Originally a twitter thread, 26 August, 2021; commentary on cotton shopping bags
Hey, let’s talk about a couple of terms that are going around: “cradle to gate cost” and “end of life cost”. (Also sometimes “cradle to grave cost”). Cradle to gate measures what an item costs to manufacture, ship and get through the point of sale. Tracking stops after sale.
It’s a really useful metric for manufacturers, and for disposable, single use items, because single use items may see a small amount of travel before they’re used and discarded, but it’s a very minor addition to the cost of the item.
And it can be used to estimate the carbon footprint, the water footprint, and the landfill footprint. What it DOESN’T cover is the cost of disposal, because that is totally externalized for 95% of consumer products. Nor does it account for the return of recycled components.
A good example of a cradle to gate cost is $3.15 for a gallon of gasoline (or whatever your local price/volume is), because nobody in the supply chain is going to clean up the waste products (CO2, CO, particulates, ozone, nitrates, etc) after the gallon is burned.
And with gas, nothing gets recycled (unlike, say, crop water.) Cradle to gate is 100% a metric that depends on externalization. And it’s most useful for anything that is only used once.
But most consumer goods are not single use. They’re durable. If a teeshirt has a cradle to gate cost of $10, its end of life cost is also $10 if, the first time you wear it, you get hit with a bottle of indelible ink or a tear gas grenade. Then there’s no point keeping it.
But if you wear that teeshirt once a week for a year, its end of life cost is ALSO around $10 (plus maybe $2 in detergent, water & energy to clean it 52 times.) HOWEVER: its cost per use? 23 cents. If you turn it into a shopping bag after the neck wears out? There’s another year, down to 12 cents. And if, in the end, you turn it into a wicking pot liner and grow basil in it until it decomposes, your cost of disposal is zero.
If you have to throw it out after tear gas? You’re likely paying $1-2 for a bag of garbage, so add 50 cents to cradle to gate/cost to use.
Once the shirt is manufactured, it adds only very small amounts to its carbon footprint — a little for the energy to wash it, for the energy to clean the water before and after use, a little for the detergent — but those are negligible compared to manufacture.
That’s why the cradle to gate metric is only useful as a start point for durable goods. The cost per use is the more useful metric of comparison between durable goods and disposable. A demonstration:
A stack of good paper plates — which will compost, so minimal cost of disposal — runs $18 for 165. That’s 55 days. If a person was to eat only off of paper plates for a year, they’d need 7 stacks, so $126 as their cradle to gate cost, with almost no disposal cost. So each plate costs about 11 cents.
You can get a single stoneware plate at Target for $3. You’d need to eat off of it 28 times for its cost per use to be 11 cents. You’ll also need to pay for 1000 gallons of water (the minimum municipal charge) and a bottle of soap (which, if used correctly, will last you a year.)
That adds about $1.50 for the water and $2 for the soap. Energy cost? A couple kilowatt hours a month for the dishes part of the water heater? MAYBE 25 cents. So yes, you have to use the stoneware plate for a whole month for it to be the same price as a paper plate. But the stoneware plate will last a lot longer than the 55 days for the $18 stack of paper plates, eventually reducing its cost per use to the daily cost to clean it. Fractions of a cent.
You can apply this across the board.
Things get weird when there’s a production externalization, and how it’s accounted. Agriculture is the big one here. About half of the the water that goes on a bed of lettuce ends up in your mouth because plants retain water in their cells, not because they change water into something else.
So when you pee after eating that lettuce, that water goes into your sewer system and returns to the water cycle. Someone downhill will get to shower, flush, or drink it after a trip through your town’s waste water processing plant, and the next town’s water treatment plant.
The rest of the water that was poured on that bed of lettuce either evaporated, was transpired (breathed) by the plant, or trickled down into the aquifer. The evaporated/transpired water will end up falling as rain somewhere else; a well taps the aquifer.
So… when people say it takes 1000 gallons of water to produce an almond, that’s not true in multiple ways; that’s a measure of how many gallons the almond orchard used divided by their production. (But also is simply bad math.)
What you’re not seeing in that number is
- the carbon draw down living trees provide
- the oxygen production
- both local and planetary cooling
- the recharge of the aquifer which prevents salt intrusion (there’s a layer of salt under the ground; you want water to push it down, not draw it up)
- and food.
