Aluminum smelting turns electricity into metal through a continuous electrolytic process. Unlike factories that can shut down machinery between orders, primary smelters need sustained power to keep their reduction cells operating. A sharp rise in electricity prices can therefore threaten both current margins and the physical condition of the production line.
For commodities trading, the important distinction is between a temporary increase in power bills and a cost shock severe enough to remove aluminum capacity from the market. Five operational risks determine whether an expensive megawatt-hour translates into lower metal output.
1. Electricity Costs Can Overtake the Metal’s Selling Price
Primary aluminum production commonly requires roughly 13 to 15 megawatt-hours of electricity per tonne, depending on technology and operating conditions. At that intensity, even a modest change in contracted power prices alters unit economics substantially.
Take a hypothetical smelter consuming 14 MWh per tonne and selling aluminum at $2,300 per tonne. At $45 per MWh, electricity costs $630 per tonne. If its power price rises to $105, the bill becomes $1,470, an $840 increase. Assume alumina, labor, carbon materials and other operating costs total $1,050 per tonne. The operation moves from a $620 contribution before other expenses to a $220 shortfall. A steady aluminum price on the exchange conceals the plant’s abrupt loss of competitiveness.
2. Potlines Cannot Be Switched Off Like Ordinary Machinery
Molten electrolyte must remain hot enough for electrolysis. Cutting power for too long risks freezing material inside reduction cells, damaging equipment and creating a lengthy restart process. Operators may tolerate negative operating margins temporarily rather than incur the much larger cost of shutting down and rebuilding potlines.
That persistence creates a delayed supply response. An electricity spike does not guarantee an immediate fall in aluminum production, even when published cost estimates show plants operating below break-even. The duration of the power shock and the technical condition of each potline determine when curtailment becomes rational.
3. Power Contracts Can Separate Neighbors Into Winners and Losers
Two smelters in the same region may face entirely different electricity economics. One could hold a long-term fixed-price agreement or operate captive generation; another might purchase a substantial share of its power at wholesale market prices. Contract expiry, indexation clauses and grid charges can matter more than the regional spot quotation.
For a credible supply forecast, examine how much capacity is actually exposed to repricing. Treating every plant as though it pays the latest spot rate exaggerates the number likely to close and understates the resilience of facilities with protected tariffs.
4. Curtailments Can Tighten Supply While Raising Regional Premiums
When several smelters reduce output, the effect on buyers depends on where the missing metal would have been delivered. Regional shortages can increase physical premiums over exchange benchmarks, particularly when freight costs or import constraints limit replacement supply.
A higher premium can coexist with an unchanged or falling global benchmark. That divergence matters in commodities trading because a CFD tracking an exchange-linked aluminum price may not capture the local premium paid by manufacturers. The commercial consequences of an electricity shock and the payoff of a particular derivative are not necessarily identical.
Restart Economics Can Keep Capacity Offline After Power Prices Fall
Lower electricity prices do not automatically restore idled production. Restarting can require replacement cell components, labor, financing and confidence that affordable power will remain available. A smelter may also face higher environmental compliance costs or renegotiated supply contracts before restarting.
Before opening an aluminum CFD position, identify the affected smelters’ power exposure, estimated production costs, announced curtailment volumes and realistic restart timelines. Then check whether the CFD references a cash benchmark or a futures contract, and calculate the position’s sensitivity to a specified price move rather than assuming every regional shutdown produces an equivalent rise in its quoted price.