POWER TO


THE PEOPLE Aluminium smelting is the most energy intensive of LME metals, using between 12 and 16MWh of power per Mt, with power costs often 25%-30% of the market price.


Aluminium production has been affected by changing western power markets over the past 20 years. Power market de-regulation, higher prices and volatility, increased power consumption and growing environmental awareness in the West has resulted in the closure of many older, higher cost aluminium smelters.


During the Cold War, aluminium was a strategic metal important for military applications, with an estimated 90% of Russian production consumed by their industrial-military complex, but the collapse of the USSR released a flood of Russian metal exports. With aluminium freely available on the global market after the Cold War, the strategic need for the United States or Western Europe to have its own supply was diminished.


The 1990s-2000s saw smelter production develop in regions with cheap power, like the Middle East/ GCC (natural gas) and Iceland and Scandinavia (hydro and geo thermal). Sometimes called “solid power”, aluminium allows the export of excess power without the need of gas pipelines or expensive LNG facilities or, in the case of Iceland, being too far from Europe to export electricity.


Before looking at the creative solutions used by some smelters in Western Europe, it’s useful to understand a little about the smelting process.


ALUMINIUM SMELTING (HALL-HEROULT PROCESS): Bauxite is one of the most abundant minerals, but aluminium doesn’t exist in nature, so bauxite is refined into alumina and then smelted into aluminium, usually with the Hall-Heroult process invented in 1886.


For each Mt of aluminium, 2Mts of alumina are dissolved in Cryolite at 960C (Cryolite lowers the melting point of alumina from 2072C, reducing heat loss, power and environmental impact). The mixture is held in a big steel pot acting as a cathode, and carbon anodes are inserted into the mix with a heavy current of 60kA - 600kA at a low voltage of 3V-5V.


The pots are arranged in series (called pot-lines) in large sheds up to 1.5km long, and the cast house, extrusion and rolling mills are usually located next door to take hot metal, reducing re-heat costs.


Aside from maintenance, it’s a continuous process with the alumina topped up as molten aluminium is tapped off every 1-3 days, and relies on baseload power.


Power cuts are the biggest threat to aluminium smelters, as an interruption of 4 hours or more allows the mixture to cool and can freeze the metal in the pot.


Although power cuts are a threat, smelters realised they could increase profit by shutting down and selling their baseload power back to the grid if spot power prices were high.


10 | ADMISI - The Ghost In The Machine | September/October 2019


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