01 THE SETUP

This week, we were leafing through the November 2026 issue of Resources Policy when a title jumped out: “More than half of current copper consumption can be replaced by substitutes.”

The paper looks at global copper consumption and concludes that nearly two-thirds of it could be replaced “with little or no loss of functionality, reliability or affordability in the final product.” Mostly by aluminium substitution, with stainless steel, plastic, and optical fiber filling out the cast.

That works out to about 17.4 million tonnes of copper demand that we can apparently just substitute away.

So, is the crunch solved? Are the mines optional?

02 WHY IT MATTERS

The long-term copper bull case rests on a supply gap opening in the 2030s, with the eventual supply gap blowing out to 10 Mt by 2040, per S&P. So when a peer-reviewed study claims that two-thirds of copper demand — equivalent to 17.4 Mt — is replaceable, it’s worth paying attention to the claim.

03 THE DECODE

The paper answers one question reasonably well: can a substitute do the job?

To answer that question, the authors borrow a scale from a 2015 study. Each substitution is rated either Exemplary, Good, Adequate, or Poor according to the combined “functionality, reliability and cost” of the finished product once copper is swapped out. Good means roughly equivalent. Adequate means worse, but acceptable.

For better or worse, however, markets still need an answer to a question the authors don’t answer: will anyone pay to switch, at what price, and when?

Further, when asking some of the basic questions about “functionality, reliability and cost,” the authors leave several significant pages unturned.

With that in mind, let’s take a walk through some of the evidence. We started in the plumbing aisle.

Exhibit A: Grandpa’s ball valve

One particular claim jumped out at us immediately.

The paper notes that brass still dominates plumbing valves and fittings, even though stainless steel alternatives are, per the authors, equivalent “in terms of end-product functionality, reliability and price.”

So why does brass persist? Its dominance, they suggest, “may be explained by its long history of use.”

This particular suggestion stood out the most — try as we might, we struggled to picture a plumbing contractor ordering 4,000 valves for an apartment complex, misty-eyed, choosing brass because that’s what Grandpa used back in the day.

Further, while the paper’s bibliography runs to more than 80 entries, the paragraph asserting brass-stainless price equivalence cites none of them.

So we conducted a simple exercise. We chose one prominent plumbing valve supplier (Fergo) with a publicly accessible catalogue, we chose one nominal size (1 inch), and then found the cheapest valves available in both brass and stainless in two categories:

Cheapest 1″ general purpose ball valve:

Cheapest 1″ drinking‑water certified ball valve

Obviously, two data points from one supplier aren’t a market survey (we did survey more data points, but limited it to two for space). Still, two data points are two more than the paper offers. And they do seem to suggest there’s something more than mere nostalgia/habit driving plumbing fitting procurement decisions.

Curiously, following a simple raw material cost-based logic, stainless should be cheaper. A February 2026 PricePedia analysis found European brass bar at over €7,000/t in January vs roughly €3,600/t for stainless bar. Yet trade flows showed no obvious swing from brass fittings to stainless, despite the widening gap in raw material cost between brass and stainless. The PricePedia explanation: brass is far easier to machine.

And that’s perhaps the whole story in miniature — the cost doesn’t live in the raw material price alone. In the case of plumbing fittings, it also lives in the factory, where machining time, tool wear, cycle times, and scrap rates all factor into the equation — something a raw material-price / equivalent-final-product-level comparison never sees.

The economics were in the bibliography all along

The valve is a small case of a big gap. There are really three questions hiding inside “can copper be substituted?”:

The paper mostly addresses the first question, gestures at the second, and is more or less silent on the third.

Curiously, we didn’t need a new study to find the third. In their own literature review, the authors summarise a 1972 National Materials Advisory Board report that also found plenty of scope for substitution. That study noted that the capital expenditure involved in switching was high and significantly slowed adoption.

The authors read it, dedicated a single sentence to that switching cost observation, and then went ahead and built a strong headline claim without a switching-cost model in sight.

Heads, substitution works. Tails, the market hasn’t caught up.

In reading the paper, another pattern emerges. Wherever buyers have adopted the substitute, it’s presented as evidence substitution works. Wherever they keep buying copper, the explanation tends to be something other than a good reason. To name three:

None of these are impossible. Inertia, caution, regulatory conservatism, and less-than-rational decisions all exist. But many times, persistent copper use gets explained as something approaching an emotional hang-up before checking whether the buyer was actually being rational. Meanwhile, revealed preference gets a seat at the table only when it agrees with the thesis.

2% market share, 85% “Good”

Building wire is copper’s biggest end-use. By the paper’s own figures, aluminium accounts for about 2% of it worldwide. Meanwhile, the authors rate 85% of copper installations as “Good” for substitution — a single judgement that sees them classify a full 17 percentage points of global copper consumption as “Good” for substitution.

On cost, the paper offers one sentence: the extra cost of the alloy (aluminium cables require a creep-resistant alloy such as AA8030) and the specialized terminations required is offset by savings relative to more expensive copper wire (again, with no cost data being cited). The special connectors, we’re told, “are not expensive or elaborate devices.”

