILL TEMPT YOU INTO

1. Quoting a rate without its denominator. Every recycling figure you meet this term has one, and about half of them include new scrap.
2. Conflating recoverable with recovered. "Ninety-five percent recyclable" is a chemistry claim with no rate in it at all.
3. Assuming an industry average for your own system. Three of the four inputs are measurable by you in a fortnight. Measure them.
4. Reaching for entropy. The mixing entropy of copper in steel is 0.93 kJ per kilogram, under five thousandths of one percent of primary production energy. When a separation is not done, the honest sentence is almost always no process exists, not physics forbids it.
5. Treating a fall in a ratio as a fall in performance. The world's circularity rate fell from 9.1 to 6.9 percent with about three quarters of the fall coming from the denominator.

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THE TERM PROJECT

The materials passport for one object

Choose one object you own that has at least four materials in it — a bicycle, a laptop, a kettle, a chair, a pair of boots.

Produce a six-page document.

1. The bill of materials. Every component, its material, its mass. Weigh what you can; estimate the rest and say which is which.
2. The separation map. For each component: how it is joined, what tool releases it, and how many seconds. Time yourself on three of them.
3. The assay. What each recovered fraction would assay at, and which specification it could then meet. Use the chapter's blending inequality wherever a contaminant is present.
4. The four inputs. Your measured ρc, Y, g and L for this category, with the method written down.
5. The ceiling. c = ρc·Y/(1+g)^L, computed, with a sentence saying what it means for this object.
6. The one change. The single design change — one fastener, one material substitution, one label — that would most raise the recovered value. Cost it.

The standard. Page six should be readable by the manufacturer, and should contain a number they do not have.

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SELF-ASSESSMENT

Score each honestly, 0–3. You are looking for what to do next, not a grade.

Twelve or above and you are doing what a materials analyst does. Below twelve, the fastest single improvement is almost always Exercise 2.1: measure L, because everything else in the chapter is in its exponent or beside it.

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THE WEEKLY PRACTICE

Fifteen minutes, every week of the term

Monday, five minutes — the arising log. Write down what left your possession in the last seven days and where it went. Five lines. Do not evaluate. The log is the only instrument in this workbook that cannot be reconstructed afterwards, which is why it is first and why it is short.

Wednesday, five minutes — one assay. Take one item from the log and write the sentence a buyer would need: what it is, how much of it there is, what is mixed into it, and what specification it could meet. One sentence a week is thirty assays by the end of the year, which is more than most procurement departments have ever written down.

Friday, five minutes — one number. Recompute one of your four inputs with the week's data. L moves slowly, g moves slowly, ρc and Y move every week. Watching a measured number move is a different experience from reading somebody else's, and it is the experience this whole edition is trying to give you.

At the end of the term you will have twelve weeks of arisings, thirty assays and a series for each of four inputs. That is a dataset, it is yours, and nobody else in your cohort will have one.

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WHAT TO CARRY OUT OF THIS TERM

Three sentences, and they will still be true in twenty years.

A ratio is only as good as its denominator. Seven percent circular and thirty-four percent circular describe the same world; the difference is what was counted as available.

A waste stream is an ore, and it competes at its grade. Nothing is waste because of what it is. It is waste because of what it assays at, relative to the cheapest alternative source of the same thing.

Growth is in the exponent. Recovery rates are linear and growth is exponential, which is why the most powerful thing you will ever do for circularity is make something last longer.