An almond tree, a peach tree, an apricot tree, an olive tree? They all use about the same amount of water. According to Cal Davis, these arid climate food trees each need about 1700 gallons per tree, per year. (Also front yard trees, park trees, street divider trees… every tree needs water.)
And since an olive tree produces about 38 pounds of olives a year, which makes about 4.5 pounds of oil, you could say that every gallon of olive oil contains 1700 gallons of water. (See how the almond math is bad? The production of every almond TREE is closer to 1000 gallons of water a year.)
But we can’t just drink that 1700 gallons of water per year and live. We’d die. We cannot live on water or petroleum alone. We must grow plants. We depend on photosynthesis. And plants don’t return to us gallon per gallon of water, but this planet is a closed system. We get it all back eventually.
I note here: almonds & olives in North America will not grow anywhere except California, Arizona, parts of New Mexico and Mexico. They cannot tolerate hard freezes, they won’t produce well in humid climates. If we have learned nothing from the last year: a global supply chain is fragile. Local production is better.
Nor can we just grow the most water thrifty plants — grasses — and survive on those.
Well, we could. Vegans would be mad.
We have to feed grasses to grazers, and then eat the grazers.
Which have been eating the grass full of water, and drinking their own water…
So, see the problem with the weird water externalization?
It means a straight “gallons per thingie” is a terrible measure of what we’re doing with our resources.
Of the plants we spend a lot of water on, cotton is actually an outlier — most of our watered crops are food, so it only really gets used once. (At least the goal is to only use it once.) And we benefit from the water by consuming it, then sweating/peeing it out.
But cotton makes both disposable and durable goods; more durable goods than disposable. Which is why all of this math gets REALLY complex, because we’ve got stuff that’s suited for cradle to gate, and stuff that totally ISN’T.
The cotton plant to make a cotton tote bag may have had 250 gallons of water poured on it during their growth, but very little of that water ended up in the white fluff that becomes cotton yarn & fabric. You know how a wet cotton ball is kinda useless? Also impossible to harvest.
And of that 250 gallons, some was evaporated/transpired and rained downwind; some was used for carbon uptake to make leaves, stems, seeds & fiber; some trickled downwards to keep the salt down and recharge the aquifer.
All of this is valuable and good use of our resources. Our plant textile resources (linen, cotton) are the lowest on the planetary damage scale. Then rayons (here’s where hemp comes in, as well as bamboo, beech, eucalyptus) and ramie; then wool — sheep are really efficient, and wool is durable.
aside: Isn’t hemp a weed?
Yeah, that’s the problem. It’s itchy AF in the raw state. You can ret it (rot it in water ponds) like linen to improve it, but if you want to ret it, you better water it while it’s growing (~250 gal/plant/season) because it’s gonna need very long, high quality fiber. Which water stressed plants don’t make.
Or you can water stress it and just turn it into rayon, which moves the water to production instead of the field (and dramatically increases the water needed).
The best use of hemp (and junk forest plants) is cellulose feedstock for paper, and let the trees grow for actual wood. Sorry.
What’s NOT sustainable is synthetics of any sort. Drilling for oil produces thousands of gallons of badly polluted, fossil water that is almost impossible to reclaim. (Fossil water is the stuff below the aquifer, that we never should have had access to.)
Then refining the oil takes even more water that is also hard to reclaim.
The water debt for a pound of cotton is water that cycles within the usual plant water cycle, but the water debt for a pound of polyester is orders of magnitude larger and once it’s polluted, it’s gone.
Recycling plastics into fiber helps some, but
a) we don’t do enough of it
b) when it is recycled, it sheds microplastics worse than virgin stock, and
c) still requires a percentage of virgin stock to make a functional polyester for spinning.
And once we have that plastic/polyester fabric, it’s ours forever. It doesn’t compost, it doesn’t decompose, at best it grinds itself up into microplastics. In theory it can be converted back into an petroleum product that can be burned, but that’s really not a good plan.
Plants are better than plastics, always.
Plants need water. There’s no getting around this.
So… the big issue is not that plants exist and need water. It’s that human consumption cannot infinitely expand. Doesn’t matter what the economists say — we need the production of goods to contract.
We simply make more stuff than we need. Contracting production doesn’t mean the economy contracts. The wages & services side is where the real economic magic happens.
And I mean magic — it’s a spell we all agree exists, and only exists because we all believe in it.
Politics – textiles – media