The paper holds up COPALUM connectors as its  “gold standard”, and its source is the US Consumer Product Safety Commission’s Repairing Aluminum Wiring. However, while it may be true that the devices are neither “expensive or elaborate,” the cited guide does describe COPALUM as requiring connections be made with dedicated power tools, and only by electricians specially trained by the manufacturer. Thus, while the authors may show that safe terminations may exist, they don’t properly investigate even the immediate costs pointed at in their sources —  tooling and additional training — much less other potential complications.

There’s also the number itself. Why 85%? The 15% rated Poor exists, in the authors’ words, “to make provision for the possibility” that the remedies aren’t practical somewhere. In other words, it appears to be an arbitrary magic number. There’s no breakdown by circuit size, building type, jurisdiction, labour cost or containment — a commercial feeder is not a domestic branch circuit, and a code allowance is not an installed-cost comparison.

The plug says IP68, so what’s the problem?

Solar DC cables are another prime candidate for substitution according to the authors.

The basic argument runs like this: the standards worry about water getting into outdoor connections; but panels are linked with MC4 connectors; MC4 connectors are waterproof; aluminium shows no special connection trouble in power lines; therefore, aluminium is a suitable material here.

The trouble is that a waterproof rating says nothing about what wire belongs inside the connector (remember, aluminium cables require specialized terminations). Further, the assembly instructions for Stäubli’s MC4-Evo connector, from the company behind the original MC4, specifically require tinned copper conductors. Tinned copper is usually specified for its superior corrosion resistance over bare copper; presumably, installation standards allow for eventual degradation of initial water ingress resistance in the connector.

As such, swapping in aluminium is presumably a little more complicated than a simple cable change. It means a different, separately certified connector-and-cable system. Then come the standards bodies, module makers, insurers and lenders, all of whom underwrite assets expected to run for 25 years or more.

That’s not to say that aluminium PV systems are impossible. North America’s UL 4703, for instance, does allow aluminium cable. However, the paper never shows that the existing, standardized systems could be converted at a competitive all-in cost — a waterproof plug being used with a cable type that’s not approved for said connector is not a business case.

The 29% nobody examined

In total, the paper studies nine end-uses in detail — more than we have the space to cover here — covering about 71% of copper consumption.

The remaining 28.9% (industrial heat exchangers, appliance heating and a long tail of “other”) isn’t assessed at all. It’s simply assigned the same mix of rankings as the nine that were. Here’s what that does to the headline, from the paper’s Table 5:

In other words, the remaining 29% of global copper demand was simply assumed to behave exactly like the 71% that was examined.

To be clear, none of this is hidden. However, our issue is with how much weight it carries — the abstract declares that nearly two thirds of global consumption could have been replaced by substitutes, but never mentions that more than a quarter of it is inferred from an untested assumption.

Then there’s the word “adequate.” By the paper’s own definition, adequate means the substitute-containing product is “not as good as the original.” Yet the abstract folds those 14.2 points into the two-thirds figure described as involving “little or no loss.”

If we strip both away and take only the end-uses the authors actually assessed, and only what they rated Good, what we’re left with is 35.8% of global copper consumption — a 35.8% claim that is itself far from settled given what we’ve looked at above.

The paper’s best moment comes near the end. The authors write:

“If the substitutability of copper is as high as this analysis has concluded, then what is stopping it from happening? After all, the benchmark real price of copper has been at record high levels for the best part of 20 years, suggesting that the profit incentive to shift to substitutes is high and has been for a long time.”

According to the authors, this question “is the subject of ongoing study and will be presented in a proposed follow-up paper.”

We’d keep an eye out for that follow-up paper before taking the headline substitutability numbers at face value.

/ Chile Slashes Copper Production Outlook as Mine Problems Mount.

Chile’s Cochilco cut its 2026 copper production forecast by 330,000 tonnes to 4.94 Mt while lowering its 2027 estimate from 5.55 Mt to 5.08 Mt. Escondida, Spence and Codelco account for more than 77% of this year’s net decline.

/ Copper Concentrate Pricing Slips Into the Shadows.

Spot treatment charges have reportedly fallen as low as minus $370/t. However, increasingly complex contracts make headline charges less representative of smelter economics as by-product credits, impurity penalties and other negotiated terms become more important.

/ Mongolian Copper Exports Plunge 70% Amid Chinese Border Restrictions.

Copper concentrate shipments from Rio Tinto’s Oyu Tolgoi mine to China have fallen approximately 70% over two weeks as border upgrades restrict truck movements. Daily convoys have declined from 12-13 to around four.

/ Copper’s AI-Fuelled Boom Gets a Reality Check.

The Financial Times reports growing scepticism over how much of copper’s rally is justified by AI-related demand, with data centres expected to account for roughly 350,000 tonnes of additional demand this year against a global market of approximately 28 million tonnes.

/ Rio Tinto Explores Further Investment in Argentina’s Mining Sector.

Rio Tinto is evaluating further investment opportunities in Argentina, including potential copper developments. The company already has a $4.4 billion investment pipeline in the country, where the government is seeking to accelerate major resource projects through investment incentives.

That’s the wire for today. Until next time, keep Grandpa out of the procurement department.